As filed with the Securities and Exchange Commission on May 23, 2022.

Registration No. 333-264222

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Amendment No. 1 to

FORM S-4

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

BROOKLINE CAPITAL ACQUISITION CORP.

(Exact name of registrant as specified in its charter)

Delaware	6770	85-1260244
(State or other jurisdiction of incorporation or organization)	(Primary Standard Industrial Classification Code Number) 280 Park Avenue, Suite 43W, New York, NY 10017 Telephone: (646) 603-6716	(I.R.S. Employer Identification Number)

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Samuel P. Wertheimer

Chief Executive Officer

280 Park Avenue

Suite 43W

New York, NY 10017

Telephone: (646) 643-6716

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Jeffrey C. Selman Carole H. Bellis Alan D. Seem DLA Piper LLP (US) 2000 University Avenue East Palo Alto, California 94303 Tel: (650) 833-2000 James L. Kelly Peter J. Ekberg DLA Piper LLP (US) 1251 Avenue of the Americas New York, New York 10020 Tel: (212) 335-4500 Kenneth A. Clark Michael E. Coke Lance E. Brady Wilson Sonsini Goodrich & Rosati, P.C. 650 Page Mill Road Palo Alto, CA 94304 Tel: (650) 493-9300 Robert T. Ishii Wilson Sonsini Goodrich & Rosati, P.C. One Market Plaza Spear Tower, Suite 3300 San Francisco, CA 94105 Tel: (415) 947-2000

Approximate date of commencement of proposed sale of the securities to the public: As soon as practicable after this registration statement becomes effective and upon completion of the merger.

If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box:  ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or emerging growth company. See the definitions of “large accelerated filer”, “accelerated filer”, “smaller reporting company”, and “emerging growth company” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☒
		Emerging growth company	☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction: Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)  ☐

Exchange Act Rule 14d-1(d) (Cross-Border Third-Party Tender Offer)  ☐

The Registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, or until this registration statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

The information in this preliminary proxy statement/prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary proxy statement/prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED MAY 23, 2022

BROOKLINE CAPITAL ACQUISITION CORP.

280 Park Avenue, Suite 43W, New York, NY 10017

PRELIMINARY PROXY STATEMENT FOR 2022 ANNUAL MEETING OF STOCKHOLDERS

PROSPECTUS FOR 16,434,875 SHARES OF COMMON STOCK OF BROOKLINE CAPITAL ACQUISITION CORP.

On March 17, 2022, Brookline Capital Acquisition Corp., a Delaware corporation (“BCAC”), and Project Barolo Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of BCAC (“Merger Sub”), entered into a Business Combination Agreement (as it may be amended, supplemented or otherwise modified from time to time in accordance with its terms, the “Business Combination Agreement”) with Apexigen, Inc., a Delaware corporation (“Apexigen”), pursuant to which Merger Sub will merge with and into Apexigen, with Apexigen surviving the merger as a wholly owned subsidiary of BCAC (the “Merger” and, together with the other transactions contemplated by the Business Combination Agreement and any other agreement executed and delivered in connection therewith, the “Business Combination”). Following the closing of the Merger (the “Closing”), BCAC will be referred to as the “Combined Company.”

Subject to the terms of the Business Combination Agreement, the aggregate closing merger consideration with respect to all holders of Apexigen securities outstanding immediately prior to the Closing, to be issued in the form of shares or equity awards relating to shares of common stock, par value $0.0001 per share, of BCAC (the “BCAC Common Stock”), will be that number of shares of BCAC Common Stock equal to the quotient of (a) the sum of (i) $205,000,000, and (ii) the sum of the exercise prices of all options to purchase shares of common stock of Apexigen outstanding immediately prior to the effective time of the Merger (the “Effective Time”), divided by (b) $10.00 (the “Aggregate Closing Merger Consideration”).

At the Effective Time of the Business Combination, among other things, each share of capital stock of Apexigen (including shares of capital stock resulting from the conversion or exercise of shares of preferred stock of Apexigen (“Apexigen Preferred Stock”), warrants to purchase shares of common stock or preferred stock of Apexigen (“Apexigen Warrants”) and options to purchase shares of common stock of Apexigen (“Apexigen Options”), but excluding any dissenting shares), will be canceled and converted into the right to receive a number of shares of BCAC Common Stock equal to the Exchange Ratio (as defined in the Business Combination Agreement).

The BCAC public units (“BCAC units”), each comprised of one share of BCAC Common Stock (the “Public Shares”) and one-half of one BCAC warrant (the “Public Warrants”) to purchase shares of BCAC Common Stock, are currently listed on Nasdaq under the symbols “BCACU,” “BCAC” and “BCACW,” respectively. We intend to apply to continue the listing of the common stock of the Combined Company and the warrants of the Combined Company on Nasdaq under the symbols “APGN” and “APGNW,” respectively, upon the Closing.

In connection with the execution of the Business Combination Agreement, BCAC entered into subscription agreements with certain investors and may enter into additional subscription agreements with other investors prior to the Closing (such investors, the “PIPE Investors”) for the subscription and purchase of additional units consisting of one share of BCAC Common Stock and one-half of one warrant, with each whole warrant entitling the PIPE Investors to purchase one share of BCAC Common Stock. None of BCAC’s sponsor, directors, officers or their affiliates will be PIPE Investors. Assuming that no BCAC public stockholders exercise their redemption rights with respect to the Public Shares, the ownership of the Combined Company after the Business Combination is expected to be as follows: former Apexigen equityholders, 68.2%; BCAC public stockholders, 19.1%; Brookline Capital Holdings, LLC, as BCAC’s sponsor, together with the BCAC IPO underwriter and certain of its employees (“Sponsor and Representative”), 6.4%; PIPE Investors, 5.7%; and Lincoln Park Capital Fund, LLC (“Lincoln Park”), 0.6%. Assuming that the BCAC public stockholders fully exercise their redemption rights with respect to all of the Public Shares they hold, the ownership of the Combined Company after the Business Combination is expected to be as follows: former Apexigen equityholders, 86.3%; PIPE Investors, 7.2%; Sponsor and Representative, 5.8%; and Lincoln Park, 0.7%.

We are providing the accompanying proxy statement/prospectus and accompanying proxy card to our stockholders in connection with the solicitation of proxies to be voted at the 2022 annual meeting of the stockholders (the “Stockholders’ Meeting”), including following any adjournments or postponements of the Stockholders’ Meeting. Information about the Stockholders’ Meeting, the Business Combination and other related business to be considered by our stockholders at the Stockholders’ Meeting is included in this proxy statement/prospectus. Whether or not you plan to attend, we urge all you to read this proxy statement/prospectus, itn its entirety. In particular, we urge you to read carefully the section entitled “Risk Factors” beginning on page 50 of the attached proxy statement/prospectus.

BCAC’s board of directors (the “BCAC Board”) has unanimously approved the Business Combination Agreement and the transactions contemplated thereby and recommends that BCAC’s stockholders vote “FOR” the adoption and approval of the Business Combination Agreement and the other matters to be considered at the Stockholders’ Meeting.

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES REGULATORY AGENCY HAS APPROVED OR DISAPPROVED THE TRANSACTIONS DESCRIBED IN THIS PROXY STATEMENT/PROSPECTUS, PASSED UPON THE MERITS OR FAIRNESS OF THE BUSINESS COMBINATION OR RELATED TRANSACTIONS OR PASSED UPON THE ADEQUACY OR ACCURACY OF THE DISCLOSURE IN THIS PROXY STATEMENT/PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY CONSTITUTES A CRIMINAL OFFENSE.

This proxy statement/prospectus is dated [●], 2022, and is expected to be first mailed or otherwise delivered to BCAC stockholders on or about [●], 2022.

BROOKLINE CAPITAL ACQUISITION CORP.

280 Park Avenue, Suite 43W, New York, NY 10017

Dear Stockholder:

On March 17, 2022, Brookline Capital Acquisition Corp., a Delaware corporation (“BCAC”), and Project Barolo Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of BCAC (“Merger Sub”), entered into a Business Combination Agreement (as it may be amended, supplemented or otherwise modified from time to time in accordance with its terms, the “Business Combination Agreement”) with Apexigen, Inc., a Delaware corporation (“Apexigen”), pursuant to which Merger Sub will merge with and into Apexigen, with Apexigen surviving the merger as a wholly owned subsidiary of BCAC (the “Merger” and, together with the other transactions contemplated by the Business Combination Agreement and any other agreement executed and delivered in connection therewith, the “Business Combination”). Following the closing of the Merger (the “Closing”), BCAC will be referred to as the “Combined Company.”

Subject to the terms of the Business Combination Agreement, the aggregate closing merger consideration with respect to all holders of Apexigen securities outstanding immediately prior to the Closing, which will be issued in the form of shares or equity awards relating to shares of common stock, par value $0.0001 per share, of BCAC (the “BCAC Common Stock”), will be that number of shares of BCAC Common Stock equal to the quotient of (a) the sum of (i) $205,000,000, and (ii) the sum of the exercise prices of all options to purchase shares of common stock of Apexigen outstanding immediately prior to the effective time of the Merger (the “Effective Time”), divided by (b) $10.00 (the “Aggregate Closing Merger Consideration”).

At the Effective Time of the Business Combination:

• each issued and outstanding share of capital stock of Apexigen (including shares of capital stock that are issued and outstanding immediately prior to the Effective Time resulting from the conversion or exercise of shares of preferred stock of Apexigen (“Apexigen Preferred Stock”), warrants to purchase shares of common stock or preferred stock of Apexigen (“Apexigen Warrants”) and options to purchase shares of common stock of Apexigen (“Apexigen Options”), but excluding any dissenting shares), will be canceled and converted into the right to receive a number of shares of BCAC Common Stock equal to the Exchange Ratio (as defined below);

• each share of capital stock of Apexigen held in the treasury of Apexigen shall be canceled without any conversion thereof and no payment or distribution shall be made with respect thereto;

• each Apexigen Option that is outstanding immediately prior to the Effective Time, whether vested or unvested, will be assumed by BCAC and converted into an option to purchase shares of BCAC Common Stock (a “BCAC Option”) on substantially the same vesting and exercisability terms and conditions as such Apexigen Options, except that (i) such BCAC Option will represent the right to purchase a number of shares of BCAC Common Stock equal to the product (rounded down to the nearest whole share) of the number of shares of Apexigen Common Stock subject to such Apexigen Option multiplied by the Exchange Ratio, and (ii) the exercise price per share for each such BCAC Option will be equal to the quotient of (A) the exercise price per share of such Apexigen Option in effect immediately prior to the Effective Time, divided by (B) the Exchange Ratio (the exercise price per share, as so determined, being rounded up to the nearest full cent); and

• each Apexigen Warrant that is issued and outstanding immediately prior to the Effective Time will be treated in accordance with the terms thereof, as may be amended prior to the Effective Time by Apexigen and the holder thereof with the consent of BCAC.

The Aggregate Closing Merger Consideration will be issued to holders of Apexigen securities at the Closing in accordance with the Business Combination Agreement. The portion of the Aggregate Closing Merger Consideration issuable to any person by virtue of the Merger will be calculated on an aggregate basis with respect to all shares of capital stock of Apexigen held of record by such person immediately prior to the Effective Time, and after such aggregation, any fractional share of BCAC Common Stock that would otherwise be issuable to such person following such aggregation will be rounded up to a whole share of BCAC Common Stock.

The “Exchange Ratio” is equal to the quotient of (i) the Aggregate Closing Merger Consideration, divided by (ii) the aggregate number of shares of Apexigen capital stock that are issued and outstanding immediately prior to the Effective Time, calculated on a fully diluted basis, including (without duplication) shares of Apexigen Common Stock that are issued and outstanding immediately prior to the Effective Time (including shares issued upon the exercise or conversion of Apexigen Options and Apexigen Warrants in each case prior to the Effective Time that are issued and outstanding immediately prior to the Effective Time), shares of common stock issuable upon the conversion of all issued and outstanding shares of Apexigen Preferred Stock immediately prior to the Effective Time, and shares of Apexigen Common Stock that are issued or issuable upon the full exercise or conversion of all Apexigen Options and Apexigen Warrants outstanding as of the Effective Time.

Brookline Capital Holdings, LLC (the “Sponsor”) has agreed to vote its shares of BCAC Common Stock, issued to it prior to BCAC’s initial public offering (the “BCAC IPO”, and such shares, the “Sponsor Shares”), as well as the shares of common stock that are a part of units purchased in a private placement simultaneous to the BCAC IPO, and any Public Shares (as defined below) purchased during or after the BCAC IPO, in favor of the Business Combination.

In connection with the execution of the Business Combination Agreement, BCAC entered into subscription agreements with certain investors and may enter into additional subscription agreements with other investors prior to the Closing (collectively, the “Subscription Agreements” and such investors, the “PIPE Investors”), pursuant to which the PIPE Investors, contingent upon the consummation of the Business Combination, agreed to subscribe for and purchase, and BCAC agreed to issue and sell to the PIPE Investors, an aggregate of 1,502,000 units (each a “PIPE Unit”) at a purchase price of $10.00 per unit for an aggregate purchase price of $15,020,000 (the “PIPE Investment”). Each PIPE Unit consists of one share of BCAC Common Stock and one-half of one warrant. Each whole warrant entitles the PIPE Investor to purchase one share of BCAC Common Stock (a “BCAC Warrant”) at an exercise price of $11.50 per share during the period commencing 30 days after the Closing and terminating on the five-year anniversary of the Closing.

As of [●], 2022, the closing price on Nasdaq of the BCAC units was $[●] per unit and the closing price of the Common Stock was $[●] per share.

Concurrently with the execution of the Business Combination Agreement, BCAC, Apexigen, and Lincoln Park Capital Fund, LLC (“Lincoln Park”) entered into (a) a Purchase Agreement (the “Lincoln Park Purchase Agreement”), pursuant to which the Combined Company will have the right to direct Lincoln Park to purchase from the Combined Company up to an aggregate amount of $50,000,000 of the Combined Company common stock from time to time over a 24-month period following the Closing, subject to certain limitations contained in the Lincoln Park Purchase Agreement, and (b) a Registration Rights Agreement, providing for the registration of the shares of BCAC Common Stock issuable in respect of the Lincoln Park Purchase Agreement. On the date of Closing, BCAC will issue to Lincoln Park 150,000 shares of BCAC Common Stock. Additionally, the Combined Company will issue to Lincoln Park $1,500,000 of Combined Company common stock on the date that is 90 calendar days after the date of Closing at the purchase price equal to the arithmetic average of the last closing sale price for Combined Company common stock during the 10 consecutive business days ending on the business day immediately preceding the delivery of such shares, provided, that in no event shall the amount of such shares exceed 500,000.

In the event that the cash proceeds from (i) the PIPE Investment, as actually received by BCAC prior to or substantially concurrently with the Closing from investors to the Trust Account or that were first introduced by BCAC or its representatives or (ii) as a result of public stockholders not redeeming shares reflecting cash that is currently maintained in the Trust Account (as defined below) (the “BCAC Related Funds Amount”) at Closing that are available to the Combined Company are less than $20,000,000, then that number of Sponsor Shares equal to (x) one minus the quotient of the BCAC Related Funds Amount divided by $20,000,000, multiplied by (y) 1/3 of the total number of Sponsor Shares, shall be deemed automatically forfeited and cancelled without any further actions by the Sponsor or any other person, and such surrendered shares will be recorded as cancelled by the Combined Company.

At the 2022 annual meeting of the stockholders of BCAC (the “Stockholders’ Meeting”), the BCAC stockholders will vote on a proposal to approve the Business Combination Agreement (the “Business Combination Proposal”) and other proposals described in the accompanying proxy statement/prospectus, which each stockholder is encouraged to carefully read and consider.

Our public units (“BCAC units”), each comprised of one share of BCAC Common Stock (the “Public Shares”) and one-half of one BCAC Warrant (the “Public Warrants”) to purchase shares of BCAC Common Stock, are currently listed on Nasdaq under the symbols “BCACU,” “BCAC” and “BCACW,” respectively. We intend to apply to continue the listing of the common stock of the Combined Company and the warrants of the Combined Company on Nasdaq under the symbols “APGN” and “APGNW,” respectively, upon the Closing.

Pursuant to the Amended and Restated Certificate of Incorporation of BCAC, dated as of January 28, 2021 and as amended on April 26, 2022 (the “Existing Charter”), we are providing our public stockholders with the opportunity to redeem (the “Redemption Rights”), upon the Closing, shares of BCAC Common Stock then held by them for cash equal to their pro rata share of the aggregate amount on deposit in the trust account (the “Trust Account”), calculated as of two business days prior to the consummation of the Merger (including interest earned on the funds held in the Trust Account and not previously released to BCAC to pay its taxes). For illustrative purposes, based on the balance of the Trust Account of $[●] as of [●], 2022, the estimated per share redemption price would have been approximately $[●]. Public stockholders may elect to redeem their shares even if they vote for the Business Combination Proposal. A holder of shares of BCAC Common Stock, together with any affiliate of the holder or any other person with whom the holder is acting in concert or as a “group” (as defined in Section 13(d)(3) of the Securities Exchange Act of 1934, as amended), will be restricted from seeking Redemption Rights with respect to more than 15% of the aggregate number of shares of BCAC Common Stock outstanding without the consent of BCAC. Accordingly, all shares of BCAC Common Stock in excess of 15% held by a holder of shares of BCAC Common Stock, together with any affiliate of such holder or any other person with whom such holder is acting in concert or as a “group,” will not be redeemed for cash without the consent of BCAC. We have no specified maximum redemption threshold under our Existing Charter, other than the aforementioned 15% threshold. Each redemption of shares of BCAC Common Stock by our Public Stockholders will reduce the amount in the Trust Account.

After giving effect to the Business Combination (assuming no Public Shares of BCAC have been redeemed and no BCAC Warrants have been exercised), we expect that there will be approximately 26,502,166 shares of Combined Company common stock consisting of (i) 18,104,074 shares issued to holders of Apexigen securities (after giving effect to the net exercise or conversion of outstanding equity awards of Apexigen and Apexigen Warrants) (ii) 1,502,000 shares held by the PIPE Investors pursuant to the Subscription Agreements, (iii) 150,000 shares held by Lincoln Park pursuant to the Purchase Agreement, (iv) 5,061,592 shares held by BCAC’s Public Stockholders, (v) 57,500 shares held by the BCAC IPO underwriter and certain of its employees, and (vi) 1,627,000 shares held by the Sponsor.

Pursuant to the terms of the Existing Charter, in no event will we redeem shares of BCAC Common Stock in an amount that would result in our failure to have net tangible assets of at least $5,000,001 after giving effect to the redemptions of shares of BCAC Common Stock by the public stockholders, including as of the time either immediately prior to or upon the Closing.

We are providing the accompanying proxy statement/prospectus and accompanying proxy card to our stockholders in connection with the solicitation of proxies to be voted at the Stockholders’ Meeting (including following any adjournments or postponements of the Stockholders’ Meeting). Information about the Stockholders’ Meeting, the Business Combination and other related business to be considered by our stockholders at the Stockholders’ Meeting is included in this proxy statement/prospectus. Whether or not you plan to attend the Stockholders’ Meeting via the virtual meeting platform, we urge all our stockholders to read this proxy statement/prospectus, including the annexes and the accompanying financial statements of BCAC and Apexigen, carefully and in their entirety. In particular, we urge you to read carefully the section entitled “Risk Factors” beginning on page 50 of the attached proxy statement/prospectus.

After careful consideration, BCAC’s board of directors (the “BCAC Board”) has determined that the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the ESPP Proposal and the Adjournment Proposal (each as defined in the accompanying proxy statement/prospectus) are fair to and in the best interests of BCAC and its stockholders and unanimously recommends that you vote or give instruction to vote “FOR” the Business Combination Proposal, “FOR” the Charter Proposals, “FOR” the Director Election Proposal, “FOR” the Nasdaq Proposal, “FOR” the Equity Incentive Plan Proposal, “FOR” the ESPP Proposal and “FOR” the Adjournment Proposal, if presented at the Stockholders’ Meeting.

The approval of each of the Business Combination Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the ESPP Proposal and the Adjournment Proposal, if presented, requires the affirmative vote (in person or by proxy) of the holders of a majority of the shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting, voting as a single class. In addition, in accordance with the Business Combination Agreement, the parties to the Business Combination Agreement are also requiring the affirmative vote of holders of a majority of the shares of BCAC Common Stock then outstanding, voting together as a single class, for the approval of the Charter Proposals. The approval of the Director Election Proposal requires the affirmative vote (in person or by proxy) of the holders of a plurality of the outstanding shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting.

As of [●], 2022, the record date for the Stockholders’ Meeting (the “Record Date”), the Sponsor was entitled to vote an aggregate of 1,627,000 shares of BCAC Common Stock. Such shares currently constitute approximately 24.1% of the outstanding shares of BCAC Common Stock. The Sponsor has agreed to vote its shares of BCAC Common Stock in favor of each of the proposals presented at the Stockholders’ Meeting. The Sponsor, BCAC’s independent directors and certain of the Supporting Apexigen Stockholders (as defined in the accompanying proxy statement/prospectus) and other stockholders of Apexigen have, subject to limited exceptions, agreed to a lock-up following the Closing on their respective shares of Combined Company common stock which they already hold or will receive, pursuant to which such parties will not transfer shares of Combined Company common stock held by such parties for 180 days following the Closing subject to certain exceptions. The Sponsor has also agreed to a lock-up on the shares of stock that are a constituent part of its private placement units, pursuant to which the Sponsor will not transfer such shares of stock for 180 days following the Closing subject to certain exceptions.

Your vote is very important. Whether or not you plan to attend the Stockholders’ Meeting, please vote as soon as possible by following the instructions in this proxy statement/prospectus to make sure that your shares are represented at the Stockholders’ Meeting. If you hold your shares in “street name” through a bank, broker or other nominee, you will need to follow the instructions provided to you by your bank, broker or other nominee to ensure that your shares are represented and voted at the Stockholders’ Meeting. Unless waived by the parties to the Business Combination Agreement, consummation of the Business Combination is conditioned on the approval of the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal and the ESPP Proposal at the Stockholders’ Meeting, subject to the terms of the Business Combination Agreement. If the Business Combination Proposal is not approved, the other proposals (except the Adjournment Proposal) will not be presented to the stockholders for a vote. If we fail to obtain the requisite stockholder approval for any of the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal and the ESPP Proposal at the Stockholders’ Meeting, we will not satisfy the conditions to Closing set forth in the Business Combination Agreement and we may be prevented from closing the Business Combination. The Business Combination is not conditioned on approval of the Adjournment Proposal.

If you sign, date, and return your proxy card without indicating how you wish to vote, your proxy will be voted “FOR” each of the Proposals presented at the Stockholders’ Meeting. If you fail to return your proxy card or fail to instruct your bank, broker or other nominee how to vote, and do not attend the Stockholders’ Meeting in person via the virtual meeting platform, the effect will be that your shares will not be counted for purposes of determining whether a quorum is present at the Stockholders’ Meeting. If you are a stockholder of record and you attend the Stockholders’ Meeting and wish to vote in person via the virtual meeting platform, you may withdraw your proxy and vote in person via the virtual meeting platform.

TO EXERCISE YOUR REDEMPTION RIGHTS, YOU MUST DEMAND THAT BCAC REDEEM YOUR SHARES FOR A PRO RATA PORTION OF THE FUNDS HELD IN THE TRUST ACCOUNT AND TENDER YOUR SHARES TO BCAC’S TRANSFER AGENT AT LEAST TWO BUSINESS DAYS PRIOR TO THE VOTE AT THE STOCKHOLDERS’ MEETING. YOU MAY TENDER YOUR SHARES BY EITHER DELIVERING YOUR SHARE CERTIFICATE TO THE TRANSFER AGENT OR BY DELIVERING YOUR SHARES ELECTRONICALLY USING THE CONTINENTAL STOCK TRANSFER & TRUST COMPANY’S DWAC (DEPOSIT WITHDRAWAL AT CUSTODIAN) SYSTEM. IF THE BUSINESS COMBINATION IS NOT COMPLETED, THEN ANY SHARES YOU TENDERED FOR REDEMPTION WILL NOT BE REDEEMED FOR CASH. IF YOU HOLD THE SHARES IN STREET NAME, YOU WILL NEED TO INSTRUCT THE ACCOUNT EXECUTIVE AT YOUR BANK OR BROKER TO WITHDRAW THE SHARES FROM YOUR ACCOUNT IN ORDER TO EXERCISE YOUR REDEMPTION RIGHTS.

On behalf of our board of directors, I would like to thank you for your support of BCAC and look forward to a successful completion of the Business Combination.

Sincerely,

Samuel P. Wertheimer

Chief Executive Officer and Chairman

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES REGULATORY AGENCY HAS APPROVED OR DISAPPROVED THE TRANSACTIONS DESCRIBED IN THIS PROXY STATEMENT/PROSPECTUS, PASSED UPON THE MERITS OR FAIRNESS OF THE BUSINESS COMBINATION OR RELATED TRANSACTIONS OR PASSED UPON THE ADEQUACY OR ACCURACY OF THE DISCLOSURE IN THIS PROXY STATEMENT/PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY CONSTITUTES A CRIMINAL OFFENSE.

This proxy statement/prospectus is dated [●], 2022, and is expected to be first mailed or otherwise delivered to BCAC stockholders on or about [●], 2022.

BROOKLINE CAPITAL ACQUISITION CORP.

280 Park Avenue, Suite 43W, New York, NY 10017

NOTICE OF 2022 ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON [●], 2022

TO THE STOCKHOLDERS OF BCAC:

NOTICE IS HEREBY GIVEN that the 2022 annual meeting of the stockholders of Brookline Capital Acquisition Corp., a Delaware corporation (“BCAC”), will be held at [●] Eastern Time, on [●], 2022, in virtual format (the “Stockholders’ Meeting”). You are cordially invited to attend the Stockholders’ Meeting, which will be held for the following purposes:

(1) The Business Combination Proposal-To consider and vote upon a proposal to approve the Business Combination Agreement, dated as of March 17, 2022 (as it may be amended, supplemented or otherwise modified from time to time in accordance with its terms, the “Business Combination Agreement”), by and among BCAC, Project Barolo Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of BCAC (“Merger Sub”), and Apexigen, Inc., a Delaware corporation (“Apexigen”), and the transactions contemplated thereby, pursuant to which Merger Sub will merge with and into Apexigen, with Apexigen surviving the merger as a wholly owned subsidiary of BCAC (the “Merger” and, together with the other transactions contemplated by the Business Combination Agreement, the “Business Combination”). A copy of the Business Combination Agreement is attached to this proxy statement/ prospectus as Annex A (the “Business Combination Proposal”);

(2) The Charter Proposals-To consider and vote upon two proposals to adopt the proposed Amended and Restated Certificate of Incorporation of BCAC (the “Proposed Charter”), in the form attached hereto as Annex B (the “Charter Proposals”);

(3) The Director Election Proposal-To consider and vote upon a proposal to elect seven directors to serve on the Board of Directors of the Combined Company (the “Combined Company Board”) until the first annual meeting of stockholders following the effectiveness of the Proposed Charter, in the case of Class I directors, the second annual meeting of stockholders following the effectiveness of the Proposed Charter, in the case of Class II directors, and the third annual meeting of stockholders following the effectiveness of the Proposed Charter, in the case of Class III directors, and, in each case, until their respective successors are duly elected and qualified (the “Director Election Proposal”);

(4) The Nasdaq Proposal-To consider and vote upon a proposal to approve, for purposes of complying with applicable listing rules of Nasdaq: (i) the issuance of shares of BCAC Common Stock to Apexigen stockholders pursuant to the Business Combination Agreement; (ii) the issuance of shares of BCAC Common Stock to the PIPE Investors pursuant to the Subscription Agreements (including upon exercise of the warrants issued pursuant to the Subscription Agreements (the “PIPE Warrants”)); and (iii) the issuance of shares of BCAC Common Stock and Combined Company common stock to Lincoln Park pursuant to that certain Purchase Agreement entered into by BCAC in connection with the execution of the Business Combination Agreement;

(5) The Equity Incentive Plan Proposal-To consider and vote upon a proposal to approve and adopt the Apexigen, Inc. 2022 Equity Incentive Plan attached to this proxy statement/prospectus as Annex H (the “Equity Incentive Plan Proposal”);

(6) The ESPP Proposal-To consider and vote upon a proposal to approve and adopt the Apexigen, Inc. 2022 Employee Stock Purchase Plan attached to this proxy statement/prospectus as Annex I (the “ESPP Proposal”); and

(7) The Adjournment Proposal-To consider and vote upon a proposal to approve the adjournment of the Stockholders’ Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies in the event that there are insufficient votes for the approval of the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal or the ESPP

Proposal (the “Adjournment Proposal” and, together with the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal and the ESPP Proposal, each, a “Proposal” and collectively, the “Proposals”).

These items of business are described in the attached proxy statement/prospectus, which we encourage you to read in its entirety before voting. Only holders of record of shares of BCAC Common Stock at the close of business on [●], 2022 (the “Record Date”) are entitled to notice of the Stockholders’ Meeting and to vote and have their votes counted at the Stockholders’ Meeting and any adjournments or postponements of the Stockholders’ Meeting.

Pursuant to the Amended and Restated Certificate of Incorporation of BCAC, dated January 28, 2021 and as amended on April 26, 2022 (the “Existing Charter”), BCAC will provide holders of shares of BCAC Common Stock with the opportunity to redeem such shares for cash equal to their pro rata share of the aggregate amount on deposit in the trust account established in connection with BCAC’s initial public offering (the “Trust Account”), calculated as of two business days prior to the consummation of the transactions contemplated by the Business Combination Proposal (including interest earned on the funds held in the Trust Account and not previously released to BCAC to pay its taxes). For illustrative purposes, based on funds in the Trust Account of approximately $[●] on [●], 2022, the estimated per share redemption price would have been approximately $[●], excluding additional interest earned on the funds held in the Trust Account and not previously released to BCAC to pay taxes. Holders of BCAC Common Stock may elect to redeem their shares of BCAC Common Stock even if they vote for the Business Combination Proposal. A holder of shares of BCAC Common Stock, together with any affiliate of the holder or any other person with whom the holder is acting in concert or as a “group” (as defined in Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)), will be restricted from seeking Redemption Rights with respect to more than 15% of the aggregate number of shares of BCAC Common Stock outstanding without the consent of BCAC. Accordingly, all shares of BCAC Common Stock in excess of 15% held by a holder of shares of BCAC Common Stock, together with any affiliate of such holder or any other person with whom such holder is acting in concert or as a “group,” will not be redeemed for cash without the consent of BCAC. Currently, Brookline Capital Holdings, LLC, a Delaware limited liability company (the “Sponsor”) (in which each of BCAC’s directors and officers is a member), owns approximately 24.1% of the outstanding shares of BCAC Common Stock, consisting of shares of BCAC Common Stock and units, purchased in a private placement, each unit consisting of one share of BCAC Common Stock and one-half of one redeemable warrant. The Sponsor has agreed to vote any shares of BCAC Common Stock owned by it in favor of each of the Proposals presented at the Stockholders’ Meeting.

After careful consideration, BCAC’s board of directors (the “BCAC Board”) has determined that the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the ESPP Proposal and the Adjournment Proposal are fair to and in the best interests of BCAC and its stockholders and unanimously recommends that you vote or give instruction to vote “FOR” the Business Combination Proposal, “FOR” the Charter Proposals, “FOR” the Director Election Proposal, “FOR” the Nasdaq Proposal, “FOR” the Equity Incentive Plan Proposal, “FOR” the ESPP Proposal and “FOR” the Adjournment Proposal, if presented at the Stockholders’ Meeting.

The approval of each of the Business Combination Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the ESPP Proposal and the Adjournment Proposal, if presented, requires the affirmative vote (in person or by proxy) of the holders of a majority of the shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting, voting as a single class. In addition, in accordance with the Business Combination Agreement, the parties to the Business Combination Agreement are also requiring the affirmative vote of holders of a majority of the shares of BCAC Common Stock then outstanding, voting together as a single class, for the approval of the Charter Proposals. The approval of the Director Election Proposal requires the affirmative vote (in person or by proxy) of the holders of a plurality of the outstanding shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting.

Consummation of the Business Combination is conditioned on the approval of the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal and the ESPP Proposal at the Stockholders’ Meeting, subject to the terms of the Business Combination

Agreement. The Business Combination is not conditioned on the Adjournment Proposal. If the Business Combination Proposal is not approved, the other proposals (except the Adjournment Proposal) will not be presented to the stockholders for a vote. The proxy statement/prospectus accompanying this notice explains the Business Combination Agreement and the transactions contemplated thereby, as well as the Proposals to be considered at the Stockholders’ Meeting. Please review the proxy statement/prospectus carefully.

All BCAC stockholders are cordially invited to attend the Stockholders’ Meeting in virtual format. BCAC stockholders may attend, vote, and examine the list of BCAC stockholders entitled to vote at the Stockholders’ Meeting by visiting https://www.cstproxy.com/bcac/sm2022 and entering the control number found on their proxy card, voting instruction form or notice included in their proxy materials. In light of public health concerns regarding the coronavirus (“COVID-19”) pandemic, the Stockholders’ Meeting will be held in virtual meeting format only. You will not be able to attend the Stockholders’ Meeting physically. To ensure your representation at the Stockholders’ Meeting, you are urged to complete, sign, date and return the enclosed proxy card as soon as possible. If your shares are held in an account at a brokerage firm or bank, you must instruct your broker or bank on how to vote your shares.

Your vote is important regardless of the number of shares you own. Whether you plan to attend the Stockholders’ Meeting or not, please sign, date, and return the enclosed proxy card as soon as possible in the envelope provided. If your shares are held in “street name” or are in a margin or similar account, you should contact your broker to ensure that votes related to the shares you beneficially own are properly counted.

If you have any questions or need assistance voting your shares, please call our proxy solicitor, Morrow Sodali LLC, toll free at (800) 662-5200.

Thank you for your participation. We look forward to your continued support.

By Order of the Board of Directors

Samuel P. Wertheimer

Chief Executive Officer and Chairman

[●], 2022

IF YOU RETURN YOUR PROXY CARD WITHOUT AN INDICATION OF HOW YOU WISH TO VOTE, YOUR SHARES WILL BE VOTED IN FAVOR OF EACH OF THE PROPOSALS. TO EXERCISE YOUR REDEMPTION RIGHTS, YOU MUST ELECT TO HAVE BCAC REDEEM YOUR SHARES FOR A PRO RATA PORTION OF THE FUNDS HELD IN THE TRUST ACCOUNT AND TENDER YOUR SHARES TO BCAC’S TRANSFER AGENT AT LEAST TWO (2) BUSINESS DAYS PRIOR TO THE STOCKHOLDERS’ MEETING. YOU MAY TENDER YOUR SHARES BY EITHER DELIVERING YOUR SHARE CERTIFICATE TO THE TRANSFER AGENT OR BY DELIVERING YOUR SHARES ELECTRONICALLY USING THE CONTINENTAL STOCK TRANSFER & TRUST COMPANY’S DWAC (DEPOSIT AND WITHDRAWAL AT CUSTODIAN) SYSTEM. IF THE BUSINESS COMBINATION IS NOT COMPLETED, THEN ANY SHARES YOU TENDERED WILL NOT BE REDEEMED FOR CASH. IF YOU HOLD THE SHARES IN STREET NAME, YOU WILL NEED TO INSTRUCT THE ACCOUNT EXECUTIVE AT YOUR BANK OR BROKER TO WITHDRAW THE SHARES FROM YOUR ACCOUNT IN ORDER TO EXERCISE YOUR REDEMPTION RIGHTS. SEE “MEETING OF BCAC STOCKHOLDERS-REDEMPTION RIGHTS” FOR MORE SPECIFIC INSTRUCTIONS.

TABLE OF CONTENTS

	Page
BASIS OF PRESENTATION AND GLOSSARY		1
TRADEMARKS, TRADE NAMES AND SERVICE MARKS		5
QUESTIONS AND ANSWERS		6
SUMMARY		26
MARKET PRICE AND DIVIDEND INFORMATION		40
SUMMARY HISTORICAL FINANCIAL INFORMATION OF BCAC		41
SUMMARY HISTORICAL FINANCIAL INFORMATION OF APEXIGEN		43
SELECTED UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION		44
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS AND RISK FACTOR SUMMARY		48
RISK FACTORS		50
UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION		122
COMPARATIVE SHARE INFORMATION		140
MEETING OF BCAC STOCKHOLDERS		143
PROPOSAL NO. 1-THE BUSINESS COMBINATION PROPOSAL		153
PROPOSAL NO. 2-THE CHARTER PROPOSALS		154
PROPOSAL NO. 3-THE DIRECTOR ELECTION PROPOSAL		158
PROPOSAL NO. 4-THE NASDAQ PROPOSAL		159
PROPOSAL NO. 5-THE EQUITY INCENTIVE PLAN PROPOSAL		161
PROPOSAL NO. 6-THE ESPP PROPOSAL		170
PROPOSAL NO. 7-THE ADJOURNMENT PROPOSAL		176
INFORMATION ABOUT BCAC		177
MANAGEMENT OF BCAC		185
BCAC MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS		193
SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT OF BCAC AND THE COMBINED COMPANY		200
INFORMATION ABOUT APEXIGEN		203
APEXIGEN’S BUSINESS		203
APEXIGEN’S MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS		241
MANAGEMENT OF THE COMBINED COMPANY FOLLOWING THE BUSINESS COMBINATION		256
EXECUTIVE COMPENSATION OF APEXIGEN		265
THE BUSINESS COMBINATION		275
THE BUSINESS COMBINATION AGREEMENT		277
OTHER AGREEMENTS		292
BACKGROUND OF THE BUSINESS COMBINATION		297
ANTICIPATED ACCOUNTING TREATMENT		312
MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS		313
COMPARISON OF STOCKHOLDERS’ RIGHTS		320
DESCRIPTION OF CAPITAL STOCK OF THE COMBINED COMPANY		327
SECURITIES ACT RESTRICTIONS ON RESALE OF COMBINED COMPANY COMMON STOCK		332
CERTAIN RELATIONSHIPS AND RELATED PARTY TRANSACTIONS		333
PUBLIC TRADING MARKETS		336
EXPERTS		337
LEGAL MATTERS		337

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	Page
OTHER MATTERS		337
APPRAISAL RIGHTS		337
WHERE YOU CAN FIND MORE INFORMATION		338
INDEX TO FINANCIAL STATEMENTS		F-1
Annexes
A – Business Combination Agreement
B – Proposed Charter
C – Sponsor Support Agreement
D – Stockholder Support Agreement
E – Registration Rights and Lock-Up Agreement
F – Form of PIPE Subscription Agreement
G-1 – Lincoln Park Purchase Agreement
G-2 – Registration Rights Agreement
H – 2022 Equity Incentive Plan
I – 2022 Employee Stock Purchase Plan
J – Form of the Amended and Restated Bylaws of the Combined Company

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BASIS OF PRESENTATION AND GLOSSARY

As used in this proxy statement/prospectus, unless otherwise noted or the context otherwise requires, references to:

“Additional Contributions” are to the amounts the Sponsor has agreed to contribute as a non-interest bearing loan of $0.033 for each Public Share that was not redeemed in the April Partial Redemption (as defined below) to BCAC on a monthly basis commencing on May 2, 2022, and occurring on the 2nd day of each subsequent month, or portion thereof, up to October 2, 2022, that is needed by BCAC to complete the Business Combination no later than November 2, 2022 (the “Extended Date”);

“Aggregate Closing Merger Consideration” with respect to all holders of Apexigen securities outstanding immediately prior to the Closing, which will be issued in the form of shares or equity awards relating to shares of BCAC Common Stock, will equal the quotient of (a) the sum of (i) $205,000,000 and (ii) the sum of the exercise prices of all options to purchase shares of Apexigen Common Stock outstanding immediately prior to the Effective Time, divided by (b) $10.00;

“Apexigen” are to Apexigen, Inc., a Delaware corporation;

“Apexigen Board” are to the board of directors of Apexigen;

“Apexigen capital stock” are to shares of Apexigen Common Stock and Apexigen Preferred Stock;

“Apexigen Common Stock” are to shares of common stock, par value $0.001 per share, of Apexigen;

“Apexigen Option” are to each option to purchase shares of Apexigen Common Stock that is outstanding at the Effective Time;

“Apexigen Preferred Stock” are to shares of preferred stock, par value $0.001 per share, of Apexigen;

“Apexigen stockholders” are to the stockholders of Apexigen prior to the Closing;

“Apexigen Warrant” are to each warrant to purchase shares of common stock or preferred stock of Apexigen;

“April Partial Redemption” are to the BCAC Public Stockholders’ election in April 2022 to redeem 688,408 shares at $10.10 per share for total redemption proceeds of approximately $7.0 million;

“BCAC” are to Brookline Capital Acquisition Corp., a Delaware corporation;

“BCAC Common Stock” are to shares of common stock, par value $0.0001 per share, of BCAC prior to the Closing;

“BCAC Board” are to the board of directors of BCAC prior to the Closing;

“BCAC Board Recommendation” is a recommendation of the BCAC Board to BCAC stockholders that such stockholders approve the proposals included herein;

“BCAC IPO” are to the initial public offering by BCAC, which closed on February 2, 2021;

“BCAC Option” are to an option to purchase shares of BCAC Common Stock;

“BCAC Related Funds Amount” means the amount of cash proceeds from (i) the PIPE Investment, as actually received by BCAC prior to or substantially concurrently with the Closing from investors to the Trust Account or that were first introduced by BCAC or its representatives or (ii) as a result of public stockholders not redeeming shares reflecting cash that is currently maintained in the Trust Account;

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“BCAC units” are to the units, comprised on one share of BCAC Common Stock and one-half of one redeemable BCAC warrant, issued at the closing of the BCAC IPO;

“BCAC warrants” are to all outstanding warrants of BCAC, each whole warrant of which entitles the holder to purchase one share of BCAC Common Stock at an exercise price of $11.50 per share;

“Business Combination” are to the Merger and the other transactions contemplated by the Business Combination Agreement and any other agreement executed and delivered in connection therewith;

“Business Combination Agreement” are to that certain Business Combination Agreement entered into on March 17, 2022, by and among Brookline Capital Acquisition Corp., a Delaware corporation (“BCAC”), and Project Barolo Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of BCAC (“Merger Sub”), and Apexigen, Inc., a Delaware corporation (“Apexigen”) (as it may be amended, supplemented or otherwise modified from time to time in accordance with its terms), pursuant to which Merger Sub will merge with and into Apexigen, with Apexigen surviving the merger as a wholly owned subsidiary of BCAC (the “Merger”);

“Closing” are to the closing of the transactions contemplated by the Business Combination Agreement;

“Code” are to the Internal Revenue Code of 1986, as amended;

“Combined Company” are to BCAC following the Business Combination and the other transactions contemplated by the Business Combination Agreement;

“Combined Company Board” are to the board of directors of the Combined Company;

“Combined Company common stock” are to shares of BCAC Common Stock following the Closing;

“Combined Company Option” are to each option to purchase shares of Combined Company common stock following the Closing;

“Completion Window” are to the period that expires on November 2, 2022;

“DGCL” are to the Delaware General Corporation Law, as may be amended from time to time;

“Effective Time” are to such a time when the merger certificate has been accepted for filing by the Secretary of State of the State of Delaware, or at such later time as may be agreed by BCAC and Apexigen in writing and specified in the merger certificate;

“Exchange Act” are to the Securities Exchange Act of 1934, as amended;

“Exchange Ratio” are to the amount that is equal to the quotient of (i) the Aggregate Closing Merger Consideration, divided by (ii) the number of shares of Apexigen capital stock that are issued and outstanding immediately prior to the Effective Time, calculated on a fully diluted basis, including shares of common stock of Apexigen that are issued and outstanding immediately prior to the Effective Time, shares of common stock issuable upon the conversion of all issued and outstanding shares of Apexigen Preferred Stock immediately prior to the Effective Time, and shares of capital stock of Apexigen that are issued or issuable upon the full exercise or conversion of all Apexigen Options and Apexigen Warrants outstanding as of the Effective Time;

“Existing Charter” are to the Amended and Restated Certificate of Incorporation of BCAC, dated as of January 28, 2021, as amended April 26, 2022;

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“Extension Amendment” are to the amendment to the Existing Charter approved by BCAC’s stockholders on April 26, 2022 to extend the date by which the Company must consummate a business combination transaction from May 2, 2022 (the date which is 15 months from the closing date of the Company’s initial public offering of units) on a monthly basis up to November 2, 2022;

“Founder Shares” are to 1,437,500 shares of our common stock initially purchased by the Sponsor in a private placement prior to the BCAC IPO, of which 57,500 shares were subsequently transferred to Representative and 1,380,000 shares remain held by the Sponsor;

“GAAP” are to generally accepted accounting principles in the United States, as applied on a consistent basis;

“Investment Company Act” are to the Investment Company Act of 1940, as amended;

“Key Apexigen Stockholders” are to those certain stockholders of Apexigen who are parties to the Stockholder Support Agreement;

“Merger” are to the business combination transaction pursuant to which Merger Sub will merge with and into Apexigen with Apexigen surviving the Merger as a wholly owned subsidiary of BCAC;

“Merger Sub” are to Project Barolo Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of BCAC;

“Modification in Recommendation” are to a modification by the BCAC Board to change the BCAC Board Recommendation;

“Nasdaq” are to The Nasdaq Capital Market;

“PIPE Investment” are to the purchase of an aggregate of 1,502,000 PIPE Units pursuant to the Subscription Agreements;

“PIPE Unit” are to each of the units, comprised of one share of BCAC Common Stock and one-half of one BCAC warrant (a “PIPE Warrant”), purchased by certain investors pursuant to the Subscription Agreements;

“Public Shares” are to shares of BCAC Common Stock sold as part of the BCAC units (whether they were purchased in the BCAC IPO or thereafter in the open market);

“Public Stockholders” are to the holders of BCAC’s Public Shares, including the Sponsor and BCAC’s management team to the extent the Sponsor and/or members of BCAC’s management team purchase Public Shares in the open market, provided that the Sponsor’s and each member of BCAC’s management team’s status as a “public stockholder” will only exist with respect to such Public Shares;

“Record Date” are to [●], 2022, the record date for the Stockholders’ Meeting;

“Redemption Rights” are to the right to demand that BCAC redeem such shares for a pro rata portion of the cash held in the Trust Account, calculated as of two business days prior to the Closing (including interest earned on the funds held in the Trust Account and not previously released to BCAC to pay taxes) upon the Closing;

“Registrant” are to Brookline Capital Acquisition Corp., a Delaware corporation;

“Representative” are to Ladenburg Thalmann & Co. Inc., the BCAC IPO underwriter, and certain of its employees;

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“Representative Shares” are to the Founder Shares held by the Representative;

“SEC” are to the U.S. Securities and Exchange Commission;

“Securities Act” are to the Securities Act of 1933, as amended;

“Sponsor” are to Brookline Capital Holdings, LLC, a Delaware limited liability company;

“Sponsor Shares” are to the shares of BCAC Common Stock issued to Sponsor prior to BCAC’s initial public offering and not transferred to the Representative;

“Supporting Apexigen Stockholders” are to certain stockholders of Apexigen who, in the aggregate, hold (a) at least a majority of the outstanding shares of Apexigen capital stock, voting together as a single class and (b) at least a majority of the outstanding shares of Series A-1 Preferred Stock, Series B Preferred Stock and Series C Preferred Stock of Apexigen, voting together as a single class on an as-converted basis;

“Trust Account” are to the trust account established by BCAC for the benefit of its stockholders at J.P. Morgan Chase Bank, N.A.; and

“Warrants” are to BCAC warrants sold as part of the BCAC units (whether they were purchased in the BCAC IPO or thereafter in the open market).

Unless specified otherwise, amounts in this proxy statement/prospectus are presented in United States (“U.S.”) dollars.

Defined terms in the financial statements contained in this proxy statement/prospectus have the meanings ascribed to them in the financial statements.

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TRADEMARKS, TRADE NAMES AND SERVICE MARKS

BCAC and Apexigen own or have rights to trademarks, trade names and service marks that they use in connection with the operation of their business. In addition, their names, logos and website names and addresses are their trademarks or service marks. Other trademarks, trade names and service marks appearing in this proxy statement/prospectus are the property of their respective owners. Solely for convenience, in some cases, the trademarks, trade names and service marks referred to in this proxy statement/ prospectus, including logos, artwork and other visual displays, may appear without the applicable ®, TM and SM symbols, but BCAC and Apexigen will assert, to the fullest extent under applicable law, their rights to these trademarks, trade names and service marks. BCAC and Apexigen do not intend the use or display of other entities’ trade names, trademarks, or service marks to imply a relationship with, or endorsement or sponsorship of, any other entity.

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QUESTIONS AND ANSWERS

The questions and answers below highlight only selected information from this proxy statement/prospectus and only briefly address some commonly asked questions about the Business Combination, the Stockholders’ Meeting, and the Proposals (as defined herein) to be presented at the Stockholders’ Meeting. The following questions and answers do not include all the information that is important to BCAC stockholders. You are urged to carefully read this entire proxy statement/prospectus, including the annexes and the other documents referred to herein, to fully understand the Business Combination and the voting procedures for the Stockholders’ Meeting.

QUESTIONS AND ANSWERS ABOUT THE BUSINESS COMBINATION

Q: WHAT IS THE BUSINESS COMBINATION?

A: BCAC, Merger Sub and Apexigen have entered into the Business Combination Agreement, pursuant to which Merger Sub will merge with and into Apexigen, with Apexigen surviving the Merger as a wholly owned subsidiary of BCAC. In connection with the Closing, BCAC will be renamed “Apexigen, Inc.”

BCAC will hold the Stockholders’ Meeting to, among other things, obtain the approvals required for the Business Combination, and you are receiving this proxy statement/prospectus in connection with such meeting. See “The Business Combination Agreement.” In addition, a copy of the Business Combination Agreement is attached to this proxy statement/prospectus as Annex A. We urge you to carefully read this proxy statement/prospectus, including the annexes and the other documents referred to herein, in their entirety.

Q: WHY AM I RECEIVING THIS DOCUMENT?

A: BCAC is sending this proxy statement/prospectus to its stockholders to help them decide how to vote their shares of BCAC Common Stock with respect to the matters to be considered at the Stockholders’ Meeting. The Business Combination cannot be completed unless BCAC’s stockholders approve the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal and the ESPP Proposal set forth in this proxy statement/prospectus for their approval. Information about the Stockholders’ Meeting, the Business Combination, and the other business to be considered by stockholders at the Stockholders’ Meeting is contained in this proxy statement/prospectus. This document constitutes a proxy statement and a prospectus of BCAC. It is a proxy statement because the board of directors of BCAC is soliciting proxies from its stockholders using this proxy statement/prospectus. It is a prospectus because BCAC, in connection with the Business Combination, is offering shares of BCAC Common Stock to Apexigen stockholders in exchange for the outstanding shares of Apexigen capital stock and certain equity awards of Apexigen pursuant to the terms of the Business Combination Agreement. See “The Business Combination Agreement-Merger Consideration.”

Q: WHAT WILL APEXIGEN STOCKHOLDERS RECEIVE IN THE BUSINESS COMBINATION?

A: Subject to the terms of the Business Combination Agreement, the Aggregate Closing Merger Consideration with respect to all holders of Apexigen securities outstanding immediately prior to the Closing, which will be issued in the form of shares or equity awards relating to shares of BCAC Common Stock, will equal to the quotient of (a) the sum of (i) $205,000,000, and (ii) the sum of the exercise prices of all Apexigen Options to purchase shares of Apexigen Common Stock outstanding immediately prior to the Effective Time, divided by (b) $10.00.

At the Effective Time:

• each issued and outstanding share of Apexigen capital stock (including shares of capital stock that are issued and outstanding immediately prior to the Effective Time resulting from the conversion or

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exercise of shares of the Apexigen Preferred Stock, Apexigen Warrants, and Apexigen Options, but excluding any dissenting shares) will be converted into the right to receive a number of shares of BCAC Common Stock equal to the Exchange Ratio;

• each share of capital stock of Apexigen held in the treasury of Apexigen shall be canceled without any conversion thereof and no payment or distribution shall be made with respect thereto;

• each Apexigen Option that is outstanding immediately prior to the Effective Time, whether vested or unvested, will be assumed by BCAC and converted into a BCAC Option on substantially the same vesting and exercisability terms and conditions as such Apexigen Options, except that (i) such BCAC Option will represent the right to purchase that whole number of shares of BCAC Common Stock (rounded down to the nearest whole share) equal to the product of the number of shares of Apexigen Common Stock subject to such Apexigen Option multiplied by the Exchange Ratio, and (ii) the exercise price per share for each such BCAC Option will be equal to the quotient of (A) the exercise price per share of such Apexigen Option in effect immediately prior to the Effective Time, divided by (B) the Exchange Ratio (the exercise price per share, as so determined, being rounded up to the nearest full cent);

• each Apexigen Warrant that is issued and outstanding immediately prior to the Effective Time will be treated in accordance with the terms thereof, as may be amended prior to the Effective Time by Apexigen and the holder thereof with the consent of BCAC.

The Aggregate Closing Merger Consideration will be issued to holders of Apexigen securities at the Closing in accordance with the Business Combination Agreement. The portion of the Aggregate Closing Merger Consideration issuable to any person by virtue of the Merger will be calculated on an aggregate basis with respect to all shares of capital stock of Apexigen held of record by such person immediately prior to the Effective Time, and after such aggregation, any fractional share of BCAC Common Stock that would otherwise be issuable to such person following such aggregation will be rounded up to a whole share of BCAC Common Stock.

Q: WHEN DO YOU EXPECT THE BUSINESS COMBINATION TO BE COMPLETED?

A: It is currently anticipated that the Business Combination will be consummated promptly following the Stockholders’ Meeting, which is set for [●], 2022; however, such meeting could be adjourned, as described herein. Neither BCAC nor Apexigen can assure you of when or if the Business Combination will be completed and it is possible that factors outside of the control of both companies could result in the Business Combination being completed at a different time or not at all. BCAC must first obtain the approval of its stockholders for certain of the proposals set forth in this proxy statement/prospectus for their approval, Apexigen must first obtain the written consent of its stockholders for the Merger, and BCAC and Apexigen must also first obtain certain necessary regulatory approvals and satisfy other closing conditions set forth in the Business Combination Agreement. See “The Business Combination Agreement-Conditions to the Business Combination.”

Q: WHAT HAPPENS IF THE BUSINESS COMBINATION IS NOT COMPLETED?

A: If the Business Combination is not completed, Apexigen stockholders will not receive any consideration for their shares of Apexigen capital stock or Apexigen equity awards, and the issued and outstanding Apexigen Options and Apexigen Warrants will not be exercised on a cashless basis or assumed in accordance with their terms. Instead, Apexigen will remain an independent company and BCAC would search for another target business with which to complete a business combination. Further, the Existing Charter provides that BCAC must complete its initial business combination within 15 months from the closing of the IPO (or up to 21 months from the closing of the IPO, or November 2, 2022, provided that the Sponsor or its designee must deposit into the Trust Account for every additional month beyond 15 months (or May 2, 2022), funds

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equal to the product of (x) $0.033 multiplied by (y) that number of shares of BCAC Common Stock included as part of the units sold in the BCAC IPO and not otherwise redeemed). If the Business Combination is not completed, BCAC may not be able to find a suitable target business and complete the initial business combination within such time period. If BCAC has not completed the initial business combination within such time period, it will: (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten business days thereafter, redeem the Public Shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account including interest earned on the funds held in the Trust Account and not previously released to BCAC to pay its taxes (less up to $100,000 of interest to pay dissolution expenses), divided by the number of then outstanding Public Shares, which redemption will completely extinguish public stockholders’ rights as stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the remaining BCAC stockholders and board of directors, dissolve and liquidate, subject in the case of clauses (ii) and (iii) above to BCAC’s obligations under Delaware law to provide for claims of creditors and the requirements of other applicable law. In such case, the Public Stockholders may only receive $[●] per Public Share. Furthermore, the Sponsor and the Representative have no Redemption Rights with respect to their Founder Shares in the event a business combination is not effected in the Completion Window, and, accordingly, their Founder Shares will be worthless. Additionally, in the event of a liquidation of BCAC, there will be no distribution with respect to BCAC’s outstanding Warrants. Accordingly, the Warrants will expire worthless. In certain circumstances, the Public Stockholders may receive less than $[●] per share on the redemption of their Public Shares. See “The Business Combination Agreement-Termination” and “Risk Factors.”

Q: HOW WILL BCAC BE MANAGED AND GOVERNED FOLLOWING THE BUSINESS COMBINATION?

A: BCAC does not currently have any management-level employees other than Dr. Samuel Wertheimer, our Chief Executive Officer, Scott A. Katzmann, our President, and Patrick A. Sturgeon, our Chief Financial Officer. Following the Closing, the Combined Company’s executive officers are expected to be the current management team of Apexigen. See “Management of the Combined Company Following the Business Combination” for more information.

BCAC is, and after the Closing will continue to be, managed by its board of directors. Following the closing, the size of our board of directors will increase to seven directors and will consist of Xiaodong Yang, Herb Cross, Jakob Dupont, Gordon Ringold, Scott Smith, Samuel Wertheimer, and Dan Zabrowski. Following the Closing, we expect that a majority of the directors will be independent under applicable Nasdaq listing rules. Other than Mr. Wertheimer, there are no existing officers or directors of BCAC who will hold any post-combination employment or directorships with, or receive any benefits from, the Combined Company, and there have been no discussions of anyone doing so. See “Management of the Combined Company Following the Business Combination.”

Q: WILL BCAC OBTAIN NEW FINANCING IN CONNECTION WITH THE BUSINESS COMBINATION?

A: In connection with the execution of the Business Combination Agreement, BCAC entered into subscription agreements with the PIPE Investors and may enter into additional Subscription Agreements with other investors prior to the Closing, pursuant to which the PIPE Investors, contingent upon the consummation of the Business Combination, agreed to subscribe for and purchase, and BCAC agreed to issue and sell to the PIPE Investors, an aggregate of 1,502,000 PIPE Units at a purchase price of $10.00 per PIPE Unit for an aggregate purchase price of $15,020,000 (the “PIPE Investment”). Each PIPE Unit consists of one share of BCAC Common Stock and one-half of one warrant. Each whole warrant entitles the PIPE Investor to purchase one share of BCAC Common Stock at an exercise price of $11.50 per share during the period

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commencing 30 days after the Closing and terminating on the five year anniversary of the Closing. As of [●], 2022, the closing price on Nasdaq of the BCAC units was $[●] per unit and the closing price of the BCAC Common Stock was $[●] per share. The shares of BCAC Common Stock to be issued pursuant to the Subscription Agreements will not be registered under the Securities Act and will be issued in reliance upon the exemption provided under Section 4(a)(2) of the Securities Act. See “Other Agreements-Subscription Agreements.” If the 1,502,000 shares of BCAC Common Stock to be issued to the PIPE Investors were currently outstanding, such shares would have an aggregate market value of $[●] based upon the closing price of $[●] per share of BCAC Common Stock on Nasdaq on the Record Date.

In connection with the execution of the Business Combination Agreement, BCAC, Apexigen, and Lincoln Park also entered into (a) the Lincoln Park Purchase Agreement to establish an equity line, and (b) the Registration Rights Agreement. Pursuant to the terms of the Lincoln Park Purchase Agreement, the Combined Company will have the right to direct Lincoln Park to purchase from the Combined Company an aggregate of up to $50,000,000 Combined Company common stock from time to time over a 24-month period following the Closing, subject to certain limitations contained in the Lincoln Park Purchase Agreement.

Upon satisfaction of certain conditions, the Combined Company will have the right to direct Lincoln Park to purchase up to $500,000 per trading day (subject to the adjustments described in the Lincoln Park Purchase Agreement) of Combined Company common stock (each such purchase, a “Regular Purchase”). The purchase price for shares of Common Stock to be purchased by Lincoln Park under a Regular Purchase will be equal to the lower of (in each case, subject to the adjustments described in the Lincoln Park Purchase Agreement): (i) the lowest sale price for Combined Company common stock on the applicable purchase date and (ii) the arithmetic average of the three lowest closing sale prices for Combined Company common stock during the 10 consecutive trading days immediately preceding the purchase date. If the Combined Company directs Lincoln Park to purchase the maximum number of shares of Combined Company common stock that the Combined Company may sell in a Regular Purchase, then in addition to such Regular Purchase, and subject to certain conditions and limitations in the Lincoln Park Purchase Agreement, the Combined Company may direct Lincoln Park to make an “accelerated purchase” of an additional number of shares of Combined Company common stock which may not exceed the lesser of: (i) 300% of the number of shares directed by the Combined Company to be purchased by Lincoln Park pursuant to the corresponding Regular Purchase and (ii) 30% of the total number of shares of Combined Company common stock traded during a specified period on the applicable purchase date as set forth in the Lincoln Park Purchase Agreement. The purchase price for such shares will be 95% of the lower of (i) the volume weighted average price of Combined Company common stock over a certain portion of the date of sale as set forth in the Lincoln Park Purchase Agreement and (ii) the closing sale price of Combined Company common stock on the date of sale. Under certain circumstances, the Combined Company may direct Lincoln Park to purchase shares in multiple Accelerated Purchases on the same trading day.

In consideration for Lincoln Park’s execution and delivery of the Lincoln Park Purchase Agreement, BCAC will issue to Lincoln Park 150,000 shares of BCAC Common Stock on the date of Closing. Additionally, the Combined Company will issue to Lincoln Park $1,500,000 of Combined Company common stock on the date that is 90 calendar days after the date of Closing at the purchase price equal to the arithmetic average of the last closing sale price for Combined Company common stock during the 10 consecutive business days ending on the business day immediately preceding the delivery of such shares, provided, that in no event shall the number of such shares exceed 500,000. See “Other Agreements-Lincoln Park Purchase Agreement and Registration Rights Agreement.”

Q: WHAT EQUITY STAKE WILL CURRENT BCAC PUBLIC STOCKHOLDERS, THE SPONSOR, THE REPRESENTATIVE, FORMER APEXIGEN EQUITYHOLDERS, PIPE INVESTORS AND LINCOLN PARK HOLD IN BCAC FOLLOWING THE CLOSING?

A: The total number of shares of Combined Company common stock outstanding at the Closing (and your relative ownership levels) will be affected by the number of shares of BCAC Common Stock that are

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redeemed in connection with the Business Combination, and the number of BCAC warrants that are exercised. The Business Combination Agreement does not provide for any minimum cash condition.

The table below shows the relative ownership levels of holders of Combined Company common stock following the Business Combination under varying redemption scenarios (after giving effect to the April Partial Redemption and assuming a redemption price of $10.20 per share).

	No Additional Redemptions				50% Redemptions				75% Redemptions				Maximum Redemptions
	Number of Shares		%		Number of Shares		%		Number of Shares		%		Number of Shares		%
BCAC Public Stockholders		5,061,592		19.1%		2,530,796		10.6%		1,265,398		5.6%		—		0.0%
Sponsor		1,627,000		6.2%		1,627,000		6.8%		1,452,520		6.4%		1,167,000		5.5%
Representative		57,500		0.2%		57,500		0.2%		57,500		0.3%		57,500		0.3%
Former Apexigen equityholders		18,104,074		68.2%		18,104,074		75.5%		18,104,074		80.3%		18,104,074		86.3%
PIPE Investors		1,502,000		5.7%		1,502,000		6.3%		1,502,000		6.7%		1,502,000		7.2%
Lincoln Park		150,000		0.6%		150,000		0.6%		150,000		0.7%		150,000		0.7%
Total		26,502,166		100.0%		23,971,370		100.0%		22,531,492		100.0%		20,980,574		100.0%

The table below presents possible sources of dilution and the extent of such dilution that non-redeeming public stockholders could experience in connection with the Closing across a range of varying redemption scenarios (after giving effect to the April Partial Redemption and assuming a redemption price of $10.20 per share). In an effort to illustrate the extent of such dilution, the table below assumes (i) the exercise of all 2,875,000 Public Warrants, 751,000 PIPE Warrants and 123,500 Private Placement Warrants, (ii) the issuance of the maximum number of shares of Combined Company common stock to Lincoln Park 90 calendar days after the date of the Closing pursuant to the Lincoln Park Purchase Agreement (but not such shares as the Combined Company can direct Lincoln Park to purchase), (iii) the exercise of the assumed Apexigen Options and Apexigen Warrants, and (iv) the full issuance and exercise of shares under the EIP and ESPP that would be issuable upon the Closing.

	No Additional Redemptions				50% Redemptions				75% Redemptions				Maximum Redemptions
	Number of Shares		%		Number of Shares		%		Number of Shares		%		Number of Shares		%
BCAC Public Stockholders		5,061,592		13.4%		2,530,796		7.3%		1,265,398		3.8%		—		0.0%
Sponsor		1,627,000		4.3%		1,627,000		4.7%		1,452,520		4.4%		1,167,000		3.7%
Representative		57,500		0.2%		57,500		0.2%		57,500		0.2%		57,500		0.2%
Former Apexigen equityholders		18,104,074		48.0%		18,104,074		51.9%		18,104,074		54.5%		18,104,074		57.5%
PIPE Investors		1,502,000		4.0%		1,502,000		4.3%		1,502,000		4.5%		1,502,000		4.8%
Lincoln Park		150,000		0.4%		150,000		0.4%		150,000		0.4%		150,000		0.5%
Additional Potential Dilution
Common Stock issuable upon exercise of the Public Warrants (1)		2,875,000		7.6%		2,875,000		8.2%		2,875,000		8.7%		2,875,000		9.1%

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	No Additional Redemptions				50% Redemptions				75% Redemptions				Maximum Redemptions
	Number of Shares		%		Number of Shares		%		Number of Shares		%		Number of Shares		%
Common Stock issuable upon exercise of the PIPE Warrants (1)		751,000		2.0%		751,000		2.2%		751,000		2.3%		751,000		2.4%
Common Stock issuable upon exercise of the Private Placement Warrants (1)		123,500		0.3%		123,500		0.4%		123,500		0.4%		123,500		0.4%
Common Stock issuable to Lincoln Park 90 days after the Closing (2)		500,000		1.3%		500,000		1.4%		500,000		1.5%		500,000		1.6%
Common Stock issuable upon exercise of assumed Apexigen Options and Apexigen Warrants (3)		3,464,485		9.2%		3,464,485		9.9%		3,464,485		10.4%		3,464,485		11.0%
Common Stock issuable under the EIP (4)		3,180,260		8.4%		2,876,565		8.3%		2,703,780		8.1%		2,517,669		8.0%
Common Stock issuable under the ESPP (4)		318,026		0.9%		287,657		0.8%		270,378		0.8%		251,767		0.8%
Total Diluted Shares at Closing		37,714,437		100.0%		34,849,577		100.0%		33,219,635		100.0%		31,463,995		100.0%

(1) Assumes all outstanding warrants immediately following the Closing are fully exercised.

(2) In addition to the 150,000 shares that the Combined Company will issue to Lincoln Park on the date of the Closing, the Combined Company will issue to Lincoln Park $1,500,000 of Combined Company common stock on the date that is 90 calendar days after the date of Closing at the purchase price equal to the arithmetic average of the last closing sale price for Combined Company common stock during the 10 consecutive business days ending on the business day immediately preceding the delivery of such shares, provided, that in no event shall the amount of such shares exceed 500,000. Upon satisfaction of certain conditions, the Combined Company may also direct Lincoln Park to purchase up to an aggregate of $50,000,000 of Combined Company common stock.

(3) Assumes all outstanding Apexigen Options and Apexigen Warrants are fully exercised.

(4) Assumes that all the shares authorized for issuance are issued.

For more information, see “Unaudited Pro Forma Condensed Combined Financial Information.”

Q: FOLLOWING THE BUSINESS COMBINATION, WILL BCAC’S SECURITIES CONTINUE TO TRADE ON A STOCK EXCHANGE?

A: Yes. Upon the Closing, we intend to change our name from “Brookline Capital Acquisition Corp.” to “Apexigen, Inc.” and we expect that following the Closing our Common Stock and Warrants will continue to be listed on Nasdaq under the symbols “APGN” and “APGNW,” respectively.

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QUESTIONS AND ANSWERS ABOUT THE STOCKHOLDERS’ MEETING

Q: WHEN AND WHERE IS THE STOCKHOLDERS’ MEETING?

A: The Stockholders’ Meeting will be held at [●] a.m. Eastern Time, on [●], 2022, in virtual format. BCAC stockholders may attend, vote and examine the list of BCAC stockholders entitled to vote at the Stockholders’ Meeting by visiting https://www.cstproxy.com/bcac/sm2022 and entering the control number found on their proxy card, voting instruction form or notice included in their proxy materials. In light of public health concerns regarding the coronavirus (“COVID-19”) pandemic, the Stockholders’ Meeting will be held in virtual meeting format only. You will not be able to attend the Stockholders’ Meeting physically.

Q: WHAT AM I BEING ASKED TO VOTE ON AND WHY IS THIS APPROVAL NECESSARY?

A: The stockholders of BCAC are being asked to vote on the following:

• A proposal to adopt the Business Combination Agreement and the transactions contemplated thereby. See “Proposal No. 1-The Business Combination Proposal.”

• Two proposals to adopt the Proposed Charter in the form attached hereto as Annex B. See “Proposal No. 2-The Charter Proposals.”

• A proposal to elect seven directors to serve on the Combined Company Board until the first annual meeting of stockholders following the effectiveness of the Proposed Charter, in the case of Class I directors, the second annual meeting of stockholders following the effectiveness of the Proposed Charter, in the case of Class II directors, and the third annual meeting of stockholders following the effectiveness of the Proposed Charter, in the case of Class III directors, and, in each case, until their respective successors are duly elected and qualified. See “Proposal No. 3-The Director Election Proposal.”

• A proposal to approve, for purposes of complying with applicable listing rules of Nasdaq: (i) the issuance of shares of BCAC Common Stock to Apexigen stockholders pursuant to the Business Combination Agreement; (ii) the issuance of shares of BCAC Common Stock to the PIPE Investors pursuant to the Subscription Agreements; and (iii) the issuance of shares of BCAC Common Stock and Combined Company common stock to Lincoln Park pursuant to the Lincoln Park Purchase Agreement. See “Proposal No. 4-The Nasdaq Proposal.”

• A proposal to approve and adopt the 2022 Equity Incentive Plan in the form attached hereto as Annex H. See “Proposal No. 5-The Equity Incentive Plan Proposal.”

• A proposal to approve and adopt the 2022 Employee Stock Purchase Plan in the form attached hereto as Annex I. See “Proposal No. 6-The ESPP Proposal.”

• A proposal to approve the adjournment of the Stockholders’ Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies in the event that there are insufficient votes for, or otherwise in connection with, the approval of the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal or the ESPP Proposal. See “Proposal No. 7-The Adjournment Proposal.”

BCAC will hold the Stockholders’ Meeting to consider and vote upon these proposals (collectively, the “Proposals”). This proxy statement/prospectus contains important information about the proposed Merger and the other matters to be acted upon at the Stockholders’ Meeting.

Stockholders should read this proxy statement/prospectus carefully, including the annexes and the other documents referred to herein.

Pursuant to the Business Combination Agreement, consummation of the Business Combination is conditioned on the approval of each of the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal and the ESPP Proposal. If the Business Combination Proposal is not approved, the other proposals, except the Adjournment Proposal, will not be presented to stockholders for a vote.

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The vote of stockholders is important. Stockholders are encouraged to vote as soon as possible after carefully reviewing this proxy statement/prospectus.

Q: I AM A BCAC WARRANT HOLDER. WHY AM I RECEIVING THIS PROXY STATEMENT/ PROSPECTUS?

A: Upon consummation of the Merger, the BCAC Warrants will, by their terms, entitle the holders to purchase shares of Combined Company common stock at a purchase price of $11.50 per share. This proxy statement/prospectus includes important information about Apexigen, the business of Apexigen and its subsidiary, and the business of the Combined Company following consummation of the Merger. As holders of BCAC warrants, you will be entitled to purchase shares of Combined Company common stock upon consummation of the Merger; BCAC urges you to read the information contained in this proxy statement/prospectus carefully.

Q: WHO IS APEXIGEN?

A: Apexigen is a clinical-stage biopharmaceutical company focused on discovering and developing a new generation of antibody therapeutics for oncology. Since inception, Apexigen has devoted substantially all of its resources to performing research and development activities in support of its product development and licensing efforts. Apexigen has incurred net losses each year since 2010, and as of March 31, 2022, had an accumulated deficit of $153.8 million.

Apexigen’s Wholly Owned Pipeline: Apexigen’s wholly owned pipeline is focused on innovative antibody-based therapeutics for oncology, with an emphasis on new immuno-oncology agents that may harness the patient’s immune system to combat and eradicate cancer. Apexigen’s pipeline of immuno-oncology therapeutic candidates is led by sotigalimab, which is currently in Phase 2 clinical development, and also includes multiple preclinical programs.

• Sotigalimab: a CD40 agonist antibody with two key features. Sotiga is designed to specifically bind to the CD40 ligand (“CD40L”) binding domain to mimic natural CD40L signaling. In addition, Apexigen engineered a mutation into the fragment crystallizable (Fc) region to increase FcgRIIb binding to increase cross-linking and agonistic potency and eliminate FcgRIIIa binding to prevent antibody-dependent cell-mediated cytotoxicity (ADCC) against CD40-expressing immune cells. Apexigen believes that sotigalimab is the only CD40 agonist antibody in development that specifically binds to the CD40L binding domain, and that the combination of binding to the CD40L binding domain and the Fc mutation differentiates sotigalimab from other CD40 agonist antibodies in clinical development. These differentiators do not guarantee that sotigalimab will be proven effective or receive regulatory approval. Activation of CD40 initiates and amplifies a multi-cellular immune response, engaging components of both the innate and adaptive arms of the immune system to work in concert against cancer. As such, CD40 activation could play a fundamental role in tumor-specific immune activation. To maximize the therapeutic potential of sotigalimab, several Phase 2 trials are currently underway across multiple important cancer indications, lines of therapy and combination settings.

• Phase 2 preliminary data from sotigalimab in combination with chemoradiation as a neoadjuvant therapy in esophageal/gastro-esophageal junction cancer, which Apexigen plans to disclose by the end of 2022.

• Phase 2 preliminary data from sotigalimab in combination with standard of care chemotherapy in sarcoma is expected by year-end 2022.

• Apexigen plans to consult with the FDA about a potential registrational path in post-anti-PD-(L)1 melanoma in mid-2022.

• APX601: an anti-TNFR2 antagonist antibody designed to reverse immune suppression in the tumor microenvironment and unleash immune-mediated tumor killing activity through unique mechanisms of action. Based on APX601’s mechanisms of action, Apexigen believes APX601 can deplete and inactivate TNFR2-expressing Tregs, reverse myeloid-mediated T cell suppression and directly kill TNFR2-expressing tumor cells. In preclinical mouse models, APX601 shows potent anti-tumor activity

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and is well-tolerated. Apexigen plans to develop APX601 for the treatment of multiple tumor indications of unmet medical need and continues to progress toward a planned mid-2022 IND application filing.

Partnered Programs: Apexigen has out-licensed five programs to third parties for the development of product candidates that were discovered using the APXiMAB platform. One of these out-licensed programs has yielded a product that is commercially available. The other out-licensed product candidates are advancing in clinical development.

APXiMAB™ discovery platform: This platform has enabled Apexigen and its licensing partners to discover antibodies for clinical development against a variety of molecular targets, including targets that are difficult to drug with conventional antibody technologies.

Q: WHY IS BCAC PROPOSING THE BUSINESS COMBINATION?

A: BCAC was organized to effect a merger, capital stock exchange, asset acquisition, stock purchase, reorganization, or similar business combination with one or more businesses or entities. On February 2, 2021, BCAC completed its initial public offering of BCAC units, raising total gross proceeds of $57,500,000. On the same date, BCAC also completed sales of placement units to the Sponsor, raising total gross proceeds of $2,470,000. Since the BCAC IPO, BCAC’s activity has been limited to the evaluation of business combination candidates.

Based on its due diligence investigations of Apexigen and the industry in which it operates, including the financial and other information provided by Apexigen in the course of their negotiations in connection with the Business Combination Agreement, BCAC believes that consummating the Merger is advisable and in the best interests of BCAC and its stockholders. See “Meeting of BCAC’s Stockholders-Recommendation of BCAC Board of Directors” and “Background of the Business Combination-The BCAC Board’s Reasons for Approval of the Business Combination.”

Q: DID THE BCAC BOARD OBTAIN A THIRD-PARTY VALUATION OR FAIRNESS OPINION IN DETERMINING WHETHER OR NOT TO PROCEED WITH THE BUSINESS COMBINATION?

A: The BCAC Board did not obtain a third-party valuation or fairness opinion in connection with their determination to approve the Merger. The directors and officers of BCAC and BCAC’s advisors have substantial experience in evaluating the operating and financial merits of companies from a wide range of industries and concluded that their experience and backgrounds, together with the experience and sector expertise of BCAC’s financial advisors and consultants, enabled them to make the necessary analyses and determinations regarding the Merger. In addition, BCAC’s directors and officers and BCAC’s advisors have substantial experience with mergers and acquisitions. Accordingly, investors will be relying solely on the judgment of the BCAC Board and BCAC’s advisors in valuing Apexigen’s business.

Q: WHY IS BCAC PROVIDING STOCKHOLDERS WITH THE OPPORTUNITY TO VOTE ON THE BUSINESS COMBINATION?

A: We are seeking approval of the Business Combination for purposes of complying with applicable Nasdaq listing rules requiring stockholder approval of issuances of more than 20% of a listed company’s issued and outstanding common stock. In addition, pursuant to the Existing Charter, we must provide all Public Stockholders with the opportunity to redeem all or a portion of their Public Shares upon the consummation of an initial business combination, either in conjunction with a tender offer or in conjunction with a stockholder vote to approve such initial business combination. If we submit the proposed initial business combination to the stockholders for their approval, our Existing Charter requires us to conduct a redemption offer in conjunction with the proxy solicitation (but not in conjunction with a tender offer) pursuant to the applicable SEC proxy solicitation rules.

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Q: DO APEXIGEN’S STOCKHOLDERS NEED TO APPROVE THE BUSINESS COMBINATION?

A: Yes. Concurrently with the execution of the Business Combination Agreement, certain stockholders of Apexigen who, in the aggregate, hold (a) at least a majority of the outstanding shares of Apexigen capital stock, voting together as a single class and (b) at least a majority of the outstanding shares of Series A-1 Preferred Stock, Series B Preferred Stock and Series C Preferred Stock of Apexigen, voting together as a single class on an as-converted basis (the “Supporting Apexigen Stockholders”) entered into a stockholder support agreement (the “Stockholder Support Agreement”) with BCAC, pursuant to which such stockholders agreed to vote, at any meeting of the stockholders of Apexigen called for the purpose of approving the Merger, and in connection with any action by written consent of the stockholders requested by Apexigen for the purposes of approving the Merger, in favor of the approval and adoption of the Merger, the Business Combination Agreement and any other transactions contemplated thereby or under any other agreements executed and delivered in connection therewith.

Q: WHAT MATERIAL POSITIVE FACTORS DID THE BCAC BOARD CONSIDER IN CONNECTION WITH THE BUSINESS COMBINATION?

A: The BCAC Board considered a number of factors pertaining to the Business Combination. Among other things, the BCAC Board considered that Apexigen is well situated to act as a standalone public company and that Apexigen has a novel platform with the potential to exploit macro trends and for which there is the opportunity for further value creation as a public company through organic and inorganic growth, as well as a public company comparables analysis of 63 comparable companies in the oncology industry that became publicly traded companies between 2018 and 2021 with product candidates in Phase 1 or Phase 2 development to assess the value that the public markets would likely ascribe to the Combined Company following the Business Combination with BCAC. These factors are discussed in greater detail in the sections entitled “Background of the Business Combination-The BCAC Board’s Reasons for Approval of the Business Combination” and “Background of the Business Combination-Comparable Company Analysis.”

Q: WHAT MATERIAL NEGATIVE FACTORS DID THE BCAC BOARD CONSIDER IN CONNECTION WITH THE BUSINESS COMBINATION?

A: The BCAC Board considered a variety of uncertainties, risks and other potentially negative factors concerning the Business Combination. Among other things, the BCAC Board weighed (i) risk that BCAC’s Public Stockholders would vote against the Business Combination Proposal or exercise Redemption Rights, (ii) certain risks related to Apexigen’s business including the risks that Apexigen may not execute on its business plan, realize its projected financial performance or be able to raise additional, required funding, (iii) risk of litigation or regulatory action, (iv) challenges associated with Apexigen being subject to the applicable disclosure and listing requirements of a publicly traded company, (v) risk associated with the minority position in Apexigen that BCAC stockholders would hold following the consummation of the Business Combination, and (vi) the fees and expenses associated with completing the Business Combination.

These factors are discussed in greater detail in the section entitled “Background of the Business Combination—The BCAC Board’s Reasons for the Approval of the Business Combination” as well as in the section entitled “Risk Factors—Risks Related to the Business Combination.”

Q: DO I HAVE REDEMPTION RIGHTS?

A: If you are a holder of Public Shares, you have the right to demand that BCAC redeem such shares for a pro rata portion of the cash held in the Trust Account, calculated as of two business days prior to the Closing (including interest earned on the funds held in the Trust Account and not previously released to BCAC to pay taxes) upon the Closing (“Redemption Rights”).

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Notwithstanding the foregoing, a holder of Public Shares, together with any affiliate of such holder or any other person with whom such holder is acting in concert or as a “group” (as defined in Section 13(d)(3) of the Exchange Act) will be restricted from seeking redemption with respect to more than 15% of the total then outstanding Public Shares without the consent of BCAC. Accordingly, all Public Shares in excess of 15% held by a Public Stockholder, together with any affiliate of such stockholder or any other person with whom such holder is acting in concert or as a “group,” will not be redeemed without the consent of BCAC.

Under BCAC’s Existing Charter, the Public Shares can only be redeemed if BCAC has at least $5,000,001 of net tangible assets remaining, including at the time either immediately prior to or upon the Closing.

Q: WILL MY VOTE AFFECT MY ABILITY TO EXERCISE REDEMPTION RIGHTS?

A: No. You may exercise your Redemption Rights whether you vote your Public Shares for or against, or whether you abstain from voting on, the Business Combination Proposal or any other Proposal described in this proxy statement/prospectus. As a result, the Business Combination Proposal can be approved by stockholders who will redeem their Public Shares and no longer remain stockholders and the Merger may be consummated even though the funds available from the Trust Account and the number of public stockholders are substantially reduced as a result of redemptions by Public Stockholders.

Q: HOW DO I EXERCISE MY REDEMPTION RIGHTS?

A: If you are a holder of Public Shares and wish to exercise your Redemption Rights, you must demand that BCAC redeem your shares for cash no later than the second business day preceding the vote on the Business Combination Proposal by delivering your stock to BCAC’s transfer agent physically or electronically using Continental Stock Transfer & Trust Company’s DWAC (Deposit and Withdrawal at Custodian) system. Any holder of Public Shares will be entitled to demand that such holder’s shares be redeemed for a pro rata portion of the amount then in the Trust Account (which, for illustrative purposes, was approximately $[●], or $[●] per share, as of [●], 2022, the Record Date). Such amount, including interest earned on the funds held in the Trust Account and not previously released to BCAC to pay its taxes, will be paid promptly upon consummation of the Merger. However, under Delaware law, the proceeds held in the Trust Account could be subject to claims that could take priority over those of Public Stockholders exercising Redemption Rights, regardless of whether such holders vote for or against the Business Combination Proposal. Therefore, the per-share distribution from the Trust Account in such a situation may be less than originally anticipated due to such claims. Your vote on any Proposal will have no impact on the amount you will receive upon exercise of your Redemption Rights.

Any request for redemption, once made by a holder of Public Shares, may be withdrawn at any time up to the time the vote is taken with respect to the Business Combination Proposal at the Stockholders’ Meeting. If you deliver your shares for redemption to BCAC’s transfer agent and later decide prior to the Stockholders’ Meeting not to elect redemption, you may request that BCAC’s transfer agent return the shares (physically or electronically). If a holder of Public Shares properly makes a request for redemption and the Public Shares are delivered as described to BCAC’s transfer agent as described herein, then, if the Merger is consummated, BCAC will redeem these shares for a pro rata portion of funds deposited in the Trust Account. If you exercise your Redemption Rights, then you will be exchanging your Public Shares for cash and you will cease to have any rights as a BCAC stockholder (other than the right to receive the redemption amount) upon consummation of the Merger.

A BCAC stockholder holding both Public Shares and Warrants may redeem its Public Shares but retain the Warrants, which, if the Business Combination closes, will become warrants of the Combined Company. If redemption occurs at an assumed $[●] per share in which [●] Public Shares are redeemed, such redeeming public stockholders will retain an aggregate of [●] detachable redeemable warrants, which have an aggregate value of approximately $[●] based on the closing price of our detachable redeemable warrants on Nasdaq of $[●] on [●], 2022. In the event that the BCAC Related Funds Amount available to the Combined Company at Closing is less

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than $20,000,000, then that number of Sponsor Shares equal to (x) one (1) minus the quotient of the BCAC Related Funds Amount divided by $20,000,000, multiplied by (y) one-third (1/3) of the total number of Sponsor Shares, shall be deemed automatically forfeited and cancelled without any further actions by the Sponsor or any other person, and such surrendered shares will be recorded as cancelled by the Combined Company.

Q: WHAT ARE THE U.S. FEDERAL INCOME TAX CONSEQUENCES OF EXERCISING MY REDEMPTION RIGHTS?

A: It is expected that a U.S. Holder (as defined in “Material U.S. Federal Income Tax Considerations”) that exercises its Redemption Rights to receive cash from the Trust Account in exchange for its Public Shares will generally be treated as selling such Public Shares resulting in the recognition of capital gain or capital loss. There may be certain circumstances, however, in which the redemption may be treated as a distribution for U.S. federal income tax purposes depending on the amount of BCAC Common Stock that such U.S. Holder owns or is deemed to own. For a more complete discussion of the material U.S. federal income tax considerations for holders of Public Shares with respect to the exercise of Redemption Rights, see “Material U.S. Federal Income Tax Considerations—Material Tax Considerations with respect to a Redemption of Public Shares.”

All holders considering exercising Redemption Rights are urged to consult their tax advisor on the tax consequences to them of an exercise of Redemption Rights, including the applicability and effect of U.S. federal, state, local and non-U.S. tax laws. This proxy statement/prospectus shall not serve as an information statement for the stockholders of Apexigen for purposes of understanding the tax consequences of the Business Combination for such stockholders. If such an information statement is to be sent to Apexigen stockholders, Apexigen will separately prepare such document.

Q: HOW DO THE PUBLIC WARRANTS DIFFER FROM THE PRIVATE PLACEMENT WARRANTS AND WHAT ARE THE RELATED RISKS FOR ANY PUBLIC WARRANT HOLDERS POST BUSINESS COMBINATION?

A: The Public Warrants are identical to the Private Placement warrants in material terms and provisions, except that the Private Placement Warrants will not be transferable, assignable or salable until 30 days after the Closing (except in limited circumstances) and will not be redeemable by BCAC so long as they are held by the initial stockholders or any of their permitted transferees. If the Private Placement Warrants are held by holders other than the initial stockholders or any of their permitted transferees, they will be redeemable by BCAC and exercisable by the holders on the same basis as the Public Warrants. The initial stockholders agreed not to transfer, assign or sell any of the Private Placement Warrants, including the common stock issuable upon exercise of such warrants (except to certain permitted transferees), until 30 days after the Closing.

Following the Closing, BCAC may redeem your Public Warrants prior to their exercise at a time that is disadvantageous to you. BCAC will have the ability to redeem outstanding Public Warrants at any time after they become exercisable and prior to their expiration, at a price of $0.01 per Public Warrant, provided that the closing price of common stock equals or exceeds $18.00 per share (as adjusted for adjustments to the number of shares issuable upon exercise or the exercise price of a warrant) for any 20 trading days within a 30 trading day period ending on the third trading day prior to proper notice of such redemption, provided that certain other conditions are met. If and when the Public Warrants become redeemable by us, we may exercise the redemption right even if we are unable to register or qualify the underlying securities for sale under all applicable state securities laws. As a result, BCAC may redeem the warrants as set forth above even if the holders are otherwise unable to exercise the warrants. Redemption of the outstanding Public Warrants could force you (i) to exercise your Public Warrants and pay the exercise price therefor at a time when it may be disadvantageous for you to do so, (ii) to sell your Public Warrants at the then-current market price when you might otherwise wish to hold your Public Warrants or (iii) to accept the nominal redemption price which, at the time the outstanding Public Warrants are called for redemption, is likely to be

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substantially less than the market value of your public warrants. None of the Private Placement Warrants will be redeemable by BCAC so long as they are held by the initial stockholders or their permitted transferees.

Historical trading prices for our shares of common stock have varied between a low of approximately $9.81 per share on August 5, 2021 to a high of approximately $10.65 per share on February 22, 2022 but have not approached the $18.00 per share threshold for redemption (which, as described above, would be required for 20 trading days within a 30 trading-day period after they become exercisable and prior to their expiration, at which point the Public Warrants would become redeemable). In the event that BCAC elects to redeem all of the redeemable warrants as described above, BCAC will fix a date for the redemption. Notice of redemption will be mailed by first class mail, postage prepaid, by us not less than 30 days prior to the redemption date to the registered holders of the Public Warrants to be redeemed at their last addresses as they appear on the registration books. Any notice mailed in the manner provided in the Warrant Agreement dated January 28, 2021, which will be amended and restated immediately prior to the issuance of the PIPE Warrants, between BCAC and Continental Stock Transfer & Trust Company, as warrant agent (the “Warrant Agreement”) shall be conclusively presumed to have been duly given whether or not the registered holder received such notice. In addition, beneficial owners of the redeemable warrants will be notified of such redemption by our posting of the redemption notice to The Depository Trust Company.

Q: DO I HAVE APPRAISAL RIGHTS IF I OBJECT TO THE PROPOSED BUSINESS COMBINATION?

A: No. Neither BCAC stockholders nor its unit or warrant holders have appraisal rights in connection with the Business Combination under the DGCL. Under the DGCL, however, holders of Apexigen capital stock may be entitled to appraisal rights in connection with the Business Combination. See “Meeting of BCAC Stockholders- Appraisal Rights.”

Q: WHAT HAPPENS TO THE FUNDS DEPOSITED IN THE TRUST ACCOUNT AFTER CONSUMMATION OF THE BUSINESS COMBINATION?

A: After the April Partial Redemption (as defined herein), a total of approximately $51.1 million remains of the $58.1 million in net proceeds of the BCAC IPO and a portion of the amount raised from the sale of the private placement units that occurred simultaneously with the consummation of the BCAC IPO and which were placed in the Trust Account following the BCAC IPO. Such amount in the Trust Account has been accruing interest from which BCAC is entitled to make withdrawals to make tax payments. In addition, in connection with the approval of the Extension Amendment, the Sponsor has agreed to contribute the Additional Contributions. After consummation of the Merger, the funds in the Trust Account will be used to pay holders of the Public Shares who exercise Redemption Rights, to pay fees and expenses incurred in connection with the Business Combination and for the Combined Company’s working capital and general corporate purposes.

Q: HOW DOES THE SPONSOR INTEND TO VOTE ON THE PROPOSALS?

A: As of [●], 2022, the Record Date, the Sponsor was entitled to vote an aggregate of 1,627,000 shares of BCAC Common Stock, consisting of Founder Shares that were issued prior to the BCAC IPO and shares that are included as a constituent part of the placement units that were issued simultaneously with the BCAC IPO (“BCAC Voting Shares”). Such shares currently constitute approximately 24.1% of the outstanding shares of BCAC’s common stock. Concurrently with the execution of the Business Combination Agreement, the Sponsor entered into the Sponsor Support Agreement with BCAC and Apexigen, pursuant to which the Sponsor agreed, at any meeting of BCAC stockholders and in connection with any action by written consent of the stockholders of BCAC, to (i) appear or cause all shares or other voting securities of BCAC it holds, owns, or is entitled to vote, whether as shares or as a constituent part of a unit of securities to be counted present for quorum purposes, (ii) vote (or execute an action by written consent) or cause to be voted (A) in favor of the Business Combination Agreement, the Merger, and any other transactions

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contemplated by the Business Combination Agreement, (B) against any action, agreement or transaction or proposal that would result in a breach of the Business Combination Agreement or that would reasonably be expected to result in a failure to consummate the Merger, (C) in favor of the proposals and any other matters necessary or reasonably requested by BCAC for the consummation of the Business Combination, (D) against any business combination proposal other than with Apexigen and any other action that would reasonably be expected to materially impede, delay, or adversely affect the Business Combination or result in a breach of any obligation or agreement of the Sponsor contained in the Sponsor Support Agreement.

Q: WHAT CONSTITUTES A QUORUM AT THE STOCKHOLDERS’ MEETING?

A: A quorum of BCAC stockholders is necessary to hold a valid meeting. A quorum will be present at the Stockholders’ Meeting if a majority of the voting power of all outstanding shares of BCAC Common Stock entitled to vote at the Stockholders’ Meeting as of the Record Date is represented in person (which would include presence at a virtual meeting) or by proxy. Abstentions and broker non-votes will be counted as present for the purpose of determining a quorum. The Sponsor, which currently owns approximately 24.1% of the issued and outstanding shares of BCAC Common Stock, will count towards this quorum. As of [●], 2022, the Record Date, 3,373,047 shares of BCAC Common Stock would be required to achieve a quorum.

Q: WHAT VOTE IS REQUIRED TO APPROVE EACH PROPOSAL AT THE STOCKHOLDERS’ MEETING?

A: The Business Combination Proposal: The affirmative vote (in person or by proxy) of the holders of a majority of the shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting, voting as a single class, is required to approve the Business Combination Proposal. Accordingly, a stockholder’s failure to vote by proxy or to vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting, as well as an abstention from voting and a broker non-vote with regard to the Business Combination Proposal, will have no effect on the Business Combination Proposal. BCAC stockholders must approve the Business Combination Proposal in order for the Merger to occur.

The Charter Proposals: The affirmative vote (in person or by proxy) of the holders of a majority of the shares of BCAC Common Stock entitled to vote thereon, voting as a single class, is required to approve the Charter Proposals. Accordingly, a stockholder’s failure to vote by proxy or to vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting, as well as an abstention from voting and a broker non-vote with regard to the Charter Proposals, will have the same effect as a vote “AGAINST” such proposal. The Closing is conditioned on the approval of the Charter Proposals, subject to the terms of the Business Combination Agreement. If the Business Combination Proposal is not approved, the Charter Proposals will not be presented to the stockholders for a vote.

The Director Election Proposal: The affirmative vote (in person or by proxy) of the holders of a plurality of the outstanding shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting, is required to approve the Director Election Proposal. Accordingly, a stockholder’s failure to vote by proxy or to vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting, as well as an abstention from voting and a broker non-vote with regard to the Director Election Proposal, will have no effect on the election of directors. If the Business Combination Proposal is not approved, the Director Election Proposal will not be presented to the stockholders for a vote.

The Nasdaq Proposal: The affirmative vote (in person or by proxy) of the holders of a majority of the shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting, voting as a single class, is required to approve the Nasdaq Proposal. Accordingly, a stockholder’s failure to vote by proxy or to vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting, as well as an abstention from voting and a broker non-vote with regard to the Nasdaq Proposal, will have no effect on the Nasdaq Proposal. The Closing is conditioned on the approval of the Nasdaq Proposal, subject to the terms of the Business Combination Agreement. If the Business Combination Proposal is not approved, the Nasdaq Proposal will not be presented to the stockholders for a vote.

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The Equity Incentive Plan Proposal: The affirmative vote (in person or by proxy) of the holders of a majority of the shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting, voting as a single class, is required to approve the Equity Incentive Plan Proposal. Accordingly, a stockholder’s failure to vote by proxy or to vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting, as well as an abstention from voting and a broker non-vote with regard to the Equity Incentive Plan Proposal, will have no effect on the Equity Incentive Plan Proposal. The Closing is conditioned on the approval of the Equity Incentive Plan Proposal, subject to the terms of the Business Combination Agreement. If the Business Combination Proposal is not approved, the Equity Incentive Plan Proposal will not be presented to the stockholders for a vote.

The ESPP Proposal: The affirmative vote (in person or by proxy) of the holders of a majority of the shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting, voting as a single class, is required to approve the ESPP Proposal. Accordingly, a stockholder’s failure to vote by proxy or to vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting, as well as an abstention from voting and a broker non-vote with regard to the ESPP Proposal, will have no effect on the ESPP Proposal. The Closing is conditioned on the approval of the ESPP Proposal, subject to the terms of the Business Combination Agreement. If the Business Combination Proposal is not approved, the ESPP Proposal will not be presented to the stockholders for a vote.

The Adjournment Proposal: The affirmative vote (in person or by proxy) of the holders of a majority of the shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting, voting as a single class, is required to approve the Adjournment Proposal. Accordingly, a stockholder’s failure to vote by proxy or to vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting, as well as an abstention from voting and a broker non-vote with regard to the Adjournment Proposal, will have no effect on the Adjournment Proposal. The Closing is not conditioned on the approval of the Adjournment Proposal.

As of [●], 2022, the Record Date, the Sponsor was entitled to vote the BCAC Voting Shares. Such shares currently constitute approximately 24.1% of the outstanding shares of BCAC’s common stock. The Sponsor has agreed to vote all of its shares of BCAC Common Stock, in favor of each of the Proposals presented at the Stockholders’ Meeting. See “Other Agreements-Sponsor Support Agreement.”

Q: DO ANY OF BCAC’S DIRECTORS OR OFFICERS HAVE INTERESTS IN THE BUSINESS COMBINATION THAT MAY DIFFER FROM OR BE IN ADDITION TO THE INTERESTS OF BCAC STOCKHOLDERS?

A: Certain of BCAC’s executive officers and certain non-employee directors may have interests in the Merger that may be different from, or in addition to, the interests of BCAC stockholders generally.

These interests include, among other things:

• If the Business Combination with Apexigen or another business combination is not consummated within the Completion Window, BCAC will cease all operations except for the purpose of winding up, redeeming 100% of the outstanding Public Shares for cash and, subject to the approval of its remaining stockholders and the BCAC Board, dissolving and liquidating. In such event, the 1,437,500 Founder Shares held by the Sponsor, the underwriter of BCAC’s initial public offering, and certain of the underwriter’s employees, which were acquired for a purchase price of approximately $0.017 per share, would be worthless because holders of the Founder Shares are not entitled to participate in any redemption or distribution with respect to such shares. The Founder Shares had an aggregate market value of $[●] based upon the closing price of $[●] per share of BCAC Common Stock on the Nasdaq on the Record Date, of which the 1,380,000 Founder Shares held by the Sponsor had an aggregate market value of $[●]. Each of BCAC’s directors is a member of the Sponsor, and therefore will have an economic interest in the Founder Shares held by the Sponsor.

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• Given the differential in the purchase price that our Sponsor paid for the Founder Shares as compared to the price of the BCAC units sold in the BCAC IPO and the substantial number of shares of Combined Company common stock that our Sponsor will receive upon conversion of the Founder Shares in connection with the Business Combination, our Sponsor and its affiliates may earn a positive rate of return on their investment even if the Combined Company common stock trades below the price initially paid for the BCAC units in the BCAC IPO and the Public Stockholders experience a negative rate of return following the completion of the Business Combination. Thus, our Sponsor and its affiliates may have more of an economic incentive for us to, rather than liquidate if we fail to complete our initial business combination by the Completion Window, enter into an initial business combination on potentially less favorable terms with a potentially less favorable, riskier, weaker-performing or financially unstable business, or an entity lacking an established record of revenues or earnings, than would be the case if such parties had paid the full offering price for their Founder Shares.

• The Sponsor purchased an aggregate of 247,000 placement units from BCAC for an aggregate purchase price of $2,470,000 (or $10.00 per unit). This purchase took place on a private placement basis simultaneously with the consummation of the BCAC IPO. A portion of the proceeds BCAC received from this purchase were placed in the Trust Account. Such units had an aggregate market value of approximately $[●] based upon the closing price of $[●] per unit on the Nasdaq on [●], 2022, the Record Date. The placement units will become worthless if BCAC does not consummate a business combination within the Completion Window.

• Samuel Wertheimer will become a director of the Combined Company after the Closing. As such, in the future he may receive any cash fees, stock options or stock awards that the Combined Company Board determines to pay to its directors.

• BCAC’s directors and officers, and their affiliates are entitled to reimbursement of out-of-pocket expenses incurred by them in connection with certain activities on BCAC’s behalf, such as identifying and investigating possible business targets and business combinations. However, if BCAC fails to consummate a business combination within the Completion Window, they will not have any claim against the Trust Account for reimbursement. Accordingly, BCAC may not be able to reimburse these expenses if the Business Combination or another business combination is not consummated within the Completion Window. As of the date of this prospectus, there were no out-of-pocket expenses incurred by BCAC’s directors, officers or their affiliates that have not otherwise been reimbursed from BCAC’s working capital funds following the BCAC IPO. Additionally, the Sponsor is entitled to $10,000 per month for office space, utilities, administrative and support services provided to BCAC’s management team, which commenced on January 28, 2021 and will continue through the earlier of consummation of the Business Combination and BCAC’s liquidation.

• In connection with the approval of the Extension Amendment (as defined below), the Sponsor has agreed to contribute to BCAC as a loan the Additional Contributions. The amount of the Additional Contributions will not bear interest and will be repayable by BCAC to the Sponsor upon Closing.

• The continued indemnification of current directors and officers and the continuation of directors’ and officers’ liability insurance.

• In the event of the liquidation of the Trust Account, the Sponsor has agreed to indemnify and hold harmless BCAC against any and all losses, liabilities, claims, damages and expenses to which BCAC may become subject as a result of any claim by (i) any third party for services rendered or products sold to BCAC or (ii) a prospective target business with which BCAC has entered into an acquisition agreement, provided that such indemnification of BCAC by the Sponsor shall apply only to the extent necessary to ensure that such claims by a third party for services rendered or products sold to BCAC or a target do not reduce the amount of funds in the Trust Account to below (i) $10.00 per share of BCAC Common Stock or (ii) such lesser amount per share of BCAC Common Stock held in the Trust Account due to reductions in the value of the trust assets as of the date of the liquidation of the Trust Account, in each case, net of the amount of interest earned on the property in the Trust Account, which may be withdrawn to pay taxes and expenses related to the administration of the Trust Account, except

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as to any claims by a third party (including a target) who executed a waiver of any and all rights to seek access to the Trust Account and except as to any claims under BCAC’s indemnity of the underwriters of the BCAC IPO against certain liabilities, including liabilities under the Securities Act. If BCAC consummates the Business Combination, on the other hand, BCAC will be liable for all such claims.

• The Sponsor has agreed not to transfer, assign, or sell (i) 50% of its Founder Shares until the earlier of (A) six months after the date of the consummation of the Business Combination or (B) the date on which the closing price of BCAC Common Stock equals or exceeds $12.50 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within any 30-trading day period commencing after the Business Combination, and (ii) the remaining 50% of the Founder Shares until six months following the consummation of the Business Combination, subject to certain customary exceptions.

• Subject to certain limited exceptions, the placement units will not be transferable until 30 days following the completion of the Business Combination.

• For a period of six years after the Closing Date, BCAC shall defend, indemnify and hold harmless the Sponsor, its affiliates, and their respective present and former directors and officers against any costs or expenses, judgments, fines, losses, claims, damages or liabilities incurred in connection with any action by any stockholder of BCAC who has not exercised Redemption Rights arising from Sponsor’s ownership of equity securities of BCAC, or its control or ability to influence BCAC, and further arising out of or pertaining to the transactions, actions, and investments contemplated by the Business Combination Agreement or any Ancillary Agreements.

• BCAC will pay Brookline Capital Markets, a division of Arcadia Securities, LLC (“Brookline Capital Markets”), and an affiliate of our Sponsor for which certain of our officers provide services, $200,000 to act as BCAC’s financial advisor, investment banker, and consultant in connection with the Business Combination. The services provided by Brookline Capital Markets included assessment of the market environment as well as BCAC’s relative positioning within the marketplace, assessment of BCAC’s stockholder base, potential target investors and potential marketing strategies for its securities, assistance in the preparation of marketing materials for BCAC, and other customary financial advisory services and investment banking services in connection with BCAC’s contemplated business combination transaction. While Brookline Capital Markets provided assistance to BCAC in the preparation of our initial terms proposed to Apexigen, it did not otherwise participate in any discussions among the parties.

• In the event that the BCAC Related Funds Amount at Closing is less than $20,000,000, then that number of Sponsor Shares equal to (x) one minus the quotient of the BCAC Related Funds Amount divided by $20,000,000, multiplied by (y) 1/3 of the total number of Sponsor Shares, shall be deemed automatically forfeited and cancelled without any further actions by the Sponsor or any other person, and such surrendered shares will be recorded as cancelled by the Combined Company.

There will be no finder’s fees, reimbursements or cash payments made by BCAC to the Sponsor or BCAC’s officers or directors, or any of BCAC’s or its officers’ or directors’ affiliates, for services rendered to BCAC prior to or in connection with the completion of the Business Combination, other than payment of the amount described above for office space, utilities, administrative and support services, and repayments of the Additional Contributions and any working capital loans made as non-interest bearing notes (the “Working Capital Notes”) by our Sponsor or affiliates of our Sponsor to fund working capital deficiencies or finance transaction costs in connection with an initial business combination, which Working Capital Notes will be repayable by BCAC upon Closing. The Sponsor, in its discretion, may in lieu of having the Working Capital Notes repaid upon the Closing, instead convert the Working Capital Notes into units of BCAC, at a price of $10.00 per unit, upon the Closing, provided that the maximum amount that may be converted is no more than $1,500,000. The Sponsor and BCAC’s officers and directors or any of their respective affiliates will also be reimbursed for any out-of-pocket expenses incurred in connection with BCAC’s formation, the BCAC IPO and activities on BCAC’s behalf such as identifying potential target

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businesses and performing due diligence on suitable business combinations. There is no cap or ceiling on the reimbursement of out-of-pocket expenses incurred by such persons in connection with activities on our behalf. As of the date of this prospectus, the Sponsor had not incurred any out-of-pocket expenses in connection with the Business Combination that, as of such date, had not been reimbursed by BCAC from BCAC’s working capital funds following the BCAC IPO.

The BCAC Board was aware of and considered these interests to the extent such interests existed at the time, among other matters, in approving the Business Combination Agreement and in recommending that the Business Combination be approved by the stockholders of BCAC.

Q: WHAT DO I NEED TO DO NOW?

A: BCAC urges you to carefully read and consider the information contained in this proxy statement/prospectus, including the annexes and the other documents referred to herein, and to consider how the Merger will affect you as a stockholder and/or warrant holder of BCAC. Stockholders should then vote as soon as possible in accordance with the instructions provided in this proxy statement/prospectus and on the enclosed proxy card.

Q: WHAT HAPPENS IF I SELL MY SHARES OF BCAC COMMON STOCK BEFORE THE STOCKHOLDERS’ MEETING?

A: The Record Date for the Stockholders’ Meeting is earlier than the date that the Business Combination is expected to be completed. If you transfer your shares of BCAC Common Stock after the Record Date, but before the Stockholders’ Meeting, unless the transferee obtains from you a proxy to vote those shares, you will retain your right to vote at the Stockholders’ Meeting. However, you will not be able to seek redemption of your shares of BCAC Common Stock because you will no longer be able to tender them prior to the Stockholders’ Meeting in accordance with the provisions described herein. If you transferred your shares of BCAC Common Stock prior to the Record Date, you have no right to vote those shares at the Stockholders’ Meeting or redeem those shares for a pro rata portion of the proceeds held in the Trust Account.

Q: HOW DO I VOTE?

A: If you are a holder of record of BCAC Common Stock on the Record Date, you may vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting or by submitting a proxy for the Stockholders’ Meeting. You may submit your proxy by completing, signing, dating, and returning the enclosed proxy card in the accompanying pre-addressed postage paid envelope. If you hold your shares in “street name,” which means your shares are held of record by a broker, bank or nominee, you should contact your broker to ensure that votes related to the shares you beneficially own are properly counted. In this regard, you must provide the broker, bank or nominee with instructions on how to vote your shares or, if you wish to attend the meeting and vote in person (which would include presence at a virtual meeting), obtain a proxy from your broker, bank or nominee.

Q: IF MY SHARES ARE HELD IN “STREET NAME” BY A BROKER, BANK OR OTHER NOMINEE, WILL MY BROKER, BANK OR OTHER NOMINEE VOTE MY SHARES FOR ME?

A: If your shares are held in “street name” in a stock brokerage account or by a broker, bank, or other nominee, you must provide the record holder of your shares with instructions on how to vote your shares. Please follow the voting instructions provided by your broker, bank, or other nominee. Please note that you may not vote shares held in “street name” by returning a proxy card directly to BCAC or by voting in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting unless you provide a “legal proxy,” which you must obtain from your broker, bank or other nominee.

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Under the rules of Nasdaq, brokers who hold shares in “street name” for a beneficial owner of those shares typically have the authority to vote in their discretion on “routine” proposals when they have not received instructions from beneficial owners. However, brokers are not permitted to exercise their voting discretion with respect to the approval of matters that Nasdaq determines to be “non-routine” without specific instructions from the beneficial owner. It is expected that all proposals to be voted on at the Stockholders’ Meeting are “non-routine” matters. Broker non-votes occur when a broker or nominee is not instructed by the beneficial owner of shares to vote on a particular proposal for which the broker does not have discretionary voting power.

If you are a BCAC stockholder holding your shares in “street name” and you do not instruct your broker, bank or other nominee on how to vote your shares, your broker, bank or other nominee will not vote your shares on the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the ESPP Proposal or the Adjournment Proposal. Such broker non-votes will be the equivalent of a vote “AGAINST” the Charter Proposals, but will have no effect on the vote count for such other Proposals.

Q: WHAT IF I ATTEND THE STOCKHOLDERS’ MEETING AND ABSTAIN OR DO NOT VOTE?

A: For purposes of the Stockholders’ Meeting, an abstention occurs when a stockholder attends the meeting in person (which would include presence at a virtual meeting) and does not vote or returns a proxy with an “abstain” vote.

If you are a BCAC stockholder that attends the Stockholders’ Meeting virtually and fails to vote on the Charter Approval Proposal, your failure to vote will have the same effect as a vote “AGAINST” such proposal.

If you are a BCAC stockholder that attends the Stockholders’ Meeting virtually and fails to vote on the Business Combination Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the ESPP Proposal and the Adjournment Proposal, your failure to vote will have no effect on the Business Combination Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the ESPP Proposal or the Adjournment Proposal.

Q: WHAT WILL HAPPEN IF I RETURN MY PROXY CARD WITHOUT INDICATING HOW TO VOTE?

A: If you sign and return your proxy card without indicating how to vote on any particular proposal, the BCAC Common Stock represented by your proxy will be voted “FOR” each of the Proposals presented at the Stockholders’ Meeting.

Q: MAY I CHANGE MY VOTE AFTER I HAVE MAILED MY SIGNED PROXY CARD?

A: Yes. You may change your vote at any time before your proxy is exercised by doing any one of the following:

• sending another proxy card with a later date;

• notifying BCAC’s Secretary in writing before the Stockholders’ Meeting that you have revoked your proxy; or

• attending the Stockholders’ Meeting and voting electronically by visiting https://www.cstproxy.com/bcac/sm2022 and entering the control number found on your proxy card, instruction form or notice you previously received. Attendance at the Stockholders’ Meeting will not, in and of itself, revoke a proxy.

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If you are a stockholder of record of BCAC and you choose to send a written notice or to mail a new proxy, you must submit your notice of revocation or your new proxy to BCAC, 280 Park Avenue, Suite 43W, New York, NY 10017 and it must be received at any time before the vote is taken at the Stockholders’ Meeting. Any proxy that you submitted may also be revoked by submitting a new proxy by mail, or online or by telephone, not later than 11:59 p.m. prevailing Eastern Time on [●], 2022, or by voting at the Stockholders’ Meeting. Simply attending the Stockholders’ Meeting will not revoke your proxy. If your shares are held in “street name” or are in a margin or similar account, you should contact your broker for information on how to change or revoke your voting instructions, and must follow the directions you receive from your broker, bank or other nominee in order to change or revoke your vote.

Q: WHAT HAPPENS IF I FAIL TO TAKE ANY ACTION WITH RESPECT TO THE STOCKHOLDERS’ MEETING?

A: If you fail to take any action with respect to the Stockholders’ Meeting and the Merger is approved by stockholders and consummated, you will become a stockholder or warrant holder, as applicable, of the Combined Company. Failure to take any action with respect to the Stockholders’ Meeting will not affect your ability as a stockholder to exercise your Redemption Rights prior to the Stockholders’ Meeting in accordance with the procedures set forth in this proxy statement/prospectus. If you fail to take any action with respect to the Stockholders’ Meeting and the Merger is not approved, you will continue to be a stockholder and/or warrant holder of BCAC while BCAC searches for another target business with which to complete a business combination.

Q: WHAT SHOULD I DO IF I RECEIVE MORE THAN ONE SET OF VOTING MATERIALS?

A: Stockholders may receive more than one set of voting materials, including multiple copies of this proxy statement/prospectus and multiple proxy cards or voting instruction cards. For example, if you hold your shares of BCAC Common Stock in more than one brokerage account, you will receive a separate voting instruction card for each brokerage account in which you hold shares. If you are a holder of record and your shares of BCAC Common Stock are registered in more than one name, you will receive more than one proxy card. Please complete, sign, date and return each proxy card and voting instruction card that you receive in order to cast a vote with respect to all of your shares of BCAC Common Stock.

Q: WHO CAN HELP ANSWER MY QUESTIONS?

A: If you have questions about the Merger or if you need additional copies of the proxy statement/prospectus or the enclosed proxy card you should contact:

Stockholders may call toll free: (800) 662-5200

Banks and Brokers may call collect: (800) 662-5200

bcac.info@investor.morrowsodali.com

You may also obtain additional information about BCAC from documents filed with the SEC by following the instructions in the section entitled “Where You Can Find More Information.” If you are a holder of Public Shares and you intend to seek redemption of your Public Shares, you will need to deliver your shares of BCAC Common Stock (either physically or electronically) to BCAC’s transfer agent at the address below prior to the vote at the Stockholders’ Meeting. If you have questions regarding the certification of your position or delivery of your stock, please contact:

Continental Stock Transfer & Trust Company

1 State Street, 30th Floor

New York, New York 10004

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SUMMARY

This summary highlights selected information included in this proxy statement/prospectus and does not contain all of the information that may be important to you. You should read this entire document and its annexes and the other documents to which we refer before you decide how to vote. Each item in this summary includes a page reference directing you to a more complete description of that item.

The Business Combination and the Business Combination Agreement

The terms and conditions of the Business Combination are contained in the Business Combination Agreement, which is attached as Annex A to this proxy statement/prospectus. We encourage you to read the Business Combination Agreement carefully, as it is the legal document that governs the Business Combination.

If the Business Combination Agreement is approved and adopted and the Business Combination is subsequently completed, Merger Sub will merge with and into Apexigen with Apexigen surviving the Merger as a wholly owned subsidiary of BCAC. At the Closing, BCAC will be renamed as Apexigen, Inc.

Merger Consideration

Subject to the terms of the Business Combination Agreement, the Aggregate Closing Merger Consideration with respect to all holders of Apexigen securities outstanding immediately prior to the Closing, which will be issued in the form of shares or equity awards relating to shares of BCAC Common Stock, will equal to the quotient of (a) the sum of (i) $205,000,000 and (ii) the sum of the exercise prices of all options to purchase shares of common stock of Apexigen outstanding immediately prior to the Effective Time, divided by (b) $10.00.

At the Effective Time:

• each issued and outstanding share of Apexigen capital stock (including shares of capital stock that are issued and outstanding immediately prior to the Effective Time resulting from the conversion or exercise of shares of the Apexigen Preferred Stock, Apexigen Warrants, and Apexigen Options, but excluding any dissenting shares) will be converted into the right to receive a number of shares of BCAC Common Stock equal to the Exchange Ratio;

• each share of capital stock of Apexigen held in the treasury of Apexigen shall be canceled without any conversion thereof and no payment or distribution shall be made with respect thereto;

• each Apexigen Option that is outstanding immediately prior to the Effective Time, whether vested or unvested, will be assumed by BCAC and converted into a BCAC Option on substantially the same vesting and exercisability terms and conditions as such Apexigen Options, except that (i) such BCAC Option will represent the right to purchase that whole number of shares of BCAC Common Stock (rounded down to the nearest whole share) equal to the product of the number of shares of Apexigen Common Stock subject to such Apexigen Option multiplied by the Exchange Ratio, and (ii) the exercise price per share for each such BCAC Option will be equal to the quotient of (A) the exercise price per share of such Apexigen Option in effect immediately prior to the Effective Time, divided by (B) the Exchange Ratio (the exercise price per share, as so determined, being rounded up to the nearest full cent); and

• each Apexigen Warrant that is issued and outstanding immediately prior to the Effective Time will be treated in accordance with the terms thereof, as may be amended prior to the Effective Time by Apexigen and the holder thereof with the consent of BCAC.

The Aggregate Closing Merger Consideration will be issued to holders of Apexigen securities at the Closing in accordance with the Business Combination Agreement. The portion of the Aggregate Closing Merger

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Consideration issuable to any person by virtue of the Merger will be calculated on an aggregate basis with respect to all shares of capital stock of Apexigen held of record by such person immediately prior to the Effective Time, and after such aggregation, any fractional share of BCAC Common Stock that would otherwise be issuable to such person following such aggregation will be rounded up to a whole share of BCAC Common Stock.

The total number of shares of BCAC Common Stock expected to be issued to holders of Apexigen capital stock in connection with the Closing (after giving effect to the net exercise or conversion of outstanding equity awards of Apexigen and Apexigen Warrants) is 18,104,074 shares, which will represent approximately 68.2% of the total number of shares of Combined Company common stock outstanding immediately following consummation of the Business Combination (assuming no additional redemptions, other than the April Partial Redemption, by Public Stockholders and no exercises of BCAC warrants).

Ownership of the Combined Company

As of [●], 2022, the Record Date, there were 6,746,092 shares of BCAC Common Stock issued and outstanding and one holder of record of BCAC Common Stock.

After giving effect to the Business Combination (assuming no Public Shares of BCAC have been redeemed and no BCAC Warrants have been exercised), we expect that there will be approximately 26,502,166 shares of Combined Company common stock outstanding (after giving effect to the net exercise or conversion of outstanding equity awards of Apexigen and Apexigen Warrants) consisting of (i) 1,627,000 shares held by the Sponsor, (ii) 18,104,074 shares issued to holders of Apexigen securities, (iii) 1,502,000 shares held by the PIPE Investors pursuant to the Subscription Agreements, (iv) 150,000 shares held by Lincoln Park pursuant to the Lincoln Park Purchase Agreement, (v) 5,061,592 shares held by BCAC’s Public Stockholders, and (vi) 57,500 shares held by the Representative.

After giving effect to the Business Combination (assuming that Public Stockholders holding 5,061,592 shares of outstanding BCAC Common Stock exercise their Redemption Rights (representing the maximum redemptions) and no BCAC warrants have been exercised), we expect that there will be approximately 20,980,574 shares of Combined Company common stock outstanding (after giving effect to the net exercise or conversion of outstanding equity awards of Apexigen and Apexigen Warrants), consisting of (i) 1,167,000 shares held by the Sponsor, (ii) 18,104,074 shares issued to holders of Apexigen securities, (iii) 1,502,000 shares held by the PIPE Investors pursuant to the Subscription Agreements, (iv) 150,000 shares held by Lincoln Park pursuant to the Lincoln Park Purchase Agreement, and (v) 57,500 shares held by the Representative.

All shares issued as merger consideration in the Business Combination will be freely tradable without registration under the Securities Act and without restriction by persons other than our “affiliates” (as defined under Rule 144 of the Securities Act (“Rule 144”)), including our directors, executive officers and other affiliates.

The numbers of shares set forth above are based on a number of assumptions, including that neither BCAC nor Apexigen issue any additional equity securities prior to the Business Combination. If the actual facts differ from our assumptions, the numbers of shares set forth above will be different. See “Unaudited Pro Forma Condensed Combined Financial Information.”

Recommendation of the BCAC Board

The BCAC Board unanimously determined that the Business Combination Agreement and the transactions contemplated thereby, including the Merger, were advisable, fair to, and in the best interests of, BCAC and its stockholders. Accordingly, the BCAC Board unanimously recommends that its stockholders vote “FOR” each of the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal,

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the Equity Incentive Plan Proposal, the ESPP Proposal and the Adjournment Proposal. See “Meeting of BCAC’s Stockholders-Recommendation of BCAC Board of Directors” and “Background of the Business Combination-The BCAC Board’s Reasons for Approval of the Business Combination.”

The Stockholders’ Meeting

The Stockholders’ Meeting of BCAC stockholders will be held on [●], 2022, at, Eastern Time, in virtual format. At the Stockholders’ Meeting, BCAC is asking holders of BCAC Common Stock to consider and vote upon the following proposals:

• The Business Combination Proposal-To consider and vote upon a proposal to approve the Business Combination Agreement, in the form attached hereto as Annex A, and the Business Combination;

• The Charter Proposals-To consider and vote upon a proposal to adopt the Proposed Charter, in the form attached hereto as Annex B;

• The Director Election Proposal-To consider and vote upon a proposal to elect seven directors to serve on the Combined Company Board until the first annual meeting of stockholders following the effectiveness of the Proposed Charter, in the case of Class I directors, the second annual meeting of stockholders following the effectiveness of the Proposed Charter, in the case of Class II directors, and the third annual meeting of stockholders following the effectiveness of the Proposed Charter, in the case of Class III directors, and, in each case, until their respective successors are duly elected and qualified;

• The Nasdaq Proposal-To consider and vote upon a proposal to approve, for purposes of complying with applicable listing rules of Nasdaq: (i) the issuance of shares of BCAC Common Stock to Apexigen stockholders pursuant to the Business Combination Agreement; (ii) the issuance of shares of BCAC Common Stock to the PIPE Investors pursuant to the Subscription Agreements (including upon exercise of the PIPE Warrants issued pursuant to the Subscription Agreements); and (iii) the issuance of shares of BCAC Common Stock and Combined Company common stock to Lincoln Park pursuant to the Lincoln Park Purchase Agreement;

• The Equity Incentive Plan Proposal-To consider and vote upon a proposal to approve and adopt the 2022 Equity Incentive Plan, in the form attached hereto as Annex H;

• The ESPP Proposal-To consider and vote upon a proposal to approve and adopt the 2022 Employee Stock Purchase Plan, in the form attached hereto as Annex I;

• The Adjournment Proposal-To consider and vote upon a proposal to approve the adjournment of the Stockholders’ Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies in the event that there are insufficient votes for the approval of the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal or the ESPP Proposal.

You will be entitled to vote or direct votes to be cast at the Stockholders’ Meeting if you owned shares of BCAC Common Stock at the close of business on [●], 2022, the Record Date. You are entitled to one vote for each share of BCAC Common Stock that you owned as of the close of business on the Record Date. If your shares are held in “street name” or are in a margin or similar account, you should contact your broker, bank, or other nominee to ensure that votes related to the shares you beneficially own are properly counted. As of the Record Date, there were 6,746,092 shares of BCAC Common Stock outstanding, of which 5,061,592 were Public Shares, 1,437,500 were Founder Shares, and 247,000 were shares of BCAC Common Stock issued as constituent securities of the units issued in the Private Placement to Sponsor.

A quorum of BCAC stockholders is necessary to hold a valid meeting. A quorum will be present at the Stockholders’ Meeting if a majority of the voting power of all outstanding shares of BCAC Common Stock

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entitled to vote at the Stockholders’ Meeting as of the Record Date is represented in person (which would include presence at a virtual meeting) or by proxy. Abstentions and broker non-votes will be counted as present for the purpose of determining a quorum. The Sponsor, which currently owns approximately 24.1% of the issued and outstanding shares of BCAC Common Stock, will count towards this quorum. As of the Record Date, 3,373,047 shares of BCAC Common Stock would be required to achieve a quorum.

The approval of each of the Business Combination Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the ESPP Proposal and the Adjournment Proposal, if presented, requires the affirmative vote (in person or by proxy) of the holders of a majority of the shares of BCAC Common Stock entitled to vote thereon and actually cast at the Stockholders’ Meeting, voting as a single class. Accordingly, a stockholder’s failure to vote by proxy or to vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting, as well as an abstention from voting and a broker non-vote with regard to each of the Business Combination Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the ESPP Proposal or the Adjournment Proposal, if presented, will have no effect on such proposals.

The approval of the Charter Proposals requires the affirmative vote (in person or by proxy) of the holders of a majority of the shares of BCAC Common Stock entitled to vote thereon, voting as a single class. Accordingly, a stockholder’s failure to vote by proxy or to vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting, as well as an abstention from voting and a broker non-vote with regard to the Charter Proposals, will have the same effect as a vote “AGAINST” such proposal.

The approval of the Director Election Proposal requires the affirmative vote (in person or by proxy) of the holders of a plurality of the outstanding shares of BCAC Common Stock entitled to vote and actually cast thereon at the Stockholders’ Meeting. Directors are elected by a plurality of all of the votes cast by such stockholders present in person (which would include presence at a virtual meeting) or represented by proxy at the Stockholders’ Meeting and entitled to vote thereon, which means that the seven director nominees who receive the most affirmative votes will be elected. Stockholders may not cumulate their votes with respect to the election of directors. Accordingly, a stockholder’s failure to vote by proxy or to vote in person (which would include presence at a virtual meeting) at the Stockholders’ Meeting, as well as an abstention from voting and a broker non-vote with regard to election of directors, will have no effect on the election of directors.

Consummation of the Business Combination is conditioned on the approval of the Business Combination Proposal, the Charter Proposals, the Director Election Proposal, the Nasdaq Proposal, the Equity Incentive Plan Proposal and the ESPP Proposal at the Stockholders’ Meeting, subject to the terms of the Business Combination Agreement. The Business Combination is not conditioned on the approval of the Adjournment Proposal. If the Business Combination Proposal is not approved, the other proposals (except the Adjournment Proposal) will not be presented to the stockholders for a vote.

The Sponsor has agreed to vote its shares of common stock in favor of each of the Proposals presented at the Stockholders’ Meeting.

BCAC Conflicts of Interest

Certain of BCAC’s executive officers and certain non-employee directors may have interests in the Merger that may be different from, or in addition to, the interests of BCAC stockholders generally. These interests include, among other things:

• If the Business Combination with Apexigen or another business combination is not consummated within the Completion Window, BCAC will cease all operations except for the purpose of winding up, redeeming 100% of the outstanding Public Shares for cash and, subject to the approval of its remaining stockholders

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and the BCAC Board, dissolving and liquidating. In such event, the 1,380,000 Founder Shares held by the Sponsor, and the 57,500 Representative Shares, which were acquired for a purchase price of approximately $0.017 per share, would be worthless because holders of the Founder Shares are not entitled to participate in any redemption or distribution with respect to such shares. The Founder Shares held by the Sponsor had an aggregate market value of $[●] based upon the closing price of $[●] per share of BCAC Common Stock on the Nasdaq on the Record Date. Each of BCAC’s directors are a member of the Sponsor, and therefore will have an economic interest in the Founder Shares held by the Sponsor.

• Given the differential in the purchase price that our Sponsor paid for the Founder Shares as compared to the price of the BCAC units sold in the BCAC IPO and the substantial number of shares of Combined Company common stock that our Sponsor will receive upon conversion of the Founder Shares in connection with the Business Combination, our Sponsor and its affiliates may earn a positive rate of return on their investment even if the Combined Company common stock trades below the price initially paid for the BCAC units in the BCAC IPO and the Public Stockholders experience a negative rate of return following the completion of the Business Combination. Thus, our Sponsor and its affiliates may have more of an economic incentive for us to, rather than liquidate if we fail to complete our initial business combination by the Completion Window, enter into an initial business combination on potentially less favorable terms with a potentially less favorable, riskier, weaker-performing or financially unstable business, or an entity lacking an established record of revenues or earnings, than would be the case if such parties had paid the full offering price for their Founder Shares.

• The Sponsor purchased an aggregate of 247,000 placement units from BCAC for an aggregate purchase price of $2,470,000 (or $10.00 per unit). This purchase took place on a private placement basis simultaneously with the consummation of the BCAC IPO. A portion of the proceeds BCAC received from this purchase were placed in the Trust Account. Such units had an aggregate market value of approximately $[●] based upon the closing price of $[●] per warrant on the Nasdaq on [●], 2022, the Record Date.

• In connection with the approval of the Extension Amendment (as defined below), the Sponsor has agreed to contribute to BCAC as a loan the Additional Contributions. The amount of the Additional Contributions will not bear interest and will be repayable by BCAC to the Sponsor upon Closing.

• Samuel Wertheimer will become a director of the Combined Company after the Closing. As such, in the future he may receive any cash fees, stock options or stock awards that the Combined Company Board determines to pay to its directors.

• BCAC’s directors and officers, and their affiliates are entitled to reimbursement of out-of-pocket expenses incurred by them in connection with certain activities on BCAC’s behalf, such as identifying and investigating possible business targets and business combinations. However, if BCAC fails to consummate a business combination within the Completion Window, they will not have any claim against the Trust Account for reimbursement. Accordingly, BCAC may not be able to reimburse these expenses if the Business Combination or another business combination is not consummated within the Completion Window. As of the date of this prospectus, there were no out-of-pocket expenses incurred by BCAC’s directors, officers or their affiliates that have not otherwise been reimbursed from BCAC’s working capital funds following the BCAC IPO. Additionally, the Sponsor is entitled to $10,000 per month for office space, utilities, administrative and support services provided to BCAC’s management team, which commenced on January 28, 2021 and will continue through the earlier of consummation of the Business Combination and BCAC’s liquidation.

• Article X of the Existing Charter provides for the limited waiver, to the extent allowed by law and subject to certain exceptions, of the doctrine of corporate opportunity with respect to BCAC or any of its officers, directors or their respective affiliates. While this may result in a potential conflict of interest as between the fiduciary duties or contractual obligations of our officers or directors and the interests of BCAC and its stockholders, it did not impact our search for an initial business combination target, including Apexigen.

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• The continued indemnification of current directors and officers and the continuation of directors’ and officers’ liability insurance.

• In the event of the liquidation of the Trust Account, the Sponsor has agreed to indemnify and hold harmless BCAC against any and all losses, liabilities, claims, damages and expenses to which BCAC may become subject as a result of any claim by (i) any third party for services rendered or products sold to BCAC or (ii) a prospective target business with which BCAC has entered into an acquisition agreement, provided that such indemnification of BCAC by the Sponsor shall apply only to the extent necessary to ensure that such claims by a third party for services rendered or products sold to BCAC or a target do not reduce the amount of funds in the Trust Account to below (i) $10.00 per share of BCAC Common Stock or (ii) such lesser amount per share of BCAC Common Stock held in the Trust Account due to reductions in the value of the trust assets as of the date of the liquidation of the Trust Account, in each case, net of the amount of interest earned on the property in the Trust Account, which may be withdrawn to pay taxes and expenses related to the administration of the Trust Account, except as to any claims by a third party (including a target) who executed a waiver of any and all rights to seek access to the Trust Account and except as to any claims under BCAC’s indemnity of the underwriters of the BCAC IPO against certain liabilities, including liabilities under the Securities Act. If BCAC consummates the Business Combination, on the other hand, BCAC will be liable for all such claims.

• The Sponsor has agreed not to transfer, assign, or sell any of its Founder Shares until 180 days following the consummation of the Business Combination, subject to certain customary exceptions.

• Subject to certain limited exceptions, the placement units will not be transferable until 30 days following the completion of the Business Combination.

• For a period of six years after the Closing Date, BCAC shall defend, indemnify and hold harmless the Sponsor, its affiliates, and their respective present and former directors and officers against any costs or expenses, judgments, fines, losses, claims, damages or liabilities incurred in connection with any action by any stockholder of BCAC who has not exercised Redemption Rights arising from Sponsor’s ownership of equity securities of BCAC, or its control or ability to influence BCAC, and further arising out of or pertaining to the transactions, actions, and investments contemplated by the Business Combination Agreement or any Ancillary Agreements.

• BCAC will pay Brookline Capital Markets, an affiliate of our Sponsor for which certain of our officers provide services, $200,000 to act as BCAC’s financial advisor, investment banker, and consultant in connection with the Business Combination. The services provided by Brookline Capital Markets included assessment oif the market environment as well as BCAC’s relative positioning within the marketplace, assessment of BCAC’s stockholder base, potential target investors and potential marketing strategies for its securities, assistance in the preparation of marketing materials for BCAC, and other customary financial advisory services and investment banking services in connection with BCAC’s contemplated business combination transaction. While Brookline Capital Markets provided assistance to BCAC in the preparation of our initial terms proposed to Apexigen, it did not otherwise participate in any discussions among the parties.

• In the event that the BCAC Related Funds Amount at Closing is less than $20,000,000, then that number of Sponsor Shares equal to (x) one minus the quotient of the BCAC Related Funds Amount divided by $20,000,000, multiplied by (y) 1/3 of the total number of Sponsor Shares, shall be deemed automatically forfeited and cancelled without any further actions by the Sponsor or any other person, and such surrendered shares will be recorded as cancelled by the Combined Company.

There will be no finder’s fees, reimbursements or cash payments made by BCAC to the Sponsor or BCAC’s officers or directors, or any of BCAC’s or its officers’ or directors’ affiliates, for services rendered to BCAC prior to or in connection with the completion of the Business Combination, other than payment of the amount

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described above for office space, utilities, administrative and support services, and repayments of the Additional Contributions and any Working Capital Notes by our Sponsor or affiliates of our Sponsor to fund working capital deficiencies or finance transaction costs in connection with an initial business combination, which Working Capital Notes will be repayable by BCAC upon Closing. The Sponsor, in its discretion, may in lieu of having the Working Capital Notes repaid upon the Closing, instead convert the Working Capital Notes into units of BCAC, at a price of $10.00 per unit, upon the Closing, provided that the maximum amount that may be converted is no more than $1,500,000. The Sponsor and BCAC’s officers and directors or any of their respective affiliates will also be reimbursed for any out-of-pocket expenses incurred in connection with BCAC’s formation, the BCAC IPO and activities on BCAC’s behalf such as identifying potential target businesses and performing due diligence on suitable business combinations. There is no cap or ceiling on the reimbursement of out-of-pocket expenses incurred by such persons in connection with activities on our behalf. As of the date of this prospectus, the Sponsor had not incurred any out-of-pocket expenses in connection with the Business Combination that, as of such date, had not been reimbursed by BCAC from BCAC’s working capital funds following the BCAC IPO.

The BCAC Board was aware of and considered these interests to the extent such interests existed at the time, among other matters, in approving the Business Combination Agreement and in recommending that the Business Combination be approved by the stockholders of BCAC. See “Meeting of BCAC Stockholders- Recommendation of BCAC Board of Directors.”

Appraisal Rights

Holders of BCAC Common Stock and BCAC warrants are not entitled to appraisal rights in connection with the Business Combination.

Under the DGCL, however, holders of Apexigen capital stock may be entitled to appraisal rights in connection with the Business Combination. Apexigen stockholders who neither vote in favor of nor consent in writing to the Merger and who otherwise comply with Section 262 and other applicable provisions of the DGCL will be entitled to exercise rights to seek appraisal of the fair value of their shares of Apexigen capital stock, as determined by the Delaware Court of Chancery, if the Merger is completed. The “fair value” of such dissenting shares of Apexigen capital stock as determined by the Delaware Court of Chancery may be more or less than, or the same as, the value of the consideration that such stockholder would otherwise be entitled to receive under the Business Combination Agreement. Any Apexigen stockholder who wishes to preserve appraisal rights must so advise Apexigen by submitting a demand for appraisal within the period prescribed by Section 262 of the DGCL after receiving a notice from Apexigen or BCAC that appraisal rights are available, and must otherwise precisely follow the procedures prescribed by Section 262 of the DGCL Any shares of Apexigen capital stock held by such Apexigen stockholder immediately prior to the Effective Time who shall have properly demanded appraisal for his, her or its shares in accordance with the DGCL will not be converted into the merger consideration, unless such Apexigen stockholder fails to perfect, withdraws, or otherwise loses his, her or its right to appraisal and payment under the DGCL. If such Apexigen stockholder fails to perfect, withdraws or otherwise loses his, her or its appraisal rights, each share of Apexigen capital stock held by such Apexigen stockholder will be deemed to have been converted as of the Effective Time into a right to receive the merger consideration. Failure to follow any of the statutory procedures set forth in Section 262 of the DGCL will result in the loss or waiver of appraisal rights under Delaware law. In view of the complexity of Section 262 of the DGCL, Apexigen stockholders who may wish to pursue appraisal rights should consult their legal and financial advisors.

The Business Combination Agreement

Representations, Warranties and Covenants

The parties to the Business Combination Agreement have made customary representations, warranties and covenants therein, including, among others, covenants (i) with respect to the conduct of the business of BCAC

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and Apexigen and their respective subsidiaries prior to the Closing, (ii) providing for BCAC and Apexigen to use reasonable best efforts to obtain all necessary regulatory approvals, (iii) providing for BCAC and Apexigen to cooperate in the preparation of the registration statement, of which this proxy statement/prospectus forms a part, and a consent solicitation statement to be distributed by Apexigen to its stockholders, and (iv) requiring that BCAC and Apexigen will not solicit or negotiate with third parties regarding alternative transactions and will comply with certain related restrictions and will cease discussions regarding alternative transactions. Additionally, BCAC agreed to include in this proxy statement/prospectus a recommendation of the BCAC Board to BCAC stockholders that such stockholders approve the proposals included herein (the “BCAC Board Recommendation”). The BCAC Board is permitted to change the BCAC Board Recommendation (such change, a “Modification in Recommendation”) if the BCAC Board determines in good faith, after consultation with its outside legal counsel, that in response to an intervening event specified in the Business Combination Agreement, the failure to make such a Modification in Recommendation would be inconsistent with its fiduciary duties under applicable law.

Conditions to the Merger

Mutual Conditions to Closing

The obligations of BCAC, Merger Sub and Apexigen to consummate the Merger are subject to the satisfaction or waiver of the following conditions: (i) the requisite approvals of BCAC and Apexigen stockholders having been obtained; (ii) the registration statement of which this proxy statement/prospectus forms a part having become effective under the Securities Act and no stop order having been issued with respect thereto; (iii) there not being in force any governmental order or law enjoining or prohibiting, the consummation of the Merger; and (iv) BCAC having at least $5,000,001 of net tangible assets after deducting the amount required to satisfy any redemptions by BCAC stockholders in connection with the Closing.

BCAC Conditions to Closing

The obligations of BCAC and Merger Sub to consummate the Merger are subject to the satisfaction or waiver of the following additional conditions: (i) the accuracy of the representations and warranties of Apexigen as determined in accordance with the Business Combination Agreement; (ii) the performance in all material respects of each of the covenants required by the Business Combination Agreement to be performed by Apexigen as of or prior to the Closing; (iii) the delivery by Apexigen to BCAC of a customary officer’s certificate, dated as of the date of the Closing and signed by an officer of Apexigen, certifying the satisfaction of certain conditions specified in the Business Combination Agreement; (iv) there shall not have occurred a material adverse effect with respect to Apexigen between the date of the Business Combination Agreement and the date of the Closing; (v) the delivery by Apexigen to BCAC a certification that shares of Apexigen capital stock are not “U.S. real property interests” in accordance with sections 897 and 1445 of the Code, together with a notice to the IRS in accordance with the provisions of Section 1.897-2(h)(2) of the Treasury Regulations, (vi) the Subscription Agreements being in full force and effect; and (vii) the Lincoln Park Purchase Agreement being in full force and effect.

Apexigen Conditions to Closing

The obligations of Apexigen to consummate the Merger are subject to the satisfaction or waiver of the following additional conditions: (i) the accuracy of the representations and warranties of BCAC as determined in accordance with the Business Combination Agreement; (ii) the performance in all material respects of each of the covenants required by the Business Combination Agreement to be performed by BCAC as of or prior to the Closing; (iii) the delivery by BCAC to Apexigen of a customary officer’s certificate, dated as of the date of the Closing and signed by an officer of BCAC, certifying the satisfaction of certain conditions specified in the Business Combination Agreement; (iv) there shall not have occurred a material adverse effect with respect to

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Apexigen between the date of the Business Combination Agreement and the date of the Closing; (v) the resignation, effective as of the Closing, of any directors and officers of BCAC that are not identified as the initial post-Closing directors and officers of the Combined Company; (vi) the shares BCAC Common Stock to be issued in connection with the Merger having been approved for listing on Nasdaq, subject only to notice of issuance thereof; (vii) the Subscription Agreements being in full force and effect; and (viii) the Lincoln Park Purchase Agreement being in full force and effect.

Termination

The Business Combination Agreement may be terminated and the Business Combination abandoned by (i) mutual written consent of BCAC and Apexigen, (ii) either BCAC or Apexigen if the Business Combination is not consummated on or before October 31, 2022, provided that BCAC or Apexigen, as applicable, will not be entitled to exercise such termination right if it is in breach of the Business Combination Agreement and fails to satisfy any closing condition at such time, (iii) either BCAC or Apexigen if consummation of the Business Combination is permanently enjoined or prohibited by the terms of a final, non-appealable order, decree or ruling of a governmental entity or a statute, rule or regulation, (iv) either BCAC or Apexigen if the requisite approval of BCAC stockholders is not obtained at the Stockholders’ Meeting, (v) BCAC if the requisite approval of Apexigen stockholders of the Business Combination by written consent is not obtained ten business days prior to the Stockholders’ Meeting, (vi) either BCAC or Apexigen if the other party has breached any of its representations, warranties or covenants, such that the conditions to Closing would not be satisfied at the Closing, and has not cured such breach within 30 days of notice from the other party of its intent to terminate, provided that the terminating party is itself not in material breach of the Business Combination Agreement at such time, or (vii) by BCAC if Apexigen fails to deliver the Stockholder Support Agreement signed by the Key Apexigen Stockholders.

Effect of Termination

In the event of the termination of the Business Combination Agreement, the Business Combination Agreement will become void and have no effect, without any liability on the part of any party thereto (other than liability of Apexigen, BCAC or Merger Sub, as the case may be, for any willful and material breach of the Business Combination Agreement occurring prior to such termination), other than with respect to certain exceptions contemplated by the Business Combination Agreement and the confidentiality agreement between BCAC and Apexigen that will survive the termination of the Business Combination Agreement.

Other Agreements

Sponsor Support Agreement

Concurrently with the execution of the Business Combination Agreement, the Sponsor entered into the Sponsor Support Agreement with BCAC and Apexigen, pursuant to which the Sponsor agreed, at any meeting of BCAC stockholders and in connection with any action by written consent of the stockholders of BCAC, to (i) vote in favor of or consent to the Business Combination Agreement, the Merger, and any other transactions contemplated thereby or under any other agreements executed and delivered in connection therewith, (ii) comply with the lock-up provisions set forth therein and in the Letter Agreement previously entered into between BCAC and the Sponsor dated January 28, 2021, and (iii) forfeit certain shares of BCAC Common Stock held by Sponsor in the event the BCAC Related Funds Amount at Closing is less than $20,000,000. See “Other Agreements-Sponsor Support Agreement.”

As of [●], 2022, the Record Date, the Sponsor was entitled to vote BCAC Voting Shares. Such shares currently constitute approximately 24.1% of the outstanding shares of BCAC’s common stock.

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Apexigen Stockholder Support Agreement

Concurrently with the execution of the Business Combination Agreement BCAC, the Company and the Key Apexigen Stockholders entered into the Stockholder Support Agreement providing that, among other things, Key Apexigen Stockholders holding at least the shares of Apexigen capital stock sufficient to deliver the requisite approval will vote their shares of Apexigen capital stock in favor of the Business Combination Agreement, the Merger and any other transactions contemplated thereby or under any other agreements executed and delivered in connection therewith.

Registration Rights and Lock-Up Agreement

Concurrently with the execution of the Business Combination Agreement, BCAC entered into the Registration Rights and Lock-Up Agreement with certain stockholders of Apexigen (the “Registration Rights Holders”) providing that, among other things, within 45 days after the Closing, the Combined Company will be required to file a shelf registration statement pursuant to Rule 415 of the Securities Act and use reasonable best efforts to cause such registration statement to be declared effective as soon as practicable thereafter. In addition, the Registration Rights Holders will have certain demand and “piggyback” registration rights.

Subject to certain exceptions, the Registration Rights Holders, and the Sponsor with respect to the Founder Shares will, subject to limited exceptions, be subject to a lock-up on their shares of Combined Company common stock for 180 days after the date of the Closing. See “Other Agreements-Registration Rights Agreement.”

Subscription Agreements

Concurrently with the execution of the Business Combination Agreement, BCAC entered into the Subscription Agreements with certain PIPE Investors and may enter into additional Subscription Agreements with other PIPE Investors prior to the Closing. Pursuant to the Subscription Agreements, the PIPE Investors agreed to subscribe for and purchase, and BCAC agreed to issue and sell, to the PIPE Investors an aggregate of 1,502,000 PIPE Units for a purchase price of $10.00 per unit, or an aggregate of $15,020,000, in private placements. Each PIPE Unit consists of one share of BCAC Common Stock and one-half of one warrant. As of [●], 2022, the closing price on Nasdaq of the BCAC units was $[●] per unit and the closing price of the Common Stock was $[●] per share.

The shares of BCAC Common Stock to be issued pursuant to the Subscription Agreements will not be registered under the Securities Act and will be issued in reliance upon the exemption provided under Section 4(a)(2) of the Securities Act. If the [●] shares of BCAC Common Stock to be issued to the PIPE Investors were currently outstanding, such shares would have an aggregate market value of $[●] based upon the closing price of $[●] per share of BCAC Common Stock on Nasdaq on [●], 2022, the Record Date. See “Other Agreements-Subscription Agreement.”

Purchase Agreement and Registration Rights Agreement

Concurrently with the execution of the Business Combination Agreement, BCAC, Apexigen, and Lincoln Park entered into (a) the Lincoln Park Purchase Agreement, pursuant to which the Combined Company will have the right to direct Lincoln Park to purchase from the Combined Company an aggregate of up to $50,000,000 of Combined Company common stock from time to time over a 24-month period following the Closing, subject to certain limitations contained in the Lincoln Park Purchase Agreement, and (b) a Registration Rights Agreement, providing for the registration of the shares of BCAC Common Stock and Combined Company common stock issuable in respect of the Lincoln Park Purchase Agreement. On the date of Closing, BCAC will issue to Lincoln Park 150,000 shares of BCAC Common Stock. Additionally, the Combined Company will issue to Lincoln Park $1,500,000 of Combined Company common stock on the date that is 90 calendar days after the date of Closing at the purchase price equal to the arithmetic average of the last closing sale price for Combined Company common stock during the 10 consecutive business days ending on the business day immediately preceding the delivery of

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such shares, provided, that in no event shall the amount of such shares exceed 500,000. See “Other Agreements-Lincoln Park Purchase Agreement and Registration Rights Agreement.”

Nasdaq Listing

Our public units (“BCAC units”), shares of BCAC Common Stock and Warrants to purchase shares of BCAC Common Stock are currently listed on Nasdaq under the symbols “BCACU,” “BCAC” and “BCACW,” respectively. We intend to apply to continue the listing of the Combined Company common stock and the Warrants of the Combined Company to purchase shares of Combined Company common stock on Nasdaq under the symbols “APGN” and “APGNW,” respectively, upon the Closing.

Comparison of Stockholders’ Rights

There are certain differences in the rights of BCAC stockholders prior to the Business Combination and after the Business Combination. See “Comparison of Stockholders’ Rights.”

Summary Risk Factors

You should consider all the information contained in this proxy statement/prospectus in deciding how to vote for the Proposals presented in this proxy statement/prospectus. In particular, you should consider the risk factors described under “Risk Factors.” Such risks include, but are not limited to:

Risks related to Apexigen’s business and industry, including that:

• Apexigen is in the early stages of clinical drug development and has a limited operating history and no products approved for commercial sale.

• Apexigen has incurred net losses since inception and expects to continue to incur significant net losses for the foreseeable future.

• The Combined Company will require substantial additional capital to finance operations. If the Combined Company is unable to raise such capital when needed or on acceptable terms, it may be forced to delay, reduce, and/or eliminate one or more research and drug development programs or future commercialization efforts.

• Apexigen is dependent on the success of its product candidates, including its lead product candidate, sotigalimab, which is currently in multiple clinical trials.

• The clinical trials of our current and any future product candidates of Apexigen may not demonstrate safety and efficacy to the satisfaction of regulatory authorities or otherwise be timely conducted or produce positive results.

• If Apexigen’s competitors develop and market products that are more effective, safer, or less expensive than its product candidates, Apexigen will be negatively impacted.

• If Apexigen experience delays or difficulties in the enrollment of patients in clinical trials, its receipt of necessary marketing approvals could be delayed or prevented.

• The regulatory approval processes of the Federal Drug Administration, European Medicines Agency, and comparable foreign regulatory authorities are lengthy, time-consuming, and inherently unpredictable. If Apexigen is ultimately unable to obtain regulatory approval for its product candidates, it will be unable to generate product revenue and its business will be substantially harmed.

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• If Apexigen is unable to obtain, maintain, enforce, or protect its intellectual property rights in any products it develops or in its technology, if the scope of the intellectual property protection obtained is not sufficiently broad, or if Apexigen infringes the intellectual property rights of others, third parties could develop and commercialize products and technology similar or identical to those of Apexigen, Apexigen could be prevented from commercializing its products and Apexigen may not be able to compete effectively in its markets.

Risks relating to the Business Combination, including that:

• The Public Stockholders will experience immediate dilution as a consequence of the issuance of the Combined Company common stock as consideration in the Business Combination and in connection with the issuance of shares to Lincoln Park at the Closing pursuant to its financing arrangement, and will experience additional dilution following the Closing in the event of future issuances pursuant to the 2022 Equity Incentive Plan and the 2022 Employee Stock Purchase Plan, the issuance of shares of Combined Company common stock to Lincoln Park in connection with the financing arrangement (both through the obligation to issue additional shares 90 days after the Closing and pursuant to any subsequent requests for funding made by Apexigen), the exercise of outstanding Apexigen Options and Apexigen Warrants, and the exercise of the Public Warrants, the Private Placement Warrants and the PIPE Warrants.

• The market price of shares of Combined Company common stock after the Business Combination may be affected by factors different from those currently affecting the prices of shares of BCAC Common Stock.

• BCAC has not obtained an opinion from an independent investment banking firm, and consequently, there is no assurance from an independent source that the merger consideration is fair to its stockholders from a financial point of view.

• If the Business Combination’s benefits do not meet the expectations of financial analysts, the market price of Combined Company common stock may decline.

• There can be no assurance that the Combined Company common stock will be approved for listing on Nasdaq or that the Combined Company will be able to comply with the continued listing standards of Nasdaq.

• The consummation of the Business Combination is subject to a number of conditions and if those conditions are not satisfied or waived, the Business Combination Agreement may be terminated in accordance with its terms and the Business Combination may not be completed.

• The parties to the Business Combination Agreement may amend the terms of the Business Combination Agreement or waive one or more of the conditions to the Business Combination, and the exercise of discretion by our directors and officers in agreeing to changes to the terms of or waivers of closing conditions in the Business Combination Agreement may result in a conflict of interest when determining whether such changes to the terms of the Business Combination Agreement or waivers of conditions are appropriate and in the best interests of our stockholders.

• Termination of the Business Combination Agreement could negatively impact Apexigen and BCAC.

• The unaudited pro forma condensed combined financial information included in this proxy statement/ prospectus is preliminary and the actual financial condition and results of operations after the Business Combination may differ materially.

Risks relating to redemption, including that:

• If third parties bring claims against BCAC, the proceeds held in the Trust Account could be reduced and the per share redemption amount received by stockholders may be less than $10.00 per share.

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• Our independent directors may decide not to enforce the indemnification obligations of our Sponsor, resulting in a reduction in the amount of funds in the Trust Account available for distribution to our Public Stockholders.

• If Public Stockholders fail to comply with the redemption requirements specified in this proxy statement/ prospectus, they will not be entitled to redeem their Public Shares for a pro rata portion of the funds held in the Trust Account.

• Unlike some other blank check companies, BCAC is not subject to a specified maximum redemption threshold. The absence of such a redemption threshold will make it easier for BCAC to consummate the Business Combination even if a substantial number of our stockholders redeem.

Information about BCAC

BCAC is a blank check company formed for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization, or similar business combination with one or more businesses. BCAC Common Stock is listed on Nasdaq under the symbol “BCAC.” The publicly held BCAC warrants are listed on Nasdaq under the symbol “BCACW.” BCAC units are listed on Nasdaq under the symbol “BCACU.” BCAC currently maintains its executive offices at 280 Park Avenue, Suite 43W, New York, NY 10017 and BCAC’s telephone number is (646) 643-6716.

Information about Apexigen

Apexigen is a clinical-stage biopharmaceutical company focused on discovering and developing a new generation of antibody therapeutics for oncology.

Apexigen Wholly Owned Pipeline: Apexigen’s wholly owned pipeline is focused on innovative antibody-based therapeutics for oncology, with an emphasis on new immuno-oncology agents that may harness the patient’s immune system to combat and eradicate cancer. The company’s pipeline of immuno-oncology therapeutic candidates is led by sotigalimab, which is currently in Phase 2 clinical development, and also includes multiple preclinical programs.

• Sotigalimab: a CD40 agonist antibody with two key features. Sotiga is designed to specifically bind to the CD40L signaling. In addition, Apexigen engineered a mutation into the fragment crystallizable (Fc) region to increase binding to FcãRIIb to increase cross-linking and agonistic potency and eliminate FcãRIIIa binding to prevent antibody-dependent cell-mediated cytotoxicity (ADCC) against CD40-expressing immune cells. Apexigen believes that sotigalimab is the only CD40 agonist antibody in development that specifically binds to the CD40L binding domain, and that the combination of binding to the CD40L binding domain and the Fc mutation differentiates sotigalimab from other CD40 agonist antibodies in clinical development. These differentiators do not guarantee that sotigalimab will be proven effective or receive regulatory approval. Activation of CD40 initiates and amplifies a multi-cellular immune response, engaging components of both the innate and adaptive arms of the immune system to work in concert against cancer. As such, CD40 activation could play a fundamental role in tumor-specific immune activation. To maximize the therapeutic potential of sotigalimab, several Phase 2 trials are currently underway across multiple important cancer indications, lines of therapy and combination settings.

• Phase 2 preliminary data from sotigalimab in combination with chemoradiation as a neoadjuvant therapy in esophageal/gastro-esophageal junction cancer, which Apexigen plans to disclose by the end of 2022.

• Phase 2 preliminary data from sotigalimab in combination with standard of care chemotherapy in sarcoma is expected by year-end 2022.

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• Apexigen plans to consult with the FDA about a potential registrational path in post-anti-PD-(L)1 melanoma in mid-2022.

• APX601: an anti-TNFR2 antagonist antibody designed to reverse immune suppression in the tumor microenvironment and unleash immune-mediated tumor killing activity through unique mechanisms of action. Based on APX601’s mechanisms of action, Apexigen believes APX601 can deplete and inactivate TNFR2-expressing Tregs, reverse myeloid-mediated T cell suppression and directly kill TNFR2-expressing tumor cells. In preclinical mouse models, APX601 shows potent anti-tumor activity and is well-tolerated. Apexigen plans to develop APX601 for the treatment of multiple tumor indications of unmet medical need and continues to progress toward a mid-2022 IND application filing.

Partnered Programs: Apexigen has out-licensed five programs for the development of product candidates that were discovered using the APXiMAB platform. One of these out-licensed programs has yielded a product that is commercially available. The other out-licensed product candidates are advancing in clinical development.

APXiMAB™ discovery platform: This platform has enabled Apexigen and its licensing partners to discover antibodies for clinical development against a variety of molecular targets, including targets that are difficult to drug with conventional antibody technologies.

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MARKET PRICE AND DIVIDEND INFORMATION

BCAC

BCAC Common Stock is listed on Nasdaq under the symbol “BCAC.” The publicly held BCAC warrants are listed on Nasdaq under the symbol “BCACW.” BCAC units are listed on Nasdaq under the symbol “BCACU.”

On March 17, 2022, the last trading day before announcement of the execution of the Business Combination Agreement, the closing price of shares of BCAC Common Stock, BCAC units and public BCAC warrants on Nasdaq was $10.05, $10.19, and $0.20, respectively. As of [●], 2022, the Record Date, the closing price of shares of BCAC Common Stock, BCAC units and public BCAC warrants on Nasdaq was $[●], $[●] and $[●], respectively.

Holders of BCAC Common Stock, BCAC units and public BCAC warrants should obtain current market quotations for their securities. The market prices of BCAC’s securities could vary at any time before the Business Combination.

Holders

As of [●], 2022, the Record Date, there were [●] holders of record of BCAC units, [●] holders of record of BCAC Common Stock and [●] holders of record of public BCAC warrants. The number of holders of record does not include a substantially greater number of “street name” holders or beneficial holders whose BCAC units, Public Shares and public BCAC warrants are held of record by banks, brokers, and other financial institutions.

Dividend Policy

BCAC has not paid any cash dividends on the BCAC Common Stock to date and does not intend to pay cash dividends prior to the completion of the Business Combination. The payment of cash dividends in the future will be dependent upon the Combined Company’s revenues and earnings, if any, capital requirements and general financial condition subsequent to completion of the Business Combination. The payment of any cash dividends subsequent to the Business Combination will be within the discretion of the Combined Company Board at such time. The Combined Company’s ability to declare dividends may also be limited by restrictive covenants pursuant to any debt financing agreements.

Apexigen

The historical market price for Apexigen’s capital stock is not provided because there is no public market for Apexigen’s capital stock.

See “Apexigen’s Management’s Discussion and Analysis of Financial Condition and Results of Operations.”

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SUMMARY HISTORICAL FINANCIAL INFORMATION OF BCAC

The following information is only a summary and should be read in conjunction with BCAC’s financial statements and related notes contained elsewhere in this proxy statement/prospectus and information discussed under “BCAC Management’s Discussion and Analysis of Financial Condition and Results of Operations.” The historical results included below and elsewhere in this proxy statement/prospectus are not indicative of BCAC’s future performance.

The summary statements of operations data for the period from May 27, 2020 (inception) through December 31, 2020 and for the year ended December 31, 2021 and the summary balance sheet data as of December 31, 2020 and 2021 are each derived from BCAC’s audited financial statements appearing elsewhere in this proxy statement/prospectus. The summary statement of operations data for the three months ended March 31, 2021 and 2022, and the summary balance sheet data as of March 31, 2022 are derived from BCAC’s unaudited condensed financial statements appearing elsewhere in this proxy statement/prospectus. The BCAC unaudited interim financial statements were prepared on the same basis as its audited financial statements. The historical results are not necessarily indicative of the results to be expected in the future.

	For the period from May 27, 2020 (inception) through December 31, 2020			For the year ended December 31, 2021			For the three months ended March 31,
							2021			2022
	(in thousands, except per share data)
General and administrative expenses	$	2		$	411		$	82		$	2,407
Administrative expenses—related party		—			110			20			30
Franchise tax expense		—			82			21			20
Loss from operations		(2	)		(603	)		(123	)		(2,457	)
Other income (expense)
Change in fair value of derivative warrant liabilities		—			110			(49	)		(3	)
Offering costs allocated to private warrants					(1	)
Net gain from investments held in Trust Account		—			10			2			2
Total other income (expense)		—			119			(47	)		(1	)
Net loss	$	(2	)	$	(484	)	$	(170	)	$	(2,458	)
Weighted average shares outstanding—redeemable common stock		—			5,245,890			3,705,556			5,750,000
Basic and diluted net loss per share, redeemable common stock	$	—		$	(0.07	)	$	(0.03	)	$	(0.33	)
Weighted average shares outstanding—non-redeemable common stock		1,250,000			1,646,407			1,530,011			1,684,500
Basic and diluted net loss per share, non-redeemable common stock	$	(0.00	)	$	(0.07	)	$	(0.03	)	$	(0.33	)

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	As of December 31,				March 31,
	2020		2021		2022
	(in thousands)
Balance Sheet Data:
Total assets	$	97	$	58,316	$	58,279
Total liabilities		73		236		2,656
Common stock subject to possible redemption		5		58,075		58,075
Total stockholders’ equity (deficit)		24		45		(2,453	)

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SUMMARY HISTORICAL FINANCIAL INFORMATION OF APEXIGEN

The following information is only a summary and should be read in conjunction with Apexigen’s financial statements and related notes contained elsewhere in this proxy statement/prospectus and information discussed under “Apexigen’s Management’s Discussion and Analysis of Financial Condition and Results of Operations.” The historical results included below and elsewhere in this proxy statement/prospectus are not indicative of Apexigen’s future performance.

The summary statements of operations data for the years ended December 31, 2020 and 2021 and the summary balance sheet data as of December 31, 2020 and 2021 are each derived from Apexigen’s audited financial statements appearing elsewhere in this proxy statement/prospectus. The summary statement of operations data for the three months ended March 31, 2021 and 2022, and the summary balance sheet data as of March 31, 2022 are derived from Apexigen’s unaudited condensed financial statements appearing elsewhere in this proxy statement/prospectus. The Apexigen unaudited interim condensed financial statements were prepared on the same basis as its audited financial statements. The historical results are not necessarily indicative of the results to be expected in the future.

	Years Ended December 31,						Three Months Ended March 31,
	2020			2021			2021			2022
	(In thousands, except share and per share data)
Statement of Operations Data:
Operating expenses
Research and development	$	18,770		$	21,664		$	4,963		$	7,108
General and administrative		5,774			7,293			1,539			1,986
Total operating expenses		24,544			28,957			6,502			9,094
Loss from operations		(24,544	)		(28,957	)		(6,502	)		(9,094	)
Interest income, net		421			41			15			52
Net loss	$	(24,123	)	$	(28,916	)	$	(6,487	)	$	(9,042	)
Net loss per share, basic and diluted	$	(0.79	)	$	(0.94	)	$	(0.21	)	$	(0.29	)
Weighted average common shares outstanding, basic and diluted		30,512,368			30,901,032			30,651,063			31,395,518

	As of December 31,						As of March 31, 2022
	2020			2021
	(In thousands)
Balance Sheet Data:
Total assets	$	62,845		$	39,096		$	30,507
Total liabilities		13,162			17,095			18,012
Convertible preferred stock		158,707			158,707			158,707
Total stockholders’ deficit		(109,024	)		(136,706	)		(145,275	)

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SELECTED UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

The following selected unaudited pro forma condensed combined financial data (the “selected pro forma information”) gives effect to the Apexigen Business Combination and other events contemplated by the Business Combination Agreement as described in the section entitled “Unaudited Pro Forma Condensed Combined Financial Information” included in this proxy statement/prospectus. On March 17, 2022, BCAC executed the Business Combination Agreement. Pursuant to the terms of the Business Combination Agreement, BCAC will acquire Apexigen through the statutory merger of the Project Barolo Merger Sub with and into Apexigen, with Apexigen surviving the merger as a wholly owned subsidiary of BCAC. The Aggregate Closing Merger Consideration of 21,568,559 shares will be calculated as the Aggregate Closing Merger Consideration Value of $215.7 million divided by $10.00 per share. At the effective time of the Apexigen Business Combination, each share of Apexigen Common Stock will be canceled and converted into the right to receive a number of shares of BCAC Common Stock equal to the Exchange Ratio, calculated in accordance with the terms of the Business Combination Agreement. The Company currently estimates the Exchange Ratio to be approximately 0.1026.

The Merger is expected to be accounted for as a reverse recapitalization in accordance with GAAP because Apexigen has been determined to be the accounting acquirer under all redemption scenarios presented. The unaudited pro forma condensed combined balance sheet as of March 31, 2022 combines the historical unaudited condensed balance sheet of Apexigen with the historical unaudited condensed balance sheet of BCAC on a pro forma basis as if the Merger and the other events contemplated by the Business Combination Agreement, summarized below, had been consummated on March 31, 2022. The unaudited pro forma condensed combined statement of operations for the three months ended March 31, 2022 combines the historical unaudited condensed statement of operations of Apexigen for the three months ended March 31, 2022 and the historical unaudited condensed statement of operations of BCAC for the three months ended March 31, 2022, giving effect to the transaction as if the Merger and other events contemplated by the Business Combination Agreement had been consummated on January 1, 2021. The unaudited pro forma condensed combined statement of operations for the year ended December 31, 2021 combines the historical audited statement of operations of BCAC for the year ended December 31, 2021, with the historical audited statement of operations of Apexigen for the year ended December 31, 2021, giving effect to the transaction as if the Merger and other events contemplated by the Business Combination Agreement had been consummated on January 1, 2021.

The selected pro forma information has been derived from, and should be read in conjunction with, the unaudited pro forma condensed combined financial information of the Combined Company appearing elsewhere in this proxy statement/prospectus and the accompanying notes, in the section titled “Unaudited Pro Forma Condensed Combined Financial Information.” The unaudited pro forma condensed combined financial information is derived from, and should be read in conjunction with, the historical financial statements of BCAC and Apexigen and related notes included elsewhere in this proxy statement/prospectus. The selected pro forma information has been presented for informational purposes only and is not necessarily indicative of what the Combined Company’s financial position or results of operations actually would have been had the Merger and the other transactions contemplated by the Business Combination Agreement been completed as of the dates indicated. In addition, the selected pro forma information does not purport to project the future financial position or operating results of the Combined Company. BCAC and Apexigen have not had any historical relationship prior to the Merger. Accordingly, no pro forma adjustments were required to eliminate activities between the companies.

The unaudited pro forma condensed combined financial information has been prepared in accordance with Article 11 of Regulation S-X as amended by the final rule, Release 33-10786 “Amendments to Financial Disclosures about Acquired and Disposed Businesses.” The adjustments reflected in the selected pro forma information have been identified and presented to provide relevant information necessary for an accurate understanding of the Combined Company upon consummation of the Merger, the PIPE Investment, the Lincoln Park Purchase Agreement and other transactions.

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During April 2022, BCAC Public Stockholders elected to redeem 688,408 shares at $10.10 per share for total redemption proceeds of $7.0 million (the “April Partial Redemption”), after which 5,061,592 shares of BCAC Common Stock subject to redemption remained outstanding. The following table presents the selected pro forma information after giving effect to the Merger and other events contemplated by the Business Combination Agreement and the April Partial Redemption, presented under the following four scenarios:

• Assuming No Additional Redemptions: This scenario includes the April Partial Redemption and assumes that no other BCAC Public Stockholders exercise their Redemption Rights with respect to the outstanding BCAC Common Stock and that 5,061,592 shares of BCAC Common Stock remain outstanding after the completion of the Merger.

• Assuming 50% Redemptions: This scenario includes the April Partial Redemption and assumes that holders of an additional 2,530,796 shares, or 50% of the remaining shares outstanding held by BCAC Public Stockholders, will exercise their Redemption Rights for aggregate redemption proceeds of $32.8 million.

• Assuming 75% Redemptions: This scenario includes the April Partial Redemption and assumes that holders of an additional 3,796,194 shares, or 75% of the remaining shares outstanding held by BCAC Public Stockholders, will exercise their Redemption Rights for aggregate redemption proceeds of $45.7 million.

• Assuming Maximum Redemptions: This scenario assumes the April Partial Redemption and assumes that BCAC Public Stockholders holding the remaining 5,061,592 shares of BCAC Common Stock will exercise their Redemption Rights for aggregate redemption proceeds of $58.6 million.

The Business Combination Agreement does not provide for any minimum cash condition.

Under the 50% Redemptions, 75% Redemptions, and Maximum Redemptions scenarios, the pro forma financials assume a $10.20 per share redemption amount. On April 26, 2022, BCAC held a special meeting of its stockholders at which BCAC’s stockholders approved an amendment to BCAC’s Amended and Restated Certificate of Incorporation that extends the date by which BCAC must consummate a business combination transaction from May 2, 2022 on a monthly basis up to November 2, 2022. The Sponsor, or its designees, has agreed to contribute to BCAC as a loan $0.033 for each public share that was not redeemed in the April Partial Redemption for each subsequent calendar month commencing on May 2, 2022, and on the 2nd day of each subsequent month, or portion thereof, that is needed by BCAC to complete an initial business combination from May 2, 2022 (the “Extension Note”). The Extension Note is a non-convertible unsecured promissory note. For purposes of the 50% Redemptions, 75% Redemptions, and Maximum Redemptions scenarios, the $10.20 per share redemption amount assumes that the Closing will take place in July 2022. If the Merger closes subsequent to July 2022, then the Sponsor would be required to loan an additional $0.033 per month for each public share that is not redeemed, and the per share redemption amount will increase by $0.033 per share per month.

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The following summarizes the pro forma shares of Combined Company common stock issued and outstanding immediately after the Merger under the four scenarios (after giving effect to the April Partial Redemption):

	Pro Forma Combined
	No Additional Redemptions					50% Redemptions					75% Redemptions					Maximum Redemptions
	Shares		%			Shares		%			Shares		%			Shares		%
BCAC Public Stockholders(1)		5,061,592		19.1	%		2,530,796		10.6	%		1,265,398		5.6	%		—		0.0	%
Sponsor and Representative(2)		1,684,500		6.4	%		1,684,500		7.0	%		1,510,020		6.7	%		1,224,500		5.8	%
Former Apexigen equityholders(3)		18,104,074		68.2	%		18,104,074		75.5	%		18,104,074		80.3	%		18,104,074		86.3	%
PIPE Investors(4)		1,502,000		5.7	%		1,502,000		6.3	%		1,502,000		6.7	%		1,502,000		7.2	%
Lincoln Park(5)		150,000		0.6	%		150,000		0.6	%		150,000		0.7	%		150,000		0.7	%
Pro forma total shares of the Combined Company common stock outstanding at Closing		26,502,166		100.0	%		23,971,370		100.0	%		22,531,492		100.0	%		20,980,574		100.0	%

(1) Amount excludes 2,875,000 outstanding Public Warrants (as defined herein) issued in connection with the BCAC IPO as such securities are not exercisable until the date that is 30 days after the first date on which BCAC completes a merger, share exchange, asset acquisitions, share purchase, reorganization or similar transaction, involving the Company and one or more businesses.

(2) The Sponsor and Representative hold 1,684,500 shares of BCAC Common Stock, comprised of 1,380,000 Founder Shares held by the Sponsor, 57,500 Founder Shares held by the Representative and 247,000 shares of BCAC Common Stock issued as constituent securities of the units issued in the Private Placement. This amount excludes warrants to purchase 123,500 shares of BCAC Common Stock issued as constituent securities of the units issued in the Private Placement (each, a “Private Warrant”). Under the 75% Redemptions and Maximum Redemptions scenarios, the Sponsor will forfeit 174,480 and 460,000 Founder Shares upon the Closing, respectively, pursuant to the terms of the Sponsor Support Agreement. See “Other Agreements-Sponsor Support Agreement” for more information.

(3) Amount excludes Apexigen Options and Apexigen Warrants that will be converted to equivalent Combined Company options and warrants with the same terms and conditions and exercisable for an estimated 3,451,110 and 13,375 shares of Combined Company common stock, respectively.

(4) The PIPE Investors will purchase a unit that includes one share of Combined Company common stock and one-half of one warrant to purchase Combined Company common stock for $10.00 per unit at the Closing. This amount includes 1,502,000 shares of Combined Company common stock subscribed for by PIPE investors and excludes 751,000 PIPE warrants issued to the PIPE Investors.

(5) This amount includes 150,000 shares of Combined Company common stock issued to Lincoln Park associated with the financing arrangement upon the Closing and excludes the $1.5 million commitment to issue additional shares of Combined Company common stock, not to exceed 500,000 shares, to Lincoln Park 90 days after the Closing, as well as any draws on the Lincoln Park line.

If the actual facts are different than these assumptions, then the amounts and shares outstanding in the unaudited pro forma condensed combined financial information will be different and those changes could be material.

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The following summarizes the selected pro forma information under the scenarios presented (after giving effect to the April Partial Redemption):

	Pro Forma Combined
	No Additional Redemptions			50% Redemptions			75% Redemptions			Maximum Redemptions
	(in thousands, except shares and per share data)
Selected Unaudited Pro Forma Condensed Combined Statement of Operations Data - Three Months Ended March 31, 2022
Operating expenses	$	11,551		$	11,551		$	11,551		$	11,551
Loss from operations		(11,551	)		(11,551	)		(11,551	)		(11,551	)
Net loss		(11,502	)		(11,502	)		(11,502	)		(11,502	)
Net loss per share - basic and diluted	$	(0.43	)	$	(0.48	)	$	(0.51	)	$	(0.55	)
Weighted average shares - basic and diluted		26,502,169			23,971,373			22,531,495			20,980,577
Selected Unaudited Pro Forma Condensed Combined Statement of Operations Data - Year Ended December 31, 2021
Operating expenses	$	34,360		$	34,360		$	34,360		$	34,360
Loss from operations		(34,360	)		(34,360	)		(34,360	)		(34,360	)
Net loss		(34,210	)		(34,210	)		(34,210	)		(34,210	)
Net loss per share - basic and diluted	$	(1.26	)	$	(1.41	)	$	(1.51	)	$	(1.63	)
Weighted average shares - basic and diluted		27,139,864			24,264,864			22,652,884			20,929,864
Selected Unaudited Pro Forma Condensed Combined Balance Sheet Data - As of March 31, 2022
Total current assets	$	87,689		$	61,875		$	48,968		$	36,061
Total assets		90,151			64,337			51,430			38,523
Total current liabilities		18,734			18,734			18,734			18,734
Total liabilities		18,822			18,822			18,822			18,822
Total stockholders’ equity		71,329			45,515			32,608			19,701

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

AND RISK FACTOR SUMMARY

Certain statements in this prospectus may constitute “forward-looking statements” for purposes of the federal securities laws. Our forward-looking statements include, but are not limited to, statements regarding our or our management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. In addition, any statements that refer to projections, forecasts or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking statements. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. Forward-looking statements in this prospectus may include, for example, statements about:

• our ability to select an appropriate target business or businesses in the life sciences industry;

• our ability to complete our initial business combination in the life sciences industry;

• our expectations around the performance of the prospective target business or businesses in the life sciences industry;

• our success in retaining or recruiting, or changes required in, our officers, key employees or directors following our initial business combination;

• our officers and directors allocating their time to other businesses and potentially having conflicts of interest with our business or in approving our initial business combination, as a result of which they would then receive expense reimbursements;

• our potential ability to obtain additional financing to complete our initial business combination;

• our pool of prospective target businesses in the life sciences industry;

• our ability to consummate an initial business combination due to the continued uncertainty resulting from the COVID-19 pandemic;

• the ability of our officers and directors to generate a number of potential acquisition opportunities;

• our public securities’ potential liquidity and trading;

• the lack of a market for our securities;

• the use of proceeds not held in the Trust Account or available to us from interest income on the Trust Account balance;

• the Trust Account not being subject to claims of third parties;

• our financial performance following this offering;

• the timing and focus of Apexigen’s current and future clinical trials, and the reporting of data from those trials;

• Apexigen’s ability to obtain and maintain regulatory approval of its product candidates;

• Apexigen’s estimates of the number of patients in the United States who suffer from the diseases it is targeting and the number of patients that will enroll in clinical trials;

• the timing or likelihood of regulatory filings and approvals for Apexigen’s product candidates for various diseases;

• Apexigen’s plans relating to commercializing its product candidates, if approved, including which indications will be pursued;

• the ability of Apexigen’s clinical trials to demonstrate safety and efficacy, and other positive results, of its product candidates;

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• the beneficial characteristics, safety, efficacy, and therapeutic effects of Apexigen’s product candidates;