10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2022

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission file number: 001-35409

Merrimack Pharmaceuticals, Inc.

(Exact name of registrant as specified in its charter)

Delaware	04-3210530
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification Number)

One Broadway, 14th Floor Cambridge, MA	02142
(Address of principal executive offices)	(Zip Code)

(617) 720-8606

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common stock, $0.01 par value	MACK	Nasdaq Global Market

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an 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.

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 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of November 1, 2022, there were 13,410,243 shares of Common Stock, $0.01 par value per share, outstanding.

TABLE OF CONTENTS

PART I

FINANCIAL INFORMATION

		Page
Item 1.	Financial Statements.	2
	Condensed Consolidated Balance Sheets – September 30, 2022 and December 31, 2021 (unaudited)	2
	Condensed Consolidated Statements of Operations and Comprehensive Loss – Three and Nine Months Ended September 30, 2022 and 2021 (unaudited)	3
	Condensed Consolidated Statements of Stockholders’ Equity – September 30, 2022 and 2021 (unaudited)	4
	Condensed Consolidated Statements of Cash Flows – Nine Months Ended September 30, 2022 and 2021 (unaudited)	5
	Notes to Condensed Consolidated Financial Statements (unaudited)	6
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations.	10
Item 3.	Quantitative and Qualitative Disclosures About Market Risk.	15
Item 4.	Controls and Procedures.	15

PART II

OTHER INFORMATION

Item 1A.	Risk Factors.	16
Item 6.	Exhibits.	17
Signatures		18

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FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this Quarterly Report on Form 10-Q, including statements regarding our strategy, future operations, future financial position, future revenues, projected costs, prospects, plans and objectives of management, are forward-looking statements. The words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” “target,” “potential,” “will,” “would,” “could,” “should,” “continue” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

The forward-looking statements in this Quarterly Report on Form 10-Q include, among other things, statements about:

•our rights to receive payments related to the milestone events under the asset purchase and sale agreement with Ipsen S.A. when expected or at all;

•our rights to receive payments related to the milestone events under the asset purchase agreement with Elevation Oncology, Inc. (formerly known as 14ner Oncology, Inc.), when expected or at all;

•our intellectual property position;

•our cash runway and the sufficiency of our financial resources to fund our operations;

•our estimates regarding expenses, future revenues, capital requirements and needs for additional financing;

•our plans to seek to divert our remaining product candidates; and

•other risks detailed from time to time in our filings with the Securities and Exchange Commission (the “SEC”), press releases and other communications, including those set forth under “Risk Factors” included in our Annual Report on Form 10-K for the year ended December 31, 2021, and in the documents incorporated by reference herein and therein.

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures, collaborations or investments that we may make.

You should read this Quarterly Report on Form 10-Q and the documents that we have filed as exhibits to this Quarterly Report on Form 10-Q completely and with the understanding that our actual future results may be materially different from what we expect. We do not assume any obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

NOTE REGARDING TRADEMARKS

ONIVYDE® is a trademark of Ipsen S.A. Any other trademarks, trade names and service marks referred to in this Quarterly Report on Form 10-Q are the property of their respective owners.

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PART I

FINANCIAL INFORMATION

Item 1. Financial Statements.

Merrimack Pharmaceuticals, Inc.

Condensed Consolidated Balance Sheets

(unaudited)

(in thousands, except per share amounts)	September 30, 2022			December 31, 2021
Assets
Current assets:
Cash and cash equivalents	$	13,091		$	14,203
Prepaid expenses and other current assets		537			480
Total current assets		13,628			14,683
Other assets		9			66
Total assets	$	13,637		$	14,749
Liabilities and stockholders’ equity
Current liabilities:
Accounts payable, accrued expenses and other	$	448		$	562
Total current liabilities		448			562
Total liabilities		448			562
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value: 10,000 shares authorized at September 30, 2022 and    December 31, 2021; no shares issued or outstanding at September 30, 2022 or    December 31, 2021		—			—
Common stock, $0.01 par value: 30,000 shares authorized at September 30, 2022 and    December 31, 2021; 13,410 shares issued and outstanding at September 30, 2022 and    December 31, 2021		1,334			1,334
Additional paid-in capital		558,999			558,945
Accumulated deficit		(547,144	)		(546,092	)
Total stockholders’ equity		13,189			14,187
Total liabilities and stockholders’ equity	$	13,637		$	14,749

The accompanying notes are an integral part of these condensed consolidated financial statements.

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Merrimack Pharmaceuticals, Inc.

Condensed Consolidated Statements of Operations and Comprehensive Loss

(unaudited)

	Three Months Ended September 30,						Nine Months Ended September 30,
(in thousands, except per share amounts)	2022			2021			2022			2021
Operating expenses:
General and administrative expenses	$	504		$	619		$	1,567		$	2,143
Gain on sale of assets		—			(94	)		(445	)		(144	)
Total operating expenses		504			525			1,122			1,999
Loss from operations		(504	)		(525	)		(1,122	)		(1,999	)
Other income:
Interest income		62			—			70			19
Total other income		62			—			70			19
Net loss and comprehensive loss	$	(442	)	$	(525	)	$	(1,052	)	$	(1,980	)
Net loss per common share - basic and diluted	$	(0.03	)	$	(0.04	)	$	(0.08	)	$	(0.15	)
Weighted-average common shares used to compute basic and    diluted net loss per common share		13,410			13,410			13,410			13,406

The accompanying notes are an integral part of these condensed consolidated financial statements.

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Merrimack Pharmaceuticals, Inc.

Condensed Consolidated Statements of Stockholders’ Equity

(unaudited)

	Common Stock
(in thousands)	Shares		Amount		Additional Paid-In Capital		Accumulated Deficit			Total Stockholders’ Equity
Balance at December 31, 2021		13,410	$	1,334	$	558,945	$	(546,092	)	$	14,187
Stock-based compensation		—		—		20		—			20
Net loss		—		—		—		(132	)		(132	)
Balance at March 31, 2022		13,410		1,334		558,965		(546,224	)		14,075
Stock-based compensation		—		—		17		—			17
Net loss		—		—		—		(478	)		(478	)
Balance at June 30, 2022		13,410		1,334		558,982		(546,702	)		13,614
Stock-based compensation		—		—		17		—			17
Net loss		—		—		—		(442	)		(442	)
Balance at September 30, 2022		13,410	$	1,334	$	558,999	$	(547,144	)	$	13,189

	Common Stock
(in thousands)	Shares		Amount		Additional Paid-In Capital		Accumulated Deficit			Total Stockholders’ Equity
Balance at December 31, 2020		13,380	$	1,334	$	558,309	$	(543,637	)	$	16,006
Exercise of stock options		30		—		239		—			239
Stock-based compensation		—		—		208		—			208
Net loss		—		—		—		(696	)		(696	)
Balance at March 31, 2021		13,410		1,334		558,756		(544,333	)		15,757
Stock-based compensation		—		—		93		—			93
Net loss		—		—		—		(759	)		(759	)
Balance at June 30, 2021		13,410		1,334		558,849		(545,092	)		15,091
Stock-based compensation		—		—		53		—			53
Net loss		—		—		—		(525	)		(525	)
Balance at September 30, 2021		13,410	$	1,334	$	558,902	$	(545,617	)	$	14,619

The accompanying notes are an integral part of these condensed consolidated financial statements.

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Merrimack Pharmaceuticals, Inc.

Condensed Consolidated Statements of Cash Flows

(unaudited)

	Nine Months Ended September 30,
(in thousands)	2022			2021
Cash flows from operating activities
Net loss	$	(1,052	)	$	(1,980	)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities
Gain on sale of in-process research and development		(445	)		(144	)
Stock-based compensation expense		54			354
Changes in operating assets and liabilities:
Prepaid expenses and other current assets		(57	)		1,870
Accounts payable, accrued expenses and other		(114	)		(87	)
Other assets		57			124
Net cash (used in) provided by operating activities		(1,557	)		137
Cash flows from investing activities
Net proceeds from sale of in process research and development		445			144
Net cash provided by investing activities		445			144
Cash flows from financing activities
Proceeds from exercise of stock options		—			239
Net cash provided by financing activities		—			239
Net (decrease) increase in cash and cash equivalents		(1,112	)		520
Cash and cash equivalents, beginning of period		14,203			14,038
Cash and cash equivalents, end of period	$	13,091		$	14,558

The accompanying notes are an integral part of these condensed consolidated financial statements.

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Merrimack Pharmaceuticals, Inc.

Notes to Condensed Consolidated Financial Statements

(unaudited)

1. Nature of the Business

Merrimack Pharmaceuticals, Inc. (the “Company”) is a biopharmaceutical company based in Cambridge, Massachusetts that is entitled to receive up to $450.0 million in contingent milestone payments related to its sale of ONIVYDE® and MM-436 (the “Commercial Business”) to Ipsen S.A. (“Ipsen”) in April 2017 (the “Ipsen Sale”). The Company does not have any ongoing research or development activities. The Company does not have any employees and instead uses external consultants for the operation of the Company.

The $450.0 million in contingent milestone payments resulting from the Ipsen Sale consist of:

•$225.0 million upon approval by the U.S. Food and Drug Administration (“FDA”) of ONIVYDE® for the first-line treatment of metastatic adenocarcinoma of the pancreas, subject to certain conditions;

•$150.0 million upon approval by the FDA of ONIVYDE® for the treatment of small-cell lung cancer after failure of first-line chemotherapy; and

•$75.0 million upon approval by the FDA of ONIVYDE® for an additional indication unrelated to those described above.

On May 30, 2019, the Company announced the completion of its review of strategic alternatives, following which the Company’s board of directors (the “Board”) implemented a series of measures designed to extend the Company’s cash runway and preserve its ability to capture the potential milestone payments resulting from the Ipsen Sale. In connection with that announcement, the Company discontinued the discovery efforts on its remaining preclinical programs: MM-401, an agonistic antibody targeting a novel immuno-oncology target, TNFR2; and MM-201, a highly stabilized agonist-Fc fusion protein targeting death receptors 4 and 5. The Company is seeking potential acquirers for its remaining preclinical and clinical assets.

The Company’s termination of its executive management team and all other employees was substantially completed by June 28, 2019 and fully completed by July 12, 2019. As a result, the Company has not had any employees since July 2019. The Company has engaged external consultants to run the day-to-day operations of the Company. The Company has also entered into consulting agreements with certain former members of its executive management team who are supporting the Company’s relationship with current partners, assisting with the potential sale of remaining preclinical and clinical assets, and assisting with certain legal and regulatory matters and the continued wind-down of operations.

On July 12, 2019, the Company completed the sale to Elevation Oncology, Inc. (formerly known as 14ner Oncology, Inc.) (“Elevation”) of its anti-HER3 antibody programs, MM-121 (seribantumab) and MM-111 (the “Elevation sale”). In connection with the Elevation sale, the Company received an upfront cash payment of $3.5 million. The Company is also eligible to receive up to $54.5 million in additional potential development, regulatory approval and commercial-based milestone payments, consisting of:

•$3.0 million for achievement of the primary endpoint in the first registrational clinical study of either MM-121 or MM-111;

•Up to $16.5 million in total payments for the achievement of various regulatory approval and reimbursement-based milestones in the United States, Europe and Japan; and

•Up to $35.0 million in total payments for achieving various cumulative worldwide net sales targets between $100.0 million and $300.0 million for MM-121 and MM-111.

On March 27, 2020, the Company entered into an Asset Purchase Agreement (the “Asset Purchase Agreement”) with Celator Pharmaceuticals, Inc. (the “Buyer”), pursuant to which the Buyer agreed to purchase certain assets (the “Transferred Assets”) relating to certain of the Company’s preclinical nanoliposome programs (the “Transaction”). The Company and the Buyer completed the Transaction simultaneously with the execution of the Asset Purchase Agreement. Under the terms of the Asset Purchase Agreement, the Buyer paid to the Company a cash payment of $2.3 million and reimbursed the Company for $0.2 million related to certain specified expenses. The Company incurred $0.4 million expenses related to the Transaction.

On September 15, 2021, the Company entered into an Asset Purchase Option Agreement (the “Asset Purchase Option Agreement”) with a third party (the “Purchaser”), pursuant to which the Purchaser agreed to obtain an exclusive option (the “Option”), to purchase one of the Company’s preclinical programs with a consideration of $0.5 million. Under the terms of the Asset Purchase Option Agreement, the Purchaser paid to the Company the Option fee of $0.1 million. The Purchaser had the right to exercise the Option within 24 months from September 15, 2021. The Company recognized a gain of $0.1 million related to the Option fee payment

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for the year ended December 31, 2021. On January 18, 2022, the Purchaser provided written notice to the Company of its intent to exercise such Option. On March 1, 2022 the Company and the Purchaser entered into the Asset Purchase Agreement. The consideration of $0.5 million was paid to the Company and a gain of $0.5 million was recognized in March 2022.

The Company is subject to risks and uncertainties common to companies in the biopharmaceutical industry, including, among other things, development by competitors of new technological innovations, protection of proprietary technology and compliance with government regulations, approval by the FDA and other foreign health agencies to approve any pharmaceutical under development, obtaining insurance reimbursement for any drug if and when approved by regulators, and its ability to secure additional capital to fund operations. None of the Company’s product candidates are approved for any indication by the FDA or any other regulatory agency. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies, among others. In addition, the Company is dependent upon the services of its external consultants for the operation of the Company. The Company’s business strategy depends substantially upon its ability to receive future milestone payments from Ipsen and Elevation. Any failure to achieve such milestones or a perception that the milestones may not be achieved will materially and adversely affect the Company and the value of its common stock.

In accordance with Accounting Standards Codification (“ASC”) 205-40, Going Concern, the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued. As of September 30, 2022, the Company had an accumulated deficit of $547.1 million. During the nine months ended September 30, 2022, the Company incurred net loss of $1.1 million and used $1.6 million of cash in operating activities. The Company expects to continue to generate operating losses for the foreseeable future. The Company expects that its cash and cash equivalents of $13.1 million at September 30, 2022 will allow the Company to continue its operations into 2027, when the Company estimates the longest-term potential Ipsen milestone may be achieved. The continued viability of the Company beyond that point is dependent on its ability to realize milestone payments from its licensed product candidates, raise additional capital to finance its operations or to reduce operating expenses. There can be no assurance that the Company will be successful in receiving future milestone payments or able to obtain sufficient capital to cover its costs on acceptable terms, if at all.

The Company expects that it would seek to finance any future cash needs through a combination of divestitures of its product candidates or other assets, equity offerings and debt financings. There can be no assurance as to the timing, terms or consummation of any divestiture or financing, and the terms of any such financing may adversely affect the holdings or the rights of the Company’s stockholders or require the Company to relinquish rights to certain of its revenue streams or product candidates.

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying condensed consolidated financial statements reflect the operations of Merrimack Pharmaceuticals, Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated.

The condensed consolidated financial statements are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).

The accounting policies followed in the preparation of the interim condensed consolidated financial statements are consistent in all material respects with those presented in Note 1 to the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021.

Unaudited Interim Financial Information

The condensed consolidated balance sheet as of December 31, 2021 was derived from audited financial statements for the year ended December 31, 2021, but does not include all disclosures required by GAAP. The condensed consolidated balance sheet as of September 30, 2022, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2022 and 2021, the condensed consolidated statements of stockholders’ equity for the three and nine months ended September 30, 2022 and 2021 and the condensed consolidated statements of cash flows for the nine months ended September 30, 2022 and 2021 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2022, the results of its operations for the three and nine months ended September 30, 2022 and 2021, its statements of stockholders’ equity for the three and nine months ended September 30, 2022 and 2021 and its statements of cash flows for the nine months ended September 30, 2022 and 2021. The financial data and other information disclosed in the notes related to the three and nine months ended September 30, 2022

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and 2021 are unaudited. The results for the three and nine months ended September 30, 2022 and 2021 are not necessarily indicative of results to be expected for the year ending December 31, 2022, any other interim periods, or any future year or period.

The unaudited interim financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. These unaudited condensed consolidated financial statements should be read in conjunction with the audited financial statements and the notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 filed with the SEC on March 9, 2022.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates, assumptions and judgments reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.

3. Fair Value of Financial Instruments

The following tables show assets measured at fair value on a recurring basis as of September 30, 2022 and December 31, 2021:

	September 30, 2022
(in thousands)	Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	11,801	$	—	$	—
Totals	$	11,801	$	—	$	—

	December 31, 2021
(in thousands)	Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	12,934	$	—	$	—
Totals	$	12,934	$	—	$	—

There were no liabilities measured at fair value on a recurring basis as of September 30, 2022 and December 31, 2021.

4. Accounts Payable, Accrued Expenses and Other

Accounts payable, accrued expenses and other as of September 30, 2022 and December 31, 2021 consisted of the following:

(in thousands)	September 30, 2022		December 31, 2021
Accounts payable	$	67	$	120
Accrued goods and services		119		167
Accrued clinical trial costs		71		84
Others		191		191
Total accounts payable, accrued expenses and other	$	448	$	562

5. Stock-Based Compensation

On April 15, 2021, the Company’s Board of Directors adopted the 2021 Incentive Award Plan (the “2021 Plan”) to replace the 2011 Stock Incentive Plan (the “2011 Plan”). The 2021 Plan was approved by the Company’s stockholders at the Company’s Annual Meeting of Stockholders held on June 10, 2021. The 2021 Plan is administered by the Company’s Board of Directors and permits the Company to grant incentive and non-qualified stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards.

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There were 22,000 options granted during each of the nine months ended September 30, 2022 and 2021 under 2021 Plan. There were no options granted during the three months ended September 30, 2022 and 2021. The weighted-average grant date fair value per share of stock options granted during the nine months ended September 30, 2022 and 2021 was $3.11 and $3.68, respectively. At September 30, 2022, there were 231,000 shares remaining available for grant under the 2021 Plan.

The fair value of stock options granted to employees during the three and nine months ended September 30, 2022 and 2021 was estimated at the date of grant using the following assumptions:

	Three and Nine Months Ended September 30,
	2022			2021
Risk-free interest rate		2.99	%		0.73	%
Expected dividend yield	0%			0%
Expected term	5.22 years			5.22 years
Expected volatility	68.02%				68.48	%

The Company recognized stock-based compensation expense of $17 thousand, $53 thousand, $54 thousand and $354 thousand in general and administrative expense during the three and nine months ended September 30, 2022 and 2021, respectively.

6. Net Loss Per Common Share

Basic net loss per share is calculated by dividing the net loss attributable to Merrimack Pharmaceuticals, Inc. by the weighted-average number of common shares outstanding during the period.

Diluted net loss per share is computed by dividing the net loss attributable to Merrimack Pharmaceuticals, Inc. by the weighted-average number of dilutive common shares outstanding during the period. Dilutive shares outstanding is calculated by adding to the weighted shares outstanding any potential (unissued) shares of common stock from outstanding stock options based on the treasury stock method. Outstanding stock options were not included in the diluted net loss per share calculation because the options were out of the money or to do so would have been antidilutive (i.e., the total proceeds upon exercise would have exceeded the market value of the underlying common shares). In a period when a net loss is reported, all common stock equivalents are excluded from the calculation because they would have an anti-dilutive effect, meaning the loss per share would be reduced. Therefore, in periods where a loss is reported, there is no difference in basic and dilutive loss per share.

Stock options are excluded from the calculation of diluted loss per share because the net loss for the three and nine months ended September 30, 2022 and 2021 causes such securities to be anti-dilutive. Outstanding options excluded from the calculation of diluted loss per share for the three and nine months ended September 30, 2022 and 2021 are shown in the chart below:

	Three and Nine Months Ended September 30,
(in thousands)	2022		2021
Outstanding options to purchase common stock		1,628		1,778

7. Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed above, the Company does not believe that the adoption of recently issued standards has or may have a material impact on the Company’s condensed consolidated financial statements or disclosures.

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

The following discussion of our financial condition and results of operations should be read in conjunction with our financial statements and the notes to those financial statements appearing elsewhere in this Quarterly Report on Form 10-Q and the audited consolidated financial statements and notes thereto and management’s discussion and analysis of financial condition and results of operations for the year ended December 31, 2021 included in our Annual Report on Form 10-K. This discussion contains forward-looking statements that involve significant risks and uncertainties. As a result of many factors, such as those set forth in Part II, Item 1A. Risk Factors of this Quarterly Report on Form 10-Q, which are incorporated herein by reference, our actual results may differ materially from those anticipated in these forward-looking statements.

Overview

We are a biopharmaceutical company based in Cambridge, Massachusetts that is entitled to receive up to $450.0 million in contingent milestone payments related to our sale of ONIVYDE® to Ipsen S.A., or Ipsen, in April 2017 and up to $54.5 million in contingent milestone payments related to our sale of MM-121 and MM-111 to Elevation Oncology, Inc. (formerly known as 14ner Oncology, Inc.), or Elevation, in July 2019. We do not have any ongoing research or development activities and are seeking potential acquirers for our remaining preclinical and clinical assets. We do not have any employees and instead use external consultants for the operation of our company.

On April 3, 2017, we completed the sale of ONIVYDE® and MM-436 (the “commercial business”) to Ipsen (the “Ipsen sale”). In connection with the Ipsen sale, we are eligible to receive up to $450.0 million in additional regulatory approval-based milestone payments.

The remaining up to $450.0 million in potential milestone payments resulting from the Ipsen sale consist of:

•$225.0 million upon approval by the U.S. Food and Drug Administration, or FDA, of ONIVYDE® for the first-line treatment of metastatic adenocarcinoma of the pancreas, subject to certain conditions;

•$150.0 million upon approval by the FDA of ONIVYDE® for the treatment of small-cell lung cancer after failure of first-line chemotherapy; and

•$75.0 million upon approval by the FDA of ONIVYDE® for an additional indication unrelated to those described above.

Our non-commercial assets, including our clinical and preclinical development programs, were not included in the Ipsen sale and remain assets of ours.

On May 30, 2019, we announced the completion of our review of strategic alternatives, following which our board of directors implemented a series of measures which we believe allow us to extend our cash runway into 2027 and preserve our ability to capture the potential milestone payments resulting from the Ipsen sale. We have based this estimate on assumptions that may prove to be wrong, and we could use our financial resources sooner than we currently expect. In connection with that announcement, we discontinued the discovery efforts on our remaining preclinical programs: MM-401, an agonistic antibody targeting a novel immuno-oncology target, TNFR2; and MM-201, a highly stabilized agonist-Fc fusion protein targeting death receptors 4 and 5. We are seeking potential acquirers for our remaining preclinical and clinical assets.

The termination of our executive management team and all other employees was substantially completed by June 28, 2019 and fully completed by July 12, 2019. As of July 12, 2019, we do not have any employees. We have engaged external consultants to run our day-to-day operations. We have also entered into consulting agreements with certain former members of our executive management team who are supporting our relationship with current partners, assisting with the potential sale of remaining preclinical and clinical assets, and assisting with certain legal and regulatory matters and the continued wind-down of operations.

On July 12, 2019, we completed the sale to Elevation, or the Elevation sale, of our anti-HER3 antibody programs, MM-121 (seribantumab) and MM-111. In connection with the Elevation sale, we received an upfront cash payment of $3.5 million and are eligible to receive up to $54.5 million in additional potential development, regulatory approval and commercial-based milestone payments, consisting of:

•$3.0 million for achievement of the primary endpoint in the first registrational clinical study of either MM-121 or MM-111;

•Up to $16.5 million in total payments for the achievement of various regulatory approval and reimbursement-based milestones in the United States, Europe and Japan; and

•Up to $35.0 million in total payments for achieving various cumulative worldwide net sales targets between $100.0 million and $300.0 million for MM-121 and MM-111.

10

On March 27, 2020, we entered into an Asset Purchase Agreement (the “Asset Purchase Agreement”) with Celator Pharmaceuticals, Inc. (the “Buyer”), pursuant to which the Buyer agreed to purchase certain assets (the “Transferred Assets”) relating to certain of our preclinical nanoliposome programs (the “Transaction”). We completed the Transaction simultaneously with the execution of the Asset Purchase Agreement. Under the terms of the Asset Purchase Agreement, the Buyer paid to us a cash payment of $2.3 million and reimbursed us for $0.2 million related to certain specified expenses and to assume certain liabilities with respect to the Transferred Assets. We incurred $0.4 million expenses related to the Transaction.

On September 15, 2021, we entered into an Asset Purchase Option Agreement (the “Asset Purchase Option Agreement”) with a third party (the “Purchaser”), pursuant to which the Purchaser agreed to obtain an exclusive option (the “Option”), to purchase one of our preclinical programs with a consideration of $0.5 million. Under the terms of the Asset Purchase Option Agreement, the Purchaser paid to us the Option fee of $0.1 million. The Purchaser had the right to exercise the Option within 24 months from September 15, 2021. We recognized a gain of $0.1 million related to the Option fee payment for the year ended December 31, 2021. On January 18, 2022, the Purchaser provided written notice to us of its intent to exercise such Option. On March 1, 2022, we entered the Asset Purchase Agreement with the Purchaser. The consideration of $0.5 million was paid to us and a gain of $0.5 million was recognized in March 2022.

We previously devoted substantially all of our resources to our drug discovery and development efforts, including conducting clinical trials for our product candidates, protecting our intellectual property and providing general and administrative support for these operations. We have financed our operations primarily through private placements of convertible preferred stock, collaborations, public offerings of our securities, secured debt financings, sales of ONIVYDE® and the Ipsen sale.

As of September 30, 2022, we had unrestricted cash and cash equivalents of $13.1 million. We expect that our cash and cash equivalents as of September 30, 2022 will be sufficient to continue our operations into 2027, when we estimate the longest-term potential Ipsen milestone may be achieved.

As of September 30, 2022, we had an accumulated deficit of $547.1 million. Our net loss from our continuing operations was $1.1 million and $2.0 million for the nine months ended September 30, 2022 and 2021, respectively. We do not expect to have any research and development expenses going forward. We do not expect to be profitable from our continuing operations in the future.

Financial Operations Overview

General and administrative expenses

General and administrative expenses consist primarily of stock-based compensation expenses, legal, intellectual property, business development, finance, information technology, corporate communications and investor relations. Other general and administrative expenses include costs for board of director’s costs, insurance expenses, legal and professional fees, and accounting and information technology services fees.

Interest income

Interest income consists primarily of interest income associated with our money market fund.

Critical Accounting Policies and Significant Judgments and Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our condensed consolidated financial statements, which we have prepared in accordance with the rules and regulations of the Securities and Exchange Commission, or the SEC, and generally accepted accounting principles in the United States, or GAAP. The preparation of these condensed consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported expenses during the reporting periods. We evaluate our estimates and judgments on an ongoing basis. We base our estimates on historical experience and on various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Our actual results may differ from these estimates under different assumptions or conditions.

Our critical accounting policies and the methodologies and assumptions we apply under them have not materially changed since March 9, 2022, the date we filed our Annual Report on Form 10-K for the year ended December 31, 2021. For more information on our critical accounting policies, refer to our Annual Report on Form 10-K for the year ended December 31, 2021.

11

Results of Operations

Comparison of the three months ended September 30, 2022 and 2021

	Three Months Ended September 30,
(in thousands)	2022			2021
Operating expenses:
General and administrative expenses	$	504		$	619
Gain on sale of assets		—			(94	)
Total operating expenses		504			525
Loss from operations		(504	)		(525	)
Interest income		62			—
Net loss	$	(442	)	$	(525	)

General and administrative expenses

General and administrative expenses were $0.5 million for the three months ended September 30, 2022 compared to $0.6 million for the three months ended September 30, 2021, a decrease of $0.1 million, or 19%. This decrease was primarily attributable to the decrease in both stock-based compensation expense and consulting fees.

Gain on sale of assets

There was no gain on sale of assets for the three months ended September 30, 2022. Gain on sale of assets was $0.1 million for the three months ended September 30, 2021, attributable to the sale of certain of our preclinical programs to a third party.

Interest income

Interest income was $0.1 million for the three months ended September 30, 2022 and nil for the three months ended September 30, 2021, primarily attributable to the increase of interest rate associated with our money market fund.

Comparison of the nine months ended September 30, 2022 and 2021

	Nine Months Ended September 30,
(in thousands)	2022			2021
Operating expenses:
General and administrative expenses	$	1,567		$	2,143
Gain on sale of assets		(445	)		(144	)
Total operating expenses		1,122			1,999
Loss from operations		(1,122	)		(1,999	)
Interest income		70			19
Net loss	$	(1,052	)	$	(1,980	)

General and administrative expenses

General and administrative expenses were $1.6 million for the nine months ended September 30, 2022 compared to $2.1 million for the nine months ended September 30, 2021, a decrease of $0.5 million, or 27%. This decrease was primarily attributable to the decrease in both stock-based compensation expense and consulting fees.

Gain on sale of assets

Gain on sale of assets was $0.5 million for the nine months ended September 30, 2022, primarily attributable to the Option fee to purchase one of our preclinical programs paid by the Purchaser. Gain on sale of assets was $0.1 million for the nine months ended September 30, 2021, attributable to the sale of certain of our preclinical programs to a third party.

Interest income

Interest income was $0.1 million for the nine months ended September 30, 2022 and less than $0.1 million for the nine months ended September 30, 2021, primarily attributable to the increase of interest rate associated with our money market fund.

12

Liquidity and Capital Resources

Sources of liquidity

We have financed our operations through September 30, 2022 primarily through private placements of convertible preferred stock, collaborations, public offerings of our securities, secured debt financings, sales of our common stock and sales of our commercial and in-process research and development assets. As of September 30, 2022, we had unrestricted cash and cash equivalents of $13.1 million.

Cash flows

The following table provides information regarding our cash flows for the nine months ended September 30, 2022 and 2021:

	Nine Months Ended September 30,
(in thousands)	2022			2021
Net cash (used in) provided by operating activities	$	(1,557	)	$	137
Net cash provided by investing activities		445			144
Net cash provided by financing activities		—			239
Net (decrease) increase in cash and cash equivalents	$	(1,112	)	$	520

Operating activities

Cash used in operating activities of $1.6 million during the nine months ended September 30, 2022 was primarily a result of our $1.1 million net loss from operations. The net loss was off set by stock-based compensation expense of $0.1 million, and also adjusted by $0.4 million gain on the sale of in-process research and development and a net decrease in accounts payable, accrued expenses and other of $0.1 million.

Cash provided by operating activities of $0.1 million during the nine months ended September 30, 2021 was primarily a result of our $2.0 million net loss from operations and offset by $0.4 million of stock-based compensation expense. The net loss was adjusted by a decrease in assets and liabilities of $1.9 million. The increase in operating assets and liabilities during the nine months ended September 30, 2021 was primarily driven by a decrease of $2.0 million in prepaid expense and other assets related to our federal tax refund of $2.0 million, and offset by a $0.1 million decreases to accounts payable, accrued expenses and other expenses due to timing of payments. This net loss was adjusted by a $0.1 million gain on the sale of in-process research and development.

Investing activities

Cash provided by investing activities of $0.4 million and $0.1 million during the nine months ended September 30, 2022 and 2021, respectively, was due to proceeds from the sale of in-process research and development.

Financing activities

There was no cash provided by or used in financing activities during the nine months ended September 30, 2022. Cash provided by financing activities of $0.2 million during the nine months ended September 30, 2021 was due to proceeds from the exercise of stock options.

Funding requirements

We have incurred significant expenses and operating losses to date. On May 30, 2019, we announced the completion of our review of strategic alternatives, following which our board of directors implemented a series of measures designed to extend our cash runway into 2027 and preserve our ability to capture the potential milestone payments resulting from the Ipsen sale. In connection with that announcement, we discontinued the discovery efforts on our remaining preclinical programs and implemented a reduction in headcount resulting in the termination of all remaining employees as of July 12, 2019. Our future capital requirements will depend on many factors, including:

•the timing and amount of potential milestone payments related to ONIVYDE® that we may receive from Ipsen;

•the timing and amount of potential milestone payments that we may receive from Elevation;

•the timing and amount of any special dividend to our stockholders that our board of directors may declare;

•the timing and amount of general and administrative expenses required to continue to operate our company;

13

•the extent to which we owe any taxes for current, future or prior periods, including as a result of any audits by taxing authorities;

•the extent to which we invest in any future research or development activities of our product candidates;

•the costs of preparing, filing and prosecuting patent applications and maintaining, enforcing and defending intellectual property-related claims;

•the extent to which we acquire or invest in businesses, products and technologies; and

•the costs associated with operating as a public company and maintaining compliance with exchange listing and SEC requirements.

We do not believe that we will be able to raise a material amount of capital through the sale of our equity securities or debt financing. Rather, our goal is to judiciously expend our remaining cash until such time, if ever, as we receive additional milestone payments from Ipsen and Elevation. There can be no assurance as to the timing, terms or consummation of any financing. We do not have any committed external sources of funds. To the extent that we raise additional capital through the sale of equity or convertible debt securities, the ownership interest of our stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect the rights of our stockholders. Debt financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If we raise additional funds through arrangements with third parties, we may have to relinquish valuable rights to our future revenue streams or product candidates.

Contractual Obligations and Commitments

There were no material changes to our contractual obligations and commitments described under Management’s Discussion and Analysis of Financial Condition and Results of Operations in our Annual Report on Form 10-K for the year ended December 31, 2021, as filed with the SEC on March 9, 2022.

Off-Balance Sheet Arrangements

We did not have during the periods presented, and we do not currently have, any off-balance sheet arrangements, as defined under SEC rules.

Recent Accounting Pronouncements

See Note 7, “Recent Accounting Pronouncements,” in the accompanying notes to the condensed consolidated financial statements for a full description of recent accounting pronouncements.

14

Item 3. Quantitative and Qualitative Disclosures About Market Risk.

We invest in money market funds. The goals of our investment policy are preservation of capital, fulfillment of liquidity needs and fiduciary control of cash and investments. We also seek to maximize income from our investments without assuming significant risk.

Our primary exposure to market risk is interest income sensitivity, which is affected by changes in the general level of interest rates, particularly because our investments are money market funds. Due to the short-term duration of our investment portfolio and the low risk profile of our investments, an immediate 10% change in interest rates would not have a material effect on the fair market value of our portfolio. We have the ability and intention to hold our investments until maturity, and therefore, we would not expect our operating results or cash flows to be affected to any significant degree by the effect of a sudden change in market interest rates on our investment portfolio.

We do not currently have any auction rate or mortgage-backed securities. We do not believe our cash and cash equivalents have significant risk of default or liquidity, however we cannot provide absolute assurance that in the future our investments will not be subject to adverse changes in market value.

Item 4. Controls and Procedures.

Evaluation of Disclosure Controls and Procedures

Our management, with the participation of our principal executive and financial officer, evaluated the effectiveness of our disclosure controls and procedures as of September 30, 2022. The term “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act means controls and other procedures of a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is accumulated and communicated to the company’s management, including its principal executive and principal financial officers, as appropriate to allow timely decisions regarding required disclosure. Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. Based on the evaluation of our disclosure controls and procedures as of September 30, 2022, our principal executive and financial officer concluded that, as of such date, our disclosure controls and procedures were effective at the reasonable assurance level.

Changes in Internal Control Over Financial Reporting

No change in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) occurred during the nine months ended September 30, 2022 that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

15

PART II

OTHER INFORMATION

Item 1A. Risk Factors.

In addition to the other information set forth in this Quarterly Report on Form 10-Q, you should carefully consider the factors discussed under the caption “Risk Factors” that appear in Item 1A of our Annual Report on Form 10-K for the year ended December 31, 2021, which was filed with the SEC on March 9, 2022 (the “2021 Annual Report on Form 10-K”). There have been no material changes from the risk factors previously disclosed in the 2021 Annual Report on Form 10-K.

16

Item 6. Exhibits.

Exhibit Number	Description of Exhibit
31.1*	Certification of Principal Executive Officer pursuant to Rule 13a-14(a) or Rule 15d-14(a) of the Securities Exchange Act of 1934, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
31.2*	Certification of Principal Financial Officer pursuant to Rule 13a-14(a) or Rule 15d-14(a) of the Securities Exchange Act of 1934, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
32.1+	Certification of Principal Executive Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
32.2+	Certification of Principal Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
101.INS*	Inline XBRL Instance Document
101.SCH*	Inline XBRL Taxonomy Extension Schema Document
101.CAL*	Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF*	Inline XBRL Taxonomy Extension Definition Linkbase Document
101.LAB*	Inline XBRL Taxonomy Extension Label Linkbase Database
101.PRE*	Inline XBRL Taxonomy Extension Presentation Linkbase Document
104*	Cover Page Interactive Data File (embedded within the Inline XBRL document)

* Filed herewith.

+ Furnished herewith.

17

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	MERRIMACK PHARMACEUTICALS, INC.
Date: November 3, 2022	By:	/s/ Gary L. Crocker
		Gary L. Crocker
		President
		(Principal Financial Officer)

18

EX-31.1

Exhibit 31.1

CERTIFICATIONS

I, Gary L. Crocker, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q of Merrimack Pharmaceuticals, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 3, 2022	/s/ Gary L. Crocker
	Gary L. Crocker
	President
	(Principal Executive Officer)

EX-31.2

Exhibit 31.2

CERTIFICATIONS

I, Gary L. Crocker, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q of Merrimack Pharmaceuticals, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 3, 2022	/s/ Gary L. Crocker
	Gary L. Crocker
	President
	(Principal Financial Officer)

EX-32.1

Exhibit 32.1

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report on Form 10-Q of Merrimack Pharmaceuticals, Inc. (the “Company”) for the period ended September 30, 2022 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned, Gary L. Crocker, President of the Company, hereby certifies, pursuant to 18 U.S.C. Section 1350, that to his knowledge:

(1) the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: November 3, 2022	/s/ Gary L. Crocker
	Gary L. Crocker
	President
	(Principal Executive Officer)

EX-32.2

Exhibit 32.2

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report on Form 10-Q of Merrimack Pharmaceuticals, Inc. (the “Company”) for the period ended September 30, 2022 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned, Gary L. Crocker, President of the Company, hereby certifies, pursuant to 18 U.S.C. Section 1350, that to his knowledge:

(1) the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: November 3, 2022	/s/ Gary L. Crocker
	Gary L. Crocker
	President
	(Principal Financial Officer)

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Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2022	Nov. 01, 2022
Cover [Abstract]
Document Type	10-Q
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Document Period End Date	Sep. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
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Entity Registrant Name	MERRIMACK PHARMACEUTICALS INC
Entity Central Index Key	0001274792
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		13,410,243
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, $0.01 par value
Security Exchange Name	NASDAQ
Entity File Number	001-35409
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3210530
Entity Address, Address Line One	One Broadway
Entity Address, Address Line Two	14th Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
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Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 13,091	$ 14,203
Prepaid expenses and other current assets	537	480
Total current assets	13,628	14,683
Other assets	9	66
Total assets	13,637	14,749
Current liabilities:
Accounts payable, accrued expenses and other	448	562
Total current liabilities	448	562
Total liabilities	448	562
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value: 10,000 shares authorized at September 30, 2022 and December 31, 2021; no shares issued or outstanding at September 30, 2022 or December 31, 2021
Common stock, $0.01 par value: 30,000 shares authorized at September 30, 2022 and December 31, 2021; 13,410 shares issued and outstanding at September 30, 2022 and December 31, 2021	1,334	1,334
Additional paid-in capital	558,999	558,945
Accumulated deficit	(547,144)	(546,092)
Total stockholders’ equity	13,189	14,187
Total liabilities and stockholders’ equity	$ 13,637	$ 14,749

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Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2022	Dec. 31, 2021
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	30,000,000	30,000,000
Common stock, shares issued	13,410,000	13,410,000
Common stock, shares outstanding	13,410,000	13,410,000

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Condensed Consolidated Statements of Operations and Comprehensive (Loss) Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Operating expenses:
General and administrative expenses	$ 504	$ 619	$ 1,567	$ 2,143
Gain on sale of assets		(94)	(445)	(144)
Total operating expenses	504	525	1,122	1,999
Loss from operations	(504)	(525)	(1,122)	(1,999)
Other income:
Interest income	62		70	19
Total other income	62		70	19
Net loss and comprehensive loss	$ (442)	$ (525)	$ (1,052)	$ (1,980)
Net loss per common share - basic	$ (0.03)	$ (0.04)	$ (0.08)	$ (0.15)
Net loss per common share - diluted	$ (0.03)	$ (0.04)	$ (0.08)	$ (0.15)
Weighted-average common shares used to compute basic net loss per common share	13,410	13,410	13,410	13,406
Weighted-average common shares used to compute diluted net loss per common share	13,410	13,410	13,410	13,406

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Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2020	$ 16,006	$ 1,334	$ 558,309	$ (543,637)
Balance (in shares) at Dec. 31, 2020		13,380
Exercise of stock options	239		239
Exercise of stock options (in shares)		30
Stock-based compensation	208		208
Net loss	(696)			(696)
Balance at Mar. 31, 2021	15,757	$ 1,334	558,756	(544,333)
Balance (in shares) at Mar. 31, 2021		13,410
Balance at Dec. 31, 2020	16,006	$ 1,334	558,309	(543,637)
Balance (in shares) at Dec. 31, 2020		13,380
Net loss	(1,980)
Balance at Sep. 30, 2021	14,619	$ 1,334	558,902	(545,617)
Balance (in shares) at Sep. 30, 2021		13,410
Balance at Mar. 31, 2021	15,757	$ 1,334	558,756	(544,333)
Balance (in shares) at Mar. 31, 2021		13,410
Stock-based compensation	93		93
Net loss	(759)			(759)
Balance at Jun. 30, 2021	15,091	$ 1,334	558,849	(545,092)
Balance (in shares) at Jun. 30, 2021		13,410
Stock-based compensation	53		53
Net loss	(525)			(525)
Balance at Sep. 30, 2021	14,619	$ 1,334	558,902	(545,617)
Balance (in shares) at Sep. 30, 2021		13,410
Balance at Dec. 31, 2021	14,187	$ 1,334	558,945	(546,092)
Balance (in shares) at Dec. 31, 2021		13,410
Stock-based compensation	20		20
Net loss	(132)			(132)
Balance at Mar. 31, 2022	14,075	$ 1,334	558,965	(546,224)
Balance (in shares) at Mar. 31, 2022		13,410
Balance at Dec. 31, 2021	14,187	$ 1,334	558,945	(546,092)
Balance (in shares) at Dec. 31, 2021		13,410
Net loss	(1,052)
Balance at Sep. 30, 2022	13,189	$ 1,334	558,999	(547,144)
Balance (in shares) at Sep. 30, 2022		13,410
Balance at Mar. 31, 2022	14,075	$ 1,334	558,965	(546,224)
Balance (in shares) at Mar. 31, 2022		13,410
Stock-based compensation	17		17
Net loss	(478)			(478)
Balance at Jun. 30, 2022	13,614	$ 1,334	558,982	(546,702)
Balance (in shares) at Jun. 30, 2022		13,410
Stock-based compensation	17		17
Net loss	(442)			(442)
Balance at Sep. 30, 2022	$ 13,189	$ 1,334	$ 558,999	$ (547,144)
Balance (in shares) at Sep. 30, 2022		13,410

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Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash flows from operating activities
Net loss	$ (1,052)	$ (1,980)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities
Gain on sale of in-process research and development	(445)	(144)
Stock-based compensation expense	54	354
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(57)	1,870
Accounts payable, accrued expenses and other	(114)	(87)
Other assets	57	124
Net cash (used in) provided by operating activities	(1,557)	137
Cash flows from investing activities
Net proceeds from sale of in process research and development	445	144
Net cash provided by investing activities	445	144
Cash flows from financing activities
Proceeds from exercise of stock options		239
Net cash provided by financing activities		239
Net (decrease) increase in cash and cash equivalents	(1,112)	520
Cash and cash equivalents, beginning of period	14,203	14,038
Cash and cash equivalents, end of period	$ 13,091	$ 14,558

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Nature of the Business

9 Months Ended

Sep. 30, 2022

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of the Business

1. Nature of the Business

Merrimack Pharmaceuticals, Inc. (the “Company”) is a biopharmaceutical company based in Cambridge, Massachusetts that is entitled to receive up to $450.0 million in contingent milestone payments related to its sale of ONIVYDE® and MM-436 (the “Commercial Business”) to Ipsen S.A. (“Ipsen”) in April 2017 (the “Ipsen Sale”). The Company does not have any ongoing research or development activities. The Company does not have any employees and instead uses external consultants for the operation of the Company.

The $450.0 million in contingent milestone payments resulting from the Ipsen Sale consist of:

•$225.0 million upon approval by the U.S. Food and Drug Administration (“FDA”) of ONIVYDE® for the first-line treatment of metastatic adenocarcinoma of the pancreas, subject to certain conditions;

•$150.0 million upon approval by the FDA of ONIVYDE® for the treatment of small-cell lung cancer after failure of first-line chemotherapy; and

•$75.0 million upon approval by the FDA of ONIVYDE® for an additional indication unrelated to those described above.

On May 30, 2019, the Company announced the completion of its review of strategic alternatives, following which the Company’s board of directors (the “Board”) implemented a series of measures designed to extend the Company’s cash runway and preserve its ability to capture the potential milestone payments resulting from the Ipsen Sale. In connection with that announcement, the Company discontinued the discovery efforts on its remaining preclinical programs: MM-401, an agonistic antibody targeting a novel immuno-oncology target, TNFR2; and MM-201, a highly stabilized agonist-Fc fusion protein targeting death receptors 4 and 5. The Company is seeking potential acquirers for its remaining preclinical and clinical assets.

The Company’s termination of its executive management team and all other employees was substantially completed by June 28, 2019 and fully completed by July 12, 2019. As a result, the Company has not had any employees since July 2019. The Company has engaged external consultants to run the day-to-day operations of the Company. The Company has also entered into consulting agreements with certain former members of its executive management team who are supporting the Company’s relationship with current partners, assisting with the potential sale of remaining preclinical and clinical assets, and assisting with certain legal and regulatory matters and the continued wind-down of operations.

On July 12, 2019, the Company completed the sale to Elevation Oncology, Inc. (formerly known as 14ner Oncology, Inc.) (“Elevation”) of its anti-HER3 antibody programs, MM-121 (seribantumab) and MM-111 (the “Elevation sale”). In connection with the Elevation sale, the Company received an upfront cash payment of $3.5 million. The Company is also eligible to receive up to $54.5 million in additional potential development, regulatory approval and commercial-based milestone payments, consisting of:

•$3.0 million for achievement of the primary endpoint in the first registrational clinical study of either MM-121 or MM-111;

•Up to $16.5 million in total payments for the achievement of various regulatory approval and reimbursement-based milestones in the United States, Europe and Japan; and

•Up to $35.0 million in total payments for achieving various cumulative worldwide net sales targets between $100.0 million and $300.0 million for MM-121 and MM-111.

On March 27, 2020, the Company entered into an Asset Purchase Agreement (the “Asset Purchase Agreement”) with Celator Pharmaceuticals, Inc. (the “Buyer”), pursuant to which the Buyer agreed to purchase certain assets (the “Transferred Assets”) relating to certain of the Company’s preclinical nanoliposome programs (the “Transaction”). The Company and the Buyer completed the Transaction simultaneously with the execution of the Asset Purchase Agreement. Under the terms of the Asset Purchase Agreement, the Buyer paid to the Company a cash payment of $2.3 million and reimbursed the Company for $0.2 million related to certain specified expenses. The Company incurred $0.4 million expenses related to the Transaction.

On September 15, 2021, the Company entered into an Asset Purchase Option Agreement (the “Asset Purchase Option Agreement”) with a third party (the “Purchaser”), pursuant to which the Purchaser agreed to obtain an exclusive option (the “Option”), to purchase one of the Company’s preclinical programs with a consideration of $0.5 million. Under the terms of the Asset Purchase Option Agreement, the Purchaser paid to the Company the Option fee of $0.1 million. The Purchaser had the right to exercise the Option within 24 months from September 15, 2021. The Company recognized a gain of $0.1 million related to the Option fee payment

for the year ended December 31, 2021. On January 18, 2022, the Purchaser provided written notice to the Company of its intent to exercise such Option. On March 1, 2022 the Company and the Purchaser entered into the Asset Purchase Agreement. The consideration of $0.5 million was paid to the Company and a gain of $0.5 million was recognized in March 2022.

The Company is subject to risks and uncertainties common to companies in the biopharmaceutical industry, including, among other things, development by competitors of new technological innovations, protection of proprietary technology and compliance with government regulations, approval by the FDA and other foreign health agencies to approve any pharmaceutical under development, obtaining insurance reimbursement for any drug if and when approved by regulators, and its ability to secure additional capital to fund operations. None of the Company’s product candidates are approved for any indication by the FDA or any other regulatory agency. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies, among others. In addition, the Company is dependent upon the services of its external consultants for the operation of the Company. The Company’s business strategy depends substantially upon its ability to receive future milestone payments from Ipsen and Elevation. Any failure to achieve such milestones or a perception that the milestones may not be achieved will materially and adversely affect the Company and the value of its common stock.

In accordance with Accounting Standards Codification (“ASC”) 205-40, Going Concern, the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued. As of September 30, 2022, the Company had an accumulated deficit of $547.1 million. During the nine months ended September 30, 2022, the Company incurred net loss of $1.1 million and used $1.6 million of cash in operating activities. The Company expects to continue to generate operating losses for the foreseeable future. The Company expects that its cash and cash equivalents of $13.1 million at September 30, 2022 will allow the Company to continue its operations into 2027, when the Company estimates the longest-term potential Ipsen milestone may be achieved. The continued viability of the Company beyond that point is dependent on its ability to realize milestone payments from its licensed product candidates, raise additional capital to finance its operations or to reduce operating expenses. There can be no assurance that the Company will be successful in receiving future milestone payments or able to obtain sufficient capital to cover its costs on acceptable terms, if at all.

The Company expects that it would seek to finance any future cash needs through a combination of divestitures of its product candidates or other assets, equity offerings and debt financings. There can be no assurance as to the timing, terms or consummation of any divestiture or financing, and the terms of any such financing may adversely affect the holdings or the rights of the Company’s stockholders or require the Company to relinquish rights to certain of its revenue streams or product candidates.

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Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying condensed consolidated financial statements reflect the operations of Merrimack Pharmaceuticals, Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated.

The condensed consolidated financial statements are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).

The accounting policies followed in the preparation of the interim condensed consolidated financial statements are consistent in all material respects with those presented in Note 1 to the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021.

Unaudited Interim Financial Information

The condensed consolidated balance sheet as of December 31, 2021 was derived from audited financial statements for the year ended December 31, 2021, but does not include all disclosures required by GAAP. The condensed consolidated balance sheet as of September 30, 2022, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2022 and 2021, the condensed consolidated statements of stockholders’ equity for the three and nine months ended September 30, 2022 and 2021 and the condensed consolidated statements of cash flows for the nine months ended September 30, 2022 and 2021 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2022, the results of its operations for the three and nine months ended September 30, 2022 and 2021, its statements of stockholders’ equity for the three and nine months ended September 30, 2022 and 2021 and its statements of cash flows for the nine months ended September 30, 2022 and 2021. The financial data and other information disclosed in the notes related to the three and nine months ended September 30, 2022

and 2021 are unaudited. The results for the three and nine months ended September 30, 2022 and 2021 are not necessarily indicative of results to be expected for the year ending December 31, 2022, any other interim periods, or any future year or period.

The unaudited interim financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. These unaudited condensed consolidated financial statements should be read in conjunction with the audited financial statements and the notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 filed with the SEC on March 9, 2022.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates, assumptions and judgments reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.

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Fair Value of Financial Instruments

9 Months Ended

Sep. 30, 2022

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

3. Fair Value of Financial Instruments

The following tables show assets measured at fair value on a recurring basis as of September 30, 2022 and December 31, 2021:

	September 30, 2022
(in thousands)	Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	11,801	$	—	$	—
Totals	$	11,801	$	—	$	—

	December 31, 2021
(in thousands)	Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	12,934	$	—	$	—
Totals	$	12,934	$	—	$	—

There were no liabilities measured at fair value on a recurring basis as of September 30, 2022 and December 31, 2021.

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Accounts Payable, Accrued Expenses and Other

9 Months Ended

Sep. 30, 2022

Payables And Accruals [Abstract]

Accounts Payable, Accrued Expenses and Other

4. Accounts Payable, Accrued Expenses and Other

Accounts payable, accrued expenses and other as of September 30, 2022 and December 31, 2021 consisted of the following:

(in thousands)	September 30, 2022		December 31, 2021
Accounts payable	$	67	$	120
Accrued goods and services		119		167
Accrued clinical trial costs		71		84
Others		191		191
Total accounts payable, accrued expenses and other	$	448	$	562

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Stock-Based Compensation

9 Months Ended

Sep. 30, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

5. Stock-Based Compensation

On April 15, 2021, the Company’s Board of Directors adopted the 2021 Incentive Award Plan (the “2021 Plan”) to replace the 2011 Stock Incentive Plan (the “2011 Plan”). The 2021 Plan was approved by the Company’s stockholders at the Company’s Annual Meeting of Stockholders held on June 10, 2021. The 2021 Plan is administered by the Company’s Board of Directors and permits the Company to grant incentive and non-qualified stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards.

There were 22,000 options granted during each of the nine months ended September 30, 2022 and 2021 under 2021 Plan. There were no options granted during the three months ended September 30, 2022 and 2021. The weighted-average grant date fair value per share of stock options granted during the nine months ended September 30, 2022 and 2021 was $3.11 and $3.68, respectively. At September 30, 2022, there were 231,000 shares remaining available for grant under the 2021 Plan.

The fair value of stock options granted to employees during the three and nine months ended September 30, 2022 and 2021 was estimated at the date of grant using the following assumptions:

	Three and Nine Months Ended September 30,
	2022			2021
Risk-free interest rate		2.99	%		0.73	%
Expected dividend yield	0%			0%
Expected term	5.22 years			5.22 years
Expected volatility	68.02%				68.48	%

The Company recognized stock-based compensation expense of $17 thousand, $53 thousand, $54 thousand and $354 thousand in general and administrative expense during the three and nine months ended September 30, 2022 and 2021, respectively.

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Net Loss Per Common Share

9 Months Ended

Sep. 30, 2022

Earnings Per Share [Abstract]

Net Loss Per Common Share

6. Net Loss Per Common Share

Basic net loss per share is calculated by dividing the net loss attributable to Merrimack Pharmaceuticals, Inc. by the weighted-average number of common shares outstanding during the period.

Diluted net loss per share is computed by dividing the net loss attributable to Merrimack Pharmaceuticals, Inc. by the weighted-average number of dilutive common shares outstanding during the period. Dilutive shares outstanding is calculated by adding to the weighted shares outstanding any potential (unissued) shares of common stock from outstanding stock options based on the treasury stock method. Outstanding stock options were not included in the diluted net loss per share calculation because the options were out of the money or to do so would have been antidilutive (i.e., the total proceeds upon exercise would have exceeded the market value of the underlying common shares). In a period when a net loss is reported, all common stock equivalents are excluded from the calculation because they would have an anti-dilutive effect, meaning the loss per share would be reduced. Therefore, in periods where a loss is reported, there is no difference in basic and dilutive loss per share.

Stock options are excluded from the calculation of diluted loss per share because the net loss for the three and nine months ended September 30, 2022 and 2021 causes such securities to be anti-dilutive. Outstanding options excluded from the calculation of diluted loss per share for the three and nine months ended September 30, 2022 and 2021 are shown in the chart below:

	Three and Nine Months Ended September 30,
(in thousands)	2022		2021
Outstanding options to purchase common stock		1,628		1,778

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Recent Accounting Pronouncements

9 Months Ended

Sep. 30, 2022

Accounting Changes And Error Corrections [Abstract]

Recent Accounting Pronouncements

7. Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed above, the Company does not believe that the adoption of recently issued standards has or may have a material impact on the Company’s condensed consolidated financial statements or disclosures.

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Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2022

Accounting Policies [Abstract]

Basis of Presentation

Basis of Presentation

The accompanying condensed consolidated financial statements reflect the operations of Merrimack Pharmaceuticals, Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated.

The condensed consolidated financial statements are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).

The accounting policies followed in the preparation of the interim condensed consolidated financial statements are consistent in all material respects with those presented in Note 1 to the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021.

Unaudited Interim Financial Information

Unaudited Interim Financial Information

The condensed consolidated balance sheet as of December 31, 2021 was derived from audited financial statements for the year ended December 31, 2021, but does not include all disclosures required by GAAP. The condensed consolidated balance sheet as of September 30, 2022, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2022 and 2021, the condensed consolidated statements of stockholders’ equity for the three and nine months ended September 30, 2022 and 2021 and the condensed consolidated statements of cash flows for the nine months ended September 30, 2022 and 2021 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2022, the results of its operations for the three and nine months ended September 30, 2022 and 2021, its statements of stockholders’ equity for the three and nine months ended September 30, 2022 and 2021 and its statements of cash flows for the nine months ended September 30, 2022 and 2021. The financial data and other information disclosed in the notes related to the three and nine months ended September 30, 2022

and 2021 are unaudited. The results for the three and nine months ended September 30, 2022 and 2021 are not necessarily indicative of results to be expected for the year ending December 31, 2022, any other interim periods, or any future year or period.

The unaudited interim financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. These unaudited condensed consolidated financial statements should be read in conjunction with the audited financial statements and the notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 filed with the SEC on March 9, 2022.

Use of Estimates

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates, assumptions and judgments reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.

Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed above, the Company does not believe that the adoption of recently issued standards has or may have a material impact on the Company’s condensed consolidated financial statements or disclosures.

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Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2022

Fair Value Disclosures [Abstract]

Summary of Assets Measured at Fair Value on a Recurring Basis

The following tables show assets measured at fair value on a recurring basis as of September 30, 2022 and December 31, 2021:

	September 30, 2022
(in thousands)	Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	11,801	$	—	$	—
Totals	$	11,801	$	—	$	—

	December 31, 2021
(in thousands)	Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	12,934	$	—	$	—
Totals	$	12,934	$	—	$	—

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Accounts Payable, Accrued Expenses and Other (Tables)

9 Months Ended

Sep. 30, 2022

Payables And Accruals [Abstract]

Schedule of Accounts Payable, Accrued Expenses and Other

Accounts payable, accrued expenses and other as of September 30, 2022 and December 31, 2021 consisted of the following:

(in thousands)	September 30, 2022		December 31, 2021
Accounts payable	$	67	$	120
Accrued goods and services		119		167
Accrued clinical trial costs		71		84
Others		191		191
Total accounts payable, accrued expenses and other	$	448	$	562

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Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Assumptions Used to Calculate Fair Value of Options Granted to Employees

The fair value of stock options granted to employees during the three and nine months ended September 30, 2022 and 2021 was estimated at the date of grant using the following assumptions:

	Three and Nine Months Ended September 30,
	2022			2021
Risk-free interest rate		2.99	%		0.73	%
Expected dividend yield	0%			0%
Expected term	5.22 years			5.22 years
Expected volatility	68.02%				68.48	%

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Net Loss Per Common Share (Tables)

9 Months Ended

Sep. 30, 2022

Earnings Per Share [Abstract]

Schedule of Outstanding Options Excluded from Computation of Diluted Loss Per Share

Outstanding options excluded from the calculation of diluted loss per share for the three and nine months ended September 30, 2022 and 2021 are shown in the chart below:

	Three and Nine Months Ended September 30,
(in thousands)	2022		2021
Outstanding options to purchase common stock		1,628		1,778

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Nature of the Business - Additional Information (Detail) - USD ($)		1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 15, 2021	Mar. 31, 2022	Mar. 27, 2020	Jul. 12, 2019	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Apr. 03, 2017
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit					$ 547,144,000		$ 547,144,000		$ 546,092,000
Net loss from continuing operations					442,000	$ 525,000	1,052,000	$ 1,980,000
Cash used in operating activities							1,557,000	$ (137,000)
Cash, cash equivalents and marketable securities					$ 13,100,000		$ 13,100,000
Celator Pharmaceuticals Inc [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash payment received			$ 2,300,000
Reimbursement of expenses			200,000
Transaction expenses			$ 400,000
Asset Purchase Option Agreement [Member]
Summary Of Significant Accounting Policies [Line Items]
Gain related to option fee payment									$ 100,000
Asset Purchase Option Agreement [Member] | Pegascy SAS [Member]
Summary Of Significant Accounting Policies [Line Items]
Consideration receivable	$ 500,000
Option fee	$ 100,000
Consideration received		$ 500,000
Gain related to payment of consideration		$ 500,000
Exercise period of option	24 months
Ipsen [Member] | Asset Sale Agreement [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable										$ 450,000,000.0
Ipsen [Member] | First Line Treatment of Metastatic Adenocarcinoma of Pancreas [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable										225,000,000.0
Ipsen [Member] | After Failure of First Line Chemotherapy [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable										150,000,000.0
Ipsen [Member] | Additional Indication [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable										$ 75,000,000.0
14ner Sale [Member]
Summary Of Significant Accounting Policies [Line Items]
Upfront cash payment received				$ 3,500,000
14ner Sale [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events				54,500,000
14ner Sale [Member] | Achievement of the Primary Endpoint in the First Registrational Clinical Study of Either MM-121 or MM-111 [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events				3,000,000.0
14ner Sale [Member] | Achievement of Various Regulatory Approval and Reimbursement-Based Milestones in the United States, Europe and Japan [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events				16,500,000
14ner Sale [Member] | Achievement Various Cumulative Worldwide Net Sales Targets Between $100.0 million and $300.0 million for MM-121 and MM-111 [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events				35,000,000.0
Cumulative worldwide net sales target				$ 300,000,000.0

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Fair Value of Financial Instruments - Summary of Assets Measured at Fair Value on a Recurring Basis (Detail) - Recurring Basis [Member] - Level 1 [Member] - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 11,801	$ 12,934
Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 11,801	$ 12,934

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Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Recurring Basis [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities measured at fair value	$ 0	$ 0

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Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Payables And Accruals [Abstract]
Accounts payable	$ 67	$ 120
Accrued goods and services	119	167
Accrued clinical trial costs	71	84
Others	191	191
Total accounts payable, accrued expenses and other	$ 448	$ 562

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Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Granted	0	0	22,000	22,000
Weighted Average Exercise Price	$ 3.68	$ 3.11	$ 3.11	$ 3.68
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation expense	$ 17	$ 54	$ 53	$ 354
Stock Incentive Plan 2021 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for grant (in shares)	231,000		231,000

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Stock-Based Compensation - Schedule of Assumptions Used to Calculate Fair Value of Options Granted to Employees (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	2.99%	0.73%	2.99%	0.73%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term	5 years 2 months 19 days	5 years 2 months 19 days	5 years 2 months 19 days	5 years 2 months 19 days
Expected volatility	68.02%	68.48%	68.02%	68.48%

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Net Loss Per Common Share - Schedule of Outstanding Options Excluded from Computation of Diluted Loss Per Share (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Outstanding Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding options to purchase common stock	1,628	1,778	1,628	1,778