Stockholders' equity	6 Months Ended
Jun. 30, 2025
Stockholders' equity
Stockholders' equity	5. Stockholders’ equity The total number of shares of all classes of capital stock that the Company is authorized to issue is 440,000,000 shares, consisting of 400,000,000 shares of common stock, par value $0.001 per share and 40,000,000 shares of preferred stock, par value $0.001 per share. Series A Preferred Stock As of June 30, 2025, a total of 31,194 shares of Series A Preferred Stock remained outstanding, which are convertible into 15,596 shares of common stock. As of December 31, 2024, a total of 56,227 shares of Series A Preferred Stock remained outstanding, which were convertible into 28,112 shares of common stock. In April 2025, a total of 25,033 shares of Series A Preferred stock were converted into 12,516 shares of common stock. Common Stock The holders of common stock are entitled to one vote for each share of common stock. In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, after the payment or provision for payment of all debts and liabilities of the Company, the holders of common stock shall be entitled to share in the remaining assets of the Company available for distribution, if any. Shelf Registration Statement On January 26, 2024, the Company filed a shelf registration statement (the “2024 Shelf Registration Statement”) with the SEC for issuance of common stock, preferred stock, warrants, rights, debt securities and units up to an aggregate of $150 million, including a prospectus for the sale of $1.0 million of shares of our common stock under the ATM Agreement, as defined below, which was declared effective on February 2, 2024. The Company subsequently filed a prospectus supplement to the 2024 Shelf Registration Statement for the sale of up to $2.0 million of shares of common stock pursuant to the ATM Agreement. On January 26, 2024, the Company entered into an At the Market Offering Agreement (the “ATM Agreement”) with H.C. Wainwright & Co., LLC (“HCW”). Pursuant to the ATM Agreement and the prospectus supplement filed in connection therewith, the Company was able, from time to time, in its sole discretion, to issue and sell through HCW, acting as sales agent and/or principal, up to $2.0 million of shares of common stock. The Company did not make any sales under the ATM Agreement and in March 2024, the Company terminated the ATM Agreement with HCW. On November 8, 2024, the Company filed a prospectus supplement to the 2024 Shelf Registration Statement with the SEC for the sale of up to $3.0 million pursuant to the 2024 ATM Agreement, as discussed below. On November 8, 2024, the Company entered into an At the Market Offering Agreement (the “2024 ATM Agreement”) with HCW. Pursuant to the 2024 ATM Agreement and the prospectus supplement filed in connection therewith, the Company may, from time to time, in its sole discretion, issue and sell through HCW, acting as sales agent and/or principal, up to $3.0 million of shares of common stock. During the year ended December 31, 2024, the Company issued and sold 41,152 shares of common stock under the 2024 ATM Agreement resulting in net proceeds to the Company of approximately $0.1 million after deducting approximately $6,000 in issuance costs. During the three months ended June 30, 2025, the Company issued and sold 220,733 shares of common stock under the 2024 ATM Agreement resulting in net proceeds to the Company of approximately $0.4 million after deducting approximately $15,000 in issuance costs. During the six months ended June 30, 2025, the Company issued and sold 243,139 shares of common stock under the 2024 ATM Agreement resulting in net proceeds to the Company of approximately $0.4 million after deducting approximately $18,000 in issuance costs. March 2024 Private Placement On March 11, 2024, the Company entered into a securities purchase agreement with certain purchasers (the “Purchasers”) pursuant to which the Company agreed to issue and sell to the Purchasers in a private placement offering exempt from registration under the Securities Act of 1933, as amended, or the Securities Act, and the Purchasers agreed to purchase from the Company (i) 1,687,712 shares of the Company’s common stock at a purchase price of $7.29 per share (the “Shares”), (ii) pre-funded common stock purchase warrants at a purchase price of $7.289 to purchase an aggregate of up to 507,076 shares of the Company’s common stock at an exercise price of $0.001 per share (the “Pre-Funded Shares”), (iii) tranche A common stock purchase warrants to purchase up to 1,097,394 shares of the Company’s common stock at an exercise price of $7.29 per share (the “Tranche A Warrants”), and (iv) tranche B common stock purchase warrants to purchase up to 1,097,394 shares of the Company’s common stock at an exercise price of $9.1125 per share (the “Tranche B Warrants”). The Tranche A Warrants will be exercisable until the earlier of (i) the three-year anniversary of issuance and (ii) 30 days after the Company announces the recommended Phase 2 dose for ATRN-119, and, following such announcement, the daily volume weighted average price of the Company’s common stock equals or exceeds $14.58 for 30 consecutive trading days. The Tranche B Warrants will be exercisable until the earlier of (i) the five-year anniversary of issuance and (ii) 30 days after the Company announces the recommended Phase 2 dose for APR-1051 and, following such announcement, the daily volume weighted average price of the Company’s common stock equals or exceeds $18.225 for 30 consecutive trading days. To the extent that the exercise of a Tranche A Warrant or Tranche B Warrant would result in the holder beneficially owning greater than 4.99% (or, at the election of the holder, greater than 9.99%) of the Company’s outstanding common stock immediately following such exercise, the holder will instead receive pre-funded warrants in substantially the same form as the pre-funded warrants issued at closing. The aggregate upfront gross proceeds from the issuance of common stock and pre-funded common stock purchase warrants totaled approximately $16.0 million, before deducting placement agent fees and offering costs of approximately $1.3 million. The gross proceeds from potential future warrant cash exercises are expected to be up to approximately $18.0 million, before deducting placement agent fees. In April 2024, we registered on Form S-3 the resale of the Shares, the Pre-Funded Shares and the shares underlying the Tranche A Warrants and Tranche B Warrants. The Company evaluated the terms of the warrants issued and determined that they should be classified as equity instruments within additional paid-in capital. As of June 30, 2025 and December 31, 2024, none of the pre-funded warrants, Tranche A Warrants or Tranche B Warrants have been exercised. Stock-Based Compensation Expense The Company recorded stock-based compensation expense of $0.1 and $0.1 for the three months ended June 30, 2025 and 2024, respectively. The Company recorded stock-based compensation expense of $0.3 and $0.2 for the six months ended June 30, 2025 and 2024, respectively.

Stockholders' equity

6 Months Ended

Jun. 30, 2025

5. Stockholders’ equity

The total number of shares of all classes of capital stock that the Company is authorized to issue is 440,000,000 shares, consisting of 400,000,000 shares of common stock, par value $0.001 per share and 40,000,000 shares of preferred stock, par value $0.001 per share.

Series A Preferred Stock

As of June 30, 2025, a total of 31,194 shares of Series A Preferred Stock remained outstanding, which are convertible into 15,596 shares of common stock. As of December 31, 2024, a total of 56,227 shares of Series A Preferred Stock remained outstanding, which were convertible into 28,112 shares of common stock. In April 2025, a total of 25,033 shares of Series A Preferred stock were converted into 12,516 shares of common stock.

Common Stock

The holders of common stock are entitled to one vote for each share of common stock. In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, after the payment or provision for payment of all debts and liabilities of the Company, the holders of common stock shall be entitled to share in the remaining assets of the Company available for distribution, if any.

Shelf Registration Statement

On January 26, 2024, the Company filed a shelf registration statement (the “2024 Shelf Registration Statement”) with the SEC for issuance of common stock, preferred stock, warrants, rights, debt securities and units up to an aggregate of $150 million, including a prospectus for the sale of $1.0 million of shares of our common stock under the ATM Agreement, as defined below, which was declared effective on February 2, 2024. The Company subsequently filed a prospectus supplement to the 2024 Shelf Registration Statement for the sale of up to $2.0 million of shares of common stock pursuant to the ATM Agreement. On January 26, 2024, the Company entered into an At the Market Offering Agreement (the “ATM Agreement”) with H.C. Wainwright & Co., LLC (“HCW”). Pursuant to the ATM Agreement and the prospectus supplement filed in connection therewith, the Company was able, from time to time, in its sole discretion, to issue and sell through HCW, acting as sales agent and/or principal, up to $2.0 million of shares of common

stock. The Company did not make any sales under the ATM Agreement and in March 2024, the Company terminated the ATM Agreement with HCW.

On November 8, 2024, the Company filed a prospectus supplement to the 2024 Shelf Registration Statement with the SEC for the sale of up to $3.0 million pursuant to the 2024 ATM Agreement, as discussed below. On November 8, 2024, the Company entered into an At the Market Offering Agreement (the “2024 ATM Agreement”) with HCW. Pursuant to the 2024 ATM Agreement and the prospectus supplement filed in connection therewith, the Company may, from time to time, in its sole discretion, issue and sell through HCW, acting as sales agent and/or principal, up to $3.0 million of shares of common stock. During the year ended December 31, 2024, the Company issued and sold 41,152 shares of common stock under the 2024 ATM Agreement resulting in net proceeds to the Company of approximately $0.1 million after deducting approximately $6,000 in issuance costs. During the three months ended June 30, 2025, the Company issued and sold 220,733 shares of common stock under the 2024 ATM Agreement resulting in net proceeds to the Company of approximately $0.4 million after deducting approximately $15,000 in issuance costs. During the six months ended June 30, 2025, the Company issued and sold 243,139 shares of common stock under the 2024 ATM Agreement resulting in net proceeds to the Company of approximately $0.4 million after deducting approximately $18,000 in issuance costs.

March 2024 Private Placement

On March 11, 2024, the Company entered into a securities purchase agreement with certain purchasers (the “Purchasers”) pursuant to which the Company agreed to issue and sell to the Purchasers in a private placement offering exempt from registration under the Securities Act of 1933, as amended, or the Securities Act, and the Purchasers agreed to purchase from the Company (i) 1,687,712 shares of the Company’s common stock at a purchase price of $7.29 per share (the “Shares”), (ii) pre-funded common stock purchase warrants at a purchase price of $7.289 to purchase an aggregate of up to 507,076 shares of the Company’s common stock at an exercise price of $0.001 per share (the “Pre-Funded Shares”), (iii) tranche A common stock purchase warrants to purchase up to 1,097,394 shares of the Company’s common stock at an exercise price of $7.29 per share (the “Tranche A Warrants”), and (iv) tranche B common stock purchase warrants to purchase up to 1,097,394 shares of the Company’s common stock at an exercise price of $9.1125 per share (the “Tranche B Warrants”). The Tranche A Warrants will be exercisable until the earlier of (i) the three-year anniversary of issuance and (ii) 30 days after the Company announces the recommended Phase 2 dose for ATRN-119, and, following such announcement, the daily volume weighted average price of the Company’s common stock equals or exceeds $14.58 for 30 consecutive trading days. The Tranche B Warrants will be exercisable until the earlier of (i) the five-year anniversary of issuance and (ii) 30 days after the Company announces the recommended Phase 2 dose for APR-1051 and, following such announcement, the daily volume weighted average price of the Company’s common stock equals or exceeds $18.225 for 30 consecutive trading days. To the extent that the exercise of a Tranche A Warrant or Tranche B Warrant would result in the holder beneficially owning greater than 4.99% (or, at the election of the holder, greater than 9.99%) of the Company’s outstanding common stock immediately following such exercise, the holder will instead receive pre-funded warrants in substantially the same form as the pre-funded warrants issued at closing. The aggregate upfront gross proceeds from the issuance of common stock and pre-funded common stock purchase warrants totaled approximately $16.0 million, before deducting placement agent fees and offering costs of approximately $1.3 million. The gross proceeds from potential future warrant cash exercises are expected to be up to approximately $18.0 million, before deducting placement agent fees. In April 2024, we registered on Form S-3 the resale of the Shares, the Pre-Funded Shares and the shares underlying the Tranche A Warrants and Tranche B Warrants.

The Company evaluated the terms of the warrants issued and determined that they should be classified as equity instruments within additional paid-in capital. As of June 30, 2025 and December 31, 2024, none of the pre-funded warrants, Tranche A Warrants or Tranche B Warrants have been exercised.

Stock-Based Compensation Expense

The Company recorded stock-based compensation expense of $0.1 and $0.1 for the three months ended June 30, 2025 and 2024, respectively. The Company recorded stock-based compensation expense of $0.3 and $0.2 for the six months ended June 30, 2025 and 2024, respectively.