Warrants	6 Months Ended
Jun. 30, 2024
Warrants and Rights Note Disclosure [Abstract]
Warrants	Note 10. WARRANTS Public Warrants On October 3, 2023, the Company sold in a public offering (i) 542,857 shares of the Company’s common stock together with public warrants to purchase up to 542,857 shares of common stock and (ii) in lieu of shares of common stock, pre-funded warrants exercisable for 142,857 shares of common stock together with public warrants to purchase up to 142,857 shares of common stock (the “Offering”). Each public warrant has an initial exercise price equal to $14.00 per share. The public warrants are immediately exercisable and expire five years from the date of issuance. The shares of common stock and accompanying public warrants were sold at a combined public offering price of $14.00 per share and the accompanying public warrants, and the pre-funded warrants and accompanying public warrants were sold at a combined public offering price of $13.99 per pre-funded warrant and accompanying public warrants for aggregate gross proceeds of $9.6 million, before deductions for placement agent and offering fees payable by the Company. The public warrants may not be exercised if the aggregate number of common stock beneficially owned by the holder thereof immediately following such exercise would exceed a specified beneficial ownership limitation; provided, however, that a holder may increase or decrease the beneficial ownership limitation by giving 61 days’ notice to the Company, but not to any percentage in excess of 9.99%. The Company has the right to “call” any portion of a holder’s public warrants by delivering a call notice to the holder within 30 days after Company publicly announces an increase in pepinemab-treated patients relative to placebo-treated patients, with statistical significance having a p-value of less than or equal to 0.05, in the change of the FDG-PET standard uptake value ratio for brain metabolism between baseline and month 12 as assessed by [18F]fluorodeoxyglucose (FDG)-PET in the resting state following administration of 40 mg/kg pepinemab or placebo, as applicable, as described in the protocol for the Company’s SIGNAL-AD Alzheimer’s disease study and the associated Statistical Analysis Plan (the “Positive Data Release”). After delivery of a call notice, the public warrants will continue to be exercisable. Each public warrant will be canceled and no longer exercisable to the extent the holder fails to timely exercise the public warrant for the called portion thereof within 20 trading days following the Company’s issuance of a call notice. In the event of a fundamental transaction, the public warrants required the Company to make a payment based on a Black-Scholes pricing model valuation, using specific inputs that precluded the instruments from being considered indexed to the Company’s own stock in accordance with ASC 815. The public warrants also contained certain terms that provided for an adjustment in response to the occurrence or nonoccurrence of a specified event that is inconsistent with an implicit assumption in a standard valuation model, which also precluded the instruments from being considered indexed to the Company’s stock in accordance with ASC 815. Therefore, upon issuance, the Company accounted for the public warrants as liabilities, which were recorded at the issuance date fair value of approximately $3.5 million. In March 2024, the Company entered into warrant amendment agreements with holders of approximately 83% of the public warrants issued in the Offering to amend aforementioned terms in the public warrants. The public warrants, as amended, were no longer precluded from being considered indexed to the Company's stock in accordance with ASC 815. As a result, 572,139 of the public warrants, as amended, issued in the Offering were reclassified as equity, based on the guidance provided under ASC 815-40. The public warrants, as amended, were marked to fair value on the amendment date resulting in a gain on change in fair value of warrant liabilities of $0.7 million in the Company's condensed statements of operations and comprehensive loss for the six months ended June 30, 2024. In addition, $1.2 million of public warrant liabilities were reclassified as equity in the Company's condensed statements of stockholders' equity (deficit) for the six months ended June 30, 2024. As of June 30, 2024, all of the public warrants were outstanding. Private Placement Warrants In November 2023, pursuant to securities purchase agreements entered into with certain investors, the Company issued and sold private placement warrants to purchase 37,694 shares of common stock. Each private placement warrant has a purchase price equal to $1.75 per share, subject to proportional adjustments in the event of stock splits, combinations (including reverse stock splits), or similar events. The private placement warrants are immediately exercisable and expire five years from the date of issuance and the Company has the right to “call” any portion of the private placement warrants under the same conditions and terms as the public warrants. The private placement warrants are subject to the same beneficial ownership limitations as the public warrants and the pre-funded warrants. Upon issuance, the private placement warrants were precluded from being considered indexed to the Company’s own stock in accordance with ASC 815. Therefore, at issuance, the private placement warrants were liability-classified and recorded at their respective issuance date fair values. On February 6, 2024, the Company entered into a securities purchase agreement pursuant to which we issued and sold 274,182 shares of our common stock together with private placement warrants to purchase up to 274,182 shares of common stock and (ii) pre-funded warrants to purchase up to 90,363 shares of common stock together with private placement warrants to purchase up to 90,363 shares of our common stock (the “February 2024 SPA”). Each private placement warrant is immediately exercisable and has an initial exercise price of $14.00 per share. The shares of common stock and accompanying private placement warrants were sold at a combined price of $10.15 per share and the accompanying private placement warrants, and the pre-funded warrants and accompanying private placement warrants were sold at a combined price of $10.1486 per pre-funded warrant and accompanying private placement warrant, for aggregate gross proceeds of approximately $3.7 million. The Company has the right to “call” the exercise of any portion of a holder’s private placement warrants by delivering a call notice to the holder within 30 days, in the case of the November private placement warrants, or 120 days in the case of the February private placement warrants, after the Positive Data Release. After delivery of a call notice, the private placement warrants will continue to be exercisable. Each private placement warrant will be canceled and no longer exercisable to the extent the holder fails to timely exercise the private placement warrant for the called portion thereof within 20 trading days, in the case of the November private placement warrants, or 30 trading days in the case of the February private placement warrants, following the Company’s issuance of a call notice, provided that to the extent the exercise of a called portion of a private placement warrant would cause the holder to hold common stock in excess of a specified beneficial ownership limitation, upon exercise of such portion, as set forth in the private placement warrant, instead of shares being issued, the exercise would result in the modification of the terms of such portion to be consistent with the terms of the pre-funded warrant. Upon issuance, the private placement warrants were precluded from being considered indexed to the Company’s own stock in accordance with ASC 815. Therefore, at issuance, the private placement warrants were liability-classified and recorded at their issuance date fair value. In March 2024, the Company entered into warrant amendment agreements with holders of 100% of the private placement warrants issued in November 2023 and holders of 97% of the private placement warrants issued in the February 2024 SPA to amend the aforementioned terms in the private placement warrants. As a result, 354,693 of the November 2023 and February 2024 SPA private placement warrants, as amended, were no longer precluded from being considered indexed to the Company's stock in accordance with ASC 815. The Company reclassified $0.8 million of the amended private placement warrants, as equity, in the Company's condensed statements of stockholders' equity/deficit for the six months ended June 30, 2024, based on the guidance provided under ASC 815-40. The private placement warrants, as amended, were marked to fair value on the amendment date resulting in a gain on change in fair value of warrant liabilities of $0.36 million in the Company's condensed statements of operations and comprehensive loss for the six months ended June 30, 2024. On March 27, 2024, the Company entered into a securities purchase agreement pursuant to which the Company issued and sold 193,000 shares of the Company's common stock in a public offering together with private placement warrants to purchase up to 193,000 shares of common stock in a concurrent private placement at a combined price of $7.77 per share and accompanying private placement warrant for an aggregate purchase price of approximately $1.5 million. Separately on March 27, 2024, the Company entered into a securities purchase agreement in a different form pursuant to which the Company sold 159,683 shares of common stock and private placement warrants to purchase up to 159,683 shares of common stock in a private placement at a combined price of $7.77 per share and accompanying private placement warrant for an aggregate purchase price of approximately $1.25 million. The Company evaluated the March 2024 private placement warrants and concluded that they met the criteria to be classified within stockholders’ equity within additional paid-in-capital. These private placement warrants are equity classified because they (1) are freestanding financial instruments that are legally detachable and separately exercisable from the common stock, (2) are immediately exercisable, (3) do not embody an obligation for the Company to repurchase its shares, (4) permit the holder to receive a fixed number of shares of common stock upon exercise, (5) are indexed to the Company's common stock and (6) meet the equity classification criteria. Accordingly, the Company allocated approximately $0.84 million of the proceeds remaining (after the allocation of proceeds to the common stock in the amount equal to their issuance date fair value) to the March private placement warrants on a relative fair value basis for recognition in additional paid-in capital on the date of issuance. As of June 30, 2024, all of the private placement warrants were outstanding. ADDF Warrants In connection with the securities purchase agreement with the Alzheimer’s Drug Discovery Foundation, the Company sold ADDF Warrants to purchase up to 229,057 shares of common stock. Each ADDF Warrant has an initial exercise price equal to $7.64 per share, subject to proportional adjustments in the event of stock splits, combinations (including reverse stock splits), or similar events. These ADDF Warrants are immediately exercisable and will expire on March 29, 2029. The Company evaluated the ADDF Warrants and concluded they met the criteria to be classified within stockholders’ equity within additional paid-in-capital. The ADDF Warrants are equity classified because they (1) are freestanding financial instruments that are legally detachable and separately exercisable from the common stock, (2) are immediately exercisable, (3) do not embody an obligation for the Company to repurchase its shares, (4) permit the holder to receive a fixed number of shares of common stock upon exercise, (5) are indexed to the Company's common stock and (6) meet the equity classification criteria. As of June 30, 2024, all of the ADDF warrants were outstanding. Pre-Funded Warrants In connection with the February 2024 SPA, the Company sold pre-funded warrants exercisable for 90,363 shares of common stock. Each pre-funded warrant has an initial exercise price equal to $0.0014 per share, subject to proportional adjustments in the event of stock splits, combinations (including reverse stock splits), or similar events. The pre-funded warrants may be exercised at any time and will not expire until exercised in full. The pre-funded warrants are subject to the same beneficial owner limitations as the private placement warrants. The Company evaluated the pre-funded warrants and concluded that they met the criteria to be classified within stockholders’ equity within additional paid-in-capital. The pre-funded warrants are equity classified because they (1) are freestanding financial instruments that are legally detachable and separately exercisable from the common stock, (2) are immediately exercisable, (3) do not embody an obligation for the Company to repurchase its shares, (4) permit the holder to receive a fixed number of shares of common stock upon exercise, (5) are indexed to the Company's common stock and (6) meet the equity classification criteria. Accordingly, the Company allocated approximately $0.9 million of the proceeds remaining (after the allocation of proceeds to the liability-classified private placement warrants in the amount equal to their issuance date fair value) to the pre-funded warrants on a relative fair value basis for recognition in additional paid-in capital on the date of issuance. As of June 30, 2024, all of the pre-funded warrants were outstanding.

On October 3, 2023, the Company sold in a public offering (i) 542,857 shares of the Company’s common stock together with public warrants to purchase up to 542,857 shares of common stock and (ii) in lieu of shares of common stock, pre-funded warrants exercisable for 142,857 shares of common stock together with public warrants to purchase up to 142,857 shares of common stock (the “Offering”). Each public warrant has an initial exercise price equal to $14.00 per share. The public warrants are immediately exercisable and expire five years from the date of issuance. The shares of common stock and accompanying public warrants were sold at a combined public offering price of $14.00 per share and the accompanying public warrants, and the pre-funded warrants and accompanying public warrants were sold at a combined public offering price of $13.99 per pre-funded warrant and accompanying public warrants for aggregate gross proceeds of $9.6 million, before deductions for placement agent and offering fees payable by the Company. The public warrants may not be exercised if the aggregate number of common stock beneficially owned by the holder thereof immediately following such exercise would exceed a specified beneficial ownership limitation; provided, however, that a holder may increase or decrease the beneficial ownership limitation by giving 61 days’ notice to the Company, but not to any percentage in excess of 9.99%.

The Company has the right to “call” any portion of a holder’s public warrants by delivering a call notice to the holder within 30 days after Company publicly announces an increase in pepinemab-treated patients relative to placebo-treated patients, with statistical significance having a p-value of less than or equal to 0.05, in the change of the FDG-PET standard uptake value ratio for brain metabolism between baseline and month 12 as assessed by [18F]fluorodeoxyglucose (FDG)-PET in the resting state following administration of 40 mg/kg pepinemab or

placebo, as applicable, as described in the protocol for the Company’s SIGNAL-AD Alzheimer’s disease study and the associated Statistical Analysis Plan (the “Positive Data Release”). After delivery of a call notice, the public warrants will continue to be exercisable. Each public warrant will be canceled and no longer exercisable to the extent the holder fails to timely exercise the public warrant for the called portion thereof within 20 trading days following the Company’s issuance of a call notice.

In the event of a fundamental transaction, the public warrants required the Company to make a payment based on a Black-Scholes pricing model valuation, using specific inputs that precluded the instruments from being considered indexed to the Company’s own stock in accordance with ASC 815. The public warrants also contained certain terms that provided for an adjustment in response to the occurrence or nonoccurrence of a specified event that is inconsistent with an implicit assumption in a standard valuation model, which also precluded the instruments from being considered indexed to the Company’s stock in accordance with ASC 815. Therefore, upon issuance, the Company accounted for the public warrants as liabilities, which were recorded at the issuance date fair value of approximately $3.5 million.

In March 2024, the Company entered into warrant amendment agreements with holders of approximately 83% of the public warrants issued in the Offering to amend aforementioned terms in the public warrants. The public warrants, as amended, were no longer precluded from being considered indexed to the Company's stock in accordance with ASC 815. As a result, 572,139 of the public warrants, as amended, issued in the Offering were reclassified as equity, based on the guidance provided under ASC 815-40. The public warrants, as amended, were marked to fair value on the amendment date resulting in a gain on change in fair value of warrant liabilities of $0.7 million in the Company's condensed statements of operations and comprehensive loss for the six months ended June 30, 2024. In addition, $1.2 million of public warrant liabilities were reclassified as equity in the Company's condensed statements of stockholders' equity (deficit) for the six months ended June 30, 2024.

In November 2023, pursuant to securities purchase agreements entered into with certain investors, the Company issued and sold private placement warrants to purchase 37,694 shares of common stock. Each private placement warrant has a purchase price equal to $1.75 per share, subject to proportional adjustments in the event of stock splits, combinations (including reverse stock splits), or similar events. The private placement warrants are immediately exercisable and expire five years from the date of issuance and the Company has the right to “call” any portion of the private placement warrants under the same conditions and terms as the public warrants. The private placement warrants are subject to the same beneficial ownership limitations as the public warrants and the pre-funded warrants. Upon issuance, the private placement warrants were precluded from being considered indexed to the Company’s own stock in accordance with ASC 815. Therefore, at issuance, the private placement warrants were liability-classified and recorded at their respective issuance date fair values.

On February 6, 2024, the Company entered into a securities purchase agreement pursuant to which we issued and sold 274,182 shares of our common stock together with private placement warrants to purchase up to 274,182 shares of common stock and (ii) pre-funded warrants to purchase up to 90,363 shares of common stock together with private placement warrants to purchase up to 90,363 shares of our common stock (the “February 2024 SPA”). Each private placement warrant is immediately exercisable and has an initial exercise price of $14.00 per share. The shares of common stock and accompanying private placement warrants were sold at a combined price of $10.15 per share and the accompanying private placement warrants, and the pre-funded warrants and accompanying private placement warrants were sold at a combined price of $10.1486 per pre-funded warrant and accompanying private placement warrant, for aggregate gross proceeds of approximately $3.7 million.

The Company has the right to “call” the exercise of any portion of a holder’s private placement warrants by delivering a call notice to the holder within 30 days, in the case of the November private placement warrants, or 120 days in the case of the February private placement warrants, after the Positive Data Release. After delivery of a call notice, the private placement warrants will continue to be exercisable. Each private placement warrant will be canceled and no longer exercisable to the extent the holder fails to timely exercise the private placement warrant for the called portion thereof within 20 trading days, in the case of the November private placement warrants, or 30

trading days in the case of the February private placement warrants, following the Company’s issuance of a call notice, provided that to the extent the exercise of a called portion of a private placement warrant would cause the holder to hold common stock in excess of a specified beneficial ownership limitation, upon exercise of such portion, as set forth in the private placement warrant, instead of shares being issued, the exercise would result in the modification of the terms of such portion to be consistent with the terms of the pre-funded warrant. Upon issuance, the private placement warrants were precluded from being considered indexed to the Company’s own stock in accordance with ASC 815. Therefore, at issuance, the private placement warrants were liability-classified and recorded at their issuance date fair value.

In March 2024, the Company entered into warrant amendment agreements with holders of 100% of the private placement warrants issued in November 2023 and holders of 97% of the private placement warrants issued in the February 2024 SPA to amend the aforementioned terms in the private placement warrants. As a result, 354,693 of the November 2023 and February 2024 SPA private placement warrants, as amended, were no longer precluded from being considered indexed to the Company's stock in accordance with ASC 815. The Company reclassified $0.8 million of the amended private placement warrants, as equity, in the Company's condensed statements of stockholders' equity/deficit for the six months ended June 30, 2024, based on the guidance provided under ASC 815-40. The private placement warrants, as amended, were marked to fair value on the amendment date resulting in a gain on change in fair value of warrant liabilities of $0.36 million in the Company's condensed statements of operations and comprehensive loss for the six months ended June 30, 2024.

On March 27, 2024, the Company entered into a securities purchase agreement pursuant to which the Company issued and sold 193,000 shares of the Company's common stock in a public offering together with private placement warrants to purchase up to 193,000 shares of common stock in a concurrent private placement at a combined price of $7.77 per share and accompanying private placement warrant for an aggregate purchase price of approximately $1.5 million. Separately on March 27, 2024, the Company entered into a securities purchase agreement in a different form pursuant to which the Company sold 159,683 shares of common stock and private placement warrants to purchase up to 159,683 shares of common stock in a private placement at a combined price of $7.77 per share and accompanying private placement warrant for an aggregate purchase price of approximately $1.25 million.

The Company evaluated the March 2024 private placement warrants and concluded that they met the criteria to be classified within stockholders’ equity within additional paid-in-capital. These private placement warrants are equity classified because they (1) are freestanding financial instruments that are legally detachable and separately exercisable from the common stock, (2) are immediately exercisable, (3) do not embody an obligation for the Company to repurchase its shares, (4) permit the holder to receive a fixed number of shares of common stock upon exercise, (5) are indexed to the Company's common stock and (6) meet the equity classification criteria.

Accordingly, the Company allocated approximately $0.84 million of the proceeds remaining (after the allocation of proceeds to the common stock in the amount equal to their issuance date fair value) to the March private placement warrants on a relative fair value basis for recognition in additional paid-in capital on the date of issuance.

In connection with the securities purchase agreement with the Alzheimer’s Drug Discovery Foundation, the Company sold ADDF Warrants to purchase up to 229,057 shares of common stock. Each ADDF Warrant has an initial exercise price equal to $7.64 per share, subject to proportional adjustments in the event of stock splits, combinations (including reverse stock splits), or similar events. These ADDF Warrants are immediately exercisable and will expire on March 29, 2029.

The Company evaluated the ADDF Warrants and concluded they met the criteria to be classified within stockholders’ equity within additional paid-in-capital. The ADDF Warrants are equity classified because they (1) are freestanding financial instruments that are legally detachable and separately exercisable from the common stock, (2) are immediately exercisable, (3) do not embody an obligation for the Company to repurchase its shares, (4) permit

the holder to receive a fixed number of shares of common stock upon exercise, (5) are indexed to the Company's common stock and (6) meet the equity classification criteria.

In connection with the February 2024 SPA, the Company sold pre-funded warrants exercisable for 90,363 shares of common stock. Each pre-funded warrant has an initial exercise price equal to $0.0014 per share, subject to proportional adjustments in the event of stock splits, combinations (including reverse stock splits), or similar events. The pre-funded warrants may be exercised at any time and will not expire until exercised in full. The pre-funded warrants are subject to the same beneficial owner limitations as the private placement warrants.

The Company evaluated the pre-funded warrants and concluded that they met the criteria to be classified within stockholders’ equity within additional paid-in-capital. The pre-funded warrants are equity classified because they (1) are freestanding financial instruments that are legally detachable and separately exercisable from the common stock, (2) are immediately exercisable, (3) do not embody an obligation for the Company to repurchase its shares, (4) permit the holder to receive a fixed number of shares of common stock upon exercise, (5) are indexed to the Company's common stock and (6) meet the equity classification criteria.

Accordingly, the Company allocated approximately $0.9 million of the proceeds remaining (after the allocation of proceeds to the liability-classified private placement warrants in the amount equal to their issuance date fair value) to the pre-funded warrants on a relative fair value basis for recognition in additional paid-in capital on the date of issuance.