The Funds purchased 11,400,000 shares of the Issuer's Series A Redeemable Convertible Preferred Stock for an aggregate purchase price of $22,800,000, including $19,827,620 paid by Qualified Fund for 9,913,810 shares. The Funds purchased 2,500,000 shares of the Issuer's Series B Redeemable Convertible Preferred Stock for an aggregate purchase price of $10,000,000, including $9,590,000 paid by Qualified Fund for 2,397,500 shares. Immediately prior to the closing of the initial public offering of the Issuer's Common Stock on 1/12/2026, the shares of Series A Redeemable Convertible Preferred Stock and Series B Redeemable Convertible Preferred Stock held by the Funds automatically converted on a 3.8044-for-1 basis into 2,602,247 shares of the Issuer's Common Stock and 1,051,412 shares of the Issuer's Class A Common Stock. No additional consideration was paid on such conversion. In addition, certain of the Funds purchased 2,222,222 shares of Common Stock in the Issuer's initial public offering on 1/12/2026 for an aggregate purchase price of $39,999,996. Qualified Fund purchased 2,077,779 of these shares for a purchase price of $37,400,022. The foregoing purchases of securities were all made from the Funds' working capital. On 1/8/2026, Mr. Nodelman received a grant of options to acquire 37,866 shares of the Issuer's Common Stock for his service on the Issuer's board of directors.

EcoR1 is the investment adviser to its clients pursuant to investment management agreements or limited partnership agreements providing to EcoR1 the authority, among other things, to invest the funds of such clients in Stock, to vote and dispose of Stock and to file this statement on behalf of such clients. Pursuant to such limited partnership agreements, EcoR1 is entitled to allocations based on assets under management and realized and unrealized gains. Pursuant to such investment management agreements, EcoR1 is entitled to fees based on assets under management and realized and unrealized gains. The Funds hold the aggregate amount of 1,051,412 shares of the Issuer's Class A Common Stock. Each share of Class A Common Stock is convertible into one share of the Issuer's Common Stock at the holder's election, provided that the shares may not be converted if doing so would result in EcoR1 or any of the Funds beneficially owning more than 4.99% of the outstanding shares of Common Stock. Due to this limitation, the shares of Class A Common Stock held by the Funds are not presently convertible. The Funds are party to a Third Amended and Restated Investors' Rights Agreement, dated September 20, 2024, with the Issuer (the "Rights Agreement"). The Rights Agreement grants certain rights to the Funds, including certain demand, piggyback and Form S-3 registration rights with respect to the registrable securities held by them. The terms and provisions of the Rights Agreement are described more fully in the Issuer's Registration Statement on Form S-1/A (File No. 333-292283) declared effective by the Commission on January 7, 2026 (the "Registration Statement"), and the above summary is qualified by reference to such description and the full text of the Rights Agreement, which is filed as Exhibit 99.2 to this Schedule 13D and is incorporated herein by reference. In connection with the initial public offering of the Issuer's Common Stock, each of the Funds and Mr. Nodelman has entered into lock-up agreements, pursuant to which each of them have agreed, subject to certain exceptions, not to sell, transfer or otherwise convey any of the Issuer's securities held by the Funds for 180 days following the date of the offering. The terms and provisions of such lock-up agreements are described more fully in the Registration Statement, and the above summary is qualified by reference to such description and the full text of the lock-up agreement, a form of which is filed as Exhibit 99.3 to this Schedule 13D and is incorporated herein by reference. Mr. Nodelman, in his capacity as a director, may be entitled to receive cash compensation and equity compensation, including stock option or other equity awards, pursuant to the Issuer's 2026 Equity Incentive Plan (the "2026 Plan"), and the Issuer's non-employee director compensation policy (the "Compensation Plan"). The terms and provisions of the 2026 Plan and the Compensation Plan are described in the Registration Statement, and the above summary is qualified by reference to such description and the full text of which is filed as Exhibit 99.4 and Exhibit 99.5 to this Schedule 13D and are incorporated herein by reference. In addition, the Issuer has entered into an indemnification agreement with each of its directors and executive officers, including Mr. Nodelman. The indemnification agreement requires the Issuer, among other things, to indemnify Mr. Nodelman for some expenses, including attorneys' fees, judgments, fines and settlement amounts incurred by him in any action or proceeding arising out of his services as director. The terms and provisions of the indemnification agreement are described more fully in the Registration Statement, and the above summary is qualified by reference to such description and the full text of the Registration Statement, which is filed as Exhibit 99.6 to this Schedule 13D and is incorporated herein by reference.

Exhibit 99.1: Agreement Regarding Joint Filing of Statement on Schedule 13D or 13G. Exhibit 99.2: Third Amended and Restated Investors' Rights Agreement, dated as of September 20, 2024 (filed as Exhibit 4.1 to the Issuer's Registration Statement on Form S-1/A as filed with the Commission on January 7, 2026 (SEC File No. 333-292283) and incorporated herein by reference). Exhibit 99.3: Form of Lock-Up Agreement for certain directors, officers and other stockholders of the Issuer (filed as part of Exhibit 1.1 to the Issuer's Registration Statement on Form S-1/A as filed with the Commission on January 7, 2026 (SEC File No. 333-292283) and incorporated herein by reference). Exhibit 99.4: 2026 Equity Incentive Plan, as amended, and associated forms (filed as Exhibit 10.2 to the Issuer's Registration Statement on Form S-1/A as filed with the Commission on January 7, 2026 (SEC File No. 333-292283) and incorporated herein by reference). Exhibit 99.5: Non-Employee Director Compensation Policy, as amended, and associated forms (filed as Exhibit 10.5 to the Issuer's Registration Statement on Form S-1/A as filed with the Commisson on January 7, 2026 (SEC File No. 333-292283) and incorporated herein by reference). Exhibit 99.6: Form of Indemnification Agreement (filed as Exhibit 10.6 to the Issuer's Registration Statement on Form S-1/A as filed with the Commission on January 7, 2026 (SEC File No. 333-292283) and incorporated herein by reference).