14. RELATED-PARTY TRANSACTIONS

In August 2018, the Company entered into a ten-year management service agreement with Flagship Pioneering, Inc. (“Flagship Pioneering”) to provide management services, including accounting, human resources, information technology, legal, and consultation services (the "Flagship Managerial Agreement"). The Company also agreed to reimburse Flagship Pioneering for certain expenses, including insurance and benefits, partner and related fees, software licenses, supplies, and administration consulting services incurred on the Company’s behalf. Upon the effectiveness of the Company's Registration Statement on Form S-1 (File No. 333-293204), as amended, filed in connection with the Company's IPO (the "Registration Statement") on February 26, 2026, the Flagship Managerial Agreement was terminated. As of June 30, 2026 and December 31, 2025, the Company owed $0.1 million and $0.1 million, respectively, to Flagship. For the three and six months ended June 30, 2026, the Company recorded general and administrative expenses of $0.1 million and $0.2 million, respectively, payable to Flagship. For the three and six months ended June 30, 2025, the Company recorded general and administrative expenses of $0.1 million and $0.3 million, respectively, payable to Flagship.

In July 2022, the Company entered into a Vivarium Shared Space Operating Agreement, as amended in May 2024, with Cellarity, Inc. (“Cellarity”), an affiliate of Flagship, to use a vivarium space, along with other companies affiliated with Flagship. The Company pays Cellarity a monthly operating fee for using the vivarium and obtaining various services; the shared cost is variable depending on the actual usage. As of June 30, 2026 and December 31, 2025, the Company had less than $0.1 million and $0.1 million in accounts payable to Cellarity, respectively. For the six months ended June 30, 2026, the Company recognized expenses of $0.1 million, payable to Cellarity. For the three and six months ended June 30, 2025, the Company recognized expenses of $0.1 million and $0.3 million, respectively, payable to Cellarity.

In August 2021, the Company entered into an agreement (the “Flagship Agreement”), with Flagship Pioneering Innovations VI, LLC (“Flagship”), pursuant to which it (i) irrevocably and unconditionally assigned to Flagship all of the Company’s right, title and interest in and to certain foundational patent rights conceived prior to the Company’s launch, which is defined as the closing of its Series B financing, and its improvements to such patent rights that cannot be practiced without infringing the foregoing patent rights (such patent rights and improvements, the “Foundational IP”), and (ii) obtained an exclusive, worldwide, royalty-bearing, sublicensable, transferable license from Flagship under such Foundational IP to develop, manufacture and commercialize any product or process or component thereof in the licensed field of human therapeutics and vaccines that would, absent the license granted to the Company by Flagship, infringe at least one valid claim of the Foundational IP. Pursuant to the Flagship Agreement, the Company is obligated to use commercially reasonable efforts to diligently exploit licensed products in the licensed field and maintain such efforts during the term of the Flagship Agreement. To satisfy the due diligence requirements, the Company must spend at least $1.0 million each year on its own development and commercialization activities with respect to licensed products during the term of the Flagship Agreement and at least $10.0 million on such activities until August 2026, which may include internal or external research and development costs. The research and development costs are expensed as incurred. The Company's only financial obligation to Flagship is to pay Flagship, on a licensed product-by-licensed product and jurisdiction-by-jurisdiction basis, royalties equal to a low single-digit percentage on net sales of licensed products by the Company or its sublicensees until the expiration of the last valid claim of any Foundational IP covering such licensed product in such jurisdiction. To date, there have been no amounts paid or received by the Company under the Flagship Agreement.

In June 2023, the Company entered into a collaboration agreement with PMCo, a company newly formed and controlled by Flagship Labs VII, LLC and Flagship Pioneering Fund VII, L.P., each of which are affiliated with Flagship Pioneering (the "Prior PMCo Agreement"). On February 4, 2026, the Company entered into a stock purchase agreement (the “Stock Purchase Agreement”) with PMCo, the then sole stockholder of PMCo, Pioneering Medicines 02, LLC ("PM LLC"), and Flagship Labs, LLC ("Flagship Labs"), pursuant to which the Company agreed to purchase, and PM LLC agreed to sell, all of the issued and outstanding capital stock in PMCo. In consideration for such sale, PMCo, PM LLC and the Company agreed to terminate the Prior PMCo Agreement, and the Company agreed to pay PM LLC a portion of the net sales, if any, arising from the sale of certain products. The sale closed and the prior PMCo Agreement was terminated on February 26, 2026. See Note 15.