Material Agreement (Form 8-K)

IL-31R Antibody Discovery Agreement

On June 17, 2026, Apogee Therapeutics, Inc. (the "Company") entered into an antibody discovery agreement with Paragon Therapeutics, Inc. ("Paragon," and the antibody discovery agreement between the Company and Paragon, the "IL-31R Discovery Agreement"). Under the terms of the IL-31R Discovery Agreement, Paragon generates and characterizes monospecific antibody candidates directed to interleukin 31 receptor (IL-31R). The associated activities may be supplemented or amended from time to time upon the mutual written agreement of the parties, which could include optional manufacturing and control activities ("CMC Activities").

Under the IL-31R Discovery Agreement, the Company compensates Paragon for the activities that it performs, including reimbursement of qualifying amounts Paragon paid to unaffiliated contract research organizations, and a monthly research fee, subject to adjustment as provided in the IL-31R Discovery Agreement. If Paragon agrees to perform CMC Activities, then the Company will owe Paragon additional associated fees ranging from $1.3 million to $2.0 million, depending on the scope and type of activities.

The Company may terminate the IL-31R Discovery Agreement at any time upon 30 days' prior written notice to Paragon. Paragon may terminate the IL-31R Discovery Agreement if the Company takes an action or fails to act in a manner that causes the Research Program (as defined in the IL-31R Discovery Agreement) or all material activities under the Research Plan (as defined in the IL-31R Discovery Agreement) to be suspended, discontinued or otherwise delayed for four consecutive months. Each party to the agreement has the right to terminate the IL-31R Discovery Agreement in response to the other party's material breach or insolvency.

IL-31R License Agreement

On June 17, 2026, contemporaneously with the execution of the IL-31R Discovery Agreement, the Company entered into a license agreement with Paragon (the "IL-31R License Agreement"). Under the terms of the IL-31R License Agreement, Paragon granted to the Company an exclusive, worldwide, royalty-bearing, sublicensable right and license with respect to certain information, patent rights and sequence information related to antibodies discovered under the IL-31R Discovery Agreement and directed at the IL-31R target to use, make, sell, import, export and otherwise exploit the antibodies directed at the IL-31R target. Paragon retained a non-exclusive right under the foregoing to develop, manufacture, commercialize and otherwise exploit multispecific antibodies and multispecific products worldwide, subject to certain obligations to the Company (the "Paragon Non-Exclusive Rights"). The Company was also granted a right of first negotiation with Paragon concerning the development, license and grant of rights to certain multispecific antibodies. The Company is solely responsible for the continued development, manufacture and commercialization of products at our own cost and expense.

The Company is obligated to pay Paragon up to $23.25 million upon the achievement of specific development, clinical and regulatory milestones for the first product under the IL-31R License Agreement that achieves such specified milestones, including a payment of $5.25 million upon the first dosing of a human patient in a Phase I trial.

The Company is also obligated to pay royalties to Paragon equal to a low-single digit percentage of net sales of any products under the IL-31R License Agreement, including for IL-31R products in combination with other products licensed from Paragon, and Paragon has a similar obligation to pay royalties to the Company with respect to the Paragon Non-Exclusive Rights. Royalties are due on a product-by-product and country-by-country basis beginning upon the first commercial sale of each product and ending on the later of (i) 12 years after the first commercial sale of such product in such country and (ii) expiration of the last valid claim of a patent covering such product in such country (the "Royalty Term").

Unless earlier terminated, the IL-31R License Agreement remains in effect until the expiration of the last-to-expire Royalty Term for any and all products. The Company may terminate the IL-31R License Agreement in its entirety or on a country-by-country or product-by-product basis at any time for any or no reason upon 60 days' advance written notice to Paragon, and either party may terminate for (i) the other party's material breach that remains uncured for 90 days (or 30 days with respect to any failure to make payments) following notice of such breach and (ii) the other party's bankruptcy. Upon any termination prior to the expiration of the IL-31R License Agreement, all licenses and rights granted pursuant to the IL-31R License Agreement will terminate with respect to the terminated products and countries, and all other rights and obligations of the parties will terminate.