On June 29, 2026, Jade Biosciences, Inc. (the "Company") entered into a License Agreement (the "JADE301 License Agreement") with Paragon Therapeutics, Inc. ("Paragon"), pursuant to which Paragon granted the Company a royalty-bearing, worldwide, exclusive and sublicensable license to use, make, sell, import, export and otherwise exploit certain monospecific antibodies and products targeting an undisclosed target (the "Target") in the field of prophylaxis, palliation, treatment and diagnosis of human disease and disorders in all therapeutic areas (the "Field").

Under the terms of the JADE301 License Agreement, the Company is obligated to pay Paragon up to $22.0 million based on specific development and regulatory milestones, including a $1.5 million fee for nomination of a development candidate, which was paid in January 2026, and a further milestone payment of $2.5 million upon the first dosing of a human patient in a Phase 1 trial. On a product-by-product basis, the Company is obligated to pay sublicensing fees of up to approximately $20.1 million, mainly upon the achievement of commercial milestones. The Company will pay Paragon a low to mid-single-digit percentage royalty based on annual net sales of monospecific products in the Field and in the territory, and a mid-single-digit percentage royalty based on annual net sales of multispecific products in the Field and in the territory, subject to a 30% reduction if there is no valid patent covering the product in the country of sale. On a country-by-country basis, the royalty term for a product ends on the later of (i) the twelfth anniversary of the date of first sale of a Company product or (ii) the expiration of the last-to-expire valid patent covering the product in the country at issue.

Paragon will not conduct any new campaigns that generate monospecific antibodies targeting the Target in the Field for at least five years. The JADE301 License Agreement may be terminated on 60 days' notice by us; on material breach without cure; and to the extent permitted by law, on a party's insolvency or bankruptcy.

The foregoing is a summary description of certain terms of the JADE301 License Agreement, does not purport to be complete and is qualified in its entirety by reference to the full text of the JADE301 License Agreement to be filed as an exhibit to the Company's Quarterly Report on Form 10-Q for the quarter ending June 30, 2026.