Licensing Agreements	12 Months Ended
Licensing Agreements	Dec. 31, 2025
Licensing Agreements [Abstract]
Licensing Agreements	Licensing Agreements On July 12, 2023, December 14, 2023, and June 5, 2024, the Company exercised the Option available under the Paragon Agreement with respect to the SPY001, SPY002, and SPY003 research programs, respectively. On May 14, 2024, the Company and Paragon entered into (i) a license agreement (the “SPY001 License Agreement”), pursuant to which Paragon granted the Company a royalty-bearing, world-wide, exclusive license to develop, manufacture, commercialize or otherwise exploit certain antibodies and products targeting α4ß7 integrin and (ii) a license agreement (the “SPY002 License Agreement”), pursuant to which Paragon granted the Company a royalty-bearing, world-wide, exclusive license to develop, manufacture, commercialize or otherwise exploit certain antibodies and products targeting TL1A, respectively. On October 11, 2024, the Company and Paragon entered into a license agreement (the "SPY003 License Agreement" and, together with the SPY001 License Agreement and the SPY002 License Agreement, the "License Agreements"), pursuant to which Paragon granted the Company a royalty-bearing, world-wide, exclusive license to develop, manufacture, commercialize or otherwise exploit certain antibodies and products targeting IL-23 in the field of IBD. On February 24, 2025, the SPY003 License Agreement was amended and restated to, among other things, clarify each party's rights and obligations with respect to license exclusivity and patent prosecution and correct certain clerical errors. Under the terms of each License Agreement, the Company is obligated to pay Paragon up to $22.0 million based on specific development, regulatory and clinical milestones for the first product under each agreement, respectively, that achieves such specified milestones, including a milestone payment of $3.0 million upon the first dosing of a human patient in a Phase 2 trial. In addition, the following summarizes other key terms of each License Agreement: •Paragon will provide the Company with an exclusive license (such license, with respect to the SPY003 License Agreement only, being limited to the field of IBD) to its patents covering the related antibody, the method of use and its method of manufacture. •Paragon will not conduct any new campaigns that generate anti-α4ß7 or anti-TL1A monospecific antibodies in any field or anti-IL-23 monospecific antibodies in the field of IBD, in each case for at least 5 years. •The Company will pay Paragon a low single-digit percentage royalty for single antibody products and a mid single-digit percentage royalty for products containing more than one antibody from Paragon. •There is a royalty step-down of 1/3rd if there is no Paragon patent in effect during the royalty term. •The royalty term ends on the later of (i) the last-to-expire licensed patent or Company patent directed to the manufacture, use or sale of a licensed antibody in the country at issue or (ii) 12 years from the date of first sale of a Company product. •Agreement may be terminated on 60 days’ notice by the Company; on material breach without cure; and to the extent permitted by law, on a party’s insolvency or bankruptcy. •With respect to the SPY002 License Agreement only, on a product by product basis, the Company will pay sublicensing fees of up to approximately $20.0 million upon the achievement of mostly commercial milestones. The Company recognizes the expense associated with each milestone when the achievement of the milestone is deemed probable. During the years ended December 31, 2025 and 2024, the Company recognized expense of $8.5 million and $9.5 million, respectively, related to Paragon license milestone payments recorded within Research and development expenses in the accompanying condensed statement of operations. There was no such expense for the year ended December 31, 2023. For the years ended December 31, 2025 and 2024, the Company made cash milestone payments to Paragon totaling $8.5 million and $9.5 million. There were no such payments for the year ended December 31, 2023. As of December 31, 2025 and 2024, there were no Paragon license milestone payments outstanding and payable to Paragon. Additionally, the Company recognized $1.9 million and $0.7 million related to sublicensing fees and which was recorded as Research and development expenses in the accompanying statement of operations for the year ended December 31, 2025 and 2024, respectively. There was no such expense for the year ended December 31, 2023. For the year ended December 31, 2025 and 2024, the Company made sublicensing fees payments to Paragon totaling $2.4 million and $0.2 million. There were no such payments for the year ended December 31, 2023. As of December 31, 2025 and 2024, nil and $0.5 million in sublicensing fees were outstanding and payable to Paragon, respectively.

Spyre Therapeutics, Inc. 10-K