Collaboration Agreements and Intellectual Property Licenses	12 Months Ended
Dec. 31, 2023
Collaboration Agreements and Intellectual Property Licenses
Collaboration Agreements and Intellectual Property Licenses	6. Collaboration Agreements and Intellectual Property Licenses Clinical Trial Collaboration with F. Hoffmann-La Roche In July 2023, the Company and F. Hoffmann-La Roche Ltd. (“Roche”) entered into a clinical trial collaboration (the “Roche Clinical Collaboration”) pursuant to a clinical supply agreement to evaluate XTX101 in combination with atezolizumab (Tecentriq®) in a Phase 1/2 clinical trial consisting of a Phase 1 dose escalation cohort assessing the combination in patients with advanced solid tumors and a planned Phase 2 clinical trial assessing the combination in patients with microsatellite stable colorectal cancer. Under the clinical supply agreement, the Company is eligible to receive specified cost-sharing payments from Roche, and each company will supply its respective anti-cancer agent to support the Phase 1/2 clinical trial. The Company is responsible for conducting the Phase 1/2 clinical trial and retains global development and commercialization rights to XTX101. The Company concluded that the cost-sharing payments from the Roche Clinical Collaboration are not in the scope of ASC 606 because the Company does not consider performing research and development services for reimbursement to be part of its ongoing major or central operations. Therefore, the Company applied a reasonable, rational, and consistently applied accounting policy election to record the cost-sharing payments from the Roche Clinical Collaboration as a reduction of research and development expenses in the consolidated statements of operations and comprehensive loss for the period in which a study development event is achieved. During the year ended December 31, 2023, the Company recognized a reduction of research and development expenses of $2.0 million. Cross-License Agreement with AskGene In December 2020, Xilio Development entered into a cross-license agreement with AskGene Pharma, Inc. (“AskGene”) pursuant to which AskGene granted Xilio Development certain exclusive licenses for AskGene patent rights related to non-antigen binding IL-2 products in the field of oncology and certain co-exclusive licenses for AskGene patent rights related to antigen binding IL-2 products in all fields. Under the agreement, AskGene retains rights to the AskGene patent rights in Singapore, Thailand, Malaysia, Vietnam, the People’s Republic of China, Taiwan, Macau, Hong Kong, Korea and India (the “AskGene territory”) and granted licenses to Xilio Development for the AskGene patent rights worldwide, excluding the AskGene territory (the “Xilio Development territory”). Under the agreement, Xilio Development paid AskGene an upfront payment of $6.0 million, and for any licensed IL-2 product, Xilio Development is obligated to pay AskGene up to $13.0 million in the aggregate upon the achievement of specified regulatory milestones. In addition, subject to specified conditions, for any IL-2 licensed product, Xilio Development is obligated to pay AskGene percentage royalties in the mid-single digits on aggregate annual net sales of IL-2 licensed products in the Xilio Development territory during the applicable royalty term. During the term of the agreement, AskGene has agreed not to exploit any non-antigen binding IL-2 product comprised of specified masking technology in the field of oncology in the Xilio Development territory. In addition, Xilio Development granted a non-exclusive, royalty-free, non-transferable, worldwide license to AskGene for specified Xilio patent rights related to non-antigen binding IL-2 products in the field of immunology and for specified Xilio patent rights related to antigen binding IL-2 products in all fields. Subject to the terms of the agreement and during the time period specified, Xilio Development also granted AskGene an option to obtain a license in the AskGene territory to develop and commercialize IL-2 licensed products. If AskGene exercises its option to develop and commercialize IL-2 licensed products in the AskGene territory, then the parties will negotiate and enter into a license agreement for AskGene’s exclusive development and commercialization of such products in the AskGene territory, and AskGene would be obligated to pay Xilio Development percentage royalties in the mid-single digits on aggregate annual net sales of such licensed products in the AskGene territory. The Company accounted for the agreement as an asset acquisition, as the Company only acquired licenses to specified patents from AskGene (an input) and no additional processes or outputs as a part of the agreement. The $6.0 million upfront payment was recorded as research and development expense in the consolidated statement of operations and comprehensive loss during the year ended December 31, 2020, as the acquired licenses were determined to have no alternative future use and the technological feasibility of the intellectual property has not yet been reached. Any additional payments that are contingent upon achievement of development and regulatory milestones or upon sales of licensed products will not be recognized until it becomes probable that the Company will be required to make such payments. Amended and Restated Exclusive License Agreement with City of Hope In August 2016, Xilio Development entered into an amended and restated exclusive license agreement with City of Hope pursuant to which City of Hope granted Xilio Development an exclusive worldwide license to specified patent rights related to the Company’s anti-CTLA-4 monoclonal antibody program. Under the agreement, the Company issued 24,019 shares of common stock to City of Hope. For the first three licensed products or licensed services to achieve specified development and regulatory milestones, Xilio Development is obligated to pay City of Hope up to $10.3 million in the aggregate per licensed product or licensed service. In addition, subject to specified conditions, Xilio Development is obligated to pay City of Hope tiered royalties in the low single digits on aggregate annual net sales of licensed products or licensed services on a country-by-country basis until the expiration of the last-to-expire patent or patent application licensed from City of Hope covering the applicable licensed product or licensed service in such country. Xilio Development is also obligated to pay City of Hope a portion of any consideration Xilio Development receives for the grant of sublicenses under the agreement ranging from a low double digit to mid-twenties percentage of such consideration, subject to specified conditions under that agreement at the time that Xilio Development grants any such sublicense. The Company incurred no costs related to the payment of specified development milestones under the agreement during the years ended December 31, 2023 and 2022. Any additional payments that are contingent upon achievement of development and regulatory milestones or upon sales of licensed products will not be recognized until it becomes probable that the Company will be required to make such payments. CTLA-4 Monoclonal Antibody License Agreement with WuXi Biologics In September 2016, the Company entered into a license agreement with WuXi Biologics (Hong Kong) Limited (“WuXi Biologics”), as amended in December 2017, pursuant to which WuXi Biologics granted the Company an exclusive worldwide license to specified monoclonal antibodies and patent rights and know-how controlled by WuXi Biologics, including certain patent rights related to the Company’s anti-CTLA-4 monoclonal antibody program. For each product that exploits the rights licensed under the agreement, the Company is obligated to pay WuXi Biologics up to approximately $25.8 million in the aggregate for specified development and regulatory milestones. In addition, subject to specified conditions, the Company is obligated to pay WuXi Biologics tiered royalties in the low to mid-single digits on aggregate annual worldwide net sales of licensed products during the applicable royalty term. The Company incurred no costs related to the payment of specified development milestones under the agreement during the years ended December 31, 2023 and 2022. Any additional payments that are contingent upon the achievement of development and regulatory milestones or sales of licensed products will not be recognized until it becomes probable that the Company will be required to make such payments.

Collaboration Agreements and Intellectual Property Licenses

12 Months Ended

Dec. 31, 2023

Collaboration Agreements and Intellectual Property Licenses

Collaboration Agreements and Intellectual Property Licenses

6. Collaboration Agreements and Intellectual Property Licenses

Clinical Trial Collaboration with F. Hoffmann-La Roche

In July 2023, the Company and F. Hoffmann-La Roche Ltd. (“Roche”) entered into a clinical trial collaboration (the “Roche Clinical Collaboration”) pursuant to a clinical supply agreement to evaluate XTX101 in combination with atezolizumab (Tecentriq®) in a Phase 1/2 clinical trial consisting of a Phase 1 dose escalation cohort assessing the combination in patients with advanced solid tumors and a planned Phase 2 clinical trial assessing the combination in patients with microsatellite stable colorectal cancer.

Under the clinical supply agreement, the Company is eligible to receive specified cost-sharing payments from Roche, and each company will supply its respective anti-cancer agent to support the Phase 1/2 clinical trial. The Company is responsible for conducting the Phase 1/2 clinical trial and retains global development and commercialization rights to XTX101.

The Company concluded that the cost-sharing payments from the Roche Clinical Collaboration are not in the scope of ASC 606 because the Company does not consider performing research and development services for reimbursement to be part of its ongoing major or central operations. Therefore, the Company applied a reasonable, rational, and consistently applied accounting policy election to record the cost-sharing payments from the Roche Clinical Collaboration as a reduction of research and development expenses in the consolidated statements of operations and comprehensive loss for the period in which a study development event is achieved. During the year ended December 31, 2023, the Company recognized a reduction of research and development expenses of $2.0 million.

Cross-License Agreement with AskGene

In December 2020, Xilio Development entered into a cross-license agreement with AskGene Pharma, Inc. (“AskGene”) pursuant to which AskGene granted Xilio Development certain exclusive licenses for AskGene patent rights related to non-antigen binding IL-2 products in the field of oncology and certain co-exclusive licenses for AskGene patent rights related to antigen binding IL-2 products in all fields. Under the agreement, AskGene retains rights to the AskGene patent rights in Singapore, Thailand, Malaysia, Vietnam, the People’s Republic of China, Taiwan, Macau, Hong Kong, Korea and India (the “AskGene territory”) and granted licenses to Xilio Development for the AskGene patent rights worldwide, excluding the AskGene territory (the “Xilio Development territory”).

Under the agreement, Xilio Development paid AskGene an upfront payment of $6.0 million, and for any licensed IL-2 product, Xilio Development is obligated to pay AskGene up to $13.0 million in the aggregate upon the achievement of specified regulatory milestones. In addition, subject to specified conditions, for any IL-2 licensed product, Xilio Development is obligated to pay AskGene percentage royalties in the mid-single digits on aggregate annual net sales of IL-2 licensed products in the Xilio Development territory during the applicable royalty term.

During the term of the agreement, AskGene has agreed not to exploit any non-antigen binding IL-2 product comprised of specified masking technology in the field of oncology in the Xilio Development territory.

In addition, Xilio Development granted a non-exclusive, royalty-free, non-transferable, worldwide license to AskGene for specified Xilio patent rights related to non-antigen binding IL-2 products in the field of immunology and for specified Xilio patent rights related to antigen binding IL-2 products in all fields. Subject to the terms of the agreement and during the time period specified, Xilio Development also granted AskGene an option to obtain a license in the AskGene territory to develop and commercialize IL-2 licensed products. If AskGene exercises its option to develop and commercialize IL-2 licensed products in the AskGene territory, then the parties will negotiate and enter into a license agreement for AskGene’s exclusive development and commercialization of such products in the AskGene territory, and AskGene would be obligated to pay Xilio Development percentage royalties in the mid-single digits on aggregate annual net sales of such licensed products in the AskGene territory.

The Company accounted for the agreement as an asset acquisition, as the Company only acquired licenses to specified patents from AskGene (an input) and no additional processes or outputs as a part of the agreement. The $6.0 million upfront payment was recorded as research and development expense in the consolidated statement of operations and comprehensive loss during the year ended December 31, 2020, as the acquired licenses were determined to have no alternative future use and the technological feasibility of the intellectual property has not yet been reached. Any additional payments that are contingent upon achievement of development and regulatory milestones or upon sales of licensed products will not be recognized until it becomes probable that the Company will be required to make such payments.

Amended and Restated Exclusive License Agreement with City of Hope

In August 2016, Xilio Development entered into an amended and restated exclusive license agreement with City of Hope pursuant to which City of Hope granted Xilio Development an exclusive worldwide license to specified patent rights related to the Company’s anti-CTLA-4 monoclonal antibody program.

Under the agreement, the Company issued 24,019 shares of common stock to City of Hope. For the first three licensed products or licensed services to achieve specified development and regulatory milestones, Xilio Development is obligated to pay City of Hope up to $10.3 million in the aggregate per licensed product or licensed service. In addition, subject to

specified conditions, Xilio Development is obligated to pay City of Hope tiered royalties in the low single digits on aggregate annual net sales of licensed products or licensed services on a country-by-country basis until the expiration of the last-to-expire patent or patent application licensed from City of Hope covering the applicable licensed product or licensed service in such country. Xilio Development is also obligated to pay City of Hope a portion of any consideration Xilio Development receives for the grant of sublicenses under the agreement ranging from a low double digit to mid-twenties percentage of such consideration, subject to specified conditions under that agreement at the time that Xilio Development grants any such sublicense.

The Company incurred no costs related to the payment of specified development milestones under the agreement during the years ended December 31, 2023 and 2022. Any additional payments that are contingent upon achievement of development and regulatory milestones or upon sales of licensed products will not be recognized until it becomes probable that the Company will be required to make such payments.

CTLA-4 Monoclonal Antibody License Agreement with WuXi Biologics

In September 2016, the Company entered into a license agreement with WuXi Biologics (Hong Kong) Limited (“WuXi Biologics”), as amended in December 2017, pursuant to which WuXi Biologics granted the Company an exclusive worldwide license to specified monoclonal antibodies and patent rights and know-how controlled by WuXi Biologics, including certain patent rights related to the Company’s anti-CTLA-4 monoclonal antibody program.

For each product that exploits the rights licensed under the agreement, the Company is obligated to pay WuXi Biologics up to approximately $25.8 million in the aggregate for specified development and regulatory milestones. In addition, subject to specified conditions, the Company is obligated to pay WuXi Biologics tiered royalties in the low to mid-single digits on aggregate annual worldwide net sales of licensed products during the applicable royalty term.

The Company incurred no costs related to the payment of specified development milestones under the agreement during the years ended December 31, 2023 and 2022. Any additional payments that are contingent upon the achievement of development and regulatory milestones or sales of licensed products will not be recognized until it becomes probable that the Company will be required to make such payments.