Pharma BD Deal Intelligence
On March 27, 2024, Xilio Therapeutics granted Gilead Sciences an exclusive global license to develop and commercialize XTX301, a tumor-activated IL-12, and specified other IL-12-directed molecules. Xilio received $43.5 million in upfront payments, comprising $30.0 million in cash and an initial equity investment by Gilead of approximately $13.5 million in Xilio common stock. Xilio is eligible for up to $29.0 million in additional equity investments and a development milestone, and - if Gilead exercises its option for efarindodekin alfa (XTX301) - up to $500.0 million in development, regulatory and sales-based milestones plus tiered royalties ranging from high single digits to mid-teens. Xilio remained responsible for clinical development through an initial planned Phase 2 dose expansion; Gilead may then elect to assume development and commercialization on payment of a $75 million transition fee.
Assessment window: 5yr post-close.
Note: this deal's 5-year assessment window closes ~2029; the outcome grade above is a projected assessment, not yet finalized.
Interleukin-12 is a potent immune-activating cytokine whose clinical development has historically been limited by severe systemic toxicity. Tumor-activated ("masked") cytokine engineering aims to restrict IL-12 activity to the tumor microenvironment, where proteases cleave the masking domain, in order to decouple anti-tumor activity from systemic inflammatory toxicity.
Multiple sponsors pursue conditionally activated cytokines and cytokine prodrugs, including Werewolf Therapeutics (INDUKINE IL-12 and IL-2 programs), Bright Peak and Asher Bio in engineered IL-2/IL-18/IL-21, and Xilio itself in masked IL-2 and anti-CTLA-4. Differentiation rests on the specificity of the masking/cleavage design rather than on the cytokine payload.
Xilio granted Gilead an exclusive global license to XTX301 and other IL-12-directed molecules for $43.5M upfront ($30M cash + ~$13.5M equity), with up to $500M in option-stage milestones and tiered royalties.
Xilio initiated the Phase 2 trial of efarindodekin alfa (XTX301) and earned a $17.5 million development milestone under the Gilead agreement - the first disclosed milestone achievement of the collaboration.
| Deal | Year | Value | Outcome |
|---|---|---|---|
| Gilead Sciences, Inc. / Xilio Therapeutics, Inc. (this deal) | 2024 | $544M | 67 |
| Gilead Sciences, Inc. / MacroGenics, Inc. | 2026 | $10M | 60 |
| Nuvation Bio Inc. / AnHeart Therapeutics, Ltd. | 2024 | — | 100 |
| Novo Holdings A/S / Catalent (manufacturing sites) | 2024 | $11.0B | 81 |
| Novartis AG / PTC Therapeutics Inc. | 2024 | $2.9B | 80 |
| Vertex Pharmaceuticals Incorporated / Alpine Immune Sciences | 2024 | $4.9B | 78 |
| Johnson & Johnson / Shockwave Medical | 2024 | $13.1B | 76 |
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