Gilead Sciences announced it has entered into a definitive agreement to acquire Ouro Medicines, a privately held biotechnology company developing T cell engager therapies for autoimmune diseases. The upfront purchase price will be $1.675 billion in cash, subject to customary adjustments, and the deal includes up to $500 million in potential contingent milestone payments.
The acquisition brings OM336, also known as gamgertamig, into Gilead's inflammation portfolio. OM336 is a clinical-stage BCMAxCD3 T cell engager that has received both Fast Track and Orphan Drug Designation. The molecule is designed to enable rapid B cell depletion after subcutaneous administration. In ongoing Phase 1/2 clinical trials, OM336 has demonstrated efficacy in severe autoimmune conditions, specifically including autoimmune hemolytic anemia and immune thrombocytopenia.
Concurrently with the acquisition, Gilead plans to establish a strategic collaboration with Galapagos to advance the Ouro portfolio. Under the proposed arrangement, Galapagos would fund 50% of the upfront cash consideration and 50% of the contingent milestone payments. Galapagos would also absorb substantially all of Ouro's operating assets and retain the company's employees.
Under the collaboration terms, Galapagos would be responsible for development costs through the initiation of registrational studies. After that point, development costs would be shared equally between Gilead and Galapagos. Gilead would keep exclusive global commercialization rights except in Greater China, where existing rights belong to Keymed Biosciences. In return for Galapagos' role and cost sharing, Gilead would pay Galapagos royalties ranging from 20% to 23% of net sales.
The proposed collaboration also includes an amendment to the legacy Galapagos Option License and Collaboration Agreement. The amendment would permit up to $500 million of Galapagos' current cash to be deployed freely, and specifically would allow up to $150 million to be used for potential share repurchases.
This transaction represents a second significant deal announced by Gilead within a short period. In February 2026, Gilead disclosed a definitive agreement to acquire Arcellx for $115 per share in cash at closing plus one contingent value right of $5 per share, reflecting an implied equity value of $7.8 billion payable at closing. Arcellx is described as a biotechnology company focused on delivering immunotherapies for patients with cancer and other diseases.
Contextual note: The terms described above reflect the information provided in the transaction announcements. Details such as the precise timing of payments, the sources and use of funds following customary adjustments, and future development milestones remain subject to the conditions and contingencies articulated in the definitive agreement.