Gilead Sciences Inc. (NASDAQ: GILD) announced it entered into a definitive agreement to acquire Tubulis GmbH, a Germany-based clinical-stage biotechnology company developing antibody-drug conjugates.

Under the agreement, Gilead will pay $3.15 billion in upfront cash consideration and up to $1.85 billion in contingent milestone payments for all outstanding equity of the private company. The transaction is expected to close in the second quarter of 2026, subject to regulatory approvals and customary conditions.

Tubulis develops next-generation antibody-drug conjugates designed to deliver diverse payloads to tumors. The company's lead asset, TUB-040, is a NaPi2b-directed topoisomerase-I inhibitor ADC currently in Phase 1b/2 development for platinum-resistant ovarian cancer and non-small cell lung cancer. Gilead will also acquire TUB-030, a 5T4 targeted ADC that has demonstrated initial clinical data across various solid tumor types.

"The agreement to acquire Tubulis is a significant milestone in Gilead's progress in oncology," said Daniel O'Day, Chairman and Chief Executive Officer of Gilead Sciences. "Today's agreement follows a two-year collaboration with Tubulis, which has given us strong conviction in their programs and research capabilities."

Following the transaction's completion, Tubulis will operate as a dedicated ADC research organization within Gilead. The Munich site will serve as a hub for ADC innovation, building on its integrated discovery, manufacturing and clinical capabilities.

Gilead plans to finance the transaction with a combination of cash on hand and senior unsecured notes. Centerview Partners LLC and Allen & Company LLC are serving as financial advisors for Gilead, while J.P. Morgan Securities LLC is acting as the exclusive financial advisor for Tubulis.