US biopharmaceutical company Gilead Sciences Inc (Nasdaq:GILD) announced on Tuesday that it has entered into a definitive agreement to acquire Tubulis GmbH, a German clinical-stage biotechnology company focused on next-generation antibody-drug conjugates (ADCs).

This transaction is intended to strengthen Gilead's oncology pipeline by adding Tubulis' ADC platforms and assets designed to improve targeted tumour delivery.

The acquisition includes TUB-040, a NaPi2b-directed ADC in Phase 1b/2 development for platinum-resistant ovarian cancer and non-small cell lung cancer, as well as TUB-030, a 5T4-targeted ADC with early clinical data across multiple solid tumours. It also brings Tubulis' platform technologies, including its tubutecan linker-payload system, to enhance ADC development capabilities and broaden potential applications across tumour types.

Under the agreement, Gilead will pay USD3.15bn in upfront cash on a cash-free, debt-free basis, with up to an additional USD1.85bn in contingent milestone payments.

Tubulis will operate as a dedicated ADC research organisation within Gilead following closing, with its Munich site serving as a hub for innovation.

Subject to customary regulatory and closing conditions, the transaction is expected to close in the second quarter of 2026.