Gilead Sciences agreed to acquire German antibody-drug conjugate specialist Tubulis in a deal valued at up to $5 billion, with $3.15 billion upfront and as much as $1.85 billion in milestones. The acquisition expands Gilead’s ADC capabilities and adds Tubulis’ linker/payload platform aimed at improving tumor selectivity and reducing off-target toxicity. Tubulis’ lead candidate, TUB-040—a NaPi2b-directed topoisomerase-I inhibitor ADC—has entered a Phase Ib/II NAPISTAR1-01 study (NCT06303505) in platinum-resistant ovarian cancer and NSCLC. Tubulis also brings TUB-030, a 5T4-targeting ADC for multiple solid tumor types. Gilead is expected to finance the transaction with a mix of cash on hand and senior unsecured notes, with closing targeted for the second quarter of 2026. The deal underscores renewed investor and pharma focus on next-generation ADC engineering as companies seek differentiated clinical activity and improved safety profiles.