Pharma BD Deal Intelligence
Amgen acquired Five Prime Therapeutics in an all-cash tender offer plus merger for $1.9 billion (~$38/share), announced March 4, 2021 and completed April 16, 2021. The rationale centered on bemarituzumab, a first-in-class anti-FGFR2b monoclonal antibody for FGFR2b-overexpressing, HER2-negative gastric and gastroesophageal junction (G/GEJ) cancer. Post-close, the Phase 3 FORTITUDE-101 trial (1L bemarituzumab + mFOLFOX6) met its primary overall-survival endpoint at a pre-specified interim analysis (Amgen, June 30, 2025: median OS 17.9 vs 12.5 months, HR 0.61, p=.005) — the first FGFR2b inhibitor to show a significant OS benefit in first-line gastric cancer, and the asset holds FDA Breakthrough Therapy Designation. However, at the descriptive final analysis presented at ESMO 2025, the benefit attenuated to a non-significant 1.3 months (median OS 14.5 vs 13.2 months, HR 0.82) as the curves converged with longer follow-up; Amgen/Zai Lab indicated they would await the companion FORTITUDE-102 readout (bemarituzumab + nivolumab + chemo) before a regulatory filing decision.