Pharma BD Deal Intelligence
GSK acquired Tesaro for approximately $5.1 billion in cash ($75.00 per share) via tender offer and merger (announced 3 Dec 2018, completed 22 Jan 2019), gaining Zejula (niraparib), an oral PARP inhibitor for ovarian cancer, plus the then-early-stage anti-PD-1 antibody dostarlimab (TSR-042) and additional immuno-oncology pipeline assets. The deal was widely criticized at signing as a rich multiple (~22.9x trailing revenue) for a Zejula franchise that has since plateaued and declined (FY2025 Zejula sales GBP 419M, down 7% on US volume/price pressure, IRA Part D redesign, and a 2022 FDA label restriction). The deal's value has instead come from the pipeline: dostarlimab, marketed as Jemperli, reached ~GBP 600M in FY2025 (+89% YoY) on endometrial-cancer expansion and carries a >$2.5B 2030 sales ambition. In December 2024 Jemperli received FDA Breakthrough Therapy Designation in locally advanced dMMR/MSI-H rectal cancer after a trial reported a 100% clinical complete response in all 42 patients who completed treatment, with a pivotal readout expected in 2H 2026 and a potential filing in 2027 — a pipeline optionality that materially offsets the original 'overpaid for a niche PARP asset' critique.