Pharma BD Deal Intelligence
Pfizer acquired Trillium Therapeutics for approximately $2.26 billion ($18.50 per share) in an all-cash merger (closed November 17, 2021), gaining maplirpacept (TTI-622 / PF-07901801) and TTI-621 (PF-07901800), next-generation SIRPalpha-CD47 checkpoint inhibitors for hematological malignancies. Post-close the franchise underperformed: by May 2026 Pfizer had terminated its remaining maplirpacept clinical trials (NCT03530683 ended August 2024 and NCT05896163 ended May 2026, both cited as business decisions to pursue other oncology programs; a Phase 2 DLBCL study was terminated July 2025 for inability to recruit), and TTI-621 was discontinued. No active maplirpacept studies remain in the registry, leaving the $2.26B acquisition without a surviving clinical program — part of an industry-wide retreat from the CD47 pathway.