C4 Therapeutics Launches Phase 1b Cemsidomide and Elranatamab Trial in RRMM
C4 Therapeutics has dosed the first patient in its Phase 1b trial combining oral IKZF1/3 degrader cemsidomide with FDA-approved bispecific antibody elranatamab in relapsed/refractory multiple myeloma. The open-label study will enroll up to 54 patients at 75 µg, 50 µg and 100 µg dose levels to assess safety, tolerability and preliminary anti-myeloma activity.
1. Trial Initiation and Objective
C4 Therapeutics has administered the first dose of cemsidomide in its Phase 1b trial combining the oral IKZF1/3 degrader with elranatamab in relapsed/refractory multiple myeloma patients. The study aims to establish an optimal dosing regimen by evaluating safety, tolerability and preliminary anti-myeloma activity of the novel combination.
2. Study Design and Endpoints
This open-label, multicenter trial will enroll up to 54 patients who have received one to four prior lines of therapy. Cemsidomide dosing begins at 75 µg with cohorts exploring 50 µg and 100 µg, while elranatamab is administered per its approved regimen. The primary endpoint is safety and tolerability, with secondary measures including overall response rate, MRD-negative complete response rate and duration of response according to IMWG criteria.
3. Strategic Collaboration and Pipeline Development
Under an October 2025 agreement, Pfizer supplies elranatamab at no cost while C4 Therapeutics sponsors the trial. Phase 1b cohort data are anticipated by mid-2027, supporting a broader development strategy that includes the ongoing Phase 2 MOMENTUM trial and additional combination studies planned for announcement in mid-2026.