On October 1, 2025 C4 Therapeutics, Inc. (C4T) (Nasdaq: CCCC), a clinical-stage biopharmaceutical company dedicated to advancing targeted protein degradation science, reported that it has entered into a clinical trial collaboration and supply agreement with Pfizer Inc (Press release, C4 Therapeutics, OCT 1, 2025, View Source [SID1234656374]). Under the terms of the agreement, Pfizer will supply elranatamab (ELREXFIO), a B-cell maturation antigen CD3 targeted bispecific antibody (BCMAxCD3 bispecific), to C4T for its upcoming Phase 1b trial.

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The Phase 1b trial will evaluate the safety and tolerability of cemsidomide, an IKZF1/3 degrader, and dexamethasone in combination with elranatamab as a second line or later therapy for patients with multiple myeloma. This Phase 1b trial, which is expected to initiate in Q2 2026, will seek to establish an optimal dose for cemsidomide in combination with elranatamab. Under the terms of the agreement, Pfizer will supply elranatamab at no cost while C4T will sponsor and conduct the trial.

"We look forward to initiating this trial to evaluate cemsidomide in combination with elranatamab in the hopes we can develop a new treatment regimen and potentially improve outcomes for multiple myeloma patients in earlier lines of therapy," said Andrew Hirsch, president and chief executive officer of C4 Therapeutics. "Our supply agreement with Pfizer creates an opportunity for cemsidomide to be combined with elranatamab, which is on the path to potentially becoming a standard of care BCMAxCD3 bispecific in a growing market."

Data generated from the cemsidomide Phase 1 trial in relapsed/refractory multiple myeloma demonstrate robust T-cell activation and cytokine expression across multiple doses. By activating immune T-cells, cemsidomide, when combined with a BCMAxCD3 bispecific such as elranatamab, may amplify the anti-myeloma immune response and lead to higher quality of responses.