C4 Therapeutics presents data from Phase 1 trial of cemsidomide

C4 Therapeutics (CCCC) presented data from the Phase 1 clinical trial of cemsidomide in combination with dexamethasone for the treatment of relapsed/refractory multiple myeloma, RRMM. Safety results: Cemsidomide was generally well tolerated with manageable incidents of on-target neutropenia across all dose levels; there were low rates of febrile neutropenia across all dose levels: three patients at Grade 3, one patient at Grade 4 and no patients at Grade 5. Pharmacodynamics: Cemsidomide achieved greater than50% degradation of IKZF1 and greater than 80% degradation of IKZF3, as assessed by mass spectrometry in human peripheral blood mononuclear cells, PBMCs. Across all dose levels, cemsidomide in combination with dexamethasone led to significant T-cell activation associated with an enhancement of cytokine production, including IL-2. Anti-myeloma activity: Across all dose levels, 23 patients achieved a partial response or better, with a median duration of response of 9.3 months. At the 100 undefined dose level, seven patients achieved a PR or better. C4T expects to initiate a Phase 2 single-arm registrational trial in the first quarter of 2026 to evaluate cemsidomide in combination with dexamethasone; initial ORR data is expected in the second half of 2027. C4T plans to initiate a Phase 1b trial in the second quarter of 2026 to evaluate the safety and tolerability of cemsidomide and dexamethasone in combination with a BCMA BiTE; data are expected by mid-2027.