C4 Therapeutics Presents Cemsidomide Data at EHA 2026 Congress

C4 Therapeutics will present further analysis from its fully enrolled Phase 1 trial of cemsidomide, a next-generation oral IKZF1/3 degrader, in combination with dexamethasone for the treatment of relapsed/refractory multiple myeloma in a poster presentation at the European Hematology Association, or EHA, 2026 Congress on Friday, June 12. The poster presentation includes data on 73 patients with a data cutoff of February 27. Patients were heavily pretreated, receiving a median of seven prior lines of therapy. Fifty-five patients received prior BCMA therapy, and 55 patients received prior CAR-T or T-cell engager therapy. At the RP2D and maximum tolerated dose cemsidomide achieved a 53% overall response rate. At the 75 microgram dose level, cemsidomide achieved a 40% ORR. Across all doses evaluated, cemsidomide achieved a 36% ORR. Responses deepened over time across the cemsidomide 75 microgram and 100 microgram dose levels: at 75 microgram, one patient whose best response was previously a partial response deepened to a very good partial response. At 100 microgram, several patients achieved a deeper response: one patient whose best response was previously a PR deepened to a stringent complete response; one patient whose best response was previously a PR deepened to a VGPR; minimal residual disease negativity was achieved in two patients who achieved a sCR and complete response at 100 microgram. ORR was consistent across key subgroups. Patients experienced a median duration of response of 7.9 months. Seven patients remain on treatment currently. Cemsidomide in combination with dexamethasone was generally well tolerated. Incidences of on-target neutropenia remained manageable; 42 patients experienced Grade 3/4 neutropenia. All treatment emergent adverse events were manageable with no discontinuations deemed related to cemsidomide and minimal dose reductions.