SELLAS Life Sciences Group, Inc. announced a positive review of the ongoing Phase 3 REGAL clinical trial of galinpepimut-S (GPS) in acute myeloid leukemia (AML) by the Independent Data Monitoring Committee (IDMC). The IDMC conducted a prespecified risk-benefit assessment of unblinded data from the study and has recommended that the trial continue without modifications, and scheduled its next meeting in June 2024, earlier than prescribed in the IDMC charter schedule to review the most up-to-date information regarding the number of events (deaths) required for triggering prespecified interim analysis. As reported in March 2024, the REGAL Study Steering Committee reviewed the blinded study data with 66 patients discontinuing the treatment.

In the trial, patients are recorded as having stopped the study treatment in cases of death for any reason, relapse, intolerable toxicity, or treatment completion. Regarding the GPS arm, the company reported that have not observed any intolerable toxicities in any patient population across all clinical studies thus far, although toxicities are commonly observed with therapies used in the control arm. The IDMC also confirmed no safety issues in their recent review.

Therefore, patients off treatment likely either relapsed or passed away, but as the study sponsor, the company lack information on the actual number of events (60 events are required for interim analysis). This lies within the purview of the IDMC, which will now meet again in June and will review both efficacy and safety data from all enrolled REGAL patients (n=127) with a data cut-off date of around the end of May. REGAL is a Phase 3 open-label registrational clinical trial for GPS in AML patients who have achieved complete removal following second-line salvage therapy (CR2 patients).

The primary endpoint is overall survival. TheIDMC is an independent group of medical, scientific, and biostatistics experts who are responsible for reviewing and evaluating patient safety and efficacy data for REGAL, and for monitoring quality and overall conduct to ensure the validity, scientific and clinical merits of the study. The IDMC charter provides for periodic reviews of safety, efficacy, and futility in addition to the interim and final analyses.