On Monday, SELLAS Life Sciences Group Inc (NASDAQ: SLS) witnessed a significant positive movement in its stock price following the release of recent developments concerning its Phase 3 REGAL clinical trial. Initially trading lower in premarket sessions, the stock reversed course as market participants responded to the trial update. This change draws attention to the clinical progress and potential implications for acute myeloid leukemia (AML) treatment.
The REGAL trial is principally designed to evaluate the efficacy of GPS as a maintenance therapy in patients with AML who have attained a second complete remission. SELLAS detailed that, as of December 26, 2025, 72 events had been recorded within the study, according to reports from the contract research organization overseeing the trial. Here, an 'event' refers to an occurrence affecting overall survival metrics, with the final analysis scheduled to trigger upon reaching 80 such events, in accordance with the trial's statistical framework.
Reflecting on recent trial progress, SELLAS recalled the Independent Data Monitoring Committee's recommendation in August 2025 to proceed with the study as planned without any modifications. At that juncture, the company had projected that the milestone 80th event would occur before the conclusion of the calendar year. However, this threshold remains unmet, suggesting survival times among participants may be longer than initially anticipated.
Angelos Stergiou, President and Chief Executive Officer of SELLAS, acknowledged the ongoing commitment from patients, their families, and clinical investigators engaged in the REGAL trial. Stergiou emphasized that although the 80th event necessary for final analysis remains pending and the study remains blinded, the extended observation period could potentially enhance the probability of a successful outcome. This perspective was supported by insights shared by key opinion leaders during a recent research and development event hosted by the company.
Additional commentary came from Dr. Yair Levy, Director of Hematologic Malignancies Research at Texas Oncology Baylor University Medical Center and member of the REGAL Steering Committee. Dr. Levy expressed optimism that the ongoing trial could demonstrate an extended survival benefit coupled with a tolerable safety profile, consistent with prior GPS studies.
Market response to these developments was notable, with SELLAS Life Sciences shares rising by 16.72% to $3.35 at the time of publication on Monday. This movement propelled the stock to a new 52-week high. Investors and analysts continue to monitor the REGAL trial closely, given its implications for AML maintenance therapy and the potential impact on SELLAS Life Sciences' valuation.