SELLAS Stock Surges on Extended Survival Data from Phase 3 REGAL Trial in Acute Myeloid Leukemia Treatment

SELLAS Life Sciences Group Inc. (SLS) experienced a notable 16.72% price surge yesterday, closing at $3.35 as the biotech company announced encouraging developments from its pivotal Phase 3 REGAL trial investigating Galinpepimut-S (GPS) as a maintenance approach for acute myeloid leukemia patients.

Trial Progress Exceeds Initial Timeline Expectations

The extended survival duration observed in the REGAL study has created an unexpected delay in reaching the statistical milestone for the final analysis. As of December 26, 2025, only 72 of the required 80 fatal events had been documented, according to updates from SELLAS’s contracted research organization. This slower-than-anticipated event accumulation actually signals a positive trajectory—patients are surviving longer than historical patterns would suggest, potentially strengthening the likelihood of favorable trial outcomes.

Addressing Critical Patient Population Needs

The REGAL trial focuses on patients with acute myeloid leukemia who achieved a second complete remission (CR2) but cannot proceed to transplantation. This population typically receives treatment with hypomethylating agents or BCL-2 inhibitors, with historical median overall survival hovering around eight months—highlighting a substantial medical necessity. GPS, a WT1-targeting immunotherapeutic licensed from Memorial Sloan Kettering, represents a potential breakthrough for this challenging-to-treat demographic.

Regulatory Pathway and Study Design

The Independent Data Monitoring Committee provided its recommendation in August 2025 that the trial should proceed without modifications. Because REGAL operates under an event-driven statistical framework, SELLAS will make a public announcement upon reaching the 80th event threshold. Following unblinding, comprehensive final analyses will commence. The company maintains full blinding to efficacy and survival data, and notably, no interim efficacy reviews have taken place, ensuring statistical integrity without penalty.

Broader Pipeline Development

Beyond the myeloid leukemia program, SELLAS is advancing SLS009 (tambiciclib), a highly selective CDK9 inhibitor progressing through Phase 2a evaluation for relapsed or refractory acute myeloid leukemia cases in patients who have failed or become unresponsive to venetoclax-based regimens. This candidate completed Phase 1 testing in hematologic malignancies, with parallel monotherapy studies underway in relapsed or refractory peripheral T-cell lymphoma.

SELLAS shares have traded within a $0.85 to $3.43 range throughout the past year, reflecting market volatility in the biotech sector. The extended survival benefit potential, emphasized by key opinion leaders at the company’s recent R&D presentation, may enhance the probability of achieving positive outcomes in this critical indication.