SELLAS Life Sciences Reports Extended Survival Signal in Phase 3 GPS Trial for Acute Myeloid Leukemia

SELLAS Life Sciences Group Inc. (SLS) has announced encouraging progress in its Phase 3 REGAL trial, with patient survival rates proving more resilient than initially projected. This development is pushing back the completion timeline for the study’s final analysis, as the trial remains event-driven and awaits the 80th mortality event to trigger full unblinding and statistical review.

Trial Status and Clinical Significance

As of late December 2025, SELLAS’s monitoring partners confirmed that 72 events have been recorded—eight short of the threshold needed to conclude the final survival assessment. The REGAL study is examining Galinpepimut-S (GPS), a WT1-targeting immunotherapy licensed from Memorial Sloan Kettering, as a maintenance treatment for acute myeloid leukemia patients who have reached a second complete remission (CR2) but are ineligible for transplantation.

This patient population represents a significant clinical challenge. Standard care typically involves hypomethylating agents and/or BCL-2 inhibitors, with median overall survival historically hovering around eight months. The extended survival observed in the trial suggests GPS may meaningfully improve outcomes in this difficult-to-treat group—an area with substantial unmet medical need.

What This Means for the Program

The Independent Data Monitoring Committee recommended in August 2025 that REGAL proceed unchanged, signaling confidence in the trial’s design and execution. Notably, SELLAS remains completely blinded to efficacy data, and no interim analyses have been conducted, meaning no statistical penalties have accumulated. Industry experts have suggested that longer-than-expected survival could actually increase the probability of a positive final result.

Beyond GPS, SELLAS is advancing SLS009 (tambiciclib), a selective CDK9 inhibitor currently in Phase 2a testing for patients with relapsed or refractory AML who have failed venetoclax-based regimens. The program builds on a completed Phase 1 study in hematologic malignancies, with additional research underway in peripheral T-cell lymphoma.

Market Performance

SLS stock has traded between $0.85 and $3.43 over the past year. In recent trading, shares closed at $3.35, reflecting a 16.72% gain—a move potentially driven by market optimism surrounding the trial’s extended survival signal and the company’s broader pipeline progress.