SELLAS' GPS Immunotherapy Shows Extended Survival Trajectory in Phase 3 REGAL Trial for AML

SELLAS Life Sciences Group Inc. (SLS) has disclosed a notable development in its pivotal Phase 3 REGAL trial: patients receiving Galinpepimut-S (GPS) maintenance therapy are surviving considerably beyond historical expectations. This extended progression has pushed back the completion timeline, as only 72 of the required 80 mortality events had been documented as of late December 2025.

The REGAL trial centers on GPS, a WT1-targeting immunotherapeutic licensed from Memorial Sloan Kettering, being evaluated in acute myeloid leukemia (AML) patients who achieved second complete remission (CR2) but remain ineligible for transplantation. This patient population represents a particularly challenging segment—typically managed with hypomethylating agents or BCL-2 inhibitors—with historical median overall survival hovering around eight months. The extended survival duration observed in the trial suggests GPS may be meaningfully altering the disease trajectory in this difficult-to-treat cohort.

SELLAS remains completely blinded to interim efficacy outcomes and has incurred no statistical penalties to date. The Independent Data Monitoring Committee previously endorsed trial continuation without modifications in August 2025. Key opinion leaders have suggested that prolonged survival within the trial setting could increase the likelihood of demonstrating clinical benefit once the final 80th event occurs and the study becomes unblinded.

The company’s broader pipeline continues advancing, particularly SLS009 (tambiciclib), a selective CDK9 inhibitor progressing through Phase 2a evaluation for relapsed or refractory AML in patients who failed venetoclax-based regimens. Earlier Phase 1 data in hematologic malignancies supports continued development, with parallel monotherapy investigations underway in relapsed or refractory peripheral T-cell lymphoma.

From a market perspective, SLS shares have exhibited volatility over the trailing twelve-month period, trading within a $0.85 to $3.43 range. The stock closed recent trading at $3.35, representing a 16.72% single-session gain, reflecting investor optimism surrounding the extended survival phase symbol observed in the REGAL trial trajectory.