SELLAS Completes Enrollment and Reports Initial Positive Data in Phase 2a Trial of SLS009 in r/r AML

SELLAS Life Sciences Group, Inc., a clinical-stage biopharmaceutical company specializing in innovative cancer therapies, has announced the successful enrollment of patients ahead of schedule for its Phase 2a trial of SLS009. This trial is being conducted on patients with relapsed or refractory acute myeloid leukemia (r/r AML) who have previously been treated with venetoclax-based regimens. The trial has shown promising initial results.

Dr. Angelos Stergiou, President and CEO of SELLAS, expressed satisfaction with the progress of the trial. He highlighted the enthusiasm among clinical sites, investigators, and patients, which underscores the significant unmet need within the AML patient population. He also thanked all parties involved for achieving this milestone earlier than anticipated.

The Phase 2a trial is examining the efficacy and safety of SLS009, a highly selective CDK9 inhibitor, in combination with venetoclax and azacitidine. The trial includes 30 heavily pretreated patients enrolled across five centers in the United States. These patients had a high risk of poor cytogenetic and molecular genetics (97%) and continued treatment with venetoclax and azacitidine after failing previous regimens.

The trial has two dosing cohorts: 45 mg and 60 mg. In the 60 mg cohort, patients were further randomized into either a 60 mg once-weekly dose or a 30 mg twice-weekly dose. Initial data reveals an overall response rate (ORR) of 33% in the 60 mg once-weekly cohort and 50% in the 30 mg twice-weekly cohort, far exceeding the initial target ORR of 20%. Median overall survival (OS) for the 45 mg dose was 5.4 months, compared to the standard care median OS of 2.5 months. Median OS for the higher dose groups has not yet been reached. Notably, patients with the ASXL1 mutation in the 30 mg twice-weekly cohort achieved a 100% ORR.

The trial will continue with two additional expansion cohorts focusing on patients with ASXL1 mutations and other myelodysplasia-related molecular mutations. Further updates are expected in the third quarter of 2024.

SELLAS is also developing another lead product, GPS, licensed from Memorial Sloan Kettering Cancer Center. GPS targets the WT1 protein present in various tumor types and shows potential as both a monotherapy and in combination with other treatments for numerous hematologic malignancies and solid tumors.

The ongoing development of SLS009, licensed from GenFleet Therapeutics (Shanghai), Inc., for use outside of Greater China, represents a significant advancement in AML treatment. The drug’s promising efficacy and safety profile in heavily pretreated patients offer hope for improving outcomes in this difficult-to-treat population.

Overall, the early results from the Phase 2a trial of SLS009 are encouraging, showing both a high response rate and an extended overall survival compared to existing treatments. SELLAS remains committed to advancing this therapy to meet the needs of AML patients with limited treatment options. Further study updates and data releases are anticipated as the trial progresses.