SELLAS Life Sciences Presents Positive Phase 2 Data of SLS009 in Combination with AZA/VEN in Relapsed/Refractory AML-MR at ASH 2025

• SLS009 in combination with AZA/VEN achieved a 46% overall response rate across all cohorts, a 58% overall response rate in patients with one prior line of therapy, and encouraging survival outcomes in heavily-pretreated AML-MR following prior VEN-based treatment
  
  
• Median overall survival (mOS) of 8.9 months in the least pretreated patient cohort; across all cohorts, mOS was not yet reached in patients with one prior line of therapy vs historical benchmark of approximately 2.5 months
  
  
• SLS009 30 mg IV twice weekly added to AZA/VEN was safe and feasible, with no dose-limiting toxicities (DLTs) observed
  
  
• Study expansion to evaluate SLS009 plus AZA/VEN in newly diagnosed AML with high-risk features is planned for Q1 2026
  
  

NEW YORK, Dec. 07, 2025 (GLOBE NEWSWIRE) -- SELLAS Life Sciences Group, Inc. (NASDAQ: SLS) (“SELLAS’’ or the “Company”), a late-stage clinical biopharmaceutical company focused on the development of novel therapies for a broad range of cancer indications, today announced that clinical data from its ongoing Phase 2 study of SLS009, a highly selective CDK9 inhibitor, in combination with azacitidine (AZA) and venetoclax (VEN) for the treatment of patients with relapsed or refractory (R/R) acute myeloid leukemia (AML) with myelodysplastic syndrome-related changes (AML-MR) after prior VEN-based treatment were presented today at the 67^th American Society of Hematology (ASH) Annual Meeting and Exposition, being held December 6 – 9, 2025, in Orlando, Florida.

In this Phase 2 expansion study, R/R AML-MR patients (N = 35 evaluable) were studied in three separate cohorts (cohorts 3-5) who were previously treated with VEN-based regimens and either relapsed and/or were refractory to VEN and were then treated with SLS009 plus AZA/VEN. The median age of participating patients was 69 years, and 98% of patients had ELN adverse-risk AML, with the most frequent mutations being ASXL1, RUNX1, TP53, and SRSF2.

SLS009 in combination with AZA/VEN demonstrated clinically meaningful activity in patients with R/R AML-MR, and among the 35 evaluable patients, the overall response rate (CR+CRi+MLFS) was 46%, including 29% achieving CR/CRi. Patients harboring ASXL1 or TP53 mutations achieved response rates of 48% (19% CR/CRi) and 57% (29% CR/CRi), respectively. The median overall survival (mOS) was exceedingly higher than the expected 2.6 months in this R/R AML patient population, and in the least pretreated cohort, mOS reached 8.9 months. Across all cohorts, patients with one prior line of therapy experienced the greatest benefit, with a 58% response rate and mOS not yet reached. No dose-limiting toxicities (DLTs) or treatment-related deaths were observed, and the combination was well tolerated.