Sellas Life Sciences Group Inc. (NASDAQ:SLS) advanced 4% in premarket trading Monday after unveiling new Phase 2 data for its investigational therapy SLS009 in acute myeloid leukemia with myelodysplastic syndrome–related changes (AML-MR).
In patients who had previously been treated with venetoclax-based regimens, SLS009 — a CDK9 inhibitor — combined with azacitidine and venetoclax produced a 46% overall response rate. The findings were presented at the American Society of Hematology Annual Meeting.
Responses were even stronger in less heavily pretreated patients: those with only one prior line of therapy achieved a 58% response rate, and median overall survival in this cohort reached 8.9 months, far exceeding the roughly 2.5-month historical benchmark.
The regimen also showed activity in genetically challenging disease, with 48% response rates in ASXL1-mutated patients and 57% in those with TP53 mutations. Importantly, investigators reported no dose-limiting toxicities or treatment-related deaths.
Dr. Dragan Cicic, Senior Vice President and Chief Development Officer at Sellas, said, “These results further reinforce the therapeutic potential of SLS009 to overcome resistance to venetoclax-based regimens by suppressing the expression of MCL-1, a key mechanism of resistance to BCL-2 inhibition in AML.”
Sellas plans to broaden its clinical program in early 2026, initiating a study of SLS009 plus azacitidine and venetoclax in newly diagnosed AML patients with high-risk features.