Sellas Life Sciences to present in vivo preclinical data on SLS009

SELLAS Life Sciences (SLS) announced that preclinical efficacy of its highly selective CDK9 inhibitor, SLS009, as a monotherapy and in combination with venetoclax in T-cell prolymphocytic leukemia, will be presented at the European Society for Medical Oncology Congress 2025, being held October 17 – 21, 2025, in Berlin, Germany. The results highlight an in vivo patient-derived xenograft model of relapsed/refractory T-PLL that reproduced key human clinicopathological features of the disease. In this model, SLS009 demonstrated meaningful single-agent activity as well as in combination with the BCL2 inhibitor venetoclax. Both SLS009 monotherapy and the combination prolonged overall survival compared to venetoclax alone, a difference that was statistically significant, and SLS009 achieved better control of circulating T-PLL cells in the peripheral blood relative to other treatments. The combination regimen was also well tolerated in the study. “These results are highly encouraging and provide important preclinical evidence that selective CDK9 inhibition with SLS009 may play a critical role in the treatment of T-PLL, an aggressive leukemia with very limited treatment options,” said Dr. Dragan Cicic, CDO. “Notably, SLS009 alone and in combination with venetoclax prolonged survival more effectively than venetoclax monotherapy, while demonstrating favorable tolerability. This reinforces the potential of SLS009 to improve outcomes in T-PLL and broadens its therapeutic relevance across additional hematologic malignancies that require novel treatment approaches.”