Sellas Life Sciences presents preclinical efficacy data on SLS009

SELLAS Life Sciences (SLS) announced preclinical efficacy of SLS009 in ASXL1 mutated colorectal cancer lines. The data are featured in a presentation, entitled “In vitro efficacy of CDK9 inhibitor tambiciclib in ASXL1 mutated colorectal cancer cell lines” at the 2025 American Society of Clinical Oncology Annual Meeting, taking place May 30- June 3, 2025, in Chicago, Illinois. In a panel of cell lines, SLS009 demonstrated potent anti-proliferative activity: In 50% of ASXL1 mutant cell lines showed an IC50less than100 nM, compared to 0% of ASXL1 wild-type lines; Among cell lines harboring ASXL1 frameshift mutations, 75% responded with IC50 less than100 nM versus only 12.5% in cell lines without FSMs; All cell lines with ASXL1 FSMs in the 637-638 protein region responded to treatment with SLS009; In cell lines with IC50 less than100 nM, 75% also demonstrated IC99 values below 100 nM, indicating steep dose response curve. Importantly, effective concentrations were significantly lower than those achieved in patients treated at the recommended phase 2 dose determined to be safe, suggesting a broad therapeutic window.