Sellas enrolls first patients in 60 mg dose cohort in Phase 2a SLS009 trial

SELLAS Life Sciences Group announced that the first patients have been enrolled in the 60 mg dose cohort in its ongoing Phase 2a clinical trial of its novel and highly selective CDK9 inhibitor, SLS009, in combination with venetoclax and azacitidine in patients with relapsed/refractory acute myeloid leukemia who did not respond or stopped responding to venetoclax-based therapies. A total of nine patients have been enrolled at the 45 mg safety dose level. Eight patients remain alive and six continue treatment. The first enrolled patient achieved a complete response and is currently in the seventh month of treatment and the second enrolled patient is in the sixth month of treatment. Significant anti-leukemic effects were observed during treatment in five out of six assessable patients with no significant safety issues to date. No dose limiting toxicities were observed in any of the patients. Topline data for the 45 mg cohort are expected around year-end 2023. Patients with AML that fail venetoclax-based therapies have limited treatment options and a poor prognosis with a median overall survival of approximately 2.5 months. The Phase 2a clinical trial of SLS009 is an open label, single arm, multi-center study that is designed to evaluate safety, tolerability, and efficacy at two dose levels, 45 mg and 60 mg, in combination with aza/ven. In the 60 mg dose cohort, patients will be randomized to one of two groups, 60 mg flat (dose once per week and 30 mg fixed dose two times per week. Each group will enroll 5 – 10 patients. In addition to safety and tolerability of SLS009 in combination with aza/ven, the primary endpoints are composite complete response rate and duration of response. Additional endpoints include event free survival, OS, and pharmacokinetic and pharmacodynamic assessments. Venetoclax combinations with hypomethylating agents are a commonly used regimen in this target population but despite high efficacy approximately one-third to one-half of patients do not respond to venetoclax based regimens, and among those who respond almost all eventually relapse.