Sellas Life Sciences' CDK9 Inhibitor Shows Promise in AML Treatment

Sellas Life Sciences has reported encouraging results from a phase 2 study of its investigational CDK9 inhibitor, SLS009 (tambiciclib), in the treatment of acute myeloid leukemia (AML). The open-label, single-arm trial demonstrated significant efficacy in patients with advanced AML who had not previously responded to venetoclax therapies.

Impressive Response Rates in High-Risk AML Subtypes

The study, which included 54 evaluable patients, showed an overall response rate (ORR) of 33% across all participants, significantly exceeding the targeted 20% goal. Notably, patients with AML-myelodysplasia-related changes (AML MR) who received 30 mg of SLS009 twice weekly experienced an ORR of 44%. Even more promising results were observed in specific high-risk subgroups:

• Patients with the AML MR myelomonocytic/myelomonoblastic (M4/M5) subtype achieved an ORR of 50%.
• A 50% response rate was also recorded for patients with ASXL1 mutations, a group typically associated with poor prognosis in myeloid diseases.

Survival Outcomes Surpass Historical Benchmarks

The trial also reported impressive survival data, with median overall survival (mOS) rates significantly exceeding historical benchmarks:

• Patients with AML MR demonstrated a mOS of 8.9 months.
• Those who had received one prior line of therapy and were administered 30 mg of SLS009 twice weekly showed a mOS of 8.8 months, compared to the historical benchmark of 2.4 months for second-line AML patients receiving best available therapy.
• For patients with two prior lines of therapy, the mOS was 4.1 months, surpassing the 1.8-month benchmark for best available therapy.

Safety Profile and Future Directions

The study reported a favorable safety profile for SLS009, with no dose-limiting toxicities observed. The toxicity profile was similar to that associated with venetoclax and chemotherapy alone.

Based on these promising results and following FDA recommendations, Sellas is planning to advance SLS009 into a randomized trial for newly diagnosed AML patients. The company expects to launch an 80-patient study by the first quarter of next year, designed to support a potential new drug application.

Dr. Yair Levy, Director of Hematologic Malignancies Research at Texas Oncology Baylor University Medical Center, commented on the significance of these results: "These SLS009 results represent an important advancement for patients with relapsed/refractory AML, where treatment options remain limited and outcomes are often poor. The response rates and survival outcomes are particularly compelling, especially given the consistency of responses across high-risk molecular subtypes and the favorable safety profile."