The novel CDK9 inhibitor previously received orphan drug designations in relapsed/refractory acute myeloid leukemia and peripheral T-cell lymphoma.
The FDA has granted a fast track designation to SLS009 (formerly GFH009), a novel and highly selective CDK9 inhibitor, for the treatment of relapsed/refractory (R/R) acute myeloid leukemia (AML), according to SELLAS Life Sciences.1
The FDA fast track designation is designed to help facilitate the development and review of drugs that treat serious conditions with unmet needs. These drugs can also be eligible for priority review and accelerated approval.
SLS009 was granted orphan drug designation in October 2023 for the same indication.2
“Receiving fast track designation for SLS009 for R/R AML, following the recent orphan drug designation for the same indication, underscores the potential for SLS009 and highlights the critical unmet need for patients with AML who face a poor prognosis due to the progressive nature of the disease,” said Angelos Stergiou, MD, ScD hc, president and chief executive officer of SELLAS, in a press release.1
The agent is being investigated in a phase 2a study (NCT04588922) in patients with hematologic malignancies. Nine patients with R/R AML have been enrolled to receive the 45 mg safety dose level. One patient died from sepsis following a COVID-19 infection, and 6 patients remain on the study treatment.
One patient achieved a complete response (CR) and has been on the treatment for 7 months, while another patient has been on the treatment for 6 months. Follow-up duration ranges from 2-7 months, and the median overall survival (OS) has not been reached. Anti-leukemic effects, including a greater than 50% decrease in bone marrow blasts, were observed in 7 of 8 patients (87.5%). No significant safety issues have been reported.
The study’s primary end points are safety and tolerability of SLS009 as evaluated by dose-limiting toxicities and incidence of adverse events. The secondary end points include pharmacokinetics, CR rate, duration of response, progression-free survival, and OS.3
In the trial, patients are receiving either 45 mg or 60 mg of SLS009 in combination with azacitidine or venetoclax (Venclexta). In the 60 mg cohort, patients are being further randomized to receive a 60 mg fixed dose once per week or a 30 mg dose twice per week. Each group has a planned enrollment of 5-10 patients.1
SLS009 also received a fast track designation for patients with R/R peripheral T-cell lymphoma (PTCL) in October 2023. In a phase 1 dose-escalation trial, 4 of 11 patients (36.4%) with AML or PTCL experienced complete or partial responses compared with the PTCL standard-of-care belinostat (Beleodaq), which has demonstrated a response rate of 25.8% in a similar patient population.4
Further data from the phase 2a trial are expected to be announced in Q2 of 2024.1