Don Tracy, Associate Editor
SLS009 is a novel CDK9 inhibitor under investigation for the treatment of relapsed/refractory peripheral T-cell lymphomas.

Sellas Life Sciences announced that the FDA has granted Fast Track Designation to SLS009, its novel and highly selective CDK9 inhibitor, for the treatment of relapsed/refractory (r/r) peripheral T-cell lymphomas (PTCL). The designation intends to facilitate the development and review of drugs to treat serious conditions and fill an unmet medical need.1
“The FDA’s decision to grant SLS009 Fast Track designation signifies an important milestone towards developing a safe and effective treatment for PTCL, a group of aggressive and rare non-Hodgkin lymphomas, and underscores the urgent need for innovative therapies such as SLS009 that can significantly improve the outcome of PTCL patients,” said Angelos Stergiou, MD, ScD hc, president, CEO, Sellas, in a company press release. “SLS009 has demonstrated very promising clinical responses in PTCL patients in the recently completed dose-escalation portion of the Phase 1 trial in relapsed/refractory hematological malignancies and with the Fast Track designation we are poised to accelerate its development. We are committed to working closely with the FDA and our partner GenFleet Therapeutics to develop this promising treatment for patients in need.”
R/R PTLC is an aggressive form of lymphoma with an overall survival rate of six months. Currently, most approved therapies have overall response rates of less than 30%, low complete response rates, and short progression-free survival.2
According to Sellas, SLS009 demonstrated favorable safety and tolerability, as well as promising clinical efficacy in the recently completed dose-escalation portion of the phase 1 trial in r/r hematological malignancies, with responses observed in acute myeloid leukemia and lymphoma patients, among whom four out of eleven patients with PTCL (36.4%) achieved clinical responses, including one in continuous treatment for more than 56 weeks.1
The PTCL study, which is expected to enroll up to 95 patients, is fully funded by GenFleet Therapeutics (Shanghai) Inc. Sellas stated that it is also aiming to earn Breakthrough Therapy designation by the FDA with a meeting scheduled to discuss the possibility later this year.