FDA Grants SLS009 Orphan Drug Designation for R/R PTCL

The Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) to SLS009, a CDK9 inhibitor, for the treatment of patients with relapsed/refractory peripheral T-cell lymphomas (r/r PTCL), according to a news release from the late-stage biopharmaceutical company Stellas Life Sciences Group, the manufacturer of the drug.

Orphan Drug Designations are granted by the FDA in an effort to prevent, diagnose or treat rare diseases or conditions, according to the agency’s website.

Peripheral T-cell lymphoma is a classification of rare lymphomas that develop from a mature stage, while blood cells, specifically T-cells and natural killer (NK) cells, and is considered to be a subtype of non-Hodgkin lymphoma. Peripheral T-cell lymphoma accounts for 5% to 10% of non-Hodgkin lymphoma cases in the United States, according to the Lymphoma Research Foundation.

According to both the Lymphoma Research Foundation and the Leukemia & Lymphoma Society, there is no currently existing consensus on a standard of care for patients with relapsed/refractory peripheral T-cell lymphoma.

SLS009 inhibits cancer cells’ CDK9 protein, which is involved in lymphoma development and progression. The FDA also recently granted SLS009 a Fast Track Designation, which is applied to treatments intended to fill an unmet need in addressing serious conditions.

During a recently completed dose-escalation period of a phase 1 trial, treatment with SLS009 resulted in complete or partial responses among patients with acute myeloid leukemia and lymphoma, including four patients with peripheral T-cell lymphoma who achieved clinical responses and two with complete responses, according to the news release, which also stated that SLS009 is now being evaluated in a phase 1b/2 trial in patients with relapsed/refractory peripheral T-cell lymphoma, with topline data from that study expected to be announced in the first half of 2024.

“We are delighted to announce the FDA’s granting of ODD for SLS009, marking another significant milestone following the recent Fast Track Designation by the FDA for PTCL,” said Dr. Angelos Stergiou, president and chief executive officer of SELLAS, in the new release. “In the recently completed dose-escalation portion of the phase 1 trial in r/r hematological malignancies, SLS009 achieved clinical responses in PTCL including two patients reaching complete response. We are excited to see a favorable safety profile, strong initial efficacy signals, and evidence of anti-tumor activity across the phase 1 study as well as the ongoing phase 2 studies. With both designations in hand, we look forward to advancing the development of SLS009 and continuing to work closely with regulators with the goal of delivering this treatment to those who may benefit from it.”

According to the Lymphoma Research Foundation, PTCL-not-otherwise specified (PTCL-NOS) is the most common subtype of peripheral T-cell lymphoma, with other relatively common subtypes including anaplastic large cell lymphoma (ALCL), angioimmunoblastic T-cell lymphoma (AITL), NK-/ T-cell lymphoma (NKTCL) and adult T-cell leukemia (ATLL).

Most subtypes — including PTCL-NOS, AITL, ALCL, enteropathy-type T-cell lymphoma and extranodal natural killer (NK) cell/T-cell lymphoma — are fast-growing lymphomas, the Lymphoma Research Foundation states.

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