OBX-115 Receives FDA Fast Track Designation in Advanced Melanoma

The Food and Drug Administration (FDA) has granted a Fast Track Designation to OBX-115 for the treatment of patients with metastatic (cancer that has spread from where it started to other parts of the body) or locally advanced (cancer that has spread from its original location but not to other parts of the body) melanoma that is refractory to (does not respond to treatment) or has relapsed following treatment with PD-1/LD-L1-based immune checkpoint inhibitors.

Biotechnology company Obsidian Therapeutics noted that OBX-115 is a type of tumor-infiltrating lymphocyte, or TIL, cell therapy, in a news release announcing the Fast Track Designation.

According to the National Cancer Institute, TIL therapy involves the removal of tumor-infiltrating lymphocytes, a type of immune cell capable of recognizing and killing cancer cells, from a patient’s tumor. The cells are then grown in a laboratory and subsequently infused back into the patient to help the immune system destroy cancer cells.

“FDA Fast Track Designation underscores the ongoing unmet need for patients with melanoma that has progressed on or after [immune checkpoint inhibitor] therapy, agnostic of mutational status, and that OBX-115 may have the potential to address that unmet need,” said Dr. Madan Jagasia, Chief Executive Officer of Obsidian, in the news release.

The Fast Track process, as explained by the FDA on its website, is “designed to facilitate the development and expedite the review of drugs to treat serious conditions and fill an unmet medical need. The purpose is to get important new drugs to the patient earlier.”

OBX-115 is currently being investigated in two clinical trials: a phase 1 study of 21 adult patients with metastatic melanoma that is expected to be completed in April of 2027, and a phase 1/2 study examining the safety and efficacy of OBX-115 in advanced solid tumors, according to the respective listing on clinicaltrials.gov. The phase 1/2 study is currently recruiting participants and is estimated to be completed in October of 2027, according to the listing on clinicaltrials.gov.

Early results from the melanoma-specific study, in findings presented at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting and published in the Journal of Clinical Oncology, found that OBX-115 “was well-tolerated and produced consistently deepening and durable responses,” according to researchers.

LEARN MORE: TIL Therapy Is One of Many ‘Phenomenal Discoveries’ in Melanoma Treatment

With four of nine evaluable patients responding to treatment — two patients had a partial response, two patients had a complete response (the lack of all signs of cancer) — OBX-115 has demonstrated an objective response rate of 44.4%, according to data presented at ASCO. The disease control rate, defined as stable disease or better at least 12 weeks after infusion, was 100%, and the 24-week progression-free survival (the time a patient lives without their disease spreading or worsening) was 75%.

At a median follow-up of 29.5 weeks, grade 3 (severe) nonhematologic treatment-emergent side effects included one case each of increased alanine aminotransferase (elevated amounts of an enzyme associated with liver damage), abdominal pain and syncope (loss of consciousness), with no grade 4 (life-threatening) or 5 (deadly) nonhematologic treatment-emergent side effects reported.

Researchers reported that there were no treatment-related or disease-related deaths at the median follow-up of approximately 30 weeks, and no patients required intensive care unit care.

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