The U.S. Food and Drug Administration granted priority review to Merck’s supplemental Biologics License Application seeking accelerated approval for Keytruda (pembrolizumab) as a treatment for adults and children with recurrent locally advanced or metastatic Merkel cell carcinoma (MCC).
The regulatory agency set Dec. 28 as the deadline to reach a decision.
Merck’s application is based on results from the KEYNOTE-017 Phase 2 clinical trial (NCT02267603), in which half of advanced MCC patients showed a response to Keytruda treatment.
This trial included patients, 80% of whom were 65 or older, whose tumor could not be surgically removed or managed with treatment, or had spread to other parts of the body. Treatment was repeated every 21 days for up to two years.
Data submitted to the FDA were presented at the 2018 American Society of Clinical Oncology Annual Meeting in June.
Trial findings showed that, in 42 patients with more than 21 weeks of follow-up, the overall response rate was 50%, including 19% who had complete responses. At 18 months, 68% of patients were still alive.
Importantly, 21 weeks after beginning treatment, Keytruda was still effective in more than half of patients. Additionally, more than 50% of patients were alive and progression-free.
Treatment-related adverse events were reported in 94% of patients, including 30% that were considered severe or worse. One patient died as a result of the treatment, and six patients stopped treatment due to adverse events.
Keytruda is a type of therapy called an immune checkpoint inhibitor. It binds to a protein called PD-1 on immune T-cells, blocking their binding to PD-L1 on tumor cells. Cancer cells use this interaction between PD-1 and PD-L1 to evade immune attack. Treatment with Keytruda is intended to increase the immune system’s anti-cancer response.
In July 2017, the FDA granted Keytruda breakthrough therapy designation for MCC.
“KEYNOTE-017 represents the longest observation to date of patients with advanced Merkel cell carcinoma receiving anti-PD-1 therapy in the first-line setting, and demonstrated durable tumor control in these patients,” Scot Ebbinghaus, MD, vice president of clinical research at Merck Research Laboratories, said in a press release. “We look forward to working closely with the FDA throughout the review process and to bringing Keytruda to patients with Merkel cell carcinoma.”
MCC is a rare and aggressive skin cancer, most often caused by the Merkel cell polyomavirus. It is 35 times less common than melanoma and is typically diagnosed in people older than 50. Approximately 2,500 MCC cases are diagnosed in the U.S. each year.
Merck, known as MSD outside the U.S. and Canada, is currently sponsoring more than 10 skin cancer clinical trials, which involve more than 4,500 patients. The studies are assessing stand-alone and combinations of Keytruda with other approaches in different settings, stages, and subtypes of skin cancer.
