Merkel cell carcinoma.

The FDA has granted accelerated approval to retifanlimab-dlwr (Zynyz™, Incyte), a programmed cell death protein 1 (PD-1)–blocking antibody, for adult patients with metastatic or recurrent locally advanced Merkel cell carcinoma (MCC).

"Retifanlimab is a humanized, hinge-stabilized immunoglobulin G4 kappa (IgG4κ) anti–PD-1 monoclonal antibody with safety and clinical pharmacology that are characteristic for the class," wrote Giovanni Grignani, MD, a Medical Oncologist at the Candiolo Cancer Institute in Italy, and colleagues, in their publication of the POD1UM-201 trial (NCT03599713), on which the approval was based. "POD1UM-201 is an open-label, single-arm, multicenter, phase 2 study evaluating the efficacy and safety of retifanlimab in patients with chemotherapy-naive or chemotherapy-refractory advanced/metastatic MCC."

The trial enrolled 65 patients with metastatic or recurrent locally advanced MCC who had previously received systemic therapy for advanced disease. Patients received 500 mg of retifanlimab administered intravenously every four weeks for up to two years. The primary end points were objective response rate and duration of response as assessed by an independent central review committee.

Retifanlimab produced an overall response rate of 52% and a complete response rate of 18%. Among those who achieved a response, 26 patients (76%) experienced a response lasting 6 months or longer, and 21 (62%) experienced a response lasting 12 months or longer.

In a pooled safety population consisting of 105 patients with MCC, the most common adverse events occurring in ≥10% of patients included fatigue, musculoskeletal pain, pruritus, diarrhea, rash, pyrexia, and nausea. Serious adverse reactions occurred in 22% of patients who received retifanlimab.

"These data from the POD1UM-201 trial show that retifanlimab monotherapy at 500 mg every four weeks continues to demonstrate promising clinical activity and safety in patients with advanced/metastatic chemotherapy-naive MCC," concluded Dr. Grignani and colleagues.

The recommended dose of retifanlimab is 500 mg administered intravenously over 30 minutes every four weeks for up to 24 months, or until disease progression or unacceptable toxicity.

For More Information

US Food & Drug Administration (2023). FDA grants accelerated approval to retifanlimab-dlwr for metastatic or recurrent locally advanced Merkel cell carcinoma. Available at: https://www.fda.gov/drugs/resources-information-approved-drugs/fda-grants-accelerated-approval-retifanlimab-dlwr-metastatic-or-recurrent-locally-advanced-merkel

Image credit: Isaac Brownell, National Institute of Arthritis and Musculoskeletal and Skin Diseases. Courtesy of the National Institutes of Health (NIH) Image Gallery