Incyte’s MCC indication is approved under accelerated approval based on tumor response rate and duration of response.
The US Food and Drug Administration (FDA) has approved Incyte Corporation’s retifanlimab-dlwr (Zynyz) for the treatment of metastatic or recurrent locally advanced Merkel cell carcinoma (MCC) in adults.1 The FDA approved Incyte’s Biologics License Application for MCC treatment with retifanlimab-dlwr, a humanized monoclonal antibody targeting programmed death receptor-1, under accelerated approval based on tumor response rate and duration of response (DOR). According to Incyte, continued approval of retifanlimab-dlwr for MCC may be “contingent on verification and description of clinical benefit in confirmatory trials.”
The FDA’s approval of retifanlimab-dlwr is based on data from Incyte’s POD1UM-201 clinical trial (NCT03599713), an open-label, multiregional, single-arm study that evaluated retifanlimab-dlwr in adults with metastatic or recurrent locally advanced MCC who had not received prior systemic therapy. Out of patients who had never received chemotherapy (n=65), retifanlimab-dlwr as monotherapy demonstrated an objective response rate (ORR) of 52% (95% confidence interval: 40-65) determined by independent central review using RECIST v1.1.
"For those of us who have significant cutaneous oncology practices, the treatment of MCC has always been a challenge. Although we have treated this serious skin cancer with Mohs surgery for decades, local recurrences and metastases have always been a challenge. Incyte’s long-awaited FDA clearance of Zynyz for metastatic or recurrent locally advanced MCC provides our patients a long-needed adjunctive treatment approach," said David J. Goldberg, MD, JD, medical director of Skin Laser and Surgery Specialists of New York and New Jersey; director of cosmetic dermatology and clinical research at Schweiger Dermatology Group in New York, New York; and clinical professor of dermatology and past director of Mohs Surgery and Laser Research at the Icahn School of Medicine at Mount Sinai in New York, New York.
Complete response was observed in 12 patients (18%), and 22 patients (34%) showed partial response. Among the responding patients, the DOR ranged from 1.1 to 24.9+ months, 76% (26/34) experienced a DOR of 6 months or longer, and 62% (21/34) experienced a DOR of 12 months or longer by landmark analysis.
Some serious adverse events (AE) were observed in 22% of patients who received retifanlimab-dlwr. The most frequent serious AEs (≥ 2% of patients) were fatigue, arrhythmia, and pneumonitis. Due to AEs, 11% of patients discontinued retifanlimab-dlwr. The most common AEs (≥10%) observed in patients were fatigue, musculoskeletal pain, pruritus, diarrhea, rash, pyrexia, and nausea.
Patients received retifanlimab-dlwr 500 mg intravenously every 4 weeks until disease progression, unacceptable toxicity, for up to 24 months. Tumor response assessments were performed every 8 weeks for the first year of therapy and 12 weeks afterward.
The primary endpoint of POD1UM-201 was ORR determined by an independent central radiographic review using RECIST v1.1. Secondary endpoints included DOR, disease control rate, progression-free survival, and overall survival, as well as observed safety and pharmacokinetics.
Retifanlimab is also being studied in other POD1UM clinical trials for the treatment of squamous cell carcinoma of the anal canal.