Pembrolizumab Approved for Merkel Cell Carcinoma

The US Food and Drug Administration (FDA) has approved pembrolizumab (KEYTRUDA, Merck & Co. Inc.) for the treatment of adult and pediatric patients with recurrent locally advanced or metastatic Merkel cell carcinoma (MCC). This approval was granted under an accelerated approval.

A multicenter, non-randomized, open-label trial—Cancer Immunotherapy Trials Network protocol 9 (CITN-09), also known as KEYNOTE-017 (NCT02267603)—served as the basis for the approval. The trial included 50 patients with recurrent locally advanced or metastatic MCC who were not administered prior systemic therapy for their advanced disease. Participants were administered pembrolizumab 2 mg/kg every 3 weeks.

Overall response rate (ORR) and response duration as assessed by blinded independent central review per RECIST 1.1 served as the major efficacy outcome measures. With a complete response rate of 24%, the ORR was 56% (95% CI: 41, 70); however, the median response duration was not achieved.

Approximately 96% of the 28 patients with responses experienced response durations of greater than 6 months while 54% experienced response durations of greater than 12 months.

Fatigue, musculoskeletal pain, decreased appetite, pruritus, diarrhea, nausea, rash, pyrexia, cough, dyspnea, constipation, pain, and abdominal pain included the most common adverse reactions experienced in at least 20% of patients who received pembrolizumab as a single agent.

Pembrolizumab is recommended in doses of 200 mg as a 30-minute intravenous infusion every 3 weeks for adults and 2 mg/kg (to a maximum of 200 mg) as a 30-minute intravenous infusion every 3 weeks for patients less than 18 years of age (pediatric patients).

Previously, pembrolizumab was granted a priority review and a breakthrough therapy.

Pembrolizumab has also been approved for other indications, such as adult and pediatric patients with refractory primary mediastinal large B-cell lymphoma (PMBC) and patients with metastatic, non-squamous non-small cell lung cancer (NSqNSCLC). Additional indications include melanoma, head and neck squamous cell cancer (HNSCC), classical Hodgkin lymphoma (cHL), urothelial carcinoma, and microsatellite instability-high cancer.