Nghiem P, et al. - Considering the clinical trials of programmed cell death-1 pathway inhibitors for advanced Merkel cell carcinoma (aMCC) demonstrating increased progression-free survival (PFS) compared with historical chemotherapy data, researchers undertook this multicenter phase II trial (Cancer Immunotherapy Trials Network-09/Keynote-017) investigating the response durability and overall survival (OS). Pembrolizumab (2 mg/kg every 3 weeks) was administered to 50 adults, naïve to systemic therapy for aMCC for up to 2 years. This study reports the longest observation to date of patients with aMCC receiving first-line anti–programmed cell death-1 therapy. Compared with historical data from patients treated with first-line chemotherapy, pembrolizumab demonstrated durable tumor control, a generally manageable safety profile, and favorable OS.