Data from a phase II trial indicate that avelumab, an anti PD-L1 monoclonal antibody, is safe and effective in patients with advanced-stage Merkel-cell carcinoma. In a cohort of 88 patients, who were not selected for PD-L1 expression, 28 (31.8%) had an objective response to treatment, including eight complete responses and 20 partial responses, of which 23 patients had an ongoing response at a median of 10.4 months of follow-up monitoring. Grade 3 treatment-related adverse events ocurred in four patients, these events included lymphopenia, and increases in serum creatinine phosphokinase levels, aminotransferase levels and cholesterol levels. No grade 4 treatment-related adverse events ocurred. On the basis of these data, avelumab provides a new treatment option for patients with advanced-stage Merkel-cell carcinoma.