Avelumab (Bavencio®) is a fully human IgG1 monoclonal antibody that is directed against programmed cell death ligand 1 (PD-L1). Avelumab functions as an immune checkpoint inhibitor and has recently been approved in the USA, the EU and Japan for the treatment of metastatic Merkel cell carcinoma (MCC). It is thus the first therapeutic agent specifically approved for use in this indication, and is approved for use independent of line of treatment. Approval for avelumab in metastatic MCC was based on the two-part, single-arm, phase II trial, JAVELIN Merkel 200. In Part A of the study, confirmed objective responses were observed in approximately one-third of patients with chemotherapy-refractory metastatic MCC treated with avelumab. The responses were observed early and appeared to be durable, with an estimated 74% of responses having a duration ≥ 12 months. Furthermore, interim results from a separate cohort of patients (Part B) indicate an objective response rate for avelumab of > 60% in patients who were chemotherapy-naïve in the metastatic disease setting. Avelumab is associated with a risk of immune-related adverse events but, overall, has an acceptable and manageable safety and tolerability profile. In conclusion, currently available data suggest that avelumab presents a clinically beneficial new treatment option for metastatic MCC, a rare but aggressive cancer associated with a poor prognosis.