Merck KGaA, Darmstadt, Germany, and Pfizer announced that the US Food and Drug Administration (FDA) has granted avelumab*, an investigational fully human anti-PD-L1 IgG1 monoclonal antibody, Breakthrough Therapy designation for the treatment of patients with metastatic Merkel cell carcinoma (MCC) who have progressed after at least one previous chemotherapy regimen. Breakthrough Therapy designation is designed to accelerate the development and review of medicines that are intended to treat a serious condition, and preliminary clinical evidence indicates that the therapy may demonstrate a substantial improvement over current available therapies.