Randomized Study of Nivolumab+Ipilimumab+/- SBRT for Metastatic Merkel Cell Carcinoma

Inclusion Criteria: * At least 18 years of age * Eastern Cooperative Oncology Group (ECOG) Performance Status less than 2 * Active disease measurable by CT, MRI or clinical exam. * Prior chemotherapy or immunotherapy will be allowed if new or persistent measurable site(s) of disease are present. * Prior radiation therapy will be allowed if there is active measurable disease burden. * Must be either recurrent, unresectable or Stage IV American Joint Committee on Cancer (AJCC) (7th edition) and have histologically confirmed Merkel cell carcinoma with at least 2 distinct lesions in order to be eligible. * Must have at least 2 distinct lesions as documented by a complete physical examination or imaging studies within 4 weeks prior to randomization. Imaging studies must include a diagnostic CT scan of the involved disease sites and all known sites of resected disease and brain magnetic resonance (MRI) or CT (brain CT allowable if MRI is contraindicated or if there is no known history of resected brain lesions). * Tumor tissue from the core biopsy or resected site of disease must be provided for biomarker analyses. Exclusion Criteria: * History of Grade 3 toxicity or use of infliximab with prior immunotherapy * Patients with active brain metastasis. * Active, known, or suspected autoimmune disease. Potential participants with type I diabetes mellitus, residual hypothyroidism due to autoimmune thyroiditis only requiring hormone replacement, skin disorders (such as vitiligo, psori…