Safety Study of Enoblituzumab (MGA271) in Combination With Ipilimumab in Refractory Cancer

Inclusion Criteria - Cohort Expansion Phase: * Histologically-proven, unresectable, locally advanced or metastatic melanoma or NSCLC * Melanoma: Advanced or metastatic melanoma patients may be systemic therapy naïve or may have received systemic treatment for unresectable locally advanced or metastatic disease. A patient who previously received systemic therapy must have had progression on a checkpoint inhibitor (e.g., anti-PD-L1, anti-PD-1, anti-CTLA-4) as the most recent prior therapy. * NSCLC: NSCLC that has progressed during or following 1 or more prior systemic therapies for unresectable locally advanced or metastatic disease. Patients who are intolerant of, or have refused treatment with standard first line cancer therapy, will be allowed to enroll. Patients must not have had more than 5 prior systemic regimens (excluding experimental therapies) for unresectable locally advanced or metastatic disease. * B7-H3 expression is not required for eligibility in this study; however, tumor expression of B7-H3 will be evaluated for all patients. * Measurable disease per RECIST 1.1 criteria * ECOG performance status 0 or 1 * Acceptable laboratory parameters and adequate organ reserve. Exclusion Criteria - Cohort Expansion Phase: * Patients with a history of symptomatic central nervous system metastases, unless treated and asymptomatic * Patients with history of autoimmune disease with certain exceptions * History of allogeneic bone marrow, stem cell, or solid organ transplant * Treatment with systemic cancer therapy or investigational therapy within 4 weeks; radiation within 2 weeks; trauma or major surgery within 4 weeks * History of clinically-significant cardiovascular disease; gastrointestinal perforation; gastrointestinal bleeding, acute pancreatitis or diverticulitis within 4 weeks; * Active viral, bacterial, or systemic fungal infection requiring parenteral treatment within 7 days; positive for human immunodeficiency virus or AIDS, hepatitis B or C. * Known hypersensitivity to recombinant proteins, polysorbate 80, or any excipient contained in the drug or vehicle formulation for MGA271 or ipilimumab.