Study of Nivolumab With or Without Pazopanib in Metastatic or Unresectable Soft Tissue Sarcomas

Inclusion Criteria: * Histologic diagnosis of metastatic or unresectable soft tissue or bone sarcoma * No prior therapy with nivolumab in either cohorts or with pazopanib in the combination cohort * At least one line of systemic therapy or ineligibility for an anthracycline based chemotherapy * At least 2 distinct measurable metastatic sites * Adequate organ and marrow function as defined by initial laboratory tests * Life expectancy \> 3 months * Stable brain metastases for at least 4 weeks and no steroid dependence Exclusion Criteria: * Autoimmune disease Any underlying medical or psychiatric condition, which in the opinion of the Investigator, will make the administration of study drugs hazardous or obscure the interpretation of adverse events * Concomitant therapy with any non-study immunotherapy regimens, cytotoxic chemotherapy, immunosuppressive agents, other investigation therapies Chronic use of systemic corticosteroids greater than prednisone 10 mg daily or its equivalent * Women of childbearing potential who are unwilling or unable to use an acceptable method to avoid pregnancy for the entire study period and for at least 5 months after cessation of study drug, or have a positive pregnancy test at baseline, or are pregnant or breastfeeding; * Prisoners or subjects who are compulsorily detained (involuntarily incarcerated) for treatment of either a psychiatric or physical illness.