Nivolumab Alone or in Combination With Ipilimumab in Treating Patients With Advanced Uterine Leiomyosarcoma

PRIMARY OBJECTIVES: I. To evaluate the objective response rate per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 of patients with advanced leiomyosarcoma of the uterus (ULMS) treated with nivolumab. II. To evaluate the objective response rate per RECIST 1.1 of patients with advanced ULMS treated with nivolumab in combination with ipilimumab. SECONDARY OBJECTIVES: I. To evaluate the toxicity of nivolumab in patients with advanced ULMS. II. To evaluate the toxicity of nivolumab in combination with ipilimumab in patients with advanced ULMS. III. To evaluate the progression-free survival of ULMS treated with nivolumab. IV. To evaluate the progression-free survival of ULMS treated with nivolumab in combination with ipilimumab. V. To explore the relationship between PDL1, PD1 in infiltrating lymphocytes and PD2 status in archival tumor, and pre/post treatment biopsies in a minimum of 10 patients. TERTIARY OBJECTIVES: I. To explore the relationship between general immune response and specific markers of immunomodulation and response to nivolumab. II. To explore the relationship between tumor inflammatory gene signature and response to nivolumab in archival material. OUTLINE: Patients are assigned to 1 of 2 cohorts. Cohort A (closed to accrual on 21-Oct-2015): Patients receive nivolumab intravenously (IV) over approximately 60 minutes once every 2 weeks for up to 46 doses in the absence of disease progression or unacceptable toxicity. Cohort B: Patients receive nivolumab IV over approximately 60 minutes followed by a saline flush and ipilimumab IV over 90 minutes. Treatment repeats every 21 days for up to 4 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up for 100 days.