Nivolumab in Treating Patients With HTLV-Associated T-Cell Leukemia/Lymphoma

PRIMARY OBJECTIVES: I. To determine the safety and tolerability of nivolumab for patients with HTLV-associated adult T-cell leukemia lymphoma (ATLL). II. To determine the efficacy of nivolumab for patients with HTLV-associated ATLL. SECONDARY OBJECTIVES: I. To determine effects of nivolumab on HTLV-1 proviral deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) loads. II. To determine the effects of nivolumab on anti-HTLV-1 and anti-ATLL immune responses. III. To determine effects of nivolumab on HTLV-1 integration site clonality. OUTLINE: Patients receive nivolumab intravenously (IV) over 60 minutes on day 1. Treatment repeats every 14 days for 46 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 3 months for 1 year.