Please refer to section 10 5. Skeletal survey/alternative imaging is only needed at the pre-immunotherapy visit if the patient received bridging therapy and this is needed for re-staging. 6. If marrow was done within prior 6 weeks then this does not need to be repeated. Cycles 4 - 6 Study Assessments Day 1 Day 15 History, physical exam, weight and height X X Vital Signs1 X X Ambulatory O2 sat2 X X ECOG performance score X CBC, differential, platelet count, and blood chemistries X X TSH, Free T4, Free T3 X Evaluation of Creatinine Clearance X X Pregnancy test X Quantitative serum immunoglobulins X SPEP and immunofixation X 24 Hour Urine for UPEP, protein excretion and immunofixation X Serum free light chain ratio X B2M, CRP X Skeletal Survey or alternative imaging Bone marrow aspirate and biopsy4 X EKG X X Toxicity Assessment X X Con Meds X X Nivolumab Infusion X X Study tubes3 X 1. Vitals (BP, HR, Temp, RR, O2 sat) to be taken within 15 minutes prior to start of nivolumab infusion and within 15 minutes following completion. 2. Pulse oximetry should be obtained prior to each dose of nivolumab and at any time a subject has any new DF/HCC Protocol #: 18-280 Protocol Version Date: 10.17.2020 33 or worsening respiratory symptoms. A reading at rest and on exertion should be obtained at each time point.