CD8+ T Cell Imaging During Pre-surgery Immunotherapy in People With Melanoma

Inclusion Criteria: * Patient is capable of understanding and complying with the protocol requirements and has signed the Informed Consent document. * Adults at least 18 years of age * Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1 * Cytologically or histologically confirmed stage IIIB, IIIC, IIID, or IV melanoma that can be surgically removed. Notes: * In-transit melanoma is acceptable. * Patients can enroll regardless of their BRAF mutational status * 1cm of tumor needs to be visible on standard imaging (i.e. FDG PET or CT scan) * Screening laboratory values must meet the following criteria: * WBC ≥ 2.0x109/L * Neutrophils ≥ 1.5x109/L * Platelets ≥ 100 x109/L * Hemoglobin ≥ 5.5 mmol/L * Creatinine ≤ 1.5x ULN * AST ≤ 1.5 x ULN and ALT ≤ 1.5 x ULN * Bilirubin ≤1.5 X ULN * Women of childbearing potential (WOCBP) must use appropriate method(s) of contraception. WOCBP should use an adequate method to avoid pregnancy for 23 weeks (30 days plus the time required for nivolumab to undergo five half-lives) after the last dose of study treatment (ipilimumab/nivolumab) * Women of childbearing potential must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of HCG) within 24 hours prior to the start of ipilimumab + nivolumab * Men who are sexually active with WOCBP must use any contraceptive method with a failure rate of less than 1% per year. Men receiving nivolumab and who are sexually active with WOCBP will be instructed to adhere to contraception for a period of 31 weeks after the last dose of study treatment (ipilimumab/nivolumab) Note: Women who are not of childbearing potential (i.e., who are postmenopausal), or surgically sterile as well as azoospermic men do not require contraception Exclusion Criteria: * Subjects with any active autoimmune disease (current symptoms or requirement for immunosuppression at the time of study start). * Positive active hepatitis B viral infection (+viral load by PCR) * Prior immunotherapy targeting CTLA-4 and/or PD-1/PD-L1 for any disease. * Potentially unresectable melanoma. * History of testing positive for human immunodeficiency virus (HIV) or known acquired immunodeficiency syndrome (AIDS) * History of severe hypersensitivity reaction to any monoclonal antibody * Underlying medical conditions that, in the Investigator's opinion, will make the administration of treatment hazardous or obscure the interpretation of toxicity * Patients who have undergone splenectomy or have other splenic disorders. The normal spleen usually has CD8+ cell activity and serves as a positive control to enable proper imaging technique. * Use of other investigational drugs before study drug administration 30 days and 5 half-times before study inclusion * Pregnant or nursing