Inclusion Criteria for Cohort 1:  ECOG performance status (PS) of 0 or 1 Histologically confirmed resectable Stage III melanoma according to AJCC-8 and no history of in-transit metastases within the last 6 months Fit and planned for CLND Measurable disease according to RECIST v1.1 Availability of a representative tumor specimen Adequate hematologic and end-organ function For patients receiving therapeutic anticoagulation: stable anticoagulant regimen Negative HIV test, negative hepatitis B surface antibody (HBsAb), and negative total hepatitis B core antibody (HBcAb) test, and negative hepatitis C virus (HCV) at screening.  Exclusion Criteria for Cohort 1:  Mucosal, uveal and acral lentiginous melanoma Distantly metastasized melanoma History of in-transit metastases within the last 6 months Prior radiotherapy Prior immunotherapy, including anti-CTLA-4, anti-PD-1, and anti-PD-L1 therapeutic antibodies, and other systemic therapy for melanoma Treatment with investigational therapy within 28 days prior to initiation of study treatment Treatment with systemic immunostimulatory agents within 4 weeks or 5 drug-elimination half-lives (whichever is longer) prior to initiation of study treatment Prior allogeneic stem cell or solid organ transplantation Known immunodeficiency or conditions requiring treatment with systemic immunosuppressive medication, or anticipation of need for systemic immunosuppressant medication during study treatment Active or history of autoimmune disease or immune deficiency  Inclusion Criteria for Cohort 2:  ECOG PS of 0, 1, or 2 Life expectancy >= 3 months, as determined by the investigator Histologically confirmed Stage IV (metastatic) melanoma according to AJCC-8 Disease progression during or following at least one but no more than two lines of treatment for metastatic disease Measurable disease according to RECIST v1.1 Availability of a representative tumor specimen Adequate hematologic and end-organ function For patients receiving therapeutic anticoagulation: stable anticoagulant regimen Negative HIV test, negative hepatitis B surface antibody (HBsAb), and negative total hepatitis B core antibody (HBcAb) test, and negative hepatitis C virus (HCV) at screening.  Exclusion Criteria for Cohort 2:  Mucosal and uveal melanoma Treatment with investigational therapy within 28 days prior to initiation of study treatment Treatment with systemic immunostimulatory agents within 4 weeks or 5 drug-elimination half-lives (whichever is longer) prior to initiation of study treatment Prior allogeneic stem cell or solid organ transplantation Known immunodeficiency or conditions requiring treatment with systemic immunosuppressive medication, or anticipation of need for systemic immunosuppressant medication during study treatment Active or history of autoimmune disease or immune deficiency Symptomatic, untreated, or progressing CNS metastases Active or history of carcinomatous meningitis/leptomeningeal disease Uncontrolled tumor-related pain Uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent drainage procedures Uncontrolled or symptomatic hypercalcemia