A Biomarker Study in Advanced Mucosal or Acral Lentiginous Melanoma Receiving Nivolumab in Combination With Ipilimumab

Inclusion Criteria: * Patients must have histologically confirmed MCM or ALM that is metastatic or unresectable. * Patients must be eligible to receive nivolumab in combination with ipilimumab treatment per institutional guidelines. * Patients must have a tissue block (or 20 unstained slides) available with adequate tumor to perform multiplex immunohistochemistry and nucleic acids analyses ( i.e. whole exome sequencing) Patients with only a previous fine-needle aspirate are ineligible for enrollment. * Patients must be willing to donate a small amount of whole blood prior to treatment and during treatment for laboratory analysis. * Patients must give informed consent prior to initiation of therapy. * Patients must be ambulatory with good performance status (ECOG 0 or 1) Exclusion Criteria: * Patients who do not have available tissue for immunohistochemistry and nucleic acids analyses. * Patients who have received prior immunotherapy for unresectable or metastatic disease. * Patients with untreated brain metastases, leptomeningeal disease, or seizure disorders are ineligible. Patients with a history of brain metastases must have completed treatment (i.e. surgery or radiation) 1 month prior to enrollment and have no evidence of disease or edema on brain CT or head MRI. * Patients with inadequate tissue for analysis.