• Patients with unresectable or metastatic melanoma including unknown primary or mucosal melanomas. Histological confirmation of melanoma will be required by previous biopsy or cytology. Patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) with disease progression during or after platinum-containing chemotherapy are eligible. PD-L1 testing is not needed for OHN cancers.

• Patients who have received anti-PD1 or anti-PD-L1 in the past are eligible if it has been at least 6 months since the last anti-PD-1 or PD-L1 dose, they meet all other eligibility criteria and progression of malignancy has been documented on imaging. Progression for this patient subset is defined as the appearance of one or more new metastatic sites, or a 5% or greater increase in the sum of diameter of target lesions or an unequivocal increase in non-target site. Treatment naïve melanoma patients are eligible.

• Patients must be ≥ 18 years of age.

• ECOG performance status of 0-2.

• Women of childbearing potential must have a serum or urine pregnancy test performed within 72 hours prior to the start of protocol treatment. The results of this test must be negative in order for the patient to be eligible. In addition, women of childbearing potential as well as male patients must agree to take appropriate precautions to avoid pregnancy.

• No active bleeding.

• Anticipated lifespan greater than 12 weeks.

• Patients must sign a study-specific consent document.