GR-MD-02 Plus Pembrolizumab in Melanoma, Non-small Cell Lung Cancer, and Squamous Cell Head and Neck Cancer Patients

Inclusion Criteria: * Patients with metastatic or unresectable melanoma for whom treatment with pembrolizumab is indicated. Histological confirmation of melanoma will be required by previous biopsy or cytology. * Patients with non-small cell lung cancer for whom treatment with pembrolizumab is indicated. * Patients with squamous cell carcinoma of the head and neck for whom treatment with pembrolizumab is indicated * Patients who have radiographic progression using Response Evaluation Criteria In Solid Tumors (RECIST) currently on pembrolizumab are also eligible. * Patients must be ≥ 18 years of age. * Eastern Cooperative Oncology Group (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. Exclusion Criteria: * Patients who have previously received a galectin antagonist * Patients with active autoimmune disease except for autoimmune thyroiditis or vitiligo * Patients with history of colitis * Patients with untreated brain metastases. Patients with treated brain metastases who demonstrate control of brain metastases with follow-up imaging 4 or more weeks after initial therapy are eligible. * Other active metastatic cancer requiring treatment. * Patients with active infection requiring antibiotics. * Pregnant or lactating women, as treatment involves unforeseeable risks to the embryo or fetus. * Need for chronic steroids. Inhaled corticosteroids are acceptable. * Laboratory values (to be performed within 28 days of enrollment) outside of protocol-specified ranges. * Inability to give informed consent and comply with the protocol. Patients with a history of psychiatric illness must be judged able to understand fully the investigational nature of the study and the risks associated with the therapy. * Any medical condition that in the opinion of the Principal Investigator would compromise the safety or conduct of the study procedures. * Unresolved immune-mediated pneumonitis, diarrhea, elevation of hepatocellular enzymes or other toxicities requiring greater than physiological replacement doses of steroids.