Inclusion Criteria:

          -  Patients with unresectable or metastatic melanoma including unknown primary, mucosal
             or uveal 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.

        Exclusion Criteria:

          -  Patients who have previously received a galectin antagonist.

          -  Patients with active autoimmune disease except for autoimmune thyroiditis or vitiligo
             (see Appendix C).

          -  Patients with history of autoimmune 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.

          -  Patients requiring other systemic oncologic therapy, including experimental therapies.

          -  Patients with active infection requiring antibiotics.

          -  Pregnant or lactating women, as treatment involves unforeseeable risks to the embryo
             or fetus.

          -  Need for steroids at greater than physiologic replacement doses. Inhaled
             corticosteroids are acceptable.

          -  Laboratory exclusions (to be performed within 28 days of enrollment):

               -  WBC < 3.0 x 109/L

               -  Hgb < 9.0 g/dL

               -  AST or ALT > 1.5 times ULN

               -  Total bilirubin > 1.9 g/dL, unless due to Gilbert's Syndrome. If Gilbert's
                  Syndrome is present by clinical history, then direct bilirubin must by < 3.0
                  g/dl.

               -  Known history of HIV

               -  Known history of Hepatitis B

               -  Known history of Hepatitis C

               -  INR > 1.5x ULN

          -  Inability to give informed consent and comply with the protocol. Patients 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.