Inclusion Criteria:

• Willing to provide blood samples for correlative research purposes.

• Willing to return to enrolling institution for follow-up (during the Active Monitoring Phase of the study).

• Provide written informed consent.

• Negative pregnancy test done ≤ 7 days prior to registration, for women of childbearing potential only.

• sPD-L1 levels >1.7ng/ml by ELISA.

• ECOG Performance Status (PS) ≤ 3.

• Non-measurable disease as defined:

  • A non-nodal lesion is considered measurable if its longest diameter can be accurately measur s ≥2.0 cm with chest x-ray, or as ≥1.0 cm with CT scan, CT component of a PET/CT, or MRI;

  • A superficial non-nodal lesion is measurable if its longest diameter is ≥ 1.0 cm in diameter as assessed using calipers (e.g., skin nodules) or imaging.  In the case of skin lesions, documentation by color photography, including a ruler to estimate the size of the lesion, is recommended;

  • A malignant lymph node is considered measurable if its short axis is > 1.5 cm when assessed by CT scan (CT scan slice thickness recommended to be no greater than 5 mm). 

    • NOTE:  Tumor lesions in a previously irradiated area are not considered measurable disease.

• Measurable disease as defined: 

  • All other lesions (or sites of disease) are considered non-measurable disease, including pathological nodes (those with a short axis ≥ 1.0 to < 1.5 cm).  Bone lesions, leptomeningeal disease, ascites, pleural/pericardial effusions, lymphangitis cutis/pulmonis, inflammatory breast disease, and abdominal masses (not followed by CT or MRI), are considered as non-measurable as well.

    • NOTE: ‘Cystic lesions’ thought to represent cystic metastases can be considered as measurable lesions, if they meet the definition of measurability described above. However, if non-cystic lesions are present in the same patient, these are preferred for selection as target lesions.  In addition, lymph nodes that have a short axis < 1.0 cm are considered non-pathological (i.e., normal) and should not be recorded or followed.

• Histological confirmation of melanoma.

• Age ≥ 18 years old.

Exclusion Criteria:

• Persons taking a biotin supplement.

• sPD-L1 level <1.7ng/ml by ELISA.

• Pregnant or nursing women.

• Men or women of childbearing potential who are unwilling to employ adequate contraception.