Pembrolizumab in Patients With Locally Advanced or Metastatic Skin Cancer

Inclusion Criteria: * All subjects must have cutaneous squamous cell carcinoma that is not curable by surgery or radiation; both locally advanced and metastatic squamous cell carcinoma will be included. * Be willing and able to provide written informed consent/assent for the trial. * Have measurable disease based on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. * Be willing to provide tissue from a newly obtained core or excisional biopsy of a tumor lesion. Newly-obtained is defined as a specimen obtained up to 6 weeks (42 days) prior to initiation of treatment on day 1. Subjects for whom newly-obtained samples cannot be provided (e.g. inaccessible or subject safety concern) may submit an archived specimen only upon agreement from the sponsor. * Be willing to undergo normal skin biopsy prior to initiation of treatment and after treatment. * Have a performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG) performance scale. * Absolute neutrophil count (ANC) ≥ 1,500/microliter (mcL) * Platelets ≥ 100,000/mcL * Hemoglobin ≥ 9 g/dL or ≥ 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) * Serum creatinine ≤ 1.5 X upper limit of normal (ULN) OR measured or calculated creatinine clearance (glomerular filtration rate \[GFR\] can also be used in place of creatinine or creatinine clearance \[CrCl\]) ≥ 60 mL/min for subject with creatinine levels \> 1.5 X institutional ULN * Serum total bilirubin ≤ 1.5 X ULN…