Pembrolizumab In Central Nervous System Metastases

Inclusion Criteria: * Participants must have histologically or cytologically confirmed disease from any solid tumor * Participants must have measurable disease in the CNS, defined as at least one lesion that can be accurately measured in at least one dimension as ≥5 mm . * Age ≥18 years. * ECOG performance status ≤ 2 (Karnofsky ≥60%, see Appendix A) * Life expectancy of greater than 6 weeks * Participants must have normal organ and marrow function as defined in Table 1, all screening labs should be performed within 10 days of treatment initiation. * Adequate Organ Function Laboratory Values * Hematological \---- Absolute neutrophil count (ANC) ≥1,500 /mcL \---- Platelets ≥100,000 / mcL \---- Hemoglobin ≥9 g/dL or ≥5.6 mmol/L without transfusion or EPO dependency (within 7 days of assessment) * Renal \---- Serum creatinine ≤1.5 X upper limit of normal (ULN) \----- OR \---- Measured or calculated a creatinine clearance ≥60 mL/min for subject with creatinine levels \> 1.5 X institutional ULN (GFR can also be used in place of creatinine or CrCl) * Hepatic \---- Serum total bilirubin ≤ 1.5 X ULN \----- OR \---- Direct bilirubin ≤ ULN for subjects with total bilirubin levels \> 1.5 ULN \---- AST (SGOT) and ALT (SGPT) ≤ 2.5 X ULN \----- OR \---- ≤ 5 X ULN for subjects with liver metastases * Albumin \>2.5 mg/dL * Coagulation ---- International Normalized Ratio (INR) or Prothr…