 1. Patient at least 18 years old and has definitive histologically or cytologically confirmed metastatic solid tumor 2. Patient has one or more metastatic tumors measurable by CT scan or PETCT, if patient is allergic to CT contrast media 3. The investigator will select the appropriate treatment arm for the patient with the following requirements: a Patients cannot have had prior progression or intolerance on the single agent chemotherapy and then enrolled on an arm with that same single agent chemotherapy plus pembro b The chemotherapy on the arm selected must be considered standard of care or listed in the NCCN guidelines for that cancer type 4. Have recovered from acute toxicities of prior treatment: 