Inclusion Criteria:

          -  Be willing and able to provide written informed consent/assent for the trial.

          -  Be ≥ 18 years of age on day of signing informed consent.

          -  Have measurable disease based on defined as at least one lesion that can be accurately
             measured in at least two dimensions with a spiral CT scan, PET/CT scan, or MRI.
             Minimum measurement of >1.5 cm in longest diameter by > 1.0 cm in short axis.

          -  Have a performance status of 0 or 1 on the ECOG Performance Scale.

          -  Demonstrate adequate organ function, all screening labs should be performed within 10
             business days of treatment initiation with the exception of beta-HCG (72 hours), if
             applicable.

          -  Female subject of childbearing potential should have a negative serum pregnancy within
             72 hours prior to receiving the first dose of study medication.

          -  Male subjects of childbearing potential (Section 5.7.1) must agree to use an adequate
             method of contraception as outlined in Section 5.7.1- Contraception, starting with the
             first dose of study therapy through 120 days after the last dose of study therapy.

        Note: Abstinence is acceptable if this is the usual lifestyle and preferred contraception
        for the subject.

        Exclusion Criteria:

          -  Is currently participating and receiving study therapy or has participated in a study
             of an investigational agent and received study therapy within 4 weeks of first dose of
             treatment or used an investigational device within 4 weeks of the first dose of
             treatment.

          -  Has a diagnosis of immunodeficiency or is receiving systemic steroid therapy or any
             other form of immunosuppressive therapy within 7 days prior to the first dose of trial
             treatment.

          -  Has a known history of active TB (Bacillus Tuberculosis)

          -  Hypersensitivity to pembrolizumab or any of its excipients.

          -  Has had a prior anti-cancer monoclonal antibody (mAb) within 4 weeks prior to study
             Day 1 or who has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events
             due to agents administered more than 4 weeks earlier.

          -  Has had prior chemotherapy, targeted small molecule therapy, or radiation therapy
             within 2 weeks prior to study Day 1 or who has not recovered (i.e., ≤ Grade 1 or at
             baseline) from adverse events due to a previously administered agent.

          -  Note: Subjects with ≤ Grade 2 neuropathy are an exception to this criterion and may
             qualify for the study.

          -  Note: If subject received major surgery, they must have recovered adequately from the
             toxicity and/or complications from the intervention prior to starting therapy.

          -  Has undergone prior allogenic hematopoietic stem cell transplantation.

          -  Has a known additional malignancy that is progressing or requires active treatment.
             Exceptions include basal cell carcinoma of the skin or squamous cell carcinoma of the
             skin that has undergone potentially curative therapy or in situ cervical cancer.

          -  Has known active central nervous system (CNS) metastases and/or carcinomatous
             meningitis. Subjects with previously treated brain metastases may participate provided
             they are stable (without evidence of progression by imaging for at least four weeks
             prior to the first dose of trial treatment and any neurologic symptoms have returned
             to baseline), have no evidence of new or enlarging brain metastases, and are not using
             steroids for at least 7 days prior to trial treatment. This exception does not include
             carcinomatous meningitis which is excluded regardless of clinical stability.

          -  Has active autoimmune disease that has required systemic treatment in the past 2 years
             (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive
             drugs). Replacement therapy (eg., thyroxine, insulin, or physiologic corticosteroid
             replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a
             form of systemic treatment.

          -  Has known history of, or any evidence of active, non-infectious pneumonitis.

          -  Has an active infection requiring systemic therapy.

          -  Has a history or current evidence of any condition, therapy, or laboratory abnormality
             that might confound the results of the trial, interfere with the subject's
             participation for the full duration of the trial, or is not in the best interest of
             the subject to participate, in the opinion of the treating investigator.

          -  Has known psychiatric or substance abuse disorders that would interfere with
             cooperation with the requirements of the trial.

          -  Is pregnant or breastfeeding, or expecting to conceive or father children within the
             projected duration of the trial, starting with the pre-screening or screening visit
             through 120 days after the last dose of trial treatment.

          -  Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2 agent.

          -  Has a known history of Human Immunodeficiency Virus (HIV) (HIV 1/2 antibodies).

          -  Has known active Hepatitis B (e.g., HBsAg reactive) or Hepatitis C (e.g., HCV RNA
             [qualitative] is detected).

          -  Has received a live vaccine within 30 days of planned start of study therapy. Note:
             Seasonal influenza vaccines for injection are generally inactivated flu vaccines and
             are allowed; however intranasal influenza vaccines (e.g., Flu-Mist®) are live
             attenuated vaccines, and are not allowed.