INCLUSION CRITERIA

          1. Histologic confirmation of primary cancer approved by the FDA for treatment with an
             immune-checkpoint inhibitor, generally:

               1. Melanoma

               2. Non-Small Cell Lung Cancer

               3. Small Cell Lung Cancer

               4. Head and Neck Squamous Cell Cancer

               5. Classical Hodgkin Lymphoma

               6. Primary Mediastinal Large B-Cell Lymphoma

               7. Urothelial Carcinoma

               8. Microsatellite Instability-High Cancer

               9. Gastric Cancer

              10. Esophageal Cancer

              11. Cervical Cancer

              12. Hepatocellular Carcinoma

              13. Merkel Cell Carcinoma

              14. Renal Cell Carcinoma

          2. At least one metastatic lesion has had prior SRS. Each patient's scan must be reviewed
             by a neurosurgeon or radiation oncologist prior to enrollment.

          3. KPS ≥ 70.

          4. 18 years or older.

          5. Adequate bone marrow and organ function as defined below:

               1. ANC ≥ 1,500/mcL

               2. Platelets ≥ 100,000/mcL

               3. Hemoglobin ≥ 9 g/dL or ≥ 5.6 mmol/L (transfusion is allowed)

               4. Serum creatinine ≤ 1.5 x IULN OR creatinine clearance by Cockcroft-Gault ≥ 60
                  mL/min for patients with serum creatinine > 1.5 x IULN

               5. Serum total bilirubin ≤ 1.5 x IULN OR direct bilirubin ≤ IULN for patients with
                  total bilirubin

             i) 1.5 x IULN f) AST (SGOT) and ALT (SGPT) ≤ 3 x IULN

          6. Candidate for pembrolizumab treatment.

          7. Candidate for LITT treatment:

               1. Metastatic lesions individually measuring 3.5 cm or less

               2. Only lesions that are growing or new will be treated with LITT

               3. Five (5) or less target metastatic lesions that are new or growing

               4. Lesions accessible with a laser probe as determined by the neurosurgeon
                  performing the procedure

               5. Patient able to undergo MRI scans (no incompatible MRI hardware, etc.)

          8. A diagnostic contrast-enhanced MRI of the brain must be performed preoperatively,
             within 30 days prior to study enrollment.

          9. Participants of childbearing age must use effective contraception:

             a) Women of childbearing potential (WOCBP) must be using a highly effective method of
             contraception to avoid pregnancy throughout the study and for at least 24 weeks after
             the last dose of study drug to minimize the risk of pregnancy. Prior to study
             enrollment, women of childbearing potential must be advised of the importance of
             avoiding pregnancy during trial participation and the potential risk factors for an
             unintentional pregnancy. Refer to Section 9.3 for guidance on highly effective
             contraceptive methods.

             i) WOCBP include any woman who has experienced menarche and who has not undergone
             successful surgical sterilization (hysterectomy, bilateral tubal ligation or
             oophorectomy) or who is not post-menopausal. Post-menopause is defined as:

        (1) Amenorrhea that has lasted for ≥ 12 consecutive months without another cause, or (2)
        For women with irregular menstrual periods who are taking hormone replacement therapy
        (HRT), a documented serum follicle-stimulating hormone (FSH) level of greater than 35
        mIU/mL.

        b) Males with female partners of childbearing potential must agree to use
        physician-approved contraceptive methods (e.g., abstinence, condoms, vasectomy) throughout
        the study and should avoid conceiving children for 24 weeks following the last dose of
        study drug.

        10. Ability of the patient to understand and willingness to sign an IRB approved written
        informed consent document.

        11. Steroid dose equivalent to dexamethasone dose of ≤ 6mg daily at the time of enrollment.

        EXCLUSION CRITERIA

          1. Actively participating in another clinical trial on active study treatment; follow-up
             or observational status is acceptable if more than 2 weeks since last study treatment.

          2. History of immunodeficiency or is receiving any form of immunosuppressive therapy
             within 7 days prior to the first dose of trial treatment (with the exception of daily
             dexamethasone ≤ 6 mg).

          3. Uncontrolled intercurrent illness including, but not limited to, ongoing or active
             infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
             arrhythmia, uncontrolled hypertension, or psychiatric illness/social situations that
             would limit compliance with study requirements.

          4. History of active autoimmune disease requiring systemic treatment within the past 2
             years (i.e. with use of disease modifying agents, corticosteroids, or
             immunosuppressive drugs). Replacement therapy (e.g., thyroxine, insulin, or
             physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency,
             etc.) is not considered a form of systemic treatment.

          5. Pneumonitis within the past 3 years.

          6. Pregnant and/or breastfeeding. Patient must have a negative serum or urine pregnancy
             test at screening.

          7. Females or males of childbearing potential who are unwilling or unable to use an
             acceptable method to avoid pregnancy for the entire study period and for at least 24
             weeks after the last dose of study drug.

          8. Known active hepatitis B (e.g., HBsAg reactive) or hepatitis C (e.g., HCV RNA
             [qualitative] is detected) infection.

          9. Known history of active TB (bacillus tuberculosis).

         10. Known history of HIV (HIV 1/2 antibodies).