Inclusion Criteria:

          -  Patients with histologically confirmed metastatic melanoma

          -  Patients must have recovered from all side effects of their most recent systemic or
             local treatment for metastatic melanoma (grade ≤ 1).

          -  At least one measurable brain metastasis between 5 mm and 35 mm in diameter, not
             previously treated with surgery and/or radiosurgery and located less than 5 cm from
             the skull

          -  Patients may have received -or not- prior radiosurgery and/or surgery for brain
             metastases; if they have received prior local treatment, they must have at least 1new
             RANO and RECIST assessable brain metastases.

          -  BRAF status wild type or mutated (and in that case previous treatment with BRAF
             inhibitor and MEK inhibitor allowed)

          -  Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≤ 1.

          -  Age >18 year

          -  Hemoglobin ≥10g/dl

          -  Platelets ≥ 100000mm3

          -  Neutrophils ≥1500/mm3

          -  Creatinine Clearance ≥ 50ml/mn

          -  AST <3N

          -  ALT<3N

          -  Total bilirubin <1.5N

          -  Alkaline phosphatase <3N

          -  INR < 1.5

          -  Prothrombin ≥70%

          -  TCA <1.2

          -  No Hepatocellular insufficiency

          -  No unhealed wound on the head

          -  No allergy to poly isoprene

          -  Signed informed consent

          -  Patient with health insurance coverage

          -  Life expectancy > 3 months

        Exclusion Criteria:

          -  Patient previously treated by antiPD1 (except adjuvant antiPD1 therapy)

          -  Ocular melanoma

          -  Symptomatic or diffuse leptomeningeal involvement.

          -  Symptomatic hemorrhagic brain metastases.

          -  Symptoms of incoercible intracranial pressure; patients receiving corticosteroids and
             patients presenting intermittent seizures can be enrolled if they have a stable dose
             of corticosteroids (≤ 30mg/day corticotherapy) and anti-epileptic treatment since at
             least 2 weeks before enrolment.

          -  Indication for urgent neurosurgery or radiotherapy

          -  Prior malignancy active within the previous 2 years except for locally curable cancers
             that have been apparently cured or stage I untreated Chronic Lymphoid Leukemia.

          -  Known human immunodeficiency viruses (HIV) infection and any ongoing infectious
             disease or significant background.

          -  Concurrent administration of any anticancer therapies other than those administered in
             this study.

          -  Treatment with any cytotoxic and/or investigational drug, antiCTLA4 or targeted
             therapy ≤ 4 weeks or <5 half lives for targeted therapies or chemotherapy, prior to
             day 1 of study.

          -  Prior whole brain radiotherapy