Inclusion Criteria:  Signed study Informed Consent Form Karnofsky Performance Status (KPS) ≥ 50 Age ≥ 18 years Patients with metastatic melanoma and multiple skin metastases with a documented clinical progression despite the systemic treatments (chemotherapy, and/or Programmed cell death 1 (PD1), cytotoxic T-lymphocyte antigen-4 (CTLA4) inhibitors or tyrosine kinase inhibitors (TKIs), such as v-raf murine sarcoma viral oncogene homolog B1 (BRAF) or mitogen-activated extracellular signal-regulated kinase (MEK) inhibitors) The size of the treated lesions should be ≤ 5.5 cm in diameter and ≤ 2.8 cm thick (caliper-based measurement) The treated lesions should be at least 5 cm apart and must not be located on the face. Women of childbearing potential (WOCBP) must have a negative serum or urine pregnancy test (urine or serum) during screening WOCBP must use a contraceptive method  Exclusion Criteria:  Previous radiotherapy in the treated area Concomitant auto-immune disease with skin lesions Concomitant use of radio-sensitizer drug Women who are pregnant Current, recent (within 10 days prior start of study treatment), or planned participation in an experimental drug study. During the 4 weeks DLT period, the patient will not be able to participate to any other clinical study. Any serious underlying medical condition that could interfere with study treatment and potential adverse events Any mental or other impairment that may compromise compliance with the requirements of the study