IMMUNOSABR will include 138 patients. The trialpopulation will be divided in two cohorts: patients eligible for ablative stereotactic body radiotherapy to all metastatic sites (treatment with curative intent) and patients not eligible for stereotactic body radiotherapy to all sites (life prolongation).In this single stage phase II trial we aim to demonstrate absolute increase in progression free survival at two years. . PFS will be determined as the time between randomization and disease progression, according to RECIST 1.1, death due to any cause or last patient contact alive and progression-free. Patients will be randomized between control (no L19-IL2) and experimental arms (with L19-IL2) in a 1:1 ratio. The accrual period will be 29 months (or 2.41 years) and the minimum follow-up will be 24 months (or 2 years), making the total study duration 53 months (or 4.41 years). Comparison between control and experimental arms will be done using the Log-Rank statistic. This test for superiority will be one-sided with a desired type I error of 0.10 and power of 0.80. The randomization allocation is 1:1.