This will be a phase II trial testing if the combination of SBRT and L19-IL2 improves the progression free survival in patients with limited metastatic non-small cell lung cancer (NSCLC). Treatment 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).