Radiotherapy has the potential to sensitize tumors to immune checkpoint blockade. A recent article published by Sundahl et al. in European Urology assessed the toxicity and efficacy of stereotactic body radiotherapy (SBRT) at different time points to patients who receive pembrolizumab for mUC.1 In this randomized phase 1 trial, the investigators enrolled 18 patients who received at least one dose of SBRT and at least one dose of pembrolizumab. Patients were randomly divided into two groups, arm A included patients who received SBRT before the first cycle of pembrolizumab and arm B who received SBRT before the third cycle of pembrolizumab.