One retrospective study investigated 53 patients with metastatic melanoma treated with RT sequential or concurrent to anti-PD-1 therapy or as salvage therapy in the setting of progression on anti-PD-1 therapy (35 patients received extracranial RT or intracranial SRS and 21 patients received whole brain radiotherapy (WBRT)) and showed that median OS and ORR were not significantly different between concurrent and sequential RT/SRS cohorts (Table 2) [116]. Here, PDCD1 is linked to metastatic melanoma.