PDCD1 and metastatic melanoma: Programmed cell death protein 1 inhibitors, such as pembrolizumab, were found to prolong the progression-free and overall survival of patients with advanced melanoma.[31] In addition, the prospect of gene therapy (targeted therapy) for PIMMs has been previously explored.[19,32,33] Gene therapy (targeted therapy) combined with immunotherapy may improve the prognosis of patients with metastatic melanoma compared with immunotherapy combined with RT.[34] However, all of the aforementioned findings require further evaluation.