There are emerging data showing long-term disease control after re-challenging immunotherapy with CTLA-4 and PD-1 antibodies in patients whose tumors had progressed on single agent PD-1 blockade in melanoma [35,36], hepatocellular carcinoma [37], non-small cell lung cancer [38], and urothelial cancer [39]. The gene discussed is PDCD1; the disease is hepatocellular carcinoma.