PDCD1 and neoplasm: Based on a recent study of patients with immunoresistance to sorafenib and recurrence of HCC, and their anti-tumor response to ICIs (anti-PD-1) treatment, patients that presented no response to treatment, had in their microbiome overproduction of Proteobacteria, in comparison to those with the optimal response, which had an increased amount of Ruminococcus spp.