In a murine model of melanoma, CD8+ T cell activation in response to PD-L1 inhibitor correlated with mice, which received fecal transplantations from patients abundant in bacteria from the Ruminococcaceae family and Faecalibacterium spp., whereas nonresponders were characterized by elevated presence of CD4+/FoxP3+ T reg cells and received stools which were abundant in Bacteroidales (Gopalakrishnan et al., 2018). Here, CD8A is linked to melanoma.