PDCD1 and neoplasm: found C. aerofaciens to be more abundant in melanoma patients who responded to anti-PD-1 treatment and that reconstituted germ-free mice with responder microbiota, including C. aerofaciens, had enhanced T cell activation compared with animals that received FMT from non-responders, which resulted in enhanced anti-PD-1 activity and decreased tumor growth (Figure 2; Table 1).49