Clinical responses to anti-PD-1 immunotherapy were associated with high diversity and relative abundance of Ruminococcaceae bacteria in prospectively collected microbiome samples from patients with metastatic melanoma (271) and relative abundance of A. muciniphila in patients with NSCLC, renal cell carcinoma, or urothelial carcinoma (272). The gene discussed is PDCD1; the disease is non-small cell lung carcinoma.