TNFRSF9 and neoplasm: Immune checkpoint blockade (ICB) such as anti-programmed cell death protein 1 antibody (αPD-1), although it can restart the host’s T-cell immunity, is still poorly efficacious in the majority of patients in practice, especially in the portion of patients whose tumor genotypes are shown to be Microsatellite stabilized (MSS).34 Our recent study reveals that ILA produced by the intestinal commensal Lactobacillus johnsonii is further metabolized to IPA by Clostridium sporogenes in the gut14 (Figure 3A).