biostudies-literatureSpencer CNCancer Research UKNIAID NIH HHSNIEHS NIH HHSNHLBI NIH HHSNCI NIH HHS1632-1640https://www.ebi.ac.uk/biostudies/studies/S-EPMC8970537biostudies-literatureUnknown374(6575)Gut bacteria modulate the response to immune checkpoint blockade (ICB) treatment in cancer, but the effect of diet and supplements on this interaction is not well studied. We assessed fecal microbiota profiles, dietary habits, and commercially available probiotic supplement use in melanoma patients and performed parallel preclinical studies. Higher dietary fiber was associated with significantly improved progression-free survival in 128 patients on ICB, with the most pronounced benefit observed in patients with sufficient dietary fiber intake and no probiotic use. Findings were recapitulated in preclinical models, which demonstrated impaired treatment response to anti–programmed cell death 1 (anti–PD-1)–based therapy in mice receiving a low-fiber diet or probiotics, with a lower frequency of interferon-γ–positive cytotoxic T cells in the tumor microenvironment. Together, these data have clinical implications for patients receiving ICB for cancer.Science (New York, N.Y.)Dietary fiber and probiotics influence the gut microbiome and melanoma immunotherapy response.PMC8970537R01 AI133822P50 CA221703R25 CA203650U54 CA224070F32 CA260769P30 ES030285T32 CA009599R01 CA219896P30 CA013696R01 AI14388627140P30 CA016672R56 AI109294R01 HL124112R01 AI109294McCulloch JAWong MCLee JEAnang NASGaudreau PODay CPSimon JNelson KCWong MKMorgun AHelmink BAWargo JAWang LWani KNezi LArora RCogdill APPetrosino JFTrinchieri GSpencer CNDuncan SStraussman RAmaria RNPatel SPHoffman KLSharma PPazdrak BHuttenhower CKhan MAWLochmann BSHaydu LEDaniel CRRoss MIJamal MATetzlaff MTPerez-Guijarro EHu JVetizou MMedik YBDavies MAAjami NJKahn LMMcQuade JLBadger JHLazar AJRodrigues RRSzczepaniak-Sloane RAPeterson CBRoszik JJohnson SToker JDang MZheng JMalke JCAndrews MCDiab AWoodman SEJensen VZobniw CMWhite MGKim YSBurton EMAllison JPFutreal PAWatowich SSBaruch ENSchneider SCohen LMerlino GSirmans EMorad GGershenwald JEJenq RRZhou YYan YTawbi HAGopalakrishnan VClise-Dwyer KAnderson JHarris ALChapman TZhang XHudgens CWHwu PPosada EGarrett WSSamuels YGlitza ICRodgers TfalseDietary fiber and probiotics influence the gut microbiome and melanoma immunotherapy response.Gut bacteria modulate the response to immune checkpoint blockade (ICB) treatment in cancer, but the effect of diet and supplements on this interaction is not well studied. We assessed fecal microbiota profiles, dietary habits, and commercially available probiotic supplement use in melanoma patients and performed parallel preclinical studies. Higher dietary fiber was associated with significantly improved progression-free survival in 128 patients on ICB, with the most pronounced benefit observed in patients with sufficient dietary fiber intake and no probiotic use. Findings were recapitulated in preclinical models, which demonstrated impaired treatment response to anti–programmed cell death 1 (anti–PD-1)–based therapy in mice receiving a low-fiber diet or probiotics, with a lower frequency of interferon-γ–positive cytotoxic T cells in the tumor microenvironment. Together, these data have clinical implications for patients receiving ICB for cancer.2021-01-01T00:00:00Z2021 Dec2026-05-31T21:01:09.886Z2025-02-19T04:21:59.333ZS-EPMC89705373494139210.1126/science.aaz7015