Table 2.

Summary of outcomes induced by type of treatment and microbiota disruption in humans.

Treatment	Microbiota Feature	Outcome
Allogeneic hematopoietic stem cell transplantation	Decontamination of gut anaerobes	Lower risk of GvHD [127,132]
	Decreased duodenal Paneth cells	Higher GI GvHD and NRM [148]
	Low intestinal microbiota diversity	Higher TRM, lower OS and GvHD-related mortality [135,138]
	Enterococcus spp. domination	Increased GI GvHD severity [145] Increased GvHD-related and overall mortality [146,157] Associated with blood stream infections [110,158]
	Blautia abundance	Reduced GvHD-related mortality [136]
	Clostridia spp. depletion	Increased GvHD [150]
	Barnesiella spp. abundance	Protection against Enterococcus domination [159]
	Akkermansia muciniphila domination	Mucus degradation [128]
	Lactobacillales domination	Associated with GvHD development [140]
	Eubacterium limosum abundance	Lower risk of relapse or progression, higher OS [90]
	Picobirnivirus presence	Severe GI GvHD [160]
	Lower urinary 3-indoxyl sulfate	Higher risk of GvHD, higher TRM, lower OS, higher dysbiosis [145,155]
Autologous stem cell transplantation	Reduction in diversity index and an increased dominance index	Development of mucositis [161]
	Decreased in Firmicutes and Actinobacteria and increased in Proteobacteria	Development of GI mucositis [161]
Chemotherapy	Baseline levels of Porphyromonadaceae	Predictor of infection during induction for acute myeloid leukemia [162]
	Relative abundance of E hallii	Higher negative minimal residual disease rate in bone marrow for multiple myeloma [163]
CAR T-cell therapy	Oscillospiraceae, Ruminococcacaeae and Lachnospiraceae enriched	Association with complete remission after CAR T cell therapy [164]
	Higher abundance of Lachnospiraceae	Development of cytokine release syndrome and/or neurotoxicity [164]

GI gastrointestinal; GvHD graft versus host disease; NRM no-relapse mortality; OS overall survival; TRM, transplant-related mortality.