Although the gut microbiota modulates cancer immunotherapy efficacy and interventions such as probiotics and fecal microbiota transplantation (FMT) may enhance antitumor response, clinical evidence remains controversial, prompting this meta-analysis to evaluate their impact on immune checkpoint inhibitors (ICIs) outcomes. A systematic search was conducted in PubMed/Medline, Embase, and trial registries (ClinicalTrials.gov, chictr.org) for relevant records up to August 2025. ORR and DCR defined as primary composite endpoints, and PFS/OS as secondary endpoints. Data were synthesized using random-effects models to calculate pooled estimates for ORR, DCR, and hazard ratios (HRs) for PFS and OS. A total of 22 studies involving 3,274 patients were included. The pooled analysis demonstrated that probiotic intervention was associated with a reduced risk of progression or death, as evidenced by improved PFS (pooled HR = 0.63, P < 0.0001) and OS (pooled HR = 0.53, P < 0.00001) in cancer patients receiving ICIs. Similarly, interventions using either probiotics or FMT were associated with an increased ORR (pooled OR = 1.62, P = 0.006) and showed a trend toward improved DCR (pooled OR = 1.74, P = 0.12). This meta-analysis supports that both probiotics and FMT, as adjunctive therapies, are associated with enhanced efficacy of cancer immunotherapy. Probiotics, in particular, are supported by more robust evidence and demonstrate more consistent effects. Future large-scale, rigorous clinical trials are warranted to advance the development of personalized and precise microbiota-based interventions.
Hu et al. (2026) studied this question.