Microbiota boost immunotherapy? A meta-analysis dives into fecal microbiota transplantation and immune checkpoint inhibitors

Abstract

Background: Immune checkpoint inhibitors (ICIs) are a cornerstone of modern cancer treatment, but their effectiveness is limited. Fecal microbiota transplantation (FMT), which alters the gut microbiome, has shown promise in enhancing ICIs' therapeutic effects.

Methods: We conducted a comprehensive search of relevant studies available up to September 30, 2024, to analyze the clinical efficacy and safety of combining FMT with ICIs in cancer treatment. The primary endpoint was the objective response rate (ORR), with secondary evaluations of survival outcomes and safety.

Results: A total of 10 studies involving 164 patients with solid tumors were included. The pooled ORR was 43% (95% CI: 0.35-0.51). Subgroup analysis revealed that the combination of anti-PD-1 and anti-CTLA-4 therapies was associated with a significantly higher ORR (60%) compared to anti-PD-1 monotherapy (37%; P = 0.01). The incidence of grade 1-2 adverse events (AEs) was 42% (95% CI: 0.32-0.52), while grade 3-4 AEs occurred in 37% of patients (95% CI: 0.28-0.46).

Conclusions: This meta-analysis provides preliminary evidence supporting the use of FMT as a strategy to enhance the efficacy of ICIs in patients with advanced or refractory solid tumors. However, larger-scale randomized controlled trials with long-term follow-up are required to confirm and optimize treatment protocols.

Keywords: Adverse events; Clinical efficacy; Fecal microbiota transplantation; Immune checkpoint inhibitors; Objective response rate.

Fig. 1

Flow diagram of identification of studies via databases and registers

Fig. 2

Forest plots of subgroup analysis of clinical response of objective response rate (ORR) in the treatment of fecal microbiota transplantation (FMT) with immune checkpoints inhibitors (ICIs)

Fig. 3

Forest plots of subgroup analysis of clinical responses of complete response (CR) rate and partial response (PR) rate in the treatment of fecal microbiota transplantation (FMT) with immune checkpoint inhibitors (ICIs). A CR rate with 95% confidence intervals (CI); B PR rate with 95% CI

Fig. 4

Weighted median progression-free survival (mPFS) and median overall survival (mOS) in studies combining fecal microbiota transplantation (FMT) with immune checkpoint inhibitors (ICIs)

Fig. 5

Safety analysis of stages of adverse events (AEs) in the treatment of fecal microbiota transplantation (FMT) with immune checkpoint inhibitors (ICIs). A Incidence of stage 1/2 AEs with 95% confidence intervals (CI); B incidence of stage 3/4 AEs with 95% CI; C incidence of AEs with 95% CI in different immunotherapy