Effect of butyrate‐producing enterobacteria on advanced hepatocellular carcinoma treatment with atezolizumab and bevacizumab

AIM: Multiple studies have revealed the correlation between gut microbiome and the response to checkpoint inhibitors (CPIs) in patients with cancer, and oral administration of butyrate‐producing enterobacteria has been reported to enhance the efficacy of CPIs. However, the effects of enterobacteria on patients with hepatocellular carcinoma (HCC) are not well understood. METHODS: In this retrospective multicenter study, we enrolled 747 patients with advanced HCC, treated with atezolizumab and bevacizumab combination therapy. Tumor response, survival, and adverse effects were compared between 99 patients who ingested drugs containing butyric acid‐producing enterobacteria (butyric acid group) and the remaining patients (control group). RESULTS: Objective response and disease control rates in butyric acid group (29.7% and 77.8%, respectively) were higher than those in the control group (26.4% and 72.7%, respectively). However, the differences were not statistically significant (p = 0.543 and p = 0.222, respectively). No difference in median survival time was observed between the two groups (20.0 months and 21.4 months, respectively; p = 0.789), even after matching the backgrounds of the patients with propensity scores (p = 0.714). No adverse effects occurred upon the administration of butyrate‐producing bacteria. However, proteinuria (41.4% vs. 30.9%; p = 0.041), fever (17.2% vs. 10.2%, p = 0.036), and diarrhea (15.2% vs. 6.2%; p = 0.001) occurred more frequently in the butyric acid group. CONCLUSION: Butyrate‐producing bacteria does not enhance the efficacy of atezolizumab–bevacizumab combination therapy in patients with HCC.