Stool Microbiome Signature Associated with Response to Neoadjuvant Pembrolizumab in Patients with Muscle-invasive Bladder Cancer

Using preimmunotherapy stool samples collected from patients enrolled in the PURE-01 clinical trial, testing neoadjuvant pembrolizumab in patients with muscle-invasive bladder cancer, we identified some bacterial taxa that were enriched differentially in responders and nonresponders to immunotherapy. Among those, the genus Sutterella was enriched in responders, while the species Ruminococcus bromii was enriched in nonresponders. We further used an animal model of bladder cancer to provide further evidence suggesting a negative role of R. bromii in anti–PD-1 efficacy. However, further studies are needed to confirm our findings.