BCAN TT 2022: Investigating Diet and Benefit from Immune Checkpoint Blockade in Urothelial Cancer

(UroToday.com) Dr. Brendan Guercio, MD recently completed a medical oncology fellowship at the Memorial Sloan Kettering Cancer Center in Manhattan, NY and is starting as an Assistant Professor at the University of Rochester Medical Center in Rochester, NY. He is the recipient of the 2021 BCAN Young Investigator Award for his research focused on the impact of diet on immune checkpoint inhibitor therapeutic response and tolerability in bladder cancer patients.

Immune checkpoint blockade (ICB) is an emerging standard of care in multiple bladder cancer disease states, including metastatic and adjuvant settings. We currently have few biomarkers predictive of ICB therapeutic response, which can be multifaceted and highly dependent on the host microenvironment.

Gut microbiome drug metabolites are a potentially modifiable predictor of ICB therapeutic response and are heavily controlled by lifestyle and dietary factors. A study from the MD Anderson Cancer Center identified that sufficient dietary fiber intake, defined as at least 20 g/day, was associated with favorable progression-free survival in metastatic melanoma.

The investigators hypothesized that sufficient fiber intake, using the MDACC criteria, may improve ICB response in patients with bladder cancer. They used a prospective cohort design in patients with bladder cancer undergoing ICB therapy at MSKCC (definitive therapy for NMIBC, adjuvant or metastatic settings included). Patients underwent a baseline dietary assessment, were screened for antibiotic and probiotic use and had baseline fecal specimens collected. 

The study is expected to meet final the accruals goal of 125 patients this academic year. Preliminary data from 46 patients with advanced/metastatic disease on ICB was presented. 38% met the MDACC criteria for sufficient fiber intake and about 1 in 5 patients were exposed to antibiotics within 3 months prior to ICB initiation.

Sufficient dietary fiber intake was associated with improved progression free survival and radiographic treatment response compared to patients with low fiber intake. Notably, patients with sufficient dietary fiber intake also experienced less grade 3 or worse immune related adverse events. 

While the analysis was limited to only 5 patients who noted history of probiotic use, these patients seemed to have a more favorable response to ICB compared to no probiotics use. Likewise, recent antibiotic use seems to have a negative effect on ICB therapeutic response.

This study was limited by small patient numbers at the time of this interim analysis and lack of standardization regarding patient stage and ICB therapeutic regimen. However, these are promising findings identifying easily modifiable factors that can be used in patient counseling. Further work to confirm these findings in a prospective trial as well as analyze the gut microbiome will provide insights into these mechanisms.

Presented by: Dr. Brendan Guercio, MD who is a medical oncologist at the University of Rochester Medical Center in Rochester, NY

1. Spencer CN, McQuade JL, Gopalakrishnan V, et al. Dietary fiber and probiotics influence the gut microbiome and melanoma immunotherapy response. Science. 2021 Dec 24;374(6575):1632-1640. doi: 10.1126/science.aaz7015. Epub 2021 Dec 23. PMID: 34941392; PMCID: PMC8970537.