Bladder Cancer Response to Bacillus Calmette-Guérin May Be Linked to Urine Microbiome

Urine microbiome composition varies in patients with non-muscle-invasive bladder cancer (NMIBC), which could provide a way to predict response to immunotherapy with bacillus Calmette-Guérin (BCG), investigators reported at the 2019 Genitourinary Cancers Symposium.

“It is first important to appreciate that urine, even in the absence of any urinary tract infection, is not sterile,” said lead investigator Randy F. Sweis, MD, of the University of Chicago in Illinois, in an interview with Cancer Therapy Advisor. “A urinary commensal microbiome has recently been characterized, and we sought to determine if baseline variation in its composition can impact the efficacy of BCG, a local therapy for non-muscle invasive bladder cancer. Our early data suggest that variation in the composition of bacteria present is associated with response to BCG, and both translational and preclinical work is ongoing to elucidate a mechanism by which this might occur.”

Dr Sweis and colleagues assessed urine biome composition in 31 patients who had been newly diagnosed with NMIBC and were enrolled prior to undergoing transurethral resection of bladder tumor (TURBT). Patients had a median age of 69 years (range: 46 to 87 years), and 22 patients (71%) were male. Clinicians instilled adjuvant BCG to high-risk patients according to surgical histologic findings. Urine specimens for microbiome assessment were collected by catheterization to eliminate urethral contamination prior to TURBT and up to 8 additional time points.

After a median follow-up time of 6 months, 10 patients (32%) experienced disease recurrence and 21 (68%) did not. The most abundant phyla observed were Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, and Tenericutes. Collectively, these bacteria accounted for more than 99% of the phyla detected in this cohort. The abundance of Proteobacteria was significantly higher among patients who had disease recurrence, with stronger differences observed for specific classes, such as Gammaproteobacteria. Firmicutes such as Lactobacillales were more abundant in patients who did not have disease recurrence.

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Reference

1. Sweis RF, Golan S, Barashi N, et al. Association of the commensal urinary microbiome with response to Bacillus Calmette-Guérin (BCG) immunotherapy in nonmuscle invasive bladder cancer. Data presented at: 2019 Genitourinary Cancers Symposium; San Francisco, CA; February 14-16, 2019. Abstract 423.