Symptom Improvement with Mirabegron Treatment Is Associated with Urobiome Changes in Adult Women

The variable clinical response to oral medication for the treatment of overactive bladder challenges both patients and clinicians. While these medications are highly effective and helpful to a subgroup of patients, others experience insufficient symptom relief and/or problematic side effects. The two main classes of approved medication work through different receptors, functioning either as anticholinergic or beta-3 adrenergic agonists. However, the mechanistic interface with the urobiome has not been well studied. While sufficient evidence exists documenting differences in urobiome community characteristics between women affected by overactive bladder and unaffected women, further research, with longitudinal sampling, will be required to delineate cause versus effect.

An earlier urobiome study detected differences in the pre-treatment urobiome between individuals with good and poor clinical responses to therapy with solifenacin, an anticholinergic agonist. If this finding was replicated and validated in larger study populations, this suggests that the urobiome could be used for pre-treatment counseling. However, in this study evaluating urobiome characteristics associated with mirabegron treatment, pre-treatment differences were not associated with clinical response. Instead, we detected changes in the urobiome based on the clinical response. This raises the intriguing question regarding the relationship between overactive bladder symptoms and urobiome characteristics. It is certainly feasible that the urobiome moves toward a more “normal” state as overactive bladder symptoms respond to mirabegron treatment. The mechanistic possibilities explaining these findings, and the differences between these two classes of medication, deserve thoughtful exploration.

It is clear that there are subgroups of overactive bladder patients whose chance for clinical response can be determined with more precision. Clearly, one “anticipated symptom response rate” is not appropriate for counseling. Patients would benefit from more specific counseling regarding the probability of symptom response to overactive bladder medication – the urobiome may have potential to assist with a refined estimate for symptoms response. Clinicians would be pleased to avoid the risk of medical intolerance, bothersome side effects, and/or ineffective therapy if they knew that the chance of symptom response was negligible.

The intriguing urobiome associations reported in this study, when coupled with the prior study describing the urobiome associations with solifenacin response, maybe a key to important clinical insights that can benefit the care of the many individuals affected with overactive bladder.

Written by: Thomas Halverson, Elizabeth R. Mueller, Linda Brubaker, Alan J. Wolfe

Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA., Division of Female Pelvic Medicine and Reconstructive Surgery, Departments of Urology & Obstetrics/Gynecology, Loyola University Medical Center, Maywood, IL, USA., Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Diego, La Jolla, CA, USA., Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA.

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