Vibegron and mirabegron efficacy similar in OAB, but patients prefer vibegron

Vibegron (Gemtesa) and mirabegron (Myrbetriq) demonstrated similar efficacy and safety in a comparative study of the 2 treatments in female patients with overactive bladder (OAB); however, more patients preferred vibegron, according to a study presented at the 2023 AUA Annual Meeting.¹

The next steps for this research will be to conduct a head-to-head comparison of vibegron and mirabegron in male patients with OAB, according to lead author Naoki Wada, PhD.

Vibegron and mirabegron are both β3-adrenergic receptor agonists approved by the FDA for the treatment of patients with OAB. The investigators launched the trial because there had not been a head-to-head comparative study of the 2 treatments.

The multicenter study enrolled 83 female patients with OAB aged ≥50 years who had not yet received treatment for OAB.

Patients were randomized into 2 treatment arms. In the first arm, patients received 8 weeks of mirabegron at 50 mg/day followed by vibegron at 50 mg/day for 8 weeks (MV arm). In the other arm, the treatment dose and schedule were the same for both drugs; however, the treatment sequence was reversed, with upfront vibegron followed by mirabegron (VM group). The study allowed crossover and there was no washout period prior to crossover.

The investigators obtained OAB symptoms scores (OABSS) for each patient at baseline, week 8, and week 16. OABSS included measures of daytime frequency, nighttime frequency, urgency and urgency incontinence, and frequency-volume charts (FVC).

The primary end point of the trial was the change in OABSS from baseline. Following the completion of the study, the investigators also asked each patient which of the 2 drugs they preferred.

Overall, there were 40 patients randomized to the MV arm and 43 patients randomized to the VM arm. At week 8, 33 patients in the MV arm and 34 patients in the in the VM group remained on treatment. Of the 7 patient withdrawals in the MV arm, 1 was due to patient improvement, 1 was due to surgery for other disease, and 5 were for unknown reasons. Of the 9 patients withdrawals in the VM arm, 2 were due to adverse events and the remaining 7 were for unknown reasons. At week 16, 29 patients in the MV group and 27 patients in the VM group had completed treatment.

Mirabegron and vibegron both significantly improved OABSS (-4.3±3.4 vs -5.3±3.4). Further, both treatments significantly improved daytime (-1.0±2.0 vs -1.6±2.0) and nighttime frequency (-0.3±1.0 vs -0.4±0.9) per day, as well as mean (35±47 vs 42±47 ml) and maximum voided volume (55±96 vs 57±109 ml).

“There was no significant difference in the changes of these parameters between mirabegron and vibegron,” said lead study author Naoki Wada, PhD, department of Renal and Urological Surgery, Asahikawa Medical University, Japan.

Of the 57 patients who completed the 16 weeks of treatment, 26% preferred mirabegron and 57% preferred vibegron. The remaining 17% did not have a preference. In the MV arm, 29% preferred mirabegron, 53% preferred vibegron, and 18% had no preference. The rates in the VM arm were 24%, 60%, and 16%, respectively.

Wada said a potential explanation for the preference could be the change of the urgency incontinence score of OABSS, which was “better in patients who preferred vibegron to mirabegron (-2.1±1.6 vs -1.1±1.4; P <.05).”

Regarding safety, there were 3 adverse event–related withdrawals from the trial: 1 patient due to dizziness during mirabegron, 1 patient due to constipation during vibegron, and 1 patient due to elevated postvoid residual (PVR) during vibegron. “The change of PVR was not significantly different during mirabegron (3.1±26.5 ml) and vibegron (7.9±9.8 ml; P = 0.43),” noted Wada.

Summarizing the findings, Wada said, “The efficacy of mirabegron and vibegron for female OAB patients is similar. The patients’ preference for vibegron could be depending on the better efficacy for urgency incontinence.”

He added that the next steps for this research will be to conduct a head-to-head comparison of vibegron and mirabegron in male patients with OAB.

Reference

1. Wada N, Abe N, Miyauchi K, et al. Comparison of mirabegron and vibegron for clinical efficacy and safety in female patients with overactive bladder: a multicenter, prospective randomized crossover trial. Presented at: 2023 AUA Annual Meeting. April 28-May 1, 2023; Chicago, IL. Abstract LBA01-18. doi:10.1097/JU.0000000000003360.18