Panel backs mirabegron for OAB

FDA's Reproductive Health Drugs Advisory Committee voted 7-4, with one abstention, in favor of approval of mirabegron from Astellas Pharma Inc. (Tokyo:4503) for overactive bladder. Panelists said the adrenergic receptor beta 3 (ADRB3) agonist showed only "marginal" clinical benefit in Phase III studies, but a majority felt the compound was worth approving because of the indication's significant unmet medical need. First-line drugs for OAB include muscarinic receptor antagonists, which have low adherence rates due to poor efficacy and side effects such as dry mouth, constipation and blurred vision.

Pooled data from three Phase III studies showed that 50 mg/day mirabegron significantly reduced the number of incontinence episodes (1.48 vs. 1.09 episodes per 24 hours for placebo) and micturitions (1.77 vs. 1.18 events per 24 hours for placebo). Committee members highlighted mirabegron's significant 7% increase over placebo in the proportion of patients having eight or fewer micturitions per 24 hours, a measure which members characterized as a substantial clinical benefit. They largely agreed that Astellas should conduct postmarketing studies to identify the subset of patients who would most likely experience such a benefit from mirabegron and to better characterize the compound's side effects, although they did not vote on the topic. ...