Interim look at long-term botulinum toxin injections reassuring

Repeat intradetrusor injections of onabotulinumtoxinA ("onabotA"; Botox) are associated with sustained efficacy and no new safety signals, long-term study results show.

Results are from an interim analysis of data being collected in the long-term extension study of the two, 52-week pivotal trials leading to the agent’s approval for treatment of urinary incontinence (UI) due to neurogenic detrusor overactivity in patients with a neurologic condition who have an inadequate response to or are intolerant of an anticholinergic drug.

The interim analysis included data from 387, 336, 241, 113, and 46 patients who received 1, 2, 3, 4, and 5 onabotA treatments, respectively. Change from baseline weekly UI episodes at 6 weeks after injection was analyzed as the primary endpoint of interest and showed repeat treatments resulted in consistent reductions across all cycles, with the mean changes for cycles 1 to 5 ranging from −22.7 to −31.9 for patients receiving a 200-U dose and from −23.6 to −29.5 for patients treated with a 300-U dose.

Mean volume per void remained consistently increased regardless of the number of retreatments. Considering the data for cycles 1 and 2, for which patient follow-up is most complete, the mean time to request for repeat treatment was about 250 days. The safety profile of onabotA detrusor injections was unchanged relative to the controlled portion of the pivotal trials, reported study investigator Michael Kennelly, MD, of the University of North Carolina, Chapel Hill.

"So far, the extension study results indicate onabotoxA continues to be effective with repeated injections, and the safety data do not raise any signals about long-term adverse events," Dr. Kennelly said. "Results from longer follow-up will be clearly important for urologists around the world who are using onabotoxA to manage UI in patients with neurogenic detrusor overactivity."

Dr. Kennelly is a consultant/adviser for Allergan, Astellas, Pfizer, and Watson.

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