Allergan’s Botox Enters Phase III Clinical Trial for Major Depressive Disorder

Earlier this week, Dublin-based pharmaceutical company, Allergan, announced topline data from a Phase II clinical trial investigating the safety and efficacy of Botox to treat patients with Major Depressive Disorder (MDD). While the blockbuster drug was considered to be numerically superior in terms of efficacy, when compared to a placebo, the study team could not prove statistical significance.

The mid-stage trial evaluated the tolerability of two doses of Botox (30 units or 50 units) in female patients diagnosed with MDD. In all, 258 patients with severe MDD were enrolled in the trial, based on their scores on two major depression scales, the Hamilton Rating Scale for Depression and the Clinical Global Impressions Scale.

Patients were randomly assigned to receive a 30 or 50 unit dose of Botox, or a placebo. The study investigators measured the primary endpoint as the change in Montgomery-Asberg Depression Rating Scale (MADRS) total score from baseline to week six of the study.

According to Allergan, the 30 unit dose of Botox showed numerical superior efficacy in achieving the primary endpoint, compared to the placebo. Patients taking this dose showed an average treatment difference of -3.7 in the MADRS total score at week six of the study.

Patients taking the 50 unit dose of Botox did not show numerically superior efficacy over the placebo. Despite this, both doses were well tolerated in patients.

“We are encouraged by these data and the potential impact on adults with major depressive disorder,” said David Nicholson, Chief Research and Development Officer, Allergan. “Given our in-depth and extensive clinical trial experience in CNS including depression, we plan to move forward and develop a phase III program for a potential new treatment option for patients.”

Though Allergan did not report statistically significant results – the gold standard of showing efficacy over a placebo – the drugmaker has announced that Botox will be pushed forward into a Phase III clinical trial for MDD. While it’s not clear when this late-stage trial will commence, it’s likely that Allergan will only include the lower dose in the next phase.

Originally approved as a cosmetic product to reduce wrinkles on the face and neck, Botox has since been approved for a number of additional medical indications, including excessive perspiration, migraines and muscle stiffness. In 2016, global sales of Botox reached $2.8 billion, making it Allergan’s best seller.