Allergan says its Botox blockbuster wrinkle treatment had just missed achieving a significant improvement in treating depression in a mid-stage trial, but was encouraging enough to move into larger Phase III testing.
Allergan says results from the trial on the lower of two tested doses compared with placebo were close to what has been seen with more traditional antidepressants on the market and consistent with what had been reported from earlier, smaller Botox depression trials conducted by independent researchers.
"We are encouraged by these data and the potential impact on adults with major depressive disorder," Allergan research chief David Nicholson said in a statement. "We plan to move forward and develop a Phase 3 program for a potential new treatment option for patients."
While erasing facial wrinkles remains the best known use for Botox and accounted for roughly half of its global sales of $US2.78 billion ($A3.67 billion) in 2016, Allergan has continually tested the drug for a wide variety of medical conditions.
Among the already approved medical uses for Botox are chronic migraine, overactive bladder, severe underarm sweating, eyelid spasms and limb spasticity.
The drug, given through a series of facial injections, just missed achieving a statistically significant improvement compared with placebo on the lower of two tested doses as measured by change from baseline at week 6 in the Montgomery-Asberg Depression Rating Scale (MADRS), the company said.
In the 258-patient trial, Botox was tested in adult females suffering from major depressive disorder. The 30-unit dose lowered the MADRS score by 3.6 points at week 6 compared with placebo. The 50-unit dose failed to show a difference from placebo, but both were well tolerated, the company said.
Allergan believes that by modifying facial expression and muscle contractions via Botox injections, there may also be a modification of brain circuitry at work in depression.
In designing larger Phase III trials, Allergan hopes it can better control for any placebo effect common in depression trials and demonstrate a more clearly significant result for Botox after the near miss, Mitchell Brin, Allergan's chief scientific officer for Botox, said in a telephone interview.