US FDA advisers recommend against Otsuka's PTSD combination treatment

By Mariam Sunny and Siddhi Mahatole

July 18 (Reuters) - The U.S. Food and Drug Administration's panel of independent advisers on Friday voted against the efficacy of Otsuka Pharma's 4578.T antipsychotic drug in combination with Viatris' VTRS.O antidepressant Zoloft for treating adults with PTSD.

The panel voted 10-1 to say the available data does not establish the efficacy of the drug, brexpiprazole, in combination with Zoloft, chemically known as sertraline, for treating the condition. Its decision is in line with the FDA staff reviewers' assessment on Wednesday.

Otsuka's application was based on the data from one mid-stage and two late-stage studies testing the combination treatment compared to sertraline plus placebo. It had failed to meet the main goal of significantly reducing severity of PTSD symptoms in one of the late-stage studies.

PTSD, a disorder caused by very stressful events, affects about 4% of U.S. adults and is commonly associated with war veterans. But natural disasters, abuse or other trauma may also trigger the condition in civilians.

"We simply cannot negate one negative study and say we are going to approve based on two other positive studies," said panelist Pamela Shaw, biostatistician at Kaiser Permanente.

The advisers discussed possible side effects such as weight gain and movement disorders associated with long-term use of antipsychotics, but noted that the combination may be a better treatment option for patients who respond poorly to sertraline alone.

"The big question for me is knowing that antipsychotics can cause real problems, especially with long-term use, and the modest benefit that the combination treatment potentially can offer," said panelist Walter Dunn, assistant clinical professor of psychiatry at University of California, Los Angeles.

Otsuka said it would continue to work closely with the FDA as it completes its review of the application.

The FDA, originally set to decide on the company's application by February 8, delayed its decision to seek the advisory panel's input. The agency has not set a new action date for the drug.

The health regulator typically follows the advice of its expert advisers, but is not required to do so.

If approved, the combination drug would be the first PTSD treatment to gain U.S. nod in more than two decades after Zoloft and GSK's GSK.L Paxil.

Brexpiprazole, branded as Rexulti and co-developed by Otsuka and Danish drugmaker Lundbeck HLUNa.CO, is approved in the U.S. to treat agitation in patients with the Alzheimer's disease and for adults with major depressive disorder and schizophrenia.