Acadia pulls plug on pimavanserin for adjunctive MDD

Acadia Pharmaceuticals has terminated development of pimavanserin for major depressive disorder (MDD) after the drug failed to hit trials in this setting.

The Phase III CLARITY study, which combined two identical, double-blind, placebo-controlled studies evaluating the efficacy, safety and tolerability of pimavanserin as an adjunctive treatment for MD, failed to reduce depressive symptoms.

The study did not achieve statistical significance on the primary endpoint – the 17-item Hamilton Depression Rating Scale (HAMD-17) total score change from baseline to week 5.

Pimavanserin 34mg, given once-daily as an adjunctive treatment to standard antidepressant therapy, was associated with a mean reduction of 9.0 in HAMD-17 total score compared to 8.1 for placebo as an adjunctive treatment.

Positive results were observed on the key secondary endpoint, the Clinical Global Impression – Severity (CGI-S) score, a clinician assessment of a patient’s severity of depression, the firm noted.

“We observed a consistent improvement of depressive symptoms over time with pimavanserin but, unfortunately, the robust positive results from our CLARITY-1 study were not replicated,” said Serge Stankovic, Acadia’s president.

“While these results do not support the product profile to pursue an additional Phase III study in adjunctive MDD, we will continue to analyse the data and the findings from our earlier positive depression studies as we assess next steps.”

Other indication for the firm moves forward

In better news for the firm, US regulators have accepted for review an application to market the drug – under the brand name Nuplazid –  for the treatment of hallucinations and delusions associated with dementia-related psychosis (DRP).

Nuplazid was approved in the US in 2016 as the first and only treatment for hallucinations and delusions associated with Parkinson’s disease psychosis.

Pimavanserin was granted Breakthrough Therapy Designation by the FDA for the treatment of hallucinations and delusions associated with DRP in October 2017.