Acadia Pharmaceuticals presented detailed results at the Clinical Trials on Alzheimer's Disease (CTAD) meeting from a Phase III study, showing that pimavanserin significantly reduced the risk of relapse of psychosis by 2.8 fold compared to placebo in patients with dementia. The company, which announced in September that the HARMONY trial had met its primary endpoint, noted that there are currently no FDA-approved drugs to treat dementia-related psychosis.
Serge Stankovic, president of Acadia, remarked "pimavanserin treatment showed a meaningful reduction of the symptoms and stabilisation of psychosis across all of the five clinically diagnosed subtypes evaluated." The selective serotonin inverse agonist and antagonist, which preferentially targets 5-HT2A receptors, has been cleared in the US since 2016 under the brand name Nuplazid for use in patients with Parkinson's disease-related psychosis. Stankovic said Acadia plans to meet with the FDA in the first half of 2020 regarding a supplemental filing to market pimavanserin in dementia-related psychosis.
The HARMONY trial enrolled 392 patients, aged 74.5 years on average, with the most common forms of dementia, including Alzheimer's disease, dementia with Lewy bodies, Parkinson's disease dementia and vascular dementia, as well as frontotemporal dementia spectrum disorders. Participants had an average baseline score of 24.4 on the Scale for the Assessment of Positive Symptoms-Hallucinations and Delusions (SAPS-H+D), reflective of moderate-to-severe psychosis, and an average baseline Mini-Mental State Examination (MMSE) score of 16.7, which the company said is consistent with the greatest proportion of enrolled patients having moderate dementia. The primary endpoint was time to relapse in the study's double-blind period.
HARMONY included a 12-week open-label pimavanserin treatment period, with 61.8% of eligible patients advancing into the randomised double-blind portion of the study. Acadia reported that for patients in the open-label treatment period, change from baseline to week eight and week 12 on the SAPS-H+D score improved by 63% and 75.2%, respectively.
Meanwhile, results also showed that the drug met a key secondary goal by significantly reducing risk of discontinuation for any reason by 2.2 fold. Discontinuations due to adverse events were 2.9% for pimavanserin and 3.6% for placebo, while serious adverse event rates were 4.8% and 3.6%, respectively. One death was reported in the open-label period and another occurred in the pimavanserin group during the double-blind period, although researchers determined that neither case was related to the drug. Pimavanserin also did not lead to clinically significant differences in vital signs, weight, or daytime sedation compared to placebo, Acadia said.
In July, Acadia reported that pimavanserin had failed to improve psychosis symptoms versus placebo in adults with schizophrenia and a persistent inadequate response to their current antipsychotic therapy in the late-stage ENHANCE study.
Nuplazid carries a list price of $3100 a month and generated sales of $223.8 million in 2018.
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