US-based biotechnology company Acadia Pharmaceuticals has begun a Phase II clinical trial of ACP-204 to treat hallucinations and delusions linked to Alzheimer’s disease psychosis (ADP).

The trial is part of a Phase II/III programme consisting of a Phase II trial and two Phase III trials with almost identical designs.

The Phase II trial is designed to analyse the safety and efficacy of 30mg and 60mg doses of ACP-204 against those of placebo.

It is being conducted as a placebo-controlled, international, multicentre, randomised, double-blind trial that will enrol nearly 318 patients with ADP.

The variation in total score based on the Scale for the Assessment of Positive Symptoms–Hallucinations and Delusions subscales (SAPS-H+D) at week six from baseline will be the trial’s primary endpoint.

ACP-204 functions mainly as an inverse agonist at the 5-HT2A receptor.

Trial subjects will move to Phase III studies from the Phase II trial 'seamlessly' at study centres. Each Phase III study is expected to enrol nearly 378 ADP patients.

Subjects who complete these trials will also have the option to take part in a long-term open-label extension study.

According to the Alzheimer’s Association, more than 6.5 million people in the US currently live with Alzheimer's disease.

Around 30% of patients with the disease experience ADP, which commonly causes hallucinations and delusions.

Earlier this year, the US Food and Drug Administration (FDA) granted approval for Acadia’s Daybue (trofinetide) to treat Rett syndrome in adult and paediatric patients aged two years and older.

Daybue is understood to be the first drug to ever receive approval for Rett syndrome treatment.

The FDA's approval was based on data from the Phase III LAVENDER trial, which analysed trofinetide's safety and efficacy against those of placebo in Rett syndrome patients aged five to 20 years.