Acadia Pharmaceuticals has deemed the results of its Phase II study evaluating its Alzheimer’s disease psychosis (ADP) therapy as “Phase III enabling”, despite the drug missing its primary endpoint.
In the ongoing RADIANT study (NCT06159673), Acadia is assessing the potential of two separate doses of remlifanserin against placebo to treat hallucinations and delusions linked to ADP. The trial has enrolled an estimated 1,074 patients, as per ClinicalTrials.gov.
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At week six, patients treated with the 60mg dose of the serotonin 2A receptor inverse agonist experienced a 12.6-point reduction in hallucinations and delusions, while those in the placebo group underwent a 10.4-point drop – meaning the drug narrowly missed the trial’s primary endpoint, with a p value of 0.0603.
The 60mg dose reached nominal significance on the key secondary endpoint, which was looking at the drug’s impact on the overall severity of ADP in treated patients versus placebo. At the six-week mark, remlifanserin triggered a baseline change of -1.3 points on a common measure of general ADP severity compared with a -0.9-point reduction in the placebo group, meaning the standard effect size in the 60mg treated group was 0.37.
The high dose of remlifanserin also had an increasing impact on measures of Alzheimer’s psychosis throughout the six-week period, Acadia claims, though a 30mg dose showed minimal improvements across all endpoints versus placebo.
Patients tolerated the drug well, with the rate of adverse events (AEs) and discontinuations remaining similar across treatment and placebo arms of the study. Researchers did not identify any signs that remlifanserin can prompt any negative impacts on patient motor symptoms or cognition.
Next steps for remlifanserin amid race to ADP market
Following this data, Acadia is continuing enrolment into its ongoing Phase III studies; however, the San Diego-based biopharma plans to make some protocol amendments to the late-stage programme – one of which being the removal of the 30mg dosing arm.
If Acadia were to secure some pivotal wins for remlifanserin, it could put the drug in position to join a market with no approved therapies, despite ADP impacting around 30% of patients with Alzheimer’s disease.
According to Jeffrey Cummings, Director of the University of Nevada’s Chambers-Grundy Center for Transformative Neuroscience, patients with ADP are currently in significant need of tolerable, convenient and efficacious medicines that are compatible with medications commonly prescribed for Alzheimer’s.
He also stresses the importance of avoiding negative impacts on motor symptoms and cognition, meaning he views remlifanserin’s early tolerability signals as encouraging.
“Such a medicine could be an important treatment option for patients,” Cummings commented.
Acadia is not alone in its race to the ADP market, as Bristol Myers Squibb (BMS) is also assessing the potential of its next-generation antipsychotic, Cobenfy (trospium chloride + xanomeline tartrate) in the Phase III ADEPT programme.
According to a report from GlobalData, parent company of Clinical Trials Arena, the Alzheimer’s disease market is projected to reach a value of $17bn by 2033, representing a 21.8% compound annual growth rate from the segment’s $2.4bn 2023 value.
