ACADIA and Biovail to continue pimavanserin development, despite disappointing Ph III

San Diego, USA-based ACADIA Pharmaceuticals and Canadian biotechnology firm Biovail have said they will continue the development of their Parkinson's disease investigational drug pimavanserin despite disappointing top-line results from the first Phase III PDP trial announced in September. The companies also intend to pursue adjunctive therapy with pimavanserin for schizophrenia as a third indication in the collaboration.

The companies entered a co-development and commercialization deal for pimavanserin, a selective 5-HT2a inverse agonist, which could earn the US group as much as $395.0 million (The Pharma Letter May 5).

'We remain enthusiastic about pimavanserin's prospects in a number of specialty CNS indications, including schizophrenia where existing data for the molecule as co-therapy are compelling,' said Bill Wells, Biovail's chief executive. 'The steps we're taking today are designed to fully exploit pimavanserin's potential and to bring this novel therapeutic to market as quickly as possible,' he added.

ACADIA has conducted a substantial portion of the analysis of the data from its first Phase III PDP trial with pimavanserin (-012 Study). While the -012 Study did not meet its primary endpoint of antipsychotic efficacy and had a larger-than-expected placebo response, signals of antipsychotic efficacy were observed in the pimavanserin 40mg study arm. These signals were most prominent in the US portion of the study, which comprised nearly one-half of the patients. The efficacy signals were also supported by additional secondary and exploratory measures, including efficacy measures and favorable outcomes in assessments of sleep and caregiver burden. Several findings from the -012 Study will be used in the design of future PDP studies to help mitigate the placebo response and to increase the chances of success. These findings relate to dose selection, the method and application of ratings, and other study design elements.

ACADIA and Biovail have agreed on a development strategy for PDP that involves using the findings from the -012 Study together with those from the second, ongoing Phase III trial (-014 Study), which is testing 10mg and 20mg doses of pimavanserin, to arrive at an enhanced study design that may be used in new Phase III trials. Accordingly, the ongoing -014 Study will be concluded at its current enrollment level (about 120 patients) to allow for the analysis of data as soon as practicable. Meanwhile, the parties will begin planning for a new Phase III PDP trial using a 40mg dose of pimavanserin. Consistent with the terms of the original collaboration agreement, Biovail will be responsible for the cost of this third Phase III trial. This study is expected to start in the first half of 2010. ACADIA will continue its ongoing open-label safety extension studies in patients with PDP.

In addition, Biovail intends to pursue adjunctive therapy with pimavanserin for schizophrenia as a third indication in the collaboration. Alzheimer's disease psychosis (ADP) remains the second indication provided for in the collaboration. The partners currently intend to focus their efforts on the PDP and schizophrenia programs, but also are moving forward with planning for an initial study in ADP, they say.