Acadia keeping the faith in pimavanserin despite setbacks

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There still seems to be a level of confidence leveraged in Acadia Pharmaceuticals. Shares gained 20% yesterday on news of the initiation of a new phase III Parkinson’s disease psychosis (PDP) trial of its lead pipeline candidate, pimavanserin, despite the drug failing to meet its endpoint in a previous phase III study in the same indication.

Acadia, partnered with Biovail for the 5-HT2A antagonist program, will have to fund the trial itself from a modest cash reserve under terms of its agreement. Nevertheless, Acadia insists it is well-placed to cover the expense and its future could be bolstered, rather than hindered, by Biovail’s upcoming merger with Valeant Pharmaceuticals – a meeting of two minds looking to expand in the CNS department (Biovail and Valeant join forces to drive growth, June 22, 2010).

Seeds of recovery?

Acadia’s share price has been hovering around a 5-year low at $1.10, and on steady decline for the last 12 months, following the phase III failure last year (All or nothing strategy leaves Acadia in reduced circumstances, September 2, 2009), making the 20% gain yesterday welcome but far from a game changer.

An interesting change nonetheless, given that the company will fund the phase III trial, dubbed -020, from its $40m pot of available cash, as the deal with Biovail does not cover PDP-associated studies (Acadia finally delivers deal which could turn to takeout, May 11, 2009). Acadia management has indicated that the 200-patient trial will cost around $12m at most, and that it will book reimbursement payments from Biovail on a rolling basis, while existing cash should last until the end of 2011.

New designs to gauge psychosis

While pimavanserin failed to meet its primary endpoint in the previous PDP phase III trial, measures of psychosis are, by their very nature, difficult to gauge relative to the next patient.

The new trial has been redesigned to reduce some of these inevitable statistical obstacles. Firstly, randomisation of the 200 patients targeted for enrolment will be on a 1:1 basis (the previous 3-arm trial was on a 2:1 basis, of two doses of drug vs placebo), decreasing the potential perception that the patient has received the drug. Next, a reduction in the number of visits to patients would be made, as this added reassurance for sufferers seemed to contribute to a lessening in psychotic episodes.

Acadia has said it is learning from its past trials, also modifying its scale for the assessment of positive symptoms (SAPS) ratings endpoints, an approach approved by the FDA, to focus on the most clinically-relevant symptoms. This will decrease potential variability and provide solid baseline data to compare with. And finally, the company is running the trial in North America only, to eliminate variability in standards of patient care.

Boost of confidence

As plans for this new trial were confirmed in May, this announcement is hardly unexpected and perhaps unlikely to be the cause of the share price jump yesterday.

Confidence then, it seems, is borne from the other side of the saga. Biovail is sticking with pimavanserin beyond its merger date – the company appears intent on obtaining the required safety data for it to initiate phase III schizophrenia studies, due to start in the first quarter of next year if all goes to plan. Add to that the likelihood that Acadia would have ditched the programme altogether if it thought Biovail was going to pull out. Biovail obtained positive safety and tolerability results from its previous phase IIb trial, testing a combination of pimavanserin with risperidone.

Market clout

And rather than Biovail and Valeant’s year-end merger weighing down pimavanserin’s progress, some analysts believe the CNS-focussed deal could provide much-needed clout to Acadia, in terms of finance, therapeutic area expertise and presence. Indeed, Valeant already has some PD market experience through the sale of two products, Zelapar and Tasmar.

With some analysts musing that Acadia could eventually become a target for acquisition by the combined body of Biovail and Valeant, Acadia's persistence with pimavenserin could yet be a fruitful one.

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