Hi Piton Thanks for the update on the pimavanserin extension...

Hi Piton

Thanks for the update on the pimavanserin extension trial which was terminated by Acadia last week for “business reasons” rather than safety issues.

This extension study followed on from a main Phase 2/3 study of pimavanserin for the treatment of irritability associated with ASD. I last posted on that study a year ago. That international study in 237 patients completed in September last year. As the study was never talked about by Acadia, I’m not expecting them to talk about the results either.

My suspicion is that the results weren’t great and likely the primary endpoint wasn’t met. Hence the business decision to terminate the program.

This was, I think, the last active trial remaining for pimavanserin since Acadia announced that it was ceasing further development of the drug.

But here’s the interesting thing…

Next week Acadia is commencing a trial of pimavanserin in the treatment of rigid-compulsive symptoms in ASD. It’s only a small Phase 2 study in 30 patients. The main endpoint will be assessed using the Repetitive Behavior Scale (RBS-R) which measures stereotyped behaviour, self-injurious behaviour, compulsive behaviour, routine behaviour, sameness behaviour and restricted behaviour. I see that the RBS-R was one of the secondary endpoints used in the irritability in ASD trial. So that suggests to me that pimavanserin managed to perform well on this particular endpoint in the irritability in ASD trial.

Re your post on Harmony Biosciences’ ZYN-002 open-label extension study results for irritability associated with Fragile-X, this is a transdermal synthetic CBD product. The positive results are interesting given that one of the potential side effects of the only FDA-approved CBD product, Epidiolex, is increased irritability. Anyway, we will await with interest the Phase 3 placebo-controlled trial results in Q3.