Medivation slumps as Alzheimer's drug candidate Dimebon, partnered with Pfizer, disappoints in Ph III

USA-based Medivation saw its shares price nose dive after it announced, with development partner drug behemoth Pfizer, that two Phase III trials of the investigational drug Dimebon (latrepirdine) in patients with Alzheimer's disease did not meet co-primary or secondary efficacy endpoints compared to placebo. Co-primary endpoints were measures of cognition and global function. Medivation's stock tumbled 69%, to $12.40 ahead of yesterday's market opening, and closing the day at $13.10. Pfizer's shares dipped just 1% to $17.44 in early trading.

The news was a surprise to both companies as, in earlier studies, Dimebon - which is an old Russian antihistamine approved in that market in 1983 - had shown exceptionally good results in AD. Only a week or so ago, Alzheimer's researcher Mark Smith, of Case Western Reserve University, said that Dimebon clinical data 'is by far and away superior to anything that's ever been shown before.'

Moreover, earlier this year, advisory firm Decision Resources projected that, following its expected launch in 2012, Dimebon will garner peak year sales of $1.5 billion in the world's top seven pharmaceutical markets (the USA, France, Germany, Italy, Spain, the UK and Japan (The Pharma Letter January 12).