Bapineuzumab and Share Prices of Elan/Wyeth: What a Difference Some Undefined Thing Makes

As if you need another reason to bang your head against a wall on Wall Street.

After phase 2 data of bapineuzumab in Alzheimier's disease (AD) were released on June 17, shares of Elan and Wyeth climbed 10.6% and 4.8%, respectively. However, after the same data were presented yesterday at the International Conference on Alzheimer's Disease (ICAD) in Chicago, the share prices dropped 19.6% and 11.2%, respectively. So what were the differences between the June press release and the meeting presentation? Not a heck of a lot.

 

Both presentations provided information about the missed primary endpoint in the trial, a change in cognition or disability at 18 months (although the primary outcome was buried in the second paragraph of the June press release). Both provided information about the post-hoc assessment of subgroup data—namely, that ApoE4 noncarriers performed statistically better on the ADAS-cog at 18 months (mean score difference: 5 points, bapinueuzumab vs placebo). And both reported a risk of vasogenic brain edema with the agent, especially in ApoE4 carriers.

In June, analysts talked up the bapineuzumab phase 2 study, despite the missed primary endpoint, and the companies' prospects. Yesterday, not so much. Nevertheless, Elan and Wyeth are apparently moving forward with phase 3 investigation of the amyloid buster in AD.