(Editor's note: Come see Adam Feuerstein at the Money Show in San Francisco. Adam will be speaking to attendees on Friday, Aug. 8, at 2:15 p.m. ("Biotech Investing for Individuals: How to Turn Geeky Science Into Fat Profits"); on a lunch panel on Saturday, Aug. 9, at 12:35 p.m. ("Tech and Biotech: Picks and Pans for 2008 and Beyond"); and on Sunday, Aug. 10, at 8 a.m. ("Biotech Investing for Individuals: How to Turn Geeky Science Into Fat Profits").
CHICAGO -- Alzheimer's patients did not benefit from treatment with Elan ( ELN and Wyeth's ( WYE experimental drug bapineuzumab, according to data from a phase II study presented Tuesday evening at a closely watched Alzheimer's disease conference. But Elan and Wyeth called the results "encouraging" and said the data support the decision to conduct ongoing phase III studies because a segment of patients in the study lacking a higher genetic risk for developing Alzheimer's did benefit from bapineuzumab treatment. Shares of Elan were sinking $6.63, or 19.6%, to $27.12 in recent after-hours trading Tuesday. Wyeth shares were falling $5.06, or 11.2%, to $40.05. The phase II bapineuzumab data were presented in full at the International Conference for Alzheimer's Disease, following an announcement in June by Elan and Wyeth that the study produced mixed results. The phase II study enrolled 234 patients with mild to moderate Alzheimer's disease; 229 of which were randomized to receive injections of four doses of bapineuzumab or a placebo. Patients treated with bapineuzumab recorded a 2.3-point improvement over placebo on the ADAS-cog test, a measure of cognitive function. The result was not statistically significant. Likewise, bapineuzumab patients did not perform better on a functional endpoint, the Disability Assessment Scale for Dimentia. Elan and Wyeth broke down the phase II study based on two, retrospectively defined subgroups - patients with and without a gene called ApoE4. Patients who are non-carriers of the ApoE4 gene are not at an increased risk for developing Alzheimer's. In these non-carrier patients, treatment with bapineuzumab compared to placebo resulted in a statistically significant, five-point benefit in the ADAS-cog score. Other measures of cognition and function were also statistically significantly improved in favor of bapineuzumab. There was no benefit for ApoE4 carrier patients treated with bapineuzumab.