13 June 2007. After a Phase 2 trial of the AD experimental immunotherapy AN1792 ended prematurely because 6 percent of the patients developed encephalitis, scientists called on the sponsoring companies Elan/Wyeth to continue following the 376 patients. They had, after all, received one or two of a planned six shots of the first active vaccine in AD research. The late Leon Thal of University of California, San Diego, who headed the Alzheimer Disease Cooperative Study consortium of clinical centers, played a leading role in initiating this study, and he presented some initial data of the study at the ICAD conference last July in Madrid, Spain.

Since then, the study has gathered more data. Michael Grundman of Elan Pharmaceuticals in San Diego presented a fuller account at the second Alzheimer’s Association International Prevention Conference, which drew to a close yesterday in Washington, D.C. This space has covered the goals of the study and trends in its initial data before (see ARF Madrid news story), so here is only a brief update. These are people who have aged 4.5 years since receiving their injections and still have AD. Grundman reported that the people who responded to the antibody still showed low but measurable antibody titers. The rating of clinical activities they were still able to perform indicated that the responders had declined about half as much as the people who received placebo. Responders were slightly less dependent on caregivers, and more responders than placebo recipients still lived at home. They showed a trend toward better memory, though it has to be said that most trial participants were no longer able to complete a full psychometric test battery. A subgroup agreed to an MRI scan and they no longer showed the shrinkage that had taken the field by surprise at the 1-year follow-up point (see ARF related Philadelphia news story). No further encephalitis cases popped up as a delayed reaction to the vaccine.

The Alzforum already reported that Elan/Wyeth has decided to forge ahead with their second-generation immunotherapy (see Phase 3 trial of bapineuzumab). This data contributed to this decision, Grundman said.—Gabrielle Strobel.