In a pooled analysis from two earlier phase II studies, P-tau levels fell significantly for those on bapineuzumab compared with controls, and there was also a trend toward diminished total-tau levels in these patients, Kaj Blennow, MD, PhD, of the University of Gothenburg in Sweden, and colleagues reported.

There were no changes, however, in cerebrospinal fluid (CSF) levels of amyloid-beta, the protein that bapineuzumab targets for removal in the brain. Patients with Alzheimer's disease typically have lower levels of amyloid-beta in their CSF fluid, while levels of tau proteins are increased in CSF.

The findings may indicate that the antibody has some downstream effects on the degenerative process, but whether these effects translate to clinical improvements remains to be seen, the researchers said.

Bapineuzumab is an investigational antibody against amyloid-beta, a protein plaque that builds up, along with neurofibrillary (tau) tangles, in the brains of Alzheimer's patients. The drug is still being evaluated in a phase III trial and has previously hit some setbacks, with questions about links with amyloid-beta imaging abnormalities of edema that led to the highest dose of the agent being dropped from the study.

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