An abnormal form of the tau protein known as phospho-tau (P-tau) forms into tangles which are the other established lesions in the brain of people with Alzheimer's. The amount of P-tau in cerebrospinal fluid (CSF) is believed to be a marker of active loss of brain cells in people with Alzheimer's; prior studies have shown increases in P-tau in people with mild cognitive impairment who later develop Alzheimer's. P-tau was studied as a therapeutic biomarker in the Phase 2 clinical trials of bapineuzumab.
The pooled exploratory analysis reported at AAICAD 2010 by Kaj Blennow, MD, PhD, of the University of Gothenburg, Sweden, and colleagues included a subgroup of participants from two randomized, multicenter, double-blind, placebo-controlled, multiple-ascending-dose studies conducted in the United States (Study 201) or in the United Kingdom and Finland (Study 202). Study 201 enrolled 35 patients (20 bapineuzumab, 15 placebo) in the CSF substudy, and Study 202 enrolled 11 patients (7 bapineuzumab, 4 placebo) in the CSF substudy. CSF was collected at baseline and 2 weeks after the week 52 infusion.
The researchers found that Study 201 showed a trend (p=0.0564) towards a decrease in CSF P-tau in bapineuzumab-treated compared with placebo-treated cases. In Study 202, no significant treatment effects were seen. When they combined data from both studies, they found a statistically significant decrease (p=0.0270) in P-tau in bapineuzumab-treated compared with placebo-treated patients.
"These observations suggest that immunotherapy treatment targeting amyloid may also alter neurodegenerative processes that occur later in the disease process and that are more directly associated with loss of function," Blennow said. "However, this was a small study and these findings need to be confirmed."
Bob DeMarco is the editor of the Alzheimer's Reading Room and an Alzheimer's caregiver. Bob has written more than 1,610 articles with more than 8,000 links on the Internet. Bob resides in Delray Beach, FL.