10 March 2008. Thanks to a decade of work by advocates for public access, today a few keystrokes is all it takes to pull up a wealth of information about ongoing clinical trials for any disease of interest (see ARF related news story). A quick search of the two big clinical trial databases, the NIH-administered ClinicalTrials.gov and the World Health Organization site, pulls up more than 150 registered trials under the indication Alzheimer disease. Many of those are small, others explore the approved AD drugs, and not all trials being conducted are to be found in those databases. Here are pointers to some of the later-stage, larger trials that do show up on the list:
Elan and Wyeth Pharmaceuticals have started two large Phase 3 trials of an anti-amyloid monoclonal antibody (AAB-001, or bapineuzumab) for passive immunotherapy, which began enrolling in December in the United States (see ARF related news story). Both trials are multicenter, double-blind, placebo-controlled, randomized outpatient studies in patients with mild to moderate AD. The difference between the two trials will be the ApoE4 status of the participants: one trial aims to enroll 1,250 people who are ApoE4 negative, while the other is looking for 800 ApoE4 carriers. Approximately 200 study sites in the U.S. and Canada will be involved. Patients will be randomized to receive either bapineuzumab or placebo by infusion every 13 weeks, with cognitive function as the primary outcome measured over 18 months. The larger trial will involve three doses of antibody, infused every 13 weeks versus placebo; the smaller trial of ApoE4 carriers will feature just the lowest dose.
Elan is also testing an oral anti-amyloid therapy, scyllo-inositol. It’s a sugar that has been shown to reduce amyloid toxicity in animal models (see ARF related news story). The randomized, placebo-controlled Phase 2 trial will study 340 patients at 65 study sites and began enrolling in December.
A Phase 3 study that has been registered but is yet to start enrolling is the γ-secretase inhibitor, LY450139 from Lilly (see also ARF related news story). Recruitment of a total of 1,200 participants is slated to begin this month. Participants will get a once-a-day dose or placebo. The primary outcome measure will be the rate of cognitive and functional decline over time, but the study will incorporate numerous secondary measures including FDG-PET and PET-PIB imaging and MRI, as well as tau levels in the CSF. The study should be completed in 4 years.
GlaxoSmithKline has two Phase 3 clinical trials ongoing for rosiglitazone, their type 2 diabetes drug that has shown some beneficial cognitive effects in AD. One study will compare rosiglitazone monotherapy to donepezil or placebo in 862 patients with mild-to-moderate AD in a 24-week study. A second study aims to enroll 1,392 patients to test rosiglitazone as an adjunct to acetylcholinesterase inhibitors.
In Phase 2 work, in December 2007 Pfizer began a trial of its inhibitor of the receptor for advanced glycation end products (RAGE), which mediates amyloid transport into the brain. Pfizer intends to test the inhibitor PF-04494700 in 400 patients treated for 18 months. Finally, Abbott continues to recruit for its Phase 2 trial of ABT-089, a neuronal nicotinic receptor modulator and cognitive enhancer.—Pat McCaffrey.