A highly anticipated trial of an experimental Alzheimer’s drug failed its first large clinical trial, Pfizer, one of the companies developing the new treatment, announced on Monday.
The disappointing findings once again call into question the leading theory about what causes the memory-robbing disease: accumulation of a naturally occurring protein called beta amyloid is thought to gum up the brain and cause the nerve death and cognitive decline associated with Alzheimer’s. Indeed, a study published earlier this month found that a rare gene mutation that reduces beta amyloid production appears to protect people from developing the disease. But numerous experimental drugs — including the latest, known as bapineuzumab — that target beta amyloid have failed in trials to improve memory or cognitive functioning in Alzheimer’s patients.
According to Pfizer, which is developing bapineuzumab with Johnson & Johnson and Irish pharmaceutical company Elan, the new drug also did not improve cognition or daily function compared with a placebo in participants of a phase 3 trial. The drug was tested on 1,100 Americans with mild to moderate disease.
The details of the trial are expected to be presented in September at the European Federation of Neurological Societies meeting in Stockholm, but a principal investigator in the study, Dr. Reisa Sperling, director of the Center for Alzheimer Research and Treatment at Brigham and Women’s Hospital in Boston, told the New York Times that the drug had shown no benefit: “There was absolutely no evidence at all of a clinical benefit of treatment on either of the primary measures, one cognitive and one functional.”
While disappointing, the results didn’t surprise observers, since the drug didn’t work in an earlier phase 2 trial, the Times reports:
Moreover, the patients in the new trial…all had a gene called ApoE4, which raises the risk a person will get Alzheimer’s disease and can make the disease worse. Based on the phase 2 data, bapineuzumab has a somewhat better chance of working in patients who do not have that gene.
Also, as other experts pointed out, the reason so many promising Alzheimer’s drug may fail is that they are being administered too late in the course of the disease. Researchers say beta amyloid plaques begin forming in the brain decades before symptoms of memory loss or confusion appear, so drugs should be tried earlier — to try to prevent plaques from forming in the first place, instead of attempting to clear them away once they’ve already formed.
Other trials of bapineuzumab — a monoclonal antibody that binds to beta amyloid — are still underway, involving patients with and without the ApoE4 gene. Another drug company, Eli Lilly, is developing another antibody against beta amyloid called solanezumab. Clinical trial results are expected in future weeks.