Alzheimer’s Disease Vaccine Tests Suspended on Safety Concerns

By Rich O’Boyle, Publisher
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Elan Pharmaceuticals announced on January 18, 2002 that they had suspended the Phase II clinical trials into their experimental Alzheimer’s Disease vaccine, AN-1792 (also known as AIP-001). Researchers were concerned when individuals who were taking the drug in clinical trials developed unexpected side effects.

Elan, along with Wyeth-Ayerst Laboratories, the pharmaceutical division of American Home Products Corporation, reported that four of the 97 patients taking the drug had developed a severe inflammation in the central nervous system. According to an Elan press release, “All four patients are receiving appropriate medical care and the companies are working with clinical investigators to determine the cause of this development.” The central nervous system inflammation may be tied to a viral infection or other illness, rather than the vaccine itself, Elan said.

Early drug research is generally conducted on experimental animals such as mice genetically engineered to develop certain diseases. While these types of studies are standard practice in the scientific community, it is only after even more intensive studies in humans that a drugs safety and efficacy can be determined.

Many regarded the drug as a major breakthrough last year when research showed that it actually cleared plaques associated with Alzheimer’s Disease from the brains of experimental mice. According to the Alzheimer Research Forum, two studies performed on mice with a genetic predisposition to developing Alzheimer’s Disease show remarkable results when treated with the vaccine. One study found that virtually all of the mice treated with AN-1792 had no detectable amyloid deposits in their brains compared to controlled groups that had no reduction in the progressive deposition of plaques. Another study showed that the treated mice had significantly less plaque and neuropathology than untreated mice. Recent studies also indicate that vaccination reverses or prevents cognitive deficits in transgenic mice that are susceptible to deposit amyloid plaque.

The clinical trial is still ongoing, but has been halted for an indefinite period while researchers try to determine the cause of the inflammation and possible remedies. “The well-being of patients is always our paramount concern. Our decision to temporarily suspend further dosing, pending the results of our evaluation, is a standard approach to protect the safety of patients in clinical trials,” stated Dr. Ivan Lieberburg, Elan’s Chief Scientific and Medical Officer.

“A decision will be made on resumption of dosing pending the outcome of this investigation,” Dr. Lieberburg said.  Since the side effects were only recently discovered, a spokesman said that a date for resumption of the clinical trials unavailable.

During Phase I clinical studies, the vaccine was found to be safe in patients with mild to moderate Alzheimer’s disease in a variety of dosage regimens. Phase II trials are designed to determine the correct dose at which the vaccine immunizes the patients against the buildup of beta amyloid plaques. Phase III trials are large scale tests designed to gauge long-term efficacy.

AN-1792 is one immuno-therapeutic vaccine approach being pursued by Elan and American Home Products' Wyeth-Ayerst Laboratories for the treatment of Alzheimer’s Disease, according to a company spokesman. The Wall Street Journal reported on January 21 that analysts who followed Elan and Wyeth-Ayerst expected the vaccine to be available to patients in the U.S. by about 2005. The spokesman for Elan said that the current setback would not impact progress on the other vaccine approaches, however, the true impact of the side effects on the future availability of AN-1792 will not be known until Elan scientists finish their studies.

Additional Resources:

Elan Pharmaceuticals Website
Alzheimer Research Forum
U.S. Food and Drug Administration
Alzheimer’s Disease Diagnosis and Treatment Guide from the Alzheimer Research Forum

Related Articles:

Vaccine Trials Announcement from ADEAR
Breakthrough? Understanding the Drug Development and Testing Process
Participating in Clinical Trials: What You Need to Know
ElderCare Online’s Medical Research Assistant


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