The promising Alzheimer vaccine AN-1792, which showed impressive clinical results as a treatment for mild to moderate Alzheimer’s disease last summer, has suffered a setback in the current Phase 2A clinical trial.
The Elan corporation and Wyeth-Ayerst Laboratories have decided to temporarily suspend dosing in this Phase 2A study after four patients in France were reported to have clinical signs consistent with inflammation in the central nervous system. All four patients are receiving appropriate medical care and the companies are working with clinical investigators to determine the cause of this development.
“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.”
There are many agents and mechanisms that can result in inflammation of the central nervous system, one being a viral infection. The presence of virus within the cerebrospinal fluid was reported in some of the four patients under investigation. However, the cause of the inflammation remains to be determined.
To date, approximately 360 patients have received multiple doses of AN-1792. In the Phase 2A study, 97 patients in France have received the drug.
The study is still ongoing however, and the dosing schedule should provide time for the clinical investigation to occur without jeopardizing study conduct.
In Phase 1 safety studies, AN-1792 was administered to more than 80 patients with mild to moderate Alzheimer’s disease in a variety of dosage regimens. The results from the U.S. single dose trial, and the U.K. multiple dose trial indicated that AN-1792 was well tolerated and that a proportion of patients developed an appropriate immunological response to AN-1792.
The Phase 2A study was designed to measure the immune response to beta amyloid peptide immunization in patients with Alzheimer’s disease. Patients with mild to moderate Alzheimer’s disease were enrolled and evaluated using conventional cognitive tests and by other surrogate measures.
The results of this study are expected to provide additional information regarding the immune response to AN-1792, as well as valuable information useful for the development of other therapeutic agents being studied as part of the collaborative development program.