ACC-001 is a vaccine designed to prime the body's immune system to create antibodies against beta amyloid, the toxic protein that forms plaques in the brain believed to play a key role in Alzheimer disease.
Wyeth and Elan are developing ACC-001 as a second-generation version of an older Alzheimer vaccine, AN1792. The latter vaccine's development was stopped in 2001 after some patients were hospitalized due to swelling in the brain.
According to Elan spokesman Jonathan Birt, one patient dosed with ACC-001 in a phase II trial was hospitalized with what the patient's physician described as a "skin lesion, possibly vasculitis." The patient was treated successfully and has since been discharged from the hospital.Vasculitis is an inflammation of blood vessels that can be caused by an immune, or allergic, reaction. The severity of vasculitis can vary widely, but Birt had no more information about the ACC-001 patient. A later biopsy, however, did not confirm vasculitis, according to a Wyeth spokesperson. Elan and Wyeth have informed regulators both in the U.S. and Europe about the hospitalization, which led to the suspension of the ACC-001 clinical trial. The study has not been permanently halted, Birt says. A notice of the ACC-001 study suspension was posted on the ClinicalTrials.gov Web site. The negative safety signal detected with ACC-001 has not affected the ongoing clinical trials of bapineuzumab, the other major Alzheimer drug being developed by Elan and Wyeth, Birt says. Thursday's news comes one day after Elan shares rose sharply after the company and partner Biogen Idec (BIIB - Get Report) reported a stronger-than-expected increase in the number of patients treated with their multiple sclerosis drug Tysabri. Elan shares were down 4.1% at $23.31 in recent trading, while Wyeth shares were losing 1.5% to $43.57.