The maker of a highly touted experimental Alzheimer's vaccine has halted development of the compound after 15 patients suffered serious brain inflammation.
But Elan Corp. said it still is pursuing vigorously a vaccine to slow worsening of Alzheimer's, and has other candidates that look promising in animal testing.
Still, Friday's announcement marks a serious setback.
The Irish drug manufacturer excited researchers in 2000 when it discovered that in mice, the compound code-named AN-1792 could ward off and even reduce brain-clogging plaques that are a hallmark of Alzheimer's disease.
Initial safety tests in people showed no adverse effects. But because the vaccine works by inducing the immune system to attack the protein that makes up those plaques, called beta amyloid, some scientists had warned that brain inflammation was a potential serious side effect.
In January, Elan suspended the latest 360-patient experiment when it discovered four people suffering an encephalitis-like brain inflammation. Since then, doctors have discovered 11 more patients with those symptoms. All are stable or recovering; none is critically ill, said Elan medical officer Dr. Ivan Lieberburg.
Still, Elan decided Friday to abandon AN-1792 because of the risk. It will continue monitoring all patients in the study, both for side effects and to see if the injections had any benefit against Alzheimer's.
It is not unusual for experimental medications to hit a snag during such early testing. Lieberburg said Elan did not pin all hopes on AN-1792 but has several other candidates that studies in mice suggest are "just as good or better" at clearing away amyloid, Lieberburg said.
The idea is to try compounds that stimulate the immune system in slightly different ways, in hopes of posing less chance of inflammation