Early Data Suggest Benefit of Aducanumab in Alzheimer’s Disease

Investigators Observed Cases of ARIA

The incidence of amyloid-related imaging abnormalities (ARIA), however, did not follow this dose-dependent pattern. All eight cases of edematous ARIA (ARIA-E) in the long-term extension phase occurred in the placebo group that switched to 1 mg/kg and in the 1-mg/kg group that was titrated to 3 mg/kg. All cases occurred early in the extension phase, no new cases occurred during the past year, and all but one case occurred in carriers of APOE4.

Hemorrhagic ARIA occurred in two controls who switched to 1 mg/kg of aducanumab, five participants taking 3 mg/kg, two participants taking 6 mg/kg, and one patient taking 10 mg/kg. These cases occurred early in the trial. All of the ARIA cases, regardless of etiology, were considered mild and resolved spontaneously. In all, 46 patients in the PRIME trial have experienced ARIA, and six have had more than one episode.

The most common adverse events in the long-term extension phase were falls, headache, and ARIA. Two patients in the extension phase died, one in the 6-mg/kg group and one in the 10-mg/kg group. Neither death was considered to be related to the study medication.

—Michele G. Sullivan