Biogen slips on Phase III AD studies

Biogen Inc. (NASDAQ:BIIB) lost $20.91 to $296.08 on Wednesday after EVP and CMO Alfred Sandrock said the company will enroll a total of an additional 510 patients in the Phase III ENGAGE and EMERGE trials of aducanumab (BIIB037) to treat early Alzheimer's disease. The candidate is a human recombinant anti-beta amyloid mAb.

Sandrock said at the Leerink Partners Global Healthcare Conference that in a pre-planned blinded sample size re-estimation, the company found "variability" in the primary endpoint of Clinical Dementia Rating-Sum of Boxes (CDR-SB) score at week 78 and decided to increase enrollment to maintain 90% power. Biogen still plans to complete enrollment by mid-year.

According to ClinicalTrials.gov, each trial is enrolling about 1,350 patients at the postings' last update of Jan. 23.