Drugmaker Biogen is launching a new Phase 3 clinical trial to determine long-term safety and efficacy of its Alzheimer’s disease drug aducanumab.

The trial, called EMBARK, is a re-dosing study of aducanumab in patients with Alzheimer’s who took part in earlier clinical studies of the drug. In the 24-month study, participants will receive 10 mg/kg aducanumab via infusion every four weeks, according to Biogen. EMBARK is expected to be one of the largest clinical trials in Alzheimer’s disease, with a planned enrollment of 2,400 participants, the company said. 

Aducanumab has been shown to remove beta amyloid — a hallmark of Alzheimer’s — from the brain. But the drug has had a spotty clinical trial record, with studies halted in 2019.

Initial clinical trial results for aducanumab did not convince the independent experts who advise the Food and Drug Administration that it is ready for federal approval. In November, they voted eight to one against approving the drug, and they reaffirmed that position in a recent editorial.

That’s despite an unusual show of support from the FDA. In fact, the agency was due to vote on the drug’s approval this spring but has pushed back a scheduled vote until June. It is not bound to follow the approval committee’s vote, and others have countered that the company’s original trial findings are strong enough to win authorization for the drug, with benefits outweighing risks.

Details on the new EMBARK trial were presented at the April 2021 American Academy of Neurology annual meeting, according to Physician’s Weekly.