Clinical trials results are “exceptionally persuasive” that Biogen’s plaque-removing Alzheimer’s disease drug aducanumab is effective, Food and Drug Administration staff members say, according to a Reuters report.

An FDA advisory committee is set to vote this Friday on whether the agency should approve it for commercial use. Documents released on Wednesday, however, show that the agency’s staff members already are enthusiastic about the drug’s prospects, reported investigators Deena Beasley and Manojna Maddipatla. If approved, aducanumab could be the first drug on the market to slow Alzheimer’s progression.

Results from a “pivotal” clinical trial were strong, FDA drug reviewers said, according to the news outlet. And although a second large clinical trial did not succeed, that outcome does not detract from the positive findings, they added. 

The FDA is not bound to follow the vote by its advisers, a panel of independent experts. Notably, a panel adviser who has criticized the drug and called for more testing to prove its efficacy was officially recused from the advisory panel this week due to his involvement in some of the clinical trials.

“Aducanumab’s efficacy as a treatment for the cognitive dysfunction in Alzheimer’s disease cannot be proven by clinical trials with divergent outcomes,” wrote neurologist David Knopman, M.D., and colleagues in a perspective piece published in the journal Alzheimer’s & Dementia on Monday.

But other researchers involved in the trials have pushed back. “We believe the data are sufficient to warrant approval with Phase 4 surveillance,” wrote Marwan Noel Sabbagh M.D., and colleagues in response. “Lack of approval would be devastating not only to patients who will lose hope but advocates and the community at large,” they wrote.

Aducanumab is an antibody that targets amyloid-beta plaques, a hallmark feature of Alzheimer’s which interferes with memory and other brain functions. It was given intravenously in the trials.