In this video from Motley Fool Live, recorded on Jan. 4, Corinne Cardina, bureau chief of healthcare and cannabis, and Fool.com contributor Brian Orelli discuss the upcoming decision by the Food and Drug Administration (FDA) over whether to approve aducanumab, Biogen's (BIIB +2.26%) Alzheimer's disease drug. The FDA's leadership supports the marketing application, but the agency's advisory committee of outside experts voted against the approval, setting up a pivotal moment that could set the stage for the rest of 2021 and beyond.

Corinne Cardina: Let's talk a little bit more about the FDA. Of course, the FDA had some setbacks in 2020 because of the pandemic. They have to defer some decision dates, because they weren't able to get out there into manufacturing sites and do the checks that they need to do, but they do have some dates coming up in the next couple of months. What is the top FDA decision that you are going to be watching this year?

Brian Orelli: I mean, without a doubt, it's Biogen's Alzheimer's disease [drug] aducanumab. It's under review right now, and the FDA is scheduled to make a decision on or before March 7, although that's not quite a deadline, [it's] more of a goal for the FDA, and they can miss it if they need to. The FDA leadership was really positive in the briefing documents that the advisory committee was given in November; there was maybe some dissenting opinion among the statisticians at the agency, but the leadership seemed very gung ho about the drug. The advisory committee, which is a group of outside doctors and other people, were generally negative, and they ultimately voted not to recommend approving the drug. But the FDA has the final say, so it still could get approved.

Alzheimer's disease is a very large market, probably [an] opportunity in the $10 billion plus range, I think, for the top-selling drug. It could be the top-selling drug in the world. Even if it is approved, I think it's unlikely to reach that full potential, because the key opinion leaders -- those would be some of the doctors with clout -- aren't likely to get behind the drug and endorse it. So I think it's going to be hard for the drug to reach full potential.

I really think they need to run another clinical trial to prove out their hypothesis, which is that "more drug" helps patients than "less drug." That's the whole basis here, is that they had data that showed that more drug helps patients better than less drug, but they stopped the clinical trial early and so it's hard to interpret the data. I think they really need to run another clinical trial showing that the higher dose actually helps patients.

Cardina: Right. The endpoint of this drug is to slow the progression of Alzheimer's. Is that right?

Orelli: Yeah. Slow the cognitive decline.