The FDA has granted Fast-Track status to Biogen Inc (NASDAQ:BIIB) Alzheimer’s drug candidate aducanumab. The development comes hot on the heels of Biogen’s posting of outcomes from early stage trials of the candidate.

With the Fast-Track designation, Biogen has joined rivals Eli Lilly and Co (NYSE:LLY) and AstraZeneca plc (ADR) (NYSE:AZN), who are working in concert to develop Alzheimer’s treatments, in getting preferential regulatory status for their Alzheimer’s candidates.

Fast-Track status is intended to speed up the approval process of a drug that has shown promise in combating serious conditions. In addition to the benefit of an accelerated regulatory review, a fast-track label also comes with cost-saving opportunity for the drug developer because shorter development times mean lower expenses.

Biogen posted Phase 1b data that showed its candidate aducanumab reduced amyloid plaques in the brain of patients with Alzheimer’s disease. Scientists conjecture that removing amyloid plaques may help slow down the progression of Alzheimer’s.

The Phase 1b enrolled 165 patients with prodromal and mild Alzheimer’s disease. Something to keep in mind regarding Biogen’s Phase 1 study is that the outcomes noted were dose and time dependent.

Encouraging study outcomes

The patients who received the highest dose of aducanumab, 10 mg per kilogram of bodyweight, were shown to be free of amyloid plaques in the brain after being on treatment for 12 months. Those observations were based on brain scan images.

Adverse events with higher dose

However, the highest dose level of aducanumab was accompanied by adverse events. One of the notable adverse events associated with higher dose of the medicine was amyloid-related imaging abnormalities or ARIA. It should be noted that ARIA can cause devastating swelling in the brain.

Biogen’s aducanumab is also in Phase 3 trials were it is being aimed at early Alzheimer’s patients.

Alzheimer’s disease is associated with old age and it is characterized by memory loss. The disease afflicts an estimated 5.4 million people in the U.S. alone.

Despite the encouraging Phase 1 outcome and FDA’s fast-track designation, shares of Biogen didn’t move much in the last session, indicating how investors are trying to be cautious trading on Alzheimer’s news.