Biogen is seeking U.S. approval for Alzheimer’s disease drug aducanumab, the company announced Wednesday.

If approved by the Food and Drug Administration, the drug would be the first on the market to slow progression in Alzheimer’s, Biogen claims. Phase 3 trials in adults with early stage disease showed that the treatment reduced decline in cognition, memory, language, and activities of daily living performance, among other symptoms. Aducanumab removes amyloid beta, resulting in better clinical outcomes, the drugmaker reports.

The drug’s development has been a bit of a bumpy ride. Biogen halted four studies of aducanumab in March 2019 due to poor results, but a subsequent data analysis showed success with higher doses.

However, some experts are skeptical about the way the new data has been interpreted, and FDA approval is not guaranteed, according to Reuters. The agency has not reviewed an application for a new Alzheimer’s treatment for at least 15 years, the news outlet reported.