New Alzheimer's drug slows cognitive decline, clinical trial finds

• A clinical trial of a new Alzheimer's drug from Eisai and Biogen has shown promising results.
• The large-scale study saw cognitive decline in patients slow by 27% over 18 months.

A new Alzheimer's drug from the Japanese pharmaceutical company Eisai and the US drugmaker Biogen has shown promising results in a large-scale clinical trial.

The companies announced the trial's success in a press release Tuesday, saying that cognitive decline slowed 27% in patients using their drug — called lecanemab — over 18 months compared with those using a placebo.

The companies said 1,795 patients with early-stage Alzheimer's were randomly selected to receive a placebo treatment or doses of lecanemab every two weeks. Their cognitive decline was then measured on six fronts, including "memory, orientation, judgment and problem solving, community affairs, home and hobbies, and personal care."

The statement said lecanemab significantly "reduced clinical decline" over the 18 months.

Lecanemab, per Eisai, is a monoclonal antibody treatment, which targets toxic amyloid plaques — protein clumps that researchers proposed were the cause of the neurodegeneration seen in Alzheimer's.

The companies noted that about 21% of the patients who received the lecanemab treatment experienced brain swelling that was visible on PET scans.

"Today's announcement gives patients and their families hope that lecanemab, if approved, can potentially slow the progression of Alzheimer's disease, and provide a clinically meaningful impact on cognition and function," Biogen CEO Michel Vounatsos said in the companies' joint press release.

Eisai's CEO, Haruo Naito, said in the press release that the lecanemab study's success was "an important milestone for Eisai in fulfilling our mission to meet the expectations of the Alzheimer's disease community."

According to Eisai's press release, the company is hoping to submit its trial data to the US Food and Drug Administration for approval by March.

Speaking with Statnews, Lon Schneider, an Alzheimer's expert at the Keck School of Medicine of the University of Southern California, said it was likely that the FDA would approve lecanemab. Schneider warned, however, that experts would have to look into the trial results in more detail.

"This is a statistically robust and positive study but the treatment effect is small," Schneider told the outlet.

Ronald Petersen, a neurologist at the Mayo Clinic in Rochester, Minnesota, told NBC News that the results were "a first step in the direction of making a significant impact on the disease."

"This is really positive for the field," Petersen said. "I think it's going to motivate a lot more beneficial research down the road."