The U.S. Food and Drug Administration (FDA) on Friday granted accelerated approval for the experimental dementia drug lecanemab.

The first class of drug, aducanumab, was approved by the FDA in June 2021. That drug, marketed as Aduhelm, addresses the underlying cause of the disease rather than the symptoms. Both drugs are made by the Japanese company Eisai Biologics.

“Alzheimer’s disease immeasurably incapacitates the lives of those who suffer from it and has devastating effects on their loved ones,” said Dr. Billy Dunn, director of the Office of Neuroscience in the FDA’s Center for Drug Evaluation and Research. “This treatment option is the latest therapy to target and affect the underlying disease process of Alzheimer’s, instead of only treating the symptoms of the disease.”

While the FDA has authorized six medications, there is no cure for Alzheimer’s disease, despite all scientific efforts and many lengthy and expensive clinical studies. The other five drugs are donepezil, rivastigmine, galantamine, memantine, and a combination of memantine and donepezil.

These medications can alleviate symptoms temporarily, but they can’t modify the underlying brain changes of Alzheimer’s disease or influence the trajectory of the disease. Nonetheless, these five medications have very minor side effects, such as headache and nausea.

Lecanemab targets a soluble version of amyloid-beta, while aducanumab binds to those plaques more strongly.

The agency is awaiting the results of an 18-month Phase 3 multicenter, double-blind controlled clinical trial of about 1,800 people in the early stages of Alzheimer’s disease to confirm the drug’s clinical benefit.

The drug company said it would work quickly to file a supplemental biologics license application to the FDA based on Phase 3 clinical trial data under the traditional pathway.

For 18 months, patients with early-stage Alzheimer’s got biweekly intravenous infusions of lecanemab, whereas controls received a placebo. The individuals’ cognition performance was principally tested using a metric known as the Clinical Dementia Rating-Sum of Boxes (CDR-SB).

According to the findings, 59.1 percent of individuals had brain amyloid reduction, 44 percent had cognition improvement on the CDR-SB evaluation scores, and the average daily living (ADL) level rose by a factor of two.

The FDA’s accelerated approval track allows for expedited approval of pharmaceuticals that cure critical diseases while the drugs are still undergoing larger and longer studies, so long as the medicines “fill an unmet medical need.”

If the drugs are shown, through clinical studies, not to show benefit, the FDA has regulatory mechanisms to remove the medicine from the market. However, if studies show therapeutic benefits, the agency may grant conventional approval.

The FDA said researchers assessed Leqembi’s effectiveness in a double-blind, placebo-controlled, parallel-group, dose-finding trial of 856 Alzheimer’s disease patients. Treatment was started in patients with moderate cognitive impairment or mild dementia who had amyloid beta pathology verified.

Patients who received the approved dose of lecanemab—10 milligram/kilogram every two weeks—had “significant dose- and time-dependent reduction of amyloid beta plaque,” the FDA statement said.

However, the study generated safety concerns due to some serious side effects being found, such as brain swelling and hemorrhage.

The FDA said Leqembi would include a warning for amyloid-related imaging abnormalities (ARIA). In serious cases, ARIA symptoms can be life-threatening but rare, according to the FDA. ARIA usually has no symptoms.

The most common adverse reactions during the Phase 2 trials were reported in 5 percent of 763 patients treated with Leqembi and 2 percent from the placebo group, according to Eisai’s Biologics. These patients were treated with 10 mg/kg biweekly of Leqembi.

Among the patients treated with Leqembi who experienced adverse reactions, 20 percent had infusion-related reactions, 14 percent had headaches, 10 percent had ARIA, 9 percent had a cough, and 8 percent had diarrhea.

The most common adverse reaction that led to stopping the clinical trial was infusion-related and occurred in 2 percent of patients treated with Leqembi compared to 1 percent of patients on placebo, according to the company’s data.