The U.S. Food and Drug Administration (FDA) took a noteworthy step on Thursday by fully authorizing Leqembi, a novel Alzheimer’s drug. This development unfolds amidst concerns about the drug’s safety, cost, and availability.

This approval marks a milestone in Alzheimer’s disease management. Unlike prior treatments that merely addressed symptoms, Leqembi is the first drug designed to slow disease progression and has earned full regulatory endorsement.

University of Kentucky’s Assistant Dean of Biomedicine, Donna Wilcock, asserted, “I don’t think we can understate the significance of this moment,” per NBC News.

Created by Eisai, a Japanese pharmaceutical company, and Biogen, an American firm, Leqembi targets beta-amyloid, a brain protein scientists believe triggers Alzheimer’s disease.

It’s estimated that Alzheimer’s affects 6.7 million adults over 65 in the U.S. alone, making this drug’s introduction a consequential development.

Trials showcased Leqembi’s potential; a phase 3 study involving 1,795 patients with mild cognitive impairment or early-stage Alzheimer’s reportedly noted a 27% reduction in disease progression over 18 months.

However, Mayo Clinic Neurologist Dr. Ronald Petersen emphasized that Leqembi is not a cure but rather “a first step for hopefully more therapeutics in the future.”

Alzheimer’s Association CEO Joanne Pike said she believes Leqembi could “give people in the early stages of Alzheimer’s more time to maintain their independence and do the things they love.”

However, some experts, like Dr. Alberto Espay, a neurologist at the University of Cincinnati College of Medicine, questioned Leqembi’s benefits. Espay argued that the 27% slowdown in disease progression is hardly noticeable to patients and voiced concerns about potential side effects.

The FDA’s approval came with a strong warning about possible side effects, such as brain swelling and hemorrhage, leading to seizures and even death. These concerns were not unfounded; 12.6% and 17% of patients using Leqembi in the trial experienced brain swelling and brain bleeds, respectively.

Despite these figures, Dr. Petersen clarified that brain side effects, observable through MRI scans, were asymptomatic in about 75% of people.

Leqembi is administered intravenously every two weeks. However, with an annual price tag of $26,500, getting this drug may remain challenging for patients. Despite Medicare’s promise to cover 80% of the drug’s cost post-deductible, patients’ out-of-pocket expenses could still reach the thousands.

Despite the controversy, the Alzheimer’s Association celebrated the news of Leqembi’s approval as the first drug that “changes the underlying course of the disease.”