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Eisai, Biogen's Anti-Amyloid Alzheimer's Drug Leqembi Gains Full FDA Approval

3D illustration showing amyloid plaques in Alzheimer's disease

NEW YORK – The US Food and Drug Administration on Thursday granted Eisai full approval for its Alzheimer's disease drug Leqembi (lecanemab), converting the accelerated approval the company received for the treatment in January.

Leqembi, developed by Eisai and Biogen, is the first Alzheimer's treatment that targets beta-amyloid proteins to be converted from an accelerated approval to a traditional approval by US regulators.

When beta-amyloid proteins clump together, they form plaques that are a hallmark of the degenerative brain disease that many say is its root cause. The FDA had initially granted Leqembi accelerated approval based on its ability to clear these amyloid plaques, a surrogate endpoint that the agency felt was reasonably likely to predict clinical benefits. The FDA has now determined that Leqembi's clinical benefits have been confirmed in the CLARITY AD Phase III randomized, placebo-controlled clinical trial, allowing for a full approval.

"Today's action is the first verification that a drug targeting the underlying disease process of Alzheimer's disease has shown clinical benefit in this devastating disease," Teresa Buracchio, acting director of the Office of Neuroscience in the FDA's Center for Drug Evaluation and Research, said in a statement.

CLARITY AD trial investigators enrolled nearly 1,800 Alzheimer's patients with mild cognitive impairment or mild dementia and amyloid-beta pathophysiology and randomly assigned them to receive either placebo or Leqembi once every two weeks. Patients on Leqembi had slower disease progression based on the Clinical Dementia Rating Scale Sum of Boxes (CDR-SB) than those in the placebo arm.

Patients after 18 months on Leqembi saw an average increase of 1.21 points from baseline on the CDR-SB. Meanwhile, those on placebo averaged an increase of 1.66 points on this scale. That represented a statistically significant treatment effect, with Leqembi-treated patients experiencing a 27 percent slower rate of cognitive decline.

"This treatment, while not a cure, gives people in the early stages of Alzheimer's disease more time to maintain their independence and do the things they love," Joanne Pike, president and CEO of the Alzheimer's Association, said in a statement voicing the patient advocacy group's support for Leqembi garnering the FDA's full approval.

In June, experts on the FDA's Peripheral and Central Nervous System Drugs Advisory Committee unanimously agreed that the results of the CLARITY AD trial verified Leqembi's clinical benefit in Alzheimer's patients. While recommendations from the FDA's independent expert groups are nonbinding, the agency usually follows their advice.

The FDA controversially went against its advisory committee's recommendation when it granted accelerated approval to Aduhelm (aducanumab), another Alzheimer's drug developed by Biogen and Eisai that targets beta-amyloid, but which didn't definitively show clinical benefits to the degree that Leqembi has. While Aduhelm remains on the market, Biogen has said it is no longer marketing it as the company shifts its focus to Leqembi.

The FDA-approved indication for Leqembi makes it available to adult Alzheimer's patients with mild cognitive impairment or mild dementia. The label for the drug instructs doctors to confirm the presence of amyloid-beta pathology before starting treatment. 

The most common side effects Leqembi-treated patients experienced in clinical trials were headache, infusion-related reactions, and amyloid-related imaging abnormalities (ARIA). In Leqembi's labeling, the FDA has included a boxed warning about the risk of ARIA and recommends testing patients to assess if they carry two copies of the APOE ε4 allele before starting treatment, since homozygous carriers have a higher risk of ARIA. The agency also cautions against prescribing Leqembi to patients taking anticoagulant medications, which are associated with an increased risk of intracerebral hemorrhages.

The latest FDA decision is especially important for reimbursement and patients' ability to access Leqembi, which has a list price of $26,500 a year. The US Centers for Medicare & Medicaid Services on Thursday said it would cover the treatment, staying in line with previous statements that it would reimburse anti-amyloid monoclonal antibodies for Alzheimer's that have traditional approval from the FDA. When such drugs are under accelerated approval, Medicare has said it will cover them when given to patients in certain clinical trials. 

For Medicare patients to receive covered access to Leqembi in clinical settings, their providers must agree to collect long-term outcomes data. CMS has opened a nationwide registry to which clinicians can submit this data and has said it will post on its website other registries that may be used for this purpose as they become available in coming months.