Human head next to damaged neurons to indicate Alzheimer's disease
Credit: Science Photo Library - PASIEKA/Getty Images

Lecanemab, Biogen and Eisai’s Alzheimer’s disease drug for treating mild cognitive impairment in the early stages of the disease, has achieved positive results in a large phase III trial.

The drug met both primary and secondary endpoints and reduced clinical decline on the global cognitive and functional scale by 27% compared to placebo at 18 months.

The positive news will be a relief for both companies after the controversial and largely unsuccessful launch of Aduhelm (aducanumab), another Alzheimer’s drug developed by the partners.

Aduhelm was approved by the FDA last year, despite only showing mild improvements in symptoms in those with the condition, but its use was limited by Medicare to patients in clinical trials only and it has not been a commercial success to date.

In contrast, the results for lecanemab were highly significant. The phase III Clarity study included 1795 people with early-stage Alzheimer’s disease who were randomly assigned to receive bi-weekly 10 mg/kg lecanemab or placebo in a 1:1 ratio.

The study recruited people with a wide range of comorbidities, many of who were also taking other medications. Around 25% of the U.S. participants were Hispanic or African American.

As well as the primary endpoint of a significant improvement in the global cognitive and functional scale of 27%, the study also met all secondary endpoints. These included the change from baseline at 18 months compared with placebo in amyloid levels in the brain measured by amyloid positron emission tomography, the AD Assessment Scale-cognitive subscale14, AD Composite Score and the AD Cooperative Study-Activities of Daily Living Scale for Mild Cognitive Impairment.

Adverse events were mild-moderate. Amyloid-related imaging abnormalities of edema or effusion (ARIA-E) is an adverse event associated with anti-amyloid antibodies such as lecanemab. The rates of ARIA-E were 12.5% in the lecanemab group and 1.7% in the placebo group, but symptomatic ARIA-E was only 2.8% in the lecanemab group and 0.0% in the placebo group.

“The positive result of the lecanemab, an anti-Aβ protofibril antibody, pivotal study after almost 25 years since Aricept’s launch is an important milestone for Eisai in fulfilling our mission to meet the expectations of the Alzheimer’s disease community,” said Haruo Naito, CEO at Eisai, in a press statement.

“Additionally, the lecanemab Clarity AD study results prove the amyloid hypothesis, in which the abnormal accumulation of Aβ in the brain is one of the main causes of Alzheimer’s disease, when targeted with a protofibril-binding therapy. Eisai believes these findings will create new horizons in the diagnosis and treatment of Alzheimer’s disease as well as further activate innovation for new treatment options.”

Based on these results and others, Eisai plans to file for marketing approval in the U.S., Japan and Europe by early 2023. The company has already started the process with the FDA using the Accelerated Approval Pathway. Both companies will commercialize and promote the product following approval in different countries.

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