FDA grants priority review for traditional approval of Biogen and Eisai’s Alzheimer’s drug

The US Food and Drug Administration (FDA) has granted priority review for the traditional approval of Eisai and Biogen's Alzheimer’s treatment, Leqembi (lecanemab-irmb).

The drug was authorised for use earlier this year for patients with mild cognitive impairment or mild dementia stage of disease through the accelerated approval pathway, under which the FDA may approve drugs for serious conditions where there is an unmet medical need.

This decision was based on phase 2 data showing that Leqembi reduced the accumulation of amyloid beta plaque in the brain, a defining feature of Alzheimer’s disease.

Billy Dunn, director of the office of neuroscience in the FDA’s centre for drug evaluation and research, explained at the time: “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.”

Eisai’s supplemental biologics application for approval under the traditional pathway is now supported by data from the phase 3 confirmatory Clarity AD clinical trial.

The study met its primary endpoint, reducing clinical decline by 27% on the global cognitive and functional scale – Clinical Dementia Rating-Sum of Boxes – compared with placebo at 18 months.

All key secondary endpoints also showed highly statistically significant results compared with placebo, the companies reported, including other measures of cognition and daily function.

Affecting more than 6.5 million Americans, Alzheimer’s disease is an irreversible, progressive brain disorder that slowly destroys memory and thinking skills and, eventually, the ability to carry out simple tasks.

While the specific causes of Alzheimer’s are not fully known, it is characterised by changes in the brain, including amyloid beta plaques, that result in loss of neurons and their connections.

Eisai and Biogen have been collaborating on the joint development and commercialisation of Alzheimer’s disease treatments since 2014.

Biogen’s own Alzheimer’s drug, Aduhelm (aducanumab), received a safety-related change to its US labelling last month.

The new label states that physicians prescribing the drug should ‘inform patients that events of intracerebral haemorrhage greater than 1cm in diameter have been reported infrequently in patients taking Aduhelm, and that the use of antithrombotic or thrombolytic medications while taking Aduhelm may increase the risk of bleeding in the brain’.