Eisai Co., Ltd. and Biogen Inc. announced that Eisai submitted to the U.S. Food and Drug Administration a Supplemental Biologics License Application (sBLA) for monthly lecanemab-irmb (U.S. brand name: LEQEMBI®) intravenous (IV) maintenance dosing. LEQEMBI is indicated for the treatment of Alzheimer's disease in patients with mild cognitive impairment or mild dementia stage of disease (collectively referred to as early AD). As part of the monthly IV maintenance regimen, the patients who have completed the biweekly IV initiation phase, exact period under discussion with the FDA, would receive a monthly IV dose that maintains effective drug concentration to sustain the clearance of highly toxic protofibrils which can continue to cause neuronal injury even after the amyloid-beta (Aß) plaque has been cleared from the brain. The sBLA is based on modeling of observed data from the Phase 2 study (Study 201) and its open-label extension (OLE) as well as Clarity AD study (Study 301) and its OLE study.

Eisai had aimed to submit a Biologics License Application (BLA) for weekly maintenance therapy using subcutaneous administration in March 2024. To respond to the FDA's recent requirement of additional three-month immunogenicity data at the proposed maintenance dose of 360 mg weekly, Eisai planned to initiate a rolling BLA for lecanemab SC maintenance in March 2024, under the existing Fast Track and Breakthrough Therapy designations. However, Eisai was recently informed by the FDA that a Fast Track designation specific for the SC formulation is needed to receive rolling review.

Following the guidance, Eisai submitted a request for Fast Track designation for the SC formulation and will initiate a rolling submission should the FDA grant this designation. The Fast Track designation will be determined within 60 days from the March 2024 submission. AD is an ongoing neurotoxic process that begins before and continues after plaque deposition.

There is an urgency to treat early AD because early and ongoing treatment can slow the progression of AD and continuing treatment may prolong the benefit even after plaque is cleared from the brain. The earlier Mild Cognitive Impairment (MCI) due to AD and mild AD dementia are diagnosed and treated, the greater the opportunity for the patient to benefit. Continued maintenance dosing is intended to maintain the clinical and biomarker benefits with a dosing regimen that may be more convenient for some patients and their care partners.

LEQEMBI is now approved in the U.S., Japan and China, and applications have been submitted for review in the European Union, Australia, Brazil, Canada, Hong Kong, Great Britain, India, Israel, Russia, Saudi Arabia, South Korea, Taiwan, Singapore, and Switzerland. Eisai serves as the lead for lecanemab's development and regulatory submissions globally with both companies co-commercializing and co-promoting the product and Eisai having final decision-making authority. Monoclonal antibodies directed against aggregated forms of amyloid beta, including LEQEMBI, can cause amyloid related imaging abnormalities (ARIA), characterized as ARIA with edema (ARIA-E) and ARIA with hemosiderin deposition (ARIA-H).

Incidence and timing of ARIA vary among treatments. ARIA usually occurs early in treatment and is usually asymptomatic, although serious and life-threatening events rarely can occur. Serious intracerebral hemorrhages >1 cm, some of which have been fatal, have been observed in patients treated with this class of medications.

Apolipoprotein E e4 (ApoE e4) Homozygotes: Patients who are ApoE e4 homozygotes (approximately 15% of Alzheimer's disease patients) treated with this class of medications, including LEQEMBI, have a higher incidence of ARIA, including symptomatic, serious, and severe radiographic ARIA, compared to heterozygotes and noncarriers. Testing for ApoE e4 status should be performed prior to initiation of treatment to inform the risk of developing ARIA. Prior to testing, prescribers should discuss with patients the risk of ARIA across genotypes and the implications of genetic testing results.

Prescribers should inform patients that if genotype testing is not performed, they can still be treated with LEQEMBI; however, it cannot be determined if they are ApoE e4 homozygotes and at higher risk for ARIA. WARNINGS AND PRECAUTIONS Amyloid Related Imaging Abnormalities · LEQEMBI can cause ARIA-E and ARIA-H. ARIA-E can be observed on MRI as brain edema or sulcal effusions, and ARIA-H as microhemorrhage and superficial siderosis. ARIA can occur spontaneously in patients with Alzheimer's disease.

ARIA-H associated with monoclonal antibodies directed against aggregated forms of beta amyloid generally occurs in association with an occurrence of ARIA-E. ARIA-H and ARIA-E can occur together. ARIA usually occurs early in treatment and is usually asymptomatic, although serious and life-threatening events, including seizure and status epilepticus, rarely can occur. Reported symptoms associated with ARIA may include headache, confusion, visual changes, dizziness, nausea, and gait difficulty.

Focal neurologic deficits may also occur. Symptoms associated with ARIA usually resolve over time.