FDA: Specific Fast Track Designation for Subcutaneous Formulation of Leqembi for Alzheimer Disease Needed for Rolling Review


This alters the course of developer Eisai's regulatory submission plans for lecanemab in the treatment of early Alzheimer disease.



The US Food and Drug Administration (FDA) has informed lecanemab-irmb (US brand name: Leqembi®) developers Eisai Co Ltd and Biogen Inc that a Fast Track designation specific to the subcutaneous formulation of the drug is necessary to proceed with rolling review.1

Eisai announced in February that its goal was to have treated 10,000 patients with lecanemab by the conclusion of its fiscal year in March 2024. However, according to Eisai's third-quarter earnings presentation, as of January 26, only 2000 patients in the United States were undergoing treatment with this amyloid-busting antibody.2

The latest notification by the FDA alters the course of Eisai's regulatory submission plans for lecanemab in the treatment of early Alzheimer disease. Initially, Eisai had aimed to submit a Biologics License Application (BLA) for weekly maintenance therapy via subcutaneous administration in March 2024. However, the FDA's recent requirement for additional 3-month immunogenicity data at the proposed maintenance dose of 360 mg weekly prompted Eisai to plan a rolling BLA submission.1

Following this, the FDA notified Eisai of the necessity for a Fast Track designation specific to the subcutaneous formulation to proceed with rolling review. Eisai has submitted a request for Fast Track designation, and the decision is expected within 60 days of the March 2024 submission.1

“[T]hese are technicalities in our view and do not undermine the potential of Leqembi,” said analysts from William Blair in a recent statement to clients. “But they are disappointing delays for Biogen, which clearly needs to demonstrate better execution to improve investor sentiment.”3

This development underscores the shifting regulatory landscape surrounding lecanemab's pathway to approval for the treatment of Alzheimer disease.1 A non-subcutaneous formulation of the drug received traditional FDA approval for the treatment of Alzheimer disease in July 2023, making it the first amyloid beta-directed antibody for the treatment of Alzheimer disease treatment to transition from accelerated to traditional approval.4

The FDA's decision to grant traditional approval stemmed from the outcomes of a confirmatory trial, which substantiated the drug's clinical benefits. Initially, lecanemab received accelerated approval from the FDA in January 2023 and received unanimous endorsement for its clinical benefit and efficacy from an FDA Advisory Committee in June 2023.4

At the time of this announcement, Helen Lavretsky, MD, MS, told Psychiatric Times® that:

“The FDA approval of lecanemab is an important milestone for millions of those suffering from mild to moderate Alzheimer’s disease and their families that will allow the disease-modifying drug to delay the progression of Alzheimer’s disease by 6 months or longer. It comes with the controversies of high cost of the drugs, modest efficacy, complex and expensive monitoring of CNS severe side effects (ARIA), but it also opens the age of the disease-modifying treatments that were not previously available, and the realization for the need of multi-component interventions that include lifestyle, cognitive training, and other preventive strategies.”

Lavretsky is a professor in residence in the Department of Psychiatry at UCLA in Los Angeles, California; president-elect of the American Association for Geriatric Psychiatry; a distinguished fellow of the American Psychiatric Association and of the American Association for Geriatric Psychiatry; a fellow of the American College of Neuropsychopharmacology; and a member of the board at Psychiatric Times.

Are you interested in learning more about new treatments and developments in the Alzheimer disease space? Here is some recent coverage from Psychiatric Times®:

Phase 3 Trials Examine Gantenerumab for Early Alzheimer Disease

Drug Candidate for Schizophrenia, Alzheimer Disease Approved to Initiate Phase 2 Trial in Q2 2024

Biogen Discontinues Aducanumab for Alzheimer Disease

Exploring the Role of Brexpiprazole in Alzheimer Dementia Agitation

Stay up-to-date on news related to research on promising new interventions and developments in the treatment of a wide variety of psychiatric disorders at psychiatrictimes.com.

Note: This article was prepared with the assistance of ChatGPT.


1. Eisai completes submission of LEQEMBI® (lecanemab-irmb) Supplemental Biologics License Application for IV maintenance dosing for the treatment of early Alzheimer’s disease to the US FDA. Biogen Inc. News release. April 1, 2024. Accessed April 3, 2024. https://investors.biogen.com/news-releases/news-release-details/eisai-completes-submission-leqembir-lecanemab-irmb-supplemental

2. Kansteiner F. Eisai, Biogen likely to miss early launch goal for Alzheimer’s drug Leqembi. Fierce Pharma. February 7, 2024. Accessed April 3, 2024. https://www.fiercepharma.com/pharma/eisai-and-biogens-leqembi-rollout-alzheimers-lags-patient-demand

3. Liu A. Eisai, Biogen’s injectable Leqembi delayed as FDA asks for more data. Fierce Pharma. April 1, 2024. Accessed April 4, 2024. https://www.fiercepharma.com/pharma/eisai-biogens-injectable-leqembi-delayed-fda-asks-more-data

4. O’Brien E. FDA grants traditional approval to Leqembi for the treatment of Alzheimer disease. Psychiatric Times. July 6, 2023. Accessed April 3, 2024. https://www.psychiatrictimes.com/view/fda-grants-traditional-approval-to-leqembi-for-the-treatment-of-alzheimer-disease

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