# 2025-23865: LEQEMBI Gets Patent Boost: FDA Extends Drug Monopoly Time

2025-23865, Determination of Regulatory Review Period for Purposes of Patent Extension; LEQEMBI, is a Federal Register notice from Health and Human Services Department, Food and Drug Administration published 2025-12-29, effective 2025-12-29 (as of 2026-06-08).

- Canonical: https://policyrisk.com/federal-register/2025-23865
- As of: 2026-06-08
- Plain-text twin of the page above; the HTML and this file carry the same facts.

## Facts
- Document number: 2025-23865
- Title: Determination of Regulatory Review Period for Purposes of Patent Extension; LEQEMBI
- Type: Notice
- Agencies: Health and Human Services Department; Food and Drug Administration
- Citation: 90 FR 60717
- Published: 2025-12-29
- Effective: 2025-12-29
- Comments close: 2026-02-27
- Significant: no
- Touches household money: no
- Regulation identifier numbers: none
- Last updated: 2026-06-08

## In one line

LEQEMBI Gets Patent Boost: FDA Extends Drug Monopoly Time

## Summary

The FDA has officially set the review period for LEQEMBI, a new medicine, so its patent can be extended. This helps the company protect their invention longer, which might affect when generic versions can appear. If anyone thinks the dates are wrong or wants to challenge the company’s effort during review, they must act by early 2026.

## Abstract

The Food and Drug Administration (FDA or the Agency) has determined the regulatory review period for LEQEMBI and is publishing this notice of that determination as required by law. FDA has made the determination because of the submission of an application to the Director of the U.S. Patent and Trademark Office (USPTO), Department of Commerce, for the extension of a patent which claims that human biological product.

## Effects PRIA read

- FDA Sets LEQEMBI Review Period: cost, high. The FDA determined LEQEMBI's regulatory review period is 4,546 days (4,300 days testing phase and 246 days approval phase) using these dates: IND effective July 29, 2010; BLA submitted May 6, 2022; approval January 6, 2023. This determination establishes the maximum potential length of any patent t…
- Deadlines To Challenge Dates or Diligence: benefit, low. Anyone who believes the published dates are incorrect must request a redetermination by February 27, 2026. Any interested person may petition FDA to challenge whether the applicant acted with due diligence during the regulatory review period by June 29, 2026.

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## Sources
- [2025-23865 on federalregister.gov](https://www.federalregister.gov/documents/2025/12/29/2025-23865/determination-of-regulatory-review-period-for-purposes-of-patent-extension-leqembi)
- [2025-23865 as published (PDF)](https://www.govinfo.gov/content/pkg/FR-2025-12-29/pdf/2025-23865.pdf)

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Source: PRIA, https://policyrisk.com/federal-register/2025-23865 (as of 2026-06-08).