FDA advises increased monitoring for brain swelling in Leqembi patients.

The FDA has recommended earlier brain imaging scans for patients on Eisai and Biogen's Alzheimer's drug Leqembi to monitor for brain swelling. This increased monitoring aims to detect amyloid-related imaging abnormalities before the third infusion of the drug. The recommendation is intended to ensure patient safety while using the treatment.

The U.S. Food and Drug Administration (FDA) has recommended earlier brain imaging scans for patients taking Eisai and Biogen's Alzheimer's drug Leqembi. The aim is to monitor for brain swelling and detect amyloid-related imaging abnormalities (ARIA-E) before the third infusion of the drug. This heightened monitoring is intended to ensure patient safety while using the treatment.

Leqembi, an amyloid beta-directed antibody, was approved in 2023 to slow the progression of Alzheimer's disease in patients with mild cognitive impairment or mild dementia. The drug targets an underlying cause of the disease by removing beta-amyloid from the brain. However, ARIA-E, characterized by brain swelling or fluid buildup, can occur and can be life-threatening if not detected early. The FDA has identified six deaths early in treatment, prompting an in-depth analysis of the safety issue.

The FDA has revised the prescribing information of Leqembi to include an additional MRI monitoring between the second and third infusion. This change is intended to help identify ARIA-E events earlier, potentially mitigating serious and fatal events. The current prescribing guidelines recommend MRI imaging before the fifth, seventh, and 14th infusions, but the FDA's analysis supports the need for earlier monitoring.

The FDA's recommendation follows similar guidelines for patients on Eli Lilly's Alzheimer's drug Kisunla, which requires MRI imaging before the second, third, fourth, and seventh infusions. Biogen's Leqembi was approved in 2023 and has seen sequential growth in U.S. in-market sales, reaching approximately $63 million.

Patients who have recently started Leqembi treatment should ask their healthcare professional about MRI monitoring for ARIA-E between the 2nd and 3rd infusion. If symptoms such as headache, confusion, dizziness, vision changes, nausea, difficulty walking, or seizures occur, patients should contact their healthcare professional immediately.

Healthcare professionals should be aware of the new recommendations and perform monitoring MRIs on patients between the 2nd and 3rd Leqembi infusions. If ARIA-E is diagnosed, healthcare professionals should discuss with patients and caregivers the potential need to delay or discontinue Leqembi treatment.

The FDA's decision underscores the importance of ongoing safety monitoring for new treatments, especially those targeting complex diseases like Alzheimer's. The revised guidelines aim to balance the benefits of the treatment with the potential risks.

References:
[1] https://www.benzinga.com/news/fda/25/08/47413963/fda-tightens-safety-guidelines-for-biogen-leqembi-alzheimers-therapy
[2] https://www.reuters.com/business/healthcare-pharmaceuticals/fda-recommends-more-monitoring-alzheimers-patients-eisai-biogens-drug-leqembi-2025-08-28/
[3] https://www.fda.gov/drugs/drug-safety-and-availability/fda-recommend-additional-earlier-mri-monitoring-patients-alzheimers-disease-taking-leqembi-lecanemab