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Leqembi (Lecanemab) Can Delay Alzheimer’s by 8 Years

From Alzheimer’s and Dementia Weekly, December 16, 2025

New data presented at the 2025 CTAD conference brings good news for families facing early Alzheimer’s. Eisai and Biogen released long-term findings showing that continued LEQEMBI (lecanemab) treatment meaningfully slows disease progression, especially when started early.

Researchers analyzed outcomes from the study along with 16 clinical datasets. The results point to a powerful trend: Patients who begin treatment with lower amyloid levels experience the strongest benefit. In these early-stage patients, LEQEMBI may delay the shift from mild cognitive impairment to moderate Alzheimer’s by as much as 8.3 years.

These findings indicate that earlier initiation of LEQEMBI treatment may provide a greater delay in disease progression. Furthermore, each additional year on LEQEMBI could further delay disease progression compared to stopping treatment, even long after plaque is expected to have been cleared.

Easier Dosing

The update also highlighted promising progress on subcutaneous (SC) dosing, including the newly approved U.S. option that may make ongoing treatment more convenient than IV infusions.

Amyloid Removal

Based on clinical data and modeling analysis, the effect on amyloid removal in the brain and safety was shown to be independent of the route of administration and explained by exposure, suggesting that weekly 500 mg Subcutaeous (SC) dosing provides similar efficacy and safety to biweekly 10 mg/kg IV dosing. 

Safety evaluation showed systemic infusion reactions occurred in 0% of patients receiving 500 mg SC, all of whom had previously received IV l LEQEMBI.

These results indicate that the subcutaneous formulations of LEQEMBI, designed with consideration for the convenience of patients and their care partners, maintains efficacy with a low incidence of systemic infusion reactions, and is otherwise equivalent to conventional IV administration.

While there is no single, stand-alone test to diagnose Alzheimer’s disease today, including this newly approved test, blood testing can be an important piece of the diagnostic process. Currently, physicians primarily use other, more well-established diagnostic tools combined with medical history, neurological exams, cognitive and functional assessments, brain imaging, spinal fluid analysis and, increasingly, blood tests to make an accurate diagnosis and to understand which patients are eligible for approved treatments. 

There are a variety of laboratory-developed tests on the market that can be used to detect blood-based biomarkers associated with Alzheimer’s. This is the first that has been cleared by the FDA for use. For many years, blood tests have been used in clinical trials. Increasingly, they are being used by specialists in clinical settings, often as a first pass detection tool followed by additional testing.

 Navigating the U.S.’s federal and state health insurance program, Medicaid, to cover dementia-related long-term care can feel overwhelming, especially as the program differs widely from state to state. Medicaid planning expert Michael Guerrero helps families understand eligibility, apply for benefits, and plan ahead for care. 

 A decade ago, families confronting an Alzheimer’s diagnosis had little more than memory-boosting pills aimed at lessening symptoms but they didn’t halt disease progression. Today, the conversation has shifted from if we can slow the disease to how early we can start. With two disease-modifying antibodies now on the market in the U.S. 

 Alzheimer's is an evolving field of study. 

To keep up with the most recent and credible scientific findings, check out Being Patient's free guides on the science, research, prevention, and caregiving for the disease.

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• The roles of palliative and hospice care