Leqembi Insurance Denied? How to Appeal Lecanemab Coverage for Alzheimer's

Leqembi (lecanemab-irmb) is a monoclonal antibody that received traditional FDA approval in July 2023 for adults with early-stage Alzheimer's disease — specifically mild cognitive impairment or mild dementia with confirmed amyloid pathology. It works by targeting and removing amyloid beta plaques from the brain, slowing the progression of cognitive decline. Leqembi is the first Alzheimer's treatment proven in a large randomized trial to slow the underlying disease rather than merely managing symptoms. Despite this milestone, insurance denials — from both commercial insurers and Medicare — are common due to coverage restrictions, Prior Authorization Denied: How to Appeal" class="auto-link">prior authorization requirements, and diagnostic hurdles.

If your Leqembi coverage has been denied, this guide explains the denial landscape and how to fight back effectively.

Why Insurers and Medicare Deny Leqembi

Medicare coverage restrictions. CMS initially covered Leqembi only for patients enrolled in clinical trials or registries under a Coverage with Evidence Development (CED) policy. Following traditional FDA approval, CMS updated its National Coverage Determination (NCD) to allow broader coverage for Medicare beneficiaries under Part B. However, the coverage conditions — including confirmed amyloid diagnosis and appropriate neurologist supervision — can lead to denials when documentation is incomplete.

Amyloid confirmation requirements. Both FDA approval and payer coverage policies require confirmed amyloid beta pathology in the brain, typically demonstrated through PET imaging or CSF biomarker testing. Denials often result from missing or inconclusive amyloid confirmation rather than disagreement about the treatment itself. If amyloid testing has not been performed, this should be addressed before appealing the Leqembi denial.

Commercial insurer "experimental" classifications. Some commercial insurers continue to treat Leqembi as experimental or investigational despite traditional FDA approval, citing the relatively recent approval date or questions about long-term clinical significance.

Staging requirements. Leqembi is approved for early Alzheimer's — mild cognitive impairment or mild Alzheimer's dementia. Patients with more advanced dementia do not meet the label criteria, and denials on staging grounds may be appropriate if the diagnosis does not match the indication.

Safety monitoring requirements. Leqembi carries a risk of amyloid-related imaging abnormalities (ARIA). Insurers may deny coverage if safety monitoring protocols (pre-treatment MRI, regular imaging follow-up) are not documented.

FDA Approval and Its Significance

Leqembi received FDA traditional (full) approval on July 6, 2023, making it only the second disease-modifying Alzheimer's treatment ever approved (after aducanumab). The approval was based on the CLARITY AD Phase 3 trial, which enrolled 1,795 participants and demonstrated a statistically and clinically significant slowing of cognitive decline (27% reduction in CDR-SB decline rate) over 18 months.

This was the first large-scale Alzheimer's trial to achieve its primary endpoint with clear clinical significance. In your appeal, emphasize that traditional FDA approval (not accelerated approval) represents the FDA's highest level of confidence in the safety and efficacy evidence.

Building Your Appeal

Neurologist or geriatrician letter of medical necessity. Your prescribing physician should document the patient's cognitive status (MCI or mild AD based on neuropsychological testing), amyloid PET or CSF results confirming amyloid pathology, the clinical rationale for Leqembi, and the safety monitoring plan including baseline MRI and follow-up imaging protocol.

Amyloid confirmation documentation. Attach the amyloid PET scan report or CSF biomarker results showing elevated amyloid beta. This is a critical prerequisite for both the FDA label and payer coverage criteria.

CLARITY AD trial data. The Phase 3 results published in the New England Journal of Medicine (van Dyck et al., 2023) provide the primary clinical evidence. Cite the trial and its demonstrated 27% slowing of cognitive decline.

FDA approval documentation. Provide a copy of the FDA's July 2023 approval letter and the package insert confirming traditional approval status.

CMS coverage documentation (for Medicare). For Medicare denials, cite the updated NCD for anti-amyloid antibodies and confirm that all coverage conditions are met.

Specialty society support. The American Academy of Neurology and Alzheimer's Association have published perspectives on anti-amyloid therapy. Cite any relevant professional society guidance supporting appropriate use.

Expedited Review Rights

Alzheimer's disease is progressive and irreversible. Leqembi is approved and shown to be effective only in early-stage disease — delay means progression beyond the treatment window. If your treating neurologist can document that the patient is at risk of progressing beyond the eligible stage, this supports an expedited review request with a 72-hour turnaround.

External Independent Review: Complete Guide" class="auto-link">External Review

After internal appeal denial, external review by a neurologist or geriatric psychiatrist provides an independent clinical assessment. For an FDA-approved therapy with Phase 3 New England Journal of Medicine data, "experimental" denials are difficult to sustain in external review.

Patient Assistance Programs

Eisai and Biogen, the co-developers of Leqembi, offer patient support services. The Leqembi support program includes insurance navigation, co-pay assistance, and bridge programs for eligible patients. Contact the patient access team at the time of denial.

The Alzheimer's Association provides insurance appeal resources, advocacy support, and can connect patients with experienced advisors. NORD and local Alzheimer's foundations may offer additional assistance.

Fight Back With ClaimBack

A denial for Leqembi in early Alzheimer's disease is time-sensitive — the disease does not pause during the appeals process. ClaimBack helps patients and families build the strongest possible appeal, citing FDA approval, clinical trial evidence, and coverage rights under federal and state law.

Start your appeal at https://claimback.app/appeal.

Related Reading

• How to Write an Insurance Appeal Letter
• What Is Medical Necessity?
• Common Reasons Insurance Claims Are Denied