Leqembi (Lecanemab) Denied: Appealing Alzheimer's Coverage and ARIA Monitoring Requirements

Leqembi (lecanemab-irmb) is a humanized IgG1 monoclonal antibody targeting amyloid-beta protofibrils, FDA-approved in July 2023 under traditional approval for early Alzheimer's disease in adults with mild cognitive impairment (MCI) or mild dementia who have confirmed amyloid beta pathology. It is the first Alzheimer's treatment to receive traditional FDA approval that slows the clinical progression of the disease (as opposed to treating only symptoms). Despite this landmark approval, denials are common and reflect a collision between the drug's groundbreaking status, its monitoring requirements, its significant cost, and gaps in payer coverage policy.

Why Leqembi Gets Denied

Medicare coverage restrictions. Following full traditional FDA approval, CMS issued a National Coverage Determination (NCD) covering Leqembi for Medicare beneficiaries who meet specific criteria: confirmed diagnosis of MCI or mild Alzheimer's, confirmed amyloid positivity, Mini-Mental State Examination (MMSE) or equivalent cognitive testing on file, APOE ε4 genotyping result on file, and treatment at a CMS-qualified provider. Denials occur when any of these documentation elements is missing. Private insurers often model their coverage criteria on CMS guidance.

ARIA monitoring requirements. Leqembi causes amyloid-related imaging abnormalities (ARIA) — brain swelling (ARIA-E) and microhemorrhages (ARIA-H) — in a significant percentage of patients. ARIA can be asymptomatic or serious. The FDA label and clinical guidelines require regular MRI surveillance (baseline, then at weeks 26 and 52, with additional scans if symptoms develop). Insurers may deny the drug while awaiting confirmation that monitoring infrastructure is in place, or may deny subsequent infusion authorizations if MRI reports are not submitted.

APOE ε4 homozygosity. Patients homozygous for the APOE ε4 allele have significantly higher rates of severe ARIA than heterozygous patients or non-carriers. Some insurers (and some prescribers) are cautious about prescribing Leqembi to APOE ε4 homozygotes, and policies that require APOE genotyping may result in coverage denials for homozygous patients pending additional shared decision-making documentation.

Disease stage disputes. Leqembi is approved only for early-stage Alzheimer's — MCI or mild dementia. Patients with moderate or advanced dementia are outside the approved indication. Denials for patients who progress beyond the mild stage mid-treatment are clinically contested.

Amyloid confirmation method. Amyloid positivity must be confirmed by PET scan or CSF biomarker testing. If neither test has been performed, or if the PET scan used an off-label amyloid tracer not validated for this purpose, insurers will deny.

Building a Leqembi Appeal

Confirm all CMS/insurer documentation requirements are met:

• MMSE or MoCA score from a recent clinical assessment (within 6 months)
• Amyloid PET report or CSF tau/amyloid ratio confirming amyloid positivity
• APOE ε4 genotyping result documented in clinical record
• Prescriber documentation of mild cognitive impairment or mild Alzheimer's dementia diagnosis
• MRI brain baseline confirming no pre-existing ARIA-H or ARIA-E

Addressing ARIA risk in the appeal. Your prescriber's letter should include a plan for ARIA monitoring, confirming:

• Baseline MRI was performed and is clear
• Patient and family have been counseled about ARIA symptoms
• Follow-up MRI schedule is established (weeks 26 and 52 per label)
• Action plan if ARIA is detected (dose interruption criteria)

Challenging denials based on APOE ε4 status. If the insurer denies because the patient is APOE ε4 homozygous, your appeal should note that the FDA label does not exclude homozygous patients from treatment — it recommends additional counseling and shared decision-making, not exclusion. A documented shared decision-making conversation between the treating physician and patient (noting that the patient understands and accepts the higher ARIA risk) satisfies the clinical requirement.

Mild dementia vs. MCI distinction. If the insurer argues the patient has advanced beyond the eligible disease stage, submit neuropsychological testing results and the CDR (Clinical Dementia Rating) scale score. CDR 0.5 represents MCI; CDR 1.0 represents mild dementia — both are within the approved indication.

Medicare Beneficiaries

For Medicare patients, the prescriber must be enrolled in a CMS Evidence Development registry (such as the Alzheimer's registry required under the NCD) to bill for Leqembi administration. Denials based on registry enrollment failures are administrative and can be resolved by confirming the prescriber is appropriately enrolled.

Fight Back With ClaimBack

Leqembi denials often turn on documentation details — the right cognitive test score, the right amyloid confirmation method, the right ARIA monitoring plan. ClaimBack helps Alzheimer's patients and families compile exactly what their insurer requires.

Start your Leqembi appeal at ClaimBack

Related Reading

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