Leqembi (lecanemab-irmb) — HCPCS J0174

Anti-amyloid IV mAb landscape: Leqembi vs Kisunla FDA verified 2025

Two FDA-approved anti-amyloid IV monoclonal antibodies for early Alzheimer's disease. Both subject to CMS CED. Different dosing schedules and discontinuation rules.

Leqembi (lecanemab-irmb, Eisai/Biogen) and Kisunla (donanemab-azbt, Eli Lilly) are the two anti-amyloid IV biologics with full FDA approval for early symptomatic Alzheimer's disease (mild cognitive impairment or mild dementia stage). Both target amyloid plaques but differ in dosing schedule, planned treatment duration, and ARIA risk profile.

Dosing & unit math FDA label 2025

From FDA prescribing information (BLA 761269), most recent revision 2025.

Adult dosing (only labeled population)

• 10 mg/kg IV every 2 weeks, infused over approximately 1 hour
• No loading dose, no max dose cap (truly weight-based)
• Dilute in 250 mL of 0.9% sodium chloride before infusion
• Observe patient during infusion and post-infusion (especially first 4 doses) for infusion-related reactions
• 1 mg = 1 unit J0174 — bill the actual mg administered as units
• Treatment continues indefinitely; reassess periodically once patient progresses past mild dementia stage

Vial selection by patient weight (weight-based math)

Worked example — 70 kg patient, first-year billing

Worked example — 75 kg patient with waste

Treatment duration

FDA label does not specify a fixed maximum duration. Treatment continues indefinitely until the patient progresses past the mild dementia stage of Alzheimer's disease, at which point clinical benefit is unestablished and discontinuation should be considered. Reassess clinical response periodically using cognitive and functional scales (e.g., CDR-SB, MMSE) and document continued benefit in the chart.

NDC reference FDA NDC Directory verified May 2026

APOE genotype testing — required pre-treatment FDA label + CMS CED

APOE4 status materially changes ARIA risk and informs the risk/benefit conversation.

The FDA label and CMS CED both require APOE4 genotype testing before initiating Leqembi. Document the genotype, counsel the patient (and care partner) on ARIA risk by genotype, and place the discussion in the chart. APOE testing is one-time per patient.

APOE4 genotype risk tiers (label-derived)

Billing the APOE genotype test

• CPT 81401 — "Molecular pathology procedure, level 2" (used for APOE genotyping)
• One-time test per patient; result documented in chart and on PA
• Many lab benefit managers (e.g., Avalon, eviCore) require lab benefit PA for genetic testing — check before ordering
• Alternative reporting: some labs use Tier 2 codes or genomic sequencing procedure (GSP) codes; align with the lab's preferred CPT

ARIA monitoring & MRI surveillance schedule FDA boxed warning

Baseline MRI within 1 year before treatment + scheduled pre-infusion MRIs before doses 5, 7, and 14.

MRI surveillance schedule (per FDA label)

Symptoms suggestive of ARIA (obtain MRI)

• Headache (especially new or worsening)
• Confusion, altered mental status
• Dizziness, visual disturbances, nausea
• Focal neurologic deficits
• Seizures, gait instability

Billing the surveillance MRI

• CPT 70551 — MRI brain, without contrast (most common for ARIA surveillance)
• CPT 70553 — MRI brain, with and without contrast (if contrast indicated)
• Some sites add gradient-recalled echo (GRE) or susceptibility-weighted imaging (SWI) sequences for microhemorrhage detection — this is bundled within 70551/70553
• 4 surveillance MRIs in year 1 minimum (baseline + pre-dose 5, 7, 14); additional as symptom-triggered

Administration codes CPT verified May 2026

Leqembi is a non-chemo anti-amyloid biologic. Use therapeutic IV infusion codes, not chemo admin.

Modifiers CMS verified May 2026

JZ — required when no waste

Effective July 1, 2023, CMS requires the JZ modifier on all single-dose container claims when no drug is discarded. For Leqembi, JZ applies whenever the weight-based dose math lines up with vial sizes (e.g., 50 kg = 500 mg = exactly one 500 mg vial, no waste).

JW — required when partial vial discarded

JW reports the discarded portion of a single-dose vial. For Leqembi, JW is common because weight-based dosing rarely matches vial sizes exactly. Bill the administered units on a JZ-style line and the wasted units on a separate JW line. Both administered and waste are reimbursable.

Example: 75 kg patient receives 750 mg from 1 × 500 mg + 2 × 200 mg vials (900 mg total). Bill J0174 × 750 units (administered) and J0174 × 150 units with JW (waste). One of JZ or JW must be on every J0174 claim.

Modifier 25 — same-day E/M

Use modifier 25 on the E/M code when a significant, separately identifiable evaluation and management service is performed on the same day as the infusion (e.g., post-MRI ARIA review and dosing decision). Routine pre-infusion clinical assessment is bundled.

340B modifiers (JG, TB)

For 340B-acquired Leqembi, follow your MAC's current 340B modifier policy. Leqembi is dispensed by hospitals and infusion centers under buy-and-bill; specialty pharmacy distribution exists in some markets.

ICD-10-CM — Alzheimer's disease and related codes FY2026 verified May 2026

Document the most specific code supported by the encounter. AD-associated dementia severity codes (F02.A1x — F02.C4x family) added in FY2024 and are now expected on PAs.

Required pre-treatment documentation in addition to ICD-10

• Amyloid pathology confirmation (amyloid PET scan OR CSF biomarker testing) — document modality, date, and result
• APOE4 genotype result
• Baseline brain MRI (within 1 year)
• Cognitive staging (MMSE, MoCA, or CDR-SB)
• CMS CED registry enrollment (Medicare patients)

Site of care & place of service Verified May 2026

Leqembi is administered in a setting equipped to monitor for infusion-related reactions and ARIA. Most early utilization has been in academic medical centers and infusion centers affiliated with memory clinics; that is broadening to neurology offices and ambulatory infusion suites as workflows mature.

Claim form field mapping Eisai 2025

From Eisai's Leqembi access program billing guidance and standard CMS-1500 conventions.

CMS CED registry — mandatory for Medicare NCD 210.20

Medicare will not pay for Leqembi outside Coverage with Evidence Development. Registry enrollment is a hard prerequisite.

CMS National Coverage Determination 210.20 (Monoclonal Antibodies Directed Against Amyloid for the Treatment of Alzheimer's Disease) was finalized April 2022 and applies to Leqembi. Medicare covers Leqembi only under Coverage with Evidence Development (CED) — meaning the patient must be enrolled in a CMS-approved registry that collects defined outcomes data.

Registry options

• Alzheimer's Disease Patient Registry (most widely used) — administered through the National Alzheimer's Coordinating Center (NACC)
• Other CMS-approved registries listed at CMS Coverage Database
• Many academic medical centers and large practice networks have already onboarded; Eisai's access support team will direct providers to active registries

Documentation required for CED compliance

• Confirmed AD diagnosis with documented amyloid pathology (PET or CSF biomarker)
• MCI or mild dementia stage at treatment initiation
• APOE4 genotype result
• Baseline cognitive assessment (CDR-SB or equivalent)
• Baseline brain MRI
• Registry enrollment ID documented in chart
• Outcomes reporting at defined intervals per registry protocol

Payer policy snapshot Reviewed May 2026

All major payers require PA, amyloid biomarker confirmation, APOE genotype, baseline MRI, and (for Medicare) CED registry enrollment.

Medicare reimbursement CMS Q2 2026 (live)

Quarterly ASP from CMS Part B Drug Pricing File. Refreshes automatically each quarter.

Coverage

Medicare coverage falls under NCD 210.20 with Coverage with Evidence Development. Patient must be enrolled in a CMS-approved registry. All MACs apply NCD 210.20 uniformly; LCDs do not override.

Code history

• J0174 — permanent code, "Injection, lecanemab-irmb, 1 mg" (pre-permanent-code period used unclassified J3490)

Patient assistance — Eisai patient support Eisai verified May 2026

• Eisai Direct Patient Support / Leqembi Co-Pay Program: 1-833-453-7362 (1-833-4LEQEMBI) — benefits investigation, prior authorization assistance, appeal support
• Leqembi Co-Pay Program: commercial copay support; eligible commercially-insured patients (excludes Medicare, Medicaid, federal program patients)
• Eisai Patient Assistance Program: free product for uninsured / underinsured patients meeting income requirements
• Foundations: for Medicare patients, refer to PAN Foundation, HealthWell Foundation — verify open Alzheimer's disease funds quarterly (these open and close based on fundraising cycles)
• Web: leqembi.com (HCP and patient resources)

Common denials & how to fix them

Frequently asked questions

What is the HCPCS code for Leqembi?

Leqembi (lecanemab-irmb) is billed under HCPCS J0174 — "Injection, lecanemab-irmb, 1 mg." Each milligram equals one billable unit. Dosing is weight-based at 10 mg/kg IV every 2 weeks, so a 70 kg patient receives 700 mg = 700 units per infusion. J0174 is the permanent code.

How many units do I bill for a Leqembi dose?

Bill the actual mg administered as units (1 mg = 1 unit). Standard dose is 10 mg/kg IV q2wk. For a 70 kg patient: 700 mg = 700 units. For an 80 kg patient: 800 mg = 800 units. Vials available are 200 mg and 500 mg single-dose. Most weight-based doses produce partial-vial waste — bill JW for the discarded portion on a separate claim line.

What administration CPT do I use for Leqembi?

CPT 96365 — "Intravenous infusion, for therapy, prophylaxis, or diagnosis; initial, up to 1 hour" — for the first hour of the ~1-hour infusion. Add CPT 96366 for each additional hour beyond the first if infusion extends. Leqembi is a non-chemo anti-amyloid biologic; do NOT bill 96413 (chemo administration). 1-hour observation post-infusion is recommended, especially for the first 4 doses.

Do I bill JZ or JW for Leqembi?

Both apply, depending on the dose math. JZ on virtually any line where a single-dose vial is used with no waste; JW on the wasted portion when a partial vial is discarded. Because dosing is weight-based and vials are 200 mg and 500 mg, most adult doses produce partial-vial waste — JW is common. One of JZ or JW must be on every J0174 claim per CMS's July 2023 single-dose container policy.

What is the Medicare reimbursement for J0174?

For Q2 2026, the Medicare Part B payment limit for J0174 is $1.336 per mg (ASP + 6%). A 70 kg patient receiving 700 mg per dose reimburses at approximately $935.20 per infusion; an 80 kg patient at 800 mg reimburses at approximately $1,068.80. Annualized cost (~26 doses/year): approximately $24,300 for a 70 kg patient. Sequestration (~2%) reduces actual paid to roughly ASP + 4.3%.

What is the CMS CED requirement for Leqembi?

CMS NCD 210.20 (Monoclonal Antibodies Directed Against Amyloid for the Treatment of Alzheimer's Disease) requires Coverage with Evidence Development (CED) for Medicare to pay for anti-amyloid mAbs including Leqembi. Providers must enroll patients in a CMS-approved registry (most use the Alzheimer's Disease Patient Registry administered through NACC). Document registry enrollment ID in the chart and on the PA. Without CED enrollment, Medicare will deny the claim.

Is APOE genotype testing required before starting Leqembi?

Yes. The FDA label and CMS CED both require APOE4 genotype testing before initiating Leqembi, with results documented in the chart and discussed with the patient. APOE4 homozygotes (~15% of AD patients) have substantially higher risk of ARIA-E and ARIA-H, including symptomatic ARIA. Bill APOE genotype under CPT 81401 (molecular pathology procedure, level 2). Document genotype counseling in the encounter note.

What MRI surveillance does Leqembi require?

FDA label requires baseline brain MRI within 1 year before treatment initiation, plus pre-infusion MRIs before doses 5, 7, and 14. Additional MRIs are indicated if symptoms suggest ARIA-E (vasogenic edema) or ARIA-H (microhemorrhages or superficial siderosis). Bill MRI brain without contrast under CPT 70551 (without) or 70553 (with and without). Document MRI date and findings in chart before each scheduled-surveillance infusion.

How does Leqembi compare to Kisunla?

Leqembi (lecanemab-irmb, J0174, Eisai/Biogen) and Kisunla (donanemab-azbt, J0175, Lilly) are both anti-amyloid IV monoclonal antibodies for early symptomatic Alzheimer's disease, both subject to CMS CED. Leqembi: 10 mg/kg IV q2wk indefinitely (weight-based, ~26 doses/year). Kisunla: 700 mg IV q4wk × 3 doses then 1,400 mg q4wk (fixed-dose, ~13 doses/year), with treatment discontinuation possible once amyloid plaques cleared. Both carry boxed warnings for ARIA. Kisunla has a defined endpoint (amyloid clearance); Leqembi continues until cognitive decline progresses past mild dementia.

Source documents

1. DailyMed — LEQEMBI (lecanemab-irmb) Prescribing Information
   FDA-approved label, full approval July 6, 2023 (BLA 761269); most recent revision 2025
2. FDA Leqembi label PDF (s003, 2024)
   Boxed warning for ARIA, MRI surveillance schedule
3. CMS NCD 210.20 — Monoclonal Antibodies Directed Against Amyloid for Treatment of Alzheimer's Disease
   Coverage with Evidence Development (CED) requirement; finalized April 2022
4. CMS — Medicare Part B Drug ASP Pricing File
   Q2 2026 quarterly file, effective April 1 – June 30, 2026
5. Leqembi.com — Eisai HCP & patient resources
   Eisai Direct Patient Support program; co-pay program; PAP details
6. National Alzheimer's Coordinating Center (NACC) — Alzheimer's Disease Patient Registry
   CMS-approved CED registry administrator
7. American Academy of Neurology — clinical guidance for anti-amyloid mAb use in AD
8. UnitedHealthcare — Lecanemab (Leqembi) Medical Drug Coverage Policy
9. Aetna CPB — lecanemab clinical policy bulletin
10. FDA National Drug Code Directory

About this page

We maintain this page as a living reference. Medicare ASP pricing is bound to our underlying CareCost data layer and refreshes automatically when CMS publishes new quarterly files. Coding and policy content is reviewed at least quarterly and updated whenever a source document changes.

Found an error? Email hello@carecostestimate.com.

Refresh cadence

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Change log

• May 2, 2026 — Initial publication. ASP data: Q2 2026. Manufacturer source: Eisai 2025 Leqembi access materials. FDA label: most recent rev 2025 (BLA 761269). CMS NCD 210.20 CED requirement covered; APOE4 testing and MRI surveillance schedule documented; Kisunla cross-link added.

Methodology

Every claim on this page is sourced inline. Pricing reflects the current CMS Part B Drug ASP Pricing File. Payer policies are read directly from each payer's published medical/pharmacy policy documents. Boxed warning, MRI surveillance schedule, and APOE testing language are taken from the FDA label. CED registry guidance is taken directly from CMS NCD 210.20. We do not paraphrase from billing-software vendor blogs.