Zolgensma (onasemnogene abeparvovec-xioi) — HCPCS J3399

SMA therapy class — J3399 (Zolgensma) vs J2326 (Spinraza) vs Evrysdi (oral risdiplam) CMS HCPCS verified May 2026

Three SMA-disease-modifying therapies, three completely different billing pathways. Don't confuse them at the claim layer.

Spinal muscular atrophy is now treatable by three FDA-approved disease-modifying therapies: Zolgensma (onasemnogene abeparvovec, J3399, one-time IV AAV9 gene therapy), Spinraza (nusinersen, J2326, intrathecal antisense oligonucleotide every 4 months indefinitely), and Evrysdi (risdiplam, oral small-molecule SMN2 splicing modifier, pharmacy benefit). They have different mechanisms, different routes, different age and severity restrictions, and entirely different billing pathways.

Dosing & unit math FDA label verified May 2026

From the FDA-approved Zolgensma prescribing information (BLA 125694). Unit-of-billing is the per-treatment event, not vials or mg; the underlying physical dose is weight-based vector genome copies.

Approved indication

• Spinal muscular atrophy (SMA) in pediatric patients less than 2 years of age with bi-allelic mutations in the SMN1 gene. Includes pre-symptomatic patients identified on newborn screening (NBS, now universal across all 50 states via the Recommended Uniform Screening Panel).

Weight-based dosing

Worked example — 10 kg infant on routine pediatric SMA workflow

Dose modifications

Per FDA label, Zolgensma dosing is fixed at 1.1 × 10¹⁴ vg/kg. There is no dose reduction pathway because the therapy is one-time and the AAV9 vector is sized to deliver therapeutic SMN1 transgene copies to motor neurons. If pre-infusion LFTs or platelets are out of range, the infusion is held rather than dose-reduced; the patient receives extended glucocorticoid and supportive care until eligibility criteria are met, with the constraint that the patient must remain < 2 years old.

Anti-AAV9 antibody pre-treatment gate

Before infusion, anti-AAV9 antibody titer must be confirmed at ≤ 1:50. Testing is coordinated through OneGene Program and is the most time-sensitive element of the workflow because turn-around time can be 1–2 weeks and many patients are pre-symptomatic newborns where every week of life matters. Approximately 5–15% of infants have pre-existing anti-AAV9 antibodies above the threshold (typically maternally transferred or from environmental exposure); these patients are not eligible for Zolgensma and should be transitioned to Spinraza or Evrysdi.

NDC reference FDA NDC Directory verified May 2026

Administration codes CPT verified May 2026

Zolgensma is a therapeutic IV infusion (not chemo, not radiopharm). Use therapeutic IV admin codes.

Modifiers CMS verified May 2026

JZ / JW — generally N/A for single-dose patient-specific gene therapy

Zolgensma kits are patient-specific, lot-traceable, and built to deliver the exact weight-based dose. There is no physical "vial waste" in the conventional J-code sense — the entire shipped product is intended for administration to that named patient. JZ may be reported on J3399 to attest "no discarded amount from a single-dose container," consistent with CMS's July 2023 single-dose container policy, but practice varies by MAC and the per-treatment unit definition makes JZ/JW reporting largely moot. Confirm with your MAC.

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 (consent, extended family counseling, baseline neuromuscular exam, review of weekly monitoring plan).

340B modifiers (JG, TB)

Most Zolgensma is dispensed under the specialty product / specialty distribution pathway rather than via 340B, but a small number of pediatric DSH/CAH/critical-access hospitals may administer 340B-acquired Zolgensma. Confirm with your 340B compliance team and your MAC's modifier guidance. Outcomes-based contracts can complicate 340B reporting because the manufacturer rebate flow interacts with 340B pricing assumptions.

Contract-specific modifiers

Some commercial payers add a contract-specific modifier or claim attachment requirement to flag claims under an outcomes-based agreement (so the claim can be linked to the manufacturer's milestone-tracking dataset). Follow the payer's outcomes-based contract operational guide; OneGene Program coordinates this end-to-end.

ICD-10-CM by indication FY2026 verified May 2026

Zolgensma is indicated for pediatric SMA with bi-allelic SMN1 mutations. Use SMA-type-specific G12.x codes.

Site of care & place of service Verified May 2026

Zolgensma is administered exclusively in certified specialty treatment centers — almost always a pediatric hospital with a multi-disciplinary SMA / neuromuscular program. The administration is typically performed in a hospital inpatient unit (planned short admission) or in a hospital outpatient infusion suite within the same institution. Office-based (POS 11) and ambulatory infusion center (POS 49) administration is not appropriate given the high-cost product, glucocorticoid prophylaxis monitoring, and post-infusion hepatotoxicity surveillance requirements.

Claim form field mapping Novartis OneGene 2026

Zolgensma claims are typically submitted on UB-04 (837I) by the certified pediatric hospital.

Payer policy snapshot Reviewed May 2026

Universal PA. AAV9 antibody titer ≤ 1:50, bi-allelic SMN1, age < 2 yr, weight ≤ 21 kg, glucocorticoid plan, and post-infusion monitoring plan are the universal documentation requirements.

Outcomes-based contracts — how they work for billers

Novartis Gene Therapies offers outcomes-based agreements (OBAs) with most major commercial payers and many state Medicaid programs. The typical structure: full WAC (~$2.125M) is paid at administration; if specified clinical milestones are not met over a 5-year horizon, a percentage of the WAC is refunded by the manufacturer to the payer. Milestones commonly include motor function (e.g., achievement of sitting without support, standing, walking, ventilator-free survival). The provider's role: document the clinical outcome data the manufacturer requires for milestone verification at standardized intervals (6 mo, 12 mo, 24 mo, 36 mo, 60 mo post-infusion). OneGene Program coordinates this longitudinally. The rebate/refund flow is payer-side and does not affect the provider's payment at administration.

Step therapy & prior SMA therapy

Most payers do not require step therapy through Spinraza or Evrysdi before Zolgensma in pre-symptomatic NBS patients (where Zolgensma is first-line). For symptomatic patients diagnosed clinically, some payers do require documented assessment of Spinraza or Evrysdi as alternatives, particularly if the patient is approaching the 2-year age cutoff or has advanced respiratory compromise. Document SMA therapy history and the clinical rationale for selecting Zolgensma in the PA packet.

Newborn screening pathway

SMA is on the federal Recommended Uniform Screening Panel and is screened in newborns in all 50 states. NBS positives trigger confirmatory genetic testing (bi-allelic SMN1 mutation) and immediate referral to a pediatric neuromuscular specialty center. The window from NBS to Zolgensma administration is typically 4–8 weeks if everything goes well — an aggressive timeline that requires close coordination between NBS lab, pediatric neuromuscular team, OneGene Program, payer PA review, and the certified treatment center. Pre-symptomatic Zolgensma is associated with better motor and survival outcomes than treatment after symptom onset (per SPR1NT trial), so payer policies generally support rapid initiation for NBS positives.

Medicare / Medicaid reimbursement CMS Q2 2026 (NOC / invoice)

Most Zolgensma patients are pediatric Medicaid, not Medicare. For inpatient HOPD administration, J3399 may be packaged into the DRG with NTAP or outlier payment; for outpatient, OPPS pass-through historically applied.

Inpatient (Medicare / Medicaid)

When Zolgensma is administered inpatient, the drug cost is bundled into the assigned DRG. Pediatric Medicaid DRG bundling without a high-cost outlier or New Technology Add-On Payment (NTAP) is not financially viable for the hospital. Most state Medicaid programs have negotiated supplemental rebate agreements (SRAs) and outcomes-based agreements specifically to handle Zolgensma cash flow. Confirm the state Medicaid policy and the hospital's contract before scheduling the inpatient admission.

Outpatient (Medicare / Medicaid)

For outpatient HOPD administration, J3399 is billed with the appropriate revenue code (0636 or 0260 per payer), CPT 96365 admin, and supporting documentation. OPPS pass-through (if active) pays the drug at ASP+6% or invoice; if pass-through has expired, packaging into the APC bundle is generally not viable and outpatient billing is uncommon for this product.

Coverage

No NCD specific to Zolgensma or to AAV-based gene therapies generally. Coverage falls under MAC LCDs and payer-specific medical / pharmacy benefit policies. All MACs and major commercial payers cover J3399 for FDA-approved on-label indications with documented bi-allelic SMN1, AAV9 antibody ≤ 1:50, age < 2 yr, and the required pre-/post-infusion monitoring framework.

Code history

• J3399 — "Injection, onasemnogene abeparvovec-xioi, per treatment, up to 5 × 10¹⁵ vector genomes"; permanent effective dates vary by CMS HCPCS quarterly file. Verify the current descriptor and effective date.
• C9399 — transitional pass-through C-code historically used at launch (2019–2020); retired when J3399 became permanent.
• J3490 — unclassified drug code; historically used at launch for some payers; not appropriate once J3399 is permanent.

Patient assistance — OneGene Program Novartis verified May 2026

• OneGene Program (Novartis Gene Therapies): 1-855-441-4363 / zolgensma.com/onegene — benefits investigation, prior authorization assistance, AAV9 antibody testing logistics, certified specialty treatment center referral, travel and lodging support, glucocorticoid prophylaxis education, post-infusion monitoring scheduling, outcomes-based contract operational support
• Novartis Patient Assistance Foundation, Inc.: free product for uninsured / underinsured patients meeting income requirements (501(c)(3)); Zolgensma access pathway is highly individualized given the WAC scale
• Cure SMA: curesma.org — newborn screening advocacy, certified care center directory, peer/family support, emergency financial assistance for travel and lodging while at the specialty center, SMA Care Center accreditation program
• Foundations: PAN Foundation (rare/genetic disease funds where applicable), HealthWell Foundation, Patient Advocate Foundation — primarily supplemental for non-drug costs (travel, lodging, monitoring labs); verify open SMA / rare-disease funds quarterly
• State newborn screening / early intervention programs: coordinate with state public health for genetic counseling and developmental services pre- and post-Zolgensma
• Travel & lodging: OneGene Program coordinates with Healthcare Hospitality Network, Ronald McDonald House, and Hope Lodge for families traveling to certified Zolgensma centers (most regions have only 1–3 sites)

Safety & FDA-label monitoring FDA label / boxed warning

FDA-label warnings & precautions

• Acute serious liver injury / liver failure (boxed; fatal outcomes reported): monitor ALT, AST, total bilirubin, and prothrombin time at baseline (within 2 weeks pre-infusion), weekly × 1 month, then bi-weekly through month 3 as clinically indicated. Fatal cases of acute liver failure have been reported post-marketing; document the discussion of mortality risk in consent.
• Glucocorticoid prophylaxis: oral prednisolone 1 mg/kg/day starting 24 hr pre-infusion; continue ≥30 days post; taper if LFTs normalize. Extended courses (60+ days) may be required for elevated LFTs; some patients require IV methylprednisolone for severe transaminitis.
• Thrombocytopenia: transient decreases in platelet counts are common; monitor CBC at baseline, weekly × 1 month, every other week for second month.
• Thrombotic microangiopathy (TMA): rare but serious; monitor for hemolysis, AKI, and thrombocytopenia in the 1–2 weeks post-infusion; immediate hematology / nephrology consult if suspected.
• Elevated troponin-I: can occur; monitor troponin-I at baseline and as clinically indicated.
• Immunogenicity: patients seroconvert (develop anti-AAV9 antibodies) after Zolgensma; re-dosing is not feasible.
• Vaccination schedule: coordinate live vaccines with the glucocorticoid taper; consult pediatric infectious disease and the standard CDC immunization schedule.
• Embryo-fetal toxicity: not applicable in the typical pediatric population but relevant for older-adolescent or adult treated patients if any.

Outcomes-based milestone tracking

Beyond the FDA-label safety monitoring, the manufacturer's outcomes-based contract typically requires documentation of motor function and survival milestones at 6 mo, 12 mo, 24 mo, 36 mo, and 60 mo post-infusion. Standardized assessments include CHOP-INTEND, HFMSE, RHS, and ventilator-free survival. OneGene Program coordinates this longitudinal data collection in cooperation with the certified treatment center.

Common denials & how to fix them

Frequently asked questions

Is Zolgensma a one-time treatment?

Yes. Zolgensma is administered as a single one-time IV infusion. There is no repeat or maintenance dose. The SMN1 transgene delivered by the AAV9 vector is intended to persist in motor neurons for life. Re-dosing is not supported by the label and is generally not feasible because patients seroconvert (develop anti-AAV9 antibodies) after the first administration.

What is the HCPCS code for Zolgensma?

Zolgensma is billed under HCPCS J3399 — "Injection, onasemnogene abeparvovec-xioi, per treatment, up to 5 × 10¹⁵ vector genomes." This is a single-dose, per-treatment J-code (not per-mg or per-mCi). Each Zolgensma administration is billed as J3399 × 1 unit. Do not use J3490 unclassified or C9399 transitional pass-through (both retired/legacy).

What is the AAV9 antibody titer threshold?

Per the FDA label, anti-AAV9 antibody titer must be ≤ 1:50 before Zolgensma administration. Patients with titers above 1:50 are not eligible because pre-existing immunity to the AAV9 capsid neutralizes the vector. Missing or absent AAV9 antibody documentation is the #1 cause of Zolgensma PA denial.

How does outcomes-based contracting work for Zolgensma billers?

Novartis Gene Therapies offers outcomes-based agreements (OBAs) to payers. Full WAC is paid at administration; if specified clinical milestones (motor function, ventilator-free survival) are not met over a 5-year horizon, a percentage of WAC is refunded by the manufacturer to the payer. The provider organization is not party to the rebate flow but documents the clinical outcome data the manufacturer needs for milestone verification at 6, 12, 24, 36, and 60 months post-infusion. OneGene Program coordinates this longitudinal data collection.

Why is pediatric Medicaid the primary payer for most Zolgensma patients?

Pediatric Medicaid eligibility is broad (state CHIP, Katie Beckett, TEFRA pathways) and many infants with SMA meet eligibility through disability/medical-complexity criteria regardless of family income. State Medicaid programs have negotiated supplemental rebate agreements (SRAs) and outcomes-based contracts specifically designed for Zolgensma cash flow. >30 states have CMS-approved value-based purchasing arrangements for Zolgensma.

Inpatient billing vs outpatient billing — which is right?

Both pathways are used. Many specialty centers bill inpatient under a planned short admission (DRG with NTAP / outlier payment). Other centers bill outpatient under OPPS pass-through (if active for the calendar year). The choice is driven by payer contract, hospital revenue cycle policy, and clinical risk tolerance. Confirm with the hospital's revenue cycle team and the payer before scheduling.

Glucocorticoid prophylaxis timeline?

Per FDA label, oral prednisolone 1 mg/kg/day (or equivalent) starts 24 hours before the Zolgensma infusion and continues for at least 30 days post-infusion, then tapered if liver function is normal. Extended courses (60+ days) may be required for elevated transaminases; severe cases may need IV methylprednisolone.

What liver toxicity monitoring is required?

Per FDA label and boxed warning: ALT, AST, total bilirubin, and prothrombin time at baseline (within 2 weeks pre-infusion), weekly × 1 month, then bi-weekly through month 3 as clinically indicated. Concurrent CBC weekly for the first month for thrombocytopenia / TMA surveillance. Troponin-I at baseline and as indicated. Document the monitoring schedule in the PA packet and chart at every visit.

How does Cure SMA support families?

Cure SMA (curesma.org) does not directly pay for Zolgensma drug cost (that is the payer / Medicaid / OneGene path). It provides newborn screening advocacy, the SMA Care Center accreditation directory, peer/family support, and emergency financial assistance for travel and lodging while at the specialty center. Refer families to Cure SMA early in the PA process.

Can a patient on Spinraza switch to Zolgensma?

Possibly, with payer-specific UM and clinical review. Spinraza (nusinersen, J2326 if catalogued) is intrathecal antisense oligonucleotide every 4 months indefinitely; Zolgensma is one-time IV gene therapy. Switching requires confirming AAV9 antibody titer ≤ 1:50, patient age < 2 yr, and clinical rationale. Document SMA therapy history and antibody titer in the PA packet.

Cost: how does $2.1M get paid for?

Through payer contracts, not patient out-of-pocket. Most patients are pediatric Medicaid (which has SRAs and OBAs with Novartis). Commercial payers use a combination of standard medical benefit + stop-loss reinsurance + outcomes-based contracts + benefit-pool carve-outs. Patient family OOP exposure is typically capped at the plan's OOP maximum (varies by plan but usually $5K–$15K for the family for the year), not the WAC. OneGene Program and copay-assistance foundations help bridge any residual exposure.

Source documents

1. DailyMed — ZOLGENSMA (onasemnogene abeparvovec-xioi) current FDA label
   Current FDA-approved label (BLA 125694, rev February 2025; SETID 68cd4f06-70e1-40d8-bedb-609ec0afa471) including boxed warning for acute serious liver injury and acute liver failure (with reported fatal outcomes), dosing, AAV9 antibody titer requirement (≤ 1:50), glucocorticoid prophylaxis, monitoring schedule, NDC
2. FDA Drugs@FDA — ZOLGENSMA (BLA 125694)
   FDA approval history, supplements, and prescribing information for onasemnogene abeparvovec-xioi (originally approved May 24, 2019; manufacturer Novartis Gene Therapies, Inc., U.S. License No. 2250)
3. Novartis Gene Therapies — OneGene Program
   Manufacturer patient-support hub: benefits investigation, PA assistance, AAV9 antibody testing, certified center directory, outcomes-based contract operations
4. CMS — Medicare Part B Drug ASP Pricing File
   Quarterly ASP file; J3399 historically priced via NOC / invoice rather than via ASP file (verify quarterly)
5. CMS — OPPS Addendum A / Addendum B
   Hospital outpatient status indicators; check J3399 status quarterly (pass-through vs packaged)
6. Cure SMA — patient organization & SMA Care Center directory
   Newborn screening advocacy, accredited SMA care center directory, peer/family support, emergency financial assistance
7. Mendell et al., NEJM 2017 — START trial of AVXS-101
   Pivotal single-dose gene-therapy trial in symptomatic SMA type 1; basis for FDA approval
8. Day et al., Lancet Neurology 2021 — STR1VE-US trial
   Phase 3 confirmatory trial of one-time IV Zolgensma in symptomatic SMA type 1
9. Strauss et al., Lancet Child & Adolescent Health 2022 — SPR1NT trial
   Pre-symptomatic SMA (identified via newborn screening); supports rapid initiation in NBS positives
10. American Academy of Neurology — SMA practice guidelines
    AAN guidelines for spinal muscular atrophy management; supports clinical use of Zolgensma in pediatric SMA
11. UnitedHealthcare — Zolgensma Medical Drug Policy
12. Aetna CPB — Onasemnogene Abeparvovec
13. FDA National Drug Code Directory
14. CMS — JW/JZ modifier policy (CR 12056, eff. July 2023)

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.

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Change log

• May 22, 2026 — SME audit pass: boxed warning language updated to reflect post-marketing fatal acute liver failure reports per current February 2025 label revision; label revision date and DailyMed SETID added to source list; manufacturer license number verified.
• May 22, 2026 — Initial publication. ASP data: Q2 2026 (J3399 priced via NOC / invoice; not in standard ASP layer). First gene therapy page in the CareCost catalog. Manufacturer source: Novartis OneGene Program 2026. Three-way comparison vs Spinraza (J2326) and Evrysdi (oral risdiplam, pharmacy benefit). Boxed warning for acute serious liver injury documented per FDA label.

Methodology

Every claim on this page is sourced inline. Pricing reflects the current CMS Part B Drug ASP Pricing File and the OPPS Addendum B status indicator (where applicable; J3399 is commonly priced via NOC / invoice). Payer policies are read directly from each payer's published medical/pharmacy policy documents. Indication list, dosing, AAV9 antibody titer threshold, glucocorticoid plan, and monitoring schedule are verified against the current FDA label revision (boxed warning included). Outcomes-based contracting context is verified against Novartis OneGene Program operational guidance. We do not paraphrase from billing-software vendor blogs.