Spinraza (nusinersen) — HCPCS J2326

SMA treatment landscape — Spinraza, Zolgensma, Evrysdi FDA labels verified May 2026

Three FDA-approved SMA treatments. Different mechanisms, different routes, different benefits. Selection is patient-specific and not interchangeable at the bedside.

Spinal muscular atrophy is caused by biallelic mutations in the SMN1 gene, with the patient's copy number of the backup SMN2 gene modifying disease severity. Three FDA-approved treatments address the same molecular defect via three entirely different mechanisms — each with its own FDA-labeled patient population, administration logistics, billing pathway, and cost structure.

Dosing schedule & unit math FDA label verified May 2026

From the FDA-approved Spinraza prescribing information (NDA 209531). Single fixed dose — not BSA- or weight-based.

Loading + maintenance schedule

Worked example — per-injection unit math

Worked example — ongoing year (maintenance only)

Single fixed dose — no BSA/weight calculation

Unlike most specialty drugs, Spinraza is dosed at a flat 12 mg regardless of patient age, weight, or BSA. Pediatric (including infantile-onset Type 1) and adult patients receive the same 12 mg per injection. The single-dose vial contains exactly 12 mg in 5 mL, so there is no partial-vial waste and JW does not apply. JZ (no waste) is the appropriate modifier on every claim per CMS's July 2023 single-dose container policy.

NDC reference FDA NDC Directory verified May 2026

Administration codes CPT verified May 2026

Spinraza is an intrathecal injection by lumbar puncture. Use procedural CPT codes, not infusion codes. This is the #1 source of J2326 billing errors.

Modifiers CMS verified May 2026

JZ — required on every Spinraza claim (no waste)

JZ reports a single-dose vial dispensed with no discarded drug. Because Spinraza is supplied in a 12 mg / 5 mL single-dose vial and the standard dose is exactly 12 mg, there is no partial-vial waste. JZ applies to virtually every J2326 claim. One of JZ or JW must be on every J2326 claim per CMS's July 2023 single-dose container policy.

JW — not typically applicable

JW (discarded drug from single-dose container) is essentially never used for Spinraza because the 12 mg vial matches the 12 mg dose. The only scenario where JW could apply is a clinical event during administration (e.g., LP failure before completion of the injection) requiring documented partial discard. Document carefully and submit on a separate line.

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 intrathecal injection. Routine pre-procedure neurologic assessment and motor function evaluation (CHOP-INTEND, HFMSE) may meet the threshold for separate E/M billing — document specifically.

340B modifiers (JG, TB)

For 340B-acquired Spinraza, follow your MAC's current 340B modifier policy. Hospital outpatient departments billing under OPPS are subject to specific 340B reporting requirements; freestanding ASCs and physician offices follow their respective 340B billing rules.

ICD-10-CM by SMA type FY2026 verified May 2026

Spinraza covers all SMA types — pair the SMA-specific ICD-10 code with documented biallelic SMN1 mutation in the PA submission.

Site of care & place of service Verified May 2026

Spinraza administration requires a clinician trained in lumbar puncture, imaging guidance capability (fluoroscopy or CT), and pediatric-appropriate sedation/anesthesia capacity. Most Spinraza is administered in pediatric academic medical centers, hospital outpatient neurology suites, and adult neurology specialty clinics with interventional radiology support. Commercial site-of-care UM for Spinraza is relatively lenient compared to oncology drugs — the procedural complexity often keeps it in HOPD without significant payer pushback.

Claim form field mapping Biogen Above SMA 2026

From Biogen Above SMA HCP coding & coverage materials. Most Spinraza claims are UB-04 (HOPD) but the field mapping concept is the same on CMS-1500.

Payer policy snapshot Reviewed May 2026

All major payers require PA. Documentation requirements are highly specific to SMA — genetic confirmation, baseline motor function, and ongoing response assessments.

Step therapy

For most payers, Spinraza is a primary therapy option and does not require step through another agent. However, for pediatric patients <2 years old at diagnosis, payers may ask why Zolgensma (one-time gene therapy) was not chosen — document contraindication (high anti-AAV9 titers, hepatic disease, age >2 years) or family preference. For patients switching from Evrysdi to Spinraza, document lack of efficacy or tolerability on Evrysdi.

Response monitoring (continuation PA)

All major payers require documentation of treatment response at PA renewal:

• CHOP-INTEND (Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders) — used for infants and Type 1 patients; score 0–64; improvement of ≥4 points or stability is generally considered response
• HFMSE (Hammersmith Functional Motor Scale - Expanded) — used for older Type 2/3 patients; tracks functional motor abilities
• RHS (Revised Hammersmith Scale) — sometimes used for adult patients
• Pulmonary function — FEV1, FVC, peak expiratory flow as supportive evidence

Submit chart documentation of pre-treatment baseline and post-treatment assessments (typically every 4–6 months) with each PA renewal.

Medicare reimbursement CMS Q2 2026 (live)

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

Coverage

No NCD specific to nusinersen. Coverage falls under MAC LCDs for physician-administered drugs and SMA-specific local coverage articles published by each MAC. All MACs cover J2326 for FDA-approved indications with appropriate documentation of SMN1 genetic confirmation and SMA diagnosis. The intrathecal procedure (62321) is covered under the physician fee schedule (or OPPS in HOPD) independently.

Code history

• Pre-2018: nusinersen billed under unclassified J3490 / J3590
• J2326 — permanent HCPCS code, effective January 1, 2018; descriptor "Injection, nusinersen, 0.1 mg"

Patient assistance — Biogen Above SMA & Cure SMA Biogen verified May 2026

• Biogen Above SMA (Spinraza support program): 1-844-4-ABOVE-SMA (1-844-422-6837) · spinraza.com — benefits investigation, prior authorization assistance, appeal support, nurse case management, transportation/lodging assistance for travel to specialized centers
• Spinraza Co-Pay Assistance Program: commercial copay support for eligible commercially-insured patients; eligible patients may pay as little as $0 out-of-pocket per dose (excludes Medicare, Medicaid, TRICARE, VA, federal program patients)
• Biogen Patient Assistance Foundation: free product for uninsured / underinsured patients meeting income requirements
• Cure SMA Patient & Family Support: curesma.org — independent nonprofit; equipment grants, family support, newly-diagnosed packages, peer support, advocacy
• Foundations (Medicare and federal program patients): Patient Access Network (PAN) Foundation, HealthWell Foundation, National Organization for Rare Disorders (NORD), Good Days — verify open SMA/neurological funds (funds open and close throughout the year)
• Web: spinraza.com support

Common denials & how to fix them

Frequently asked questions

What is the HCPCS code for Spinraza?

Spinraza (nusinersen) is billed under HCPCS J2326 — "Injection, nusinersen, 0.1 mg." The full 12 mg dose equals 120 billable units. J2326 is a permanent code (effective January 1, 2018) and is the only HCPCS available for nusinersen — there is no biosimilar or therapeutic equivalent.

Why CPT 62321 and not 96365 for Spinraza?

Spinraza is administered by intrathecal injection via lumbar puncture into the cerebrospinal fluid, not by intravenous infusion. CPT 96365 ("Intravenous infusion, for therapy, prophylaxis, or diagnosis; initial, up to 1 hour") describes IV access — it does not apply to a procedural lumbar puncture. CPT 62321 specifically describes "interlaminar epidural or subarachnoid" lumbar injection with imaging guidance, which is the standard-of-care delivery method per the FDA label. Submitting 96365 for Spinraza will trigger denial — this is the single most common billing error for J2326 because it is the only intrathecal drug most coders encounter.

What is the Spinraza loading and maintenance schedule?

Per FDA label: 4 loading doses (12 mg each) on Days 0, 14, 28, and 63, followed by maintenance dosing of 12 mg every 4 months thereafter for life. First-year exposure is 6 injections (4 loading + 2 maintenance). Subsequent years are 3 maintenance injections per year. There is no defined endpoint — Spinraza is a lifetime treatment unless the patient transitions to another SMA therapy or treatment is discontinued for clinical reasons.

Spinraza vs Zolgensma vs Evrysdi — when which?

Three FDA-approved SMA treatments, three completely different products, three completely different billing pathways. Spinraza (J2326): intrathecal antisense oligonucleotide; all ages, all SMA types; lifetime q4mo dosing after loading; ~$125K/injection; medical benefit. Zolgensma (J3399): one-time IV gene therapy; FDA-approved for pediatric SMA patients <2 years old at dosing; ~$2.25M one-time; medical benefit. Evrysdi (risdiplam): daily oral SMN2 splice modifier; all ages; pharmacy benefit (Part D, not Part B). Treatment selection is patient-specific (age, SMA type, prior therapy, access logistics). See the SMA treatment landscape table for the full comparison.

Do I bill fluoroscopy (CPT 77003) separately for Spinraza?

No. CPT 62321 already includes imaging guidance ("with imaging guidance, i.e., fluoroscopy or CT") in its code descriptor. Per AMA CPT guidelines and NCCI edits, 77003 (fluoroscopic guidance) is bundled into 62321 and should NOT be billed separately. If 62322 (without imaging guidance) is billed instead, 77003 cannot be added retroactively — the imaging needs to be reflected in the primary code choice.

Is Spinraza approved for adult SMA patients?

Yes. Spinraza's FDA label covers pediatric AND adult patients with SMA — it is the only SMA treatment with a broad age indication. Zolgensma is restricted to pediatric patients under 2 years of age at dosing. Evrysdi has a broad age label like Spinraza. Major commercial payers and Medicare both cover Spinraza for adult SMA patients with documented SMN1 biallelic mutations and appropriate baseline motor function assessment.

What ICD-10 codes do I use for Spinraza?

SMA-specific. G12.0 (Werdnig-Hoffmann disease, SMA type 1, infantile-onset); G12.1 (other inherited spinal muscular atrophy — covers SMA types 2); G12.8 (other spinal muscular atrophies and related syndromes — used for adult-onset SMA types 3 and 4, Kugelberg-Welander); G12.9 (spinal muscular atrophy, unspecified). Most payers also require documentation of biallelic SMN1 deletion/mutation by genetic testing in the PA submission — the ICD-10 code alone is not sufficient.

What is the Medicare reimbursement for J2326?

Medicare Part B covers Spinraza as a physician-administered intrathecal drug. Reimbursement is at the published quarterly ASP + 6% per the CMS Part B Drug Pricing File. WAC list price is approximately $125,000 per 12 mg dose. Use the live-bound ASP figure on this page for current-quarter pricing. Sequestration (~2%) reduces actual paid amount to roughly ASP + 4.3%. The administration procedure (CPT 62321) is reimbursed separately under the physician fee schedule or OPPS depending on site of service.

Is treatment really lifetime? What if response is inadequate?

Per FDA label, there is no defined treatment endpoint for Spinraza — maintenance q4mo dosing continues indefinitely. In practice, treatment is reviewed at each PA renewal (typically every 6 months) against motor function data (CHOP-INTEND, HFMSE, RHS) and pulmonary function. Patients with documented progressive decline despite Spinraza may transition to Evrysdi (oral) or in rare cases discontinue treatment. Switching has its own PA review. Stability over treatment course is generally considered response, given that untreated SMA is progressive.

Is Medicaid or commercial primary for pediatric SMA patients?

Most pediatric SMA patients qualify for state Medicaid as a secondary or primary payer due to disability eligibility (SSI determination), even with commercial coverage. Coordination of benefits varies by state, but Medicaid TPL (third-party liability) rules generally require billing the commercial plan first, with Medicaid paying as secondary after commercial determination. Some state Medicaid programs negotiate Spinraza pricing directly with Biogen under the Medicaid Drug Rebate Program. Verify both PA processes (commercial AND Medicaid) before scheduling any loading dose.

Can a patient switch from Spinraza to Evrysdi or vice-versa?

Yes, but it requires a switch PA with documented rationale (intolerance, lack of efficacy, family logistics preferring oral over intrathecal). Concurrent therapy with Spinraza + Evrysdi is generally not covered. From Zolgensma to Spinraza is also possible (typically when gene therapy response is considered inadequate); from Spinraza to Zolgensma is more restrictive due to Zolgensma's strict <2-year age window and anti-AAV9 titer requirements.

Does Spinraza require lab monitoring before each dose?

Per FDA label, baseline and pre-dose monitoring should include: platelet count, coagulation parameters (PT/PTT), and quantitative urine protein. Monitor for thrombocytopenia, coagulation abnormalities, and renal toxicity (which is class effect for antisense oligonucleotides). Many neurology practices draw labs 1–2 weeks before each Spinraza dose; abnormalities may delay or contraindicate the next injection. Lab results are typically requested at PA renewal.

Source documents

1. FDA — SPINRAZA prescribing information (NDA 209531)
   FDA-approved label; full prescribing information including dosing, administration, W&P
2. DailyMed — SPINRAZA (nusinersen), current label (setid dd70cd5f-b0fc-4ba4-a5ea-89a34778bd94)
   Label revision March 31, 2026 — current W&P (thrombocytopenia/coagulation; renal toxicity), dosing, NDC, indication
3. Biogen Above SMA — Spinraza HCP coding & coverage
   Manufacturer billing guide, claim form mapping, copay assistance program
4. CMS — Medicare Part B Drug ASP Pricing File
   Q2 2026 quarterly file, effective April 1 – June 30, 2026
5. SEER CanMED — HCPCS J2326 reference
6. Finkel RS et al. — ENDEAR (infantile-onset Type 1)
   Pivotal Phase 3 trial; published NEJM 2017
7. Mercuri E et al. — CHERISH (later-onset SMA)
   Pivotal Phase 3 trial; published NEJM 2018
8. De Vivo DC et al. — NURTURE (presymptomatic infants)
   Open-label trial in genetically diagnosed pre-symptomatic SMA
9. American Academy of Neurology — SMA evidence-based guideline
   Professional society guidance on SMA diagnosis and treatment
10. Cure SMA — Patient & Family Resources
11. CMS HCPCS Level II Quarterly Updates
12. FDA National Drug Code Directory
13. 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.

Found an error? Email hello@carecostestimate.com.

Refresh cadence

Reviewer

Change log

• May 22, 2026 (SME audit) — Verified FDA label (DailyMed setid dd70cd5f-b0fc-4ba4-a5ea-89a34778bd94, rev. Mar 31, 2026). Added current DailyMed setid to sources; tightened W&P language to mirror current label (acute severe thrombocytopenia; potentially fatal glomerulonephritis). Updated FDA application reference to BLA 209531. Noted SMA360° as current Biogen support program brand.
• May 22, 2026 — Initial publication. ASP data: Q2 2026 (live-bound). Manufacturer source: Biogen Above SMA 2026. Sole FDA indication: SMA in pediatric and adult patients (all types). Intrathecal admin via CPT 62321. SMA treatment landscape vs Zolgensma + Evrysdi included.

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. Indication list and dosing are verified against the current FDA label revision. We do not paraphrase from billing-software vendor blogs.