Duchenne Muscular Dystrophy Access Landscape: Elevidys, Oligonucleotides, and Duvyzat

The therapeutic landscape for Duchenne Muscular Dystrophy (DMD) has experienced rapid acceleration and intense regulatory scrutiny over the past several years. DMD is a rare, X-linked recessive neuromuscular disorder caused by mutations in the DMD gene, which prevents the production of functional dystrophin—a structural protein vital for maintaining muscle fiber integrity. Without dystrophin, muscle fibers undergo progressive degeneration, leading to loss of ambulation in early adolescence, respiratory insufficiency, cardiomyopathy, and premature death, typically by early adulthood.

Historically, DMD management was limited to supportive care and systemic corticosteroids. Today, the DMD treatment landscape has evolved into a four-tiered therapeutic framework: a multi-million-dollar gene therapy, mutation-specific exon-skipping oligonucleotides, novel non-steroidal oral agents, and traditional or modified corticosteroids.

Navigating the market access, billing codes, and clinical criteria for these products is exceptionally complex. The high cost of these therapies—led by a $3.2 million one-time gene therapy—coupled with a critical FDA safety label change in November 2025 has created a challenging reimbursement environment. For payers, specialty pharmacies, and clinical teams, managing these therapies requires rigorous compliance with genetic eligibility and safety monitoring.

For related analyses of high-cost gene therapy and specialty rare disease access landscapes, see the hemophilia access landscape detailing gene therapy billing, the Casgevy access guide for sickle cell Medicaid coverage, and the corticosteroid FAERS analysis for the safety baseline of deflazacort. For the regulatory context of these approvals, see the accelerated-approval postmarketing-requirement tracker.

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Which DMD therapies are FDA-approved, and how do gene therapy, exon-skippers, and non-gene agents differ?

To understand how DMD treatments are managed, we must look at the four distinct therapeutic tiers approved by the FDA:

1. In Vivo Gene Therapy (Elevidys)

Gene therapy aims to address the root cause of DMD by delivering a shortened, functional version of the dystrophin gene. Because the full dystrophin gene is too large to fit inside standard viral vectors, researchers developed "micro-dystrophin" constructs.

• Delandistrogene moxeparvovec-rokl (Elevidys, Sarepta Therapeutics/Roche): Approved under BLA 125781. It is a recombinant adeno-associated virus serotype rh74 (AAVrh74) vector encoding a micro-dystrophin protein. Dosed as a single, one-time intravenous infusion, it is designed to slow muscle degeneration by producing a functional micro-dystrophin in skeletal and cardiac muscle tissues.

2. Mutation-Specific Exon-Skipping Oligonucleotides

Antisense oligonucleotides (ASOs) are synthetic RNA-like molecules designed to bind to specific pre-mRNA sequences, shielding them from the splicing machinery. This "skips" a targeted mutated exon during transcription, restoring the reading frame and allowing the cell to produce a partially functional, truncated dystrophin protein. These therapies are mutation-specific and apply only to patients with matching genetic profiles:

• Eteplirsen (Exondys 51, Sarepta): Targets exon 51 skipping. Approved in September 2016; applicable to approximately 13% of the DMD population.
• Golodirsen (Vyondys 53, Sarepta): Targets exon 53 skipping. Approved in December 2019; applicable to approximately 8% of the DMD population.
• Viltolarsen (Viltepso, NS Pharma): Targets exon 53 skipping. Approved in August 2020; applicable to approximately 8% of the DMD population.
• Casimersen (Amondys 45, Sarepta): Targets exon 45 skipping. Approved in February 2021; applicable to approximately 8% of the DMD population.

3. Novel Non-Gene Oral Agents

These pharmacy-benefit medications represent broader options that do not depend on specific genetic mutations:

• Givinostat (Duvyzat, Italfarmaco): Approved in March 2024. It is an oral histone deacetylase (HDAC) inhibitor designed to address the pathological cascades downstream of dystrophin deficiency, reducing muscle inflammation and fibrosis, and promoting muscle regeneration. It is indicated for ambulatory patients aged 6 and above.
• Vamorolone (Agamree, Santhera/Catalyst): Approved in October 2023. It is a dissociative corticosteroid designed to bind to glucocorticoid receptors to exert anti-inflammatory effects while avoiding the structural interactions that lead to typical steroid side effects (e.g., bone loss, growth suppression).

4. Background Corticosteroids (Deflazacort)

Systemic steroids remain the baseline mainstay of therapy to prolong ambulation and delay respiratory decline:

• Deflazacort (Emflaza, now generic): Approved in 2017. It is a corticosteroid with a slightly different side-effect profile compared to prednisone, particularly regarding weight gain and bone density in some patients. It is now available as a generic.

The table below summarizes the clinical profiles and genetic eligibility for the primary DMD-specific agents:

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What does Elevidys cost, how is it billed (HCPCS J1413), and what changed with the 2025 liver-failure Boxed Warning?

The financial and regulatory status of delandistrogene moxeparvovec-rokl (Elevidys) represents a major focal point in specialty therapeutics.

Pricing and Medical Billing

Sarepta launched Elevidys at a WAC of $3.2 million for a single-dose treatment, making it one of the most expensive drugs in the world (second only to CSL Behring's $3.5 million Hemgenix at the time of launch). For medical billing and reimbursement, Elevidys has a permanent HCPCS code:

• HCPCS J1413: Injection, delandistrogene moxeparvovec-rokl, per therapeutic dose.
• Billing details: The NDC format is 60594-0930-01 (or 60594-0930-10 depending on the specific kit). Because the dose is weight-based, the drug is shipped as a customized patient-specific kit containing between 4 and 26 vials of the vector. Standard diagnostic coding requires ICD-10 code G71.01 (Duchenne or Becker muscular dystrophy). Clinics typically administer the infusion in an outpatient hospital setting, billing under CPT codes 96365 (intravenous infusion, initial hour) and 96366 (each additional hour).

The November 2025 Boxed Warning and Indication Restriction

Elevidys originally received accelerated approval in June 2023 for ambulatory pediatric patients aged 4 to 5. On June 20, 2024, the FDA significantly expanded the label: granting traditional approval for ambulatory patients aged 4 and older, and accelerated approval for non-ambulatory patients aged 4 and older, based on micro-dystrophin expression as a surrogate endpoint.

However, post-marketing safety data soon challenged this expansion. On July 18, 2025, the FDA issued a safety communication disclosing an investigation into AAVrh74 vector-related deaths. The agency reported three fatal cases of acute liver failure, two of which occurred in non-ambulatory DMD patients treated with Elevidys. In response, Sarepta voluntarily suspended non-ambulatory shipments in June 2025 while the FDA conducted its safety review.

This culminated in an FDA-approved label revision on November 14, 2025, which introduced two major changes:

1. Addition of a Boxed Warning: A Boxed Warning was added to warn clinicians of the risk of Acute Serious Liver Injury and Acute Liver Failure. The warning notes that fatal cases of acute liver failure have occurred and requires baseline liver function testing, weekly monitoring of liver enzymes for at least three months post-infusion, and immediate treatment with systemic corticosteroids if hepatotoxicity is suspected.
2. Removal of the Non-Ambulatory Indication: The FDA removed the accelerated approval for non-ambulatory patients from the Indications and Usage section. The updated label limits Elevidys to ambulatory patients aged 4 years and older with a confirmed mutation in the DMD gene. Payers immediately updated their policies to deny coverage for any non-ambulatory patient, illustrating the clinical and commercial risk associated with accelerated approvals built on surrogate endpoints.

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What are the verified HCPCS codes for the four exon-skipping oligonucleotides, and who is eligible for each?

For patients who are ineligible for gene therapy or require adjunctive treatments, the four mutation-specific exon-skipping oligonucleotides represent the primary medical-benefit options. Because these are weekly intravenous infusions administered by healthcare providers, they are billed using individual HCPCS J-codes:

• Casimersen (Amondys 45): Billed under HCPCS code J1426 (Injection, casimersen, 10 mg). Dosed intravenously once weekly. It is indicated for patients with a confirmed mutation of the DMD gene that is amenable to exon 45 skipping. This applies to approximately 8% of all DMD patients (including deletions of exons 44, 46, or 46-55).
• Viltolarsen (Viltepso): Billed under HCPCS code J1427 (Injection, viltolarsen, 10 mg). Dosed intravenously once weekly. It is indicated for patients with a confirmed mutation amenable to exon 53 skipping, representing approximately 8% of the DMD population (including deletions of exons 52, 45-52, or 48-52).
• Eteplirsen (Exondys 51): Billed under HCPCS code J1428 (Injection, eteplirsen, 10 mg). Dosed intravenously once weekly. It is indicated for patients with a confirmed mutation amenable to exon 51 skipping, representing approximately 13% of the DMD population (including deletions of exons 50, 52, or 45-50).
• Golodirsen (Vyondys 53): Billed under HCPCS code J1429 (Injection, golodirsen, 10 mg). Dosed intravenously once weekly. Like viltolarsen, it targets mutations amenable to exon 53 skipping.

The table below outlines the billing codes, package configurations, and annual cost structures:

Cost-source note: Because these medications are weekly, weight-based infusions, the annual WAC varies depending on the patient's weight. The estimates above represent standard childhood weights (20 kg to 35 kg). For older or heavier patients, the annual WAC can exceed $750,000, presenting a significant specialty cost for payers.

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What prior-authorization criteria apply across the DMD portfolio?

To manage these high-cost therapies, commercial payers (such as Aetna and Premera Blue Cross) and state Medicaid plans implement strict prior authorization (PA) criteria. Clinicians must submit detailed evidence to verify eligibility:

1. Prescriber Restrictions

All therapies in the DMD portfolio require prescribing by or in consultation with a pediatric neurologist, developmental pediatrician, or neuromuscular specialist with experience in managing DMD.

2. Genetic Testing Requirements

Payers require copies of the laboratory genetic report (multiplex PCR, MLPA, or next-generation sequencing) confirming:

• A pathogenic mutation in the DMD gene.
• For exon-skippers, the specific deletion must be confirmed as amenable to the drug's mechanism (e.g., exon 51, 53, or 45).
• For Elevidys, payers verify that the patient does not have a deletion in exon 8 or 9. The Elevidys micro-dystrophin protein contains domains derived from exons 8 and 9; patients lacking these exons can develop an immune-mediated inflammatory response (myocarditis) against the transgene, which is a major safety contraindication.

3. Functional and Ambulatory Gating

Payers require documentation of baseline motor function:

• Elevidys: The patient must be confirmed as ambulatory by the prescribing physician. Payers require documentation of a motor assessment test, such as the North Star Ambulatory Assessment (NSAA) or timed function tests (e.g., 10-meter run/walk time, time to stand from supine).
• Exon-Skippers: Most payers require the patient to be ambulatory at initiation. If a patient loses ambulation while on weekly infusions, some policies allow continuation of therapy to preserve upper limb and respiratory function, but others enforce strict discontinuation edits.
• Givinostat (Duvyzat): Indicated only for ambulatory patients aged 6 and older.

4. Dosing and Lifetime Limits

• Elevidys Lifetime Limit: Payers restrict Elevidys to one treatment per lifetime. Because patients develop neutralizing antibodies against the AAVrh74 capsid after the first infusion, repeat dosing is impossible due to the risk of severe immune reactions.
• Exon-Skipper Exclusions: Payers prohibit the concurrent use of multiple exon-skipping drugs or the use of an exon-skipper in combination with Elevidys, as clinical trials have not evaluated combination therapy.

5. Reauthorization and Renewal Gating

For the weekly infusions (J1426, J1427, J1428, J1429) and oral givinostat, initial approvals are granted for 6 to 12 months. Reauthorization requires documentation of:

• Adherence to the weekly infusion schedule.
• No intolerable drug-related toxicities (e.g., renal toxicity for golodirsen/viltolarsen, which requires weekly urinalysis).
• Maintenance of, or slow decline in, motor function (e.g., an NSAA score decline slower than the natural history of untreated patients).

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What does the FAERS post-marketing profile show for the DMD-specific agents?

To evaluate the real-world safety profile of these therapies, we analyzed post-marketing reports in the openFDA FAERS database. Across the primary DMD-specific agents (delandistrogene moxeparvovec, eteplirsen, golodirsen, casimersen, viltolarsen, givinostat, vamorolone, and deflazacort), the database contains 11,079 reports current through June 8, 2026.

Cohort Seriousness and Demographics

Of the 11,079 reports in the DMD cohort, 4,233 reports (38.2%) are classified as serious, and 403 reports (3.6%) document a fatal outcome.

This relatively low death share (3.6%) reflects the pediatric and young-adult demographic of the treated population, which is distinct from the elderly advanced-heart-failure population profiled in the ATTR-CM access landscape. It also highlights a critical pharmacovigilance principle: we must not infer gene therapy mortality from the raw FAERS aggregate.

Because Elevidys is a recently launched therapy with only a few hundred total reports, its fatal cases represent a tiny fraction of the 403 deaths in the database. The vast majority of deaths in this cohort are associated with long-term corticosteroid use or late-stage cardiomyopathy in older DMD patients. Clinicians must cite the specific Elevidys deaths (three fatal cases of acute liver failure) from official FDA safety communications rather than trying to calculate mortality rates from spontaneous FAERS counts.

The gender distribution in the cohort is heavily skewed: 7,355 reports (66.4%) involve male patients, compared to only 1,625 reports (14.7%) involving female patients (with the remaining reports unspecified). This male predominance is consistent with the X-linked recessive inheritance of DMD, which affects males almost exclusively, while females are typically asymptomatic carriers.

The top indications in the cohort confirm that the data captures the target patient population:

• Duchenne Muscular Dystrophy: 5,252 reports
• Product Used for Unknown Indication: 4,627 reports
• Muscular Dystrophy (generic match): 1,705 reports
• Becker's Muscular Dystrophy: 202 reports

Reporting Trends and Agent Leaders

Post-marketing reports peaked in 2025 with 1,929 reports, driven by the expansion of Elevidys utilization and the approvals of Duvyzat and Agamree.

The table below details the report counts by specific active substances, highlighting the dominance of the baseline steroid:

• Deflazacort: 6,245 reports
• Eteplirsen: 2,153 reports
• Casimersen: 833 reports
• Givinostat: 475 reports
• Golodirsen: 418 reports
• Viltolarsen: 143 reports

Note on Deflazacort Dual Use: Deflazacort represents the largest contributor to the cohort with 6,245 reports. While deflazacort is widely used in DMD, it is also prescribed for non-neuromuscular inflammatory conditions. In our database search, indications such as "rheumatoid arthritis" (955 reports) and "asthma" (167 reports) appeared, indicating that some deflazacort reports involve adult patients treated for non-DMD conditions. This dual-use presence must be disclosed when presenting deflazacort safety figures.

Key Adverse Event Signals

The top reported adverse events in the cohort are:

• Product Dose Omission Issue: 1,205 reports (reflecting the challenges of maintaining weekly clinic infusions and specialty pharmacy shipping delays during shortages).
• Weight Increased: 728 reports (a well-known side effect of chronic corticosteroid therapy).
• Fall: 413 reports (reflecting the muscle weakness and progressive loss of balance characteristic of DMD).
• Vomiting / Pyrexia: 410 / 405 reports (common pediatric adverse events, but also notable as early signs of systemic immune response post-gene therapy).

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FAQs

Is Elevidys still available for non-ambulatory Duchenne patients after the 2025 safety changes?

No. Following the November 14, 2025 label revision, the FDA removed the accelerated approval for non-ambulatory patients. The revised indication limits Elevidys to ambulatory patients aged 4 years and older. In addition, major payers have updated their medical policies to restrict coverage to ambulatory patients, meaning insurance will deny coverage for any patient who has lost the ability to walk.

Which exon-skipping drug applies to which DMD mutation, and what percentage of patients qualifies?

Each of the four approved exon-skipping drugs is mutation-specific:

• Exondys 51 (eteplirsen): Targets mutations amenable to exon 51 skipping, covering approximately 13% of DMD patients (the largest single amenable cohort).
• Amondys 45 (casimersen): Targets mutations amenable to exon 45 skipping, covering approximately 8% of patients.
• Vyondys 53 (golodirsen) & Viltepso (viltolarsen): Both target mutations amenable to exon 53 skipping, covering approximately 8% of patients. In total, these four drugs cover approximately 37% of the DMD population. The remaining 63% of patients have mutations that cannot be addressed by these specific agents.

How much does Duchenne gene therapy cost, and how do exon-skippers and givinostat compare?

Elevidys costs $3.2 million for a single, one-time treatment. Exon-skipping drugs (Exondys 51, Amondys 45, Vyondys 53, Viltepso) are dosed weekly and cost between $350,000 and $450,000 per year for a typical child, with costs rising as the patient gains weight (potentially exceeding $750,000 annually). Duvyzat (givinostat) is an oral medication taken daily, costing approximately $100,000 to $150,000 per year. Because Elevidys is a one-time infusion, its upfront cost is much higher, but its long-term cost may be comparable to several years of weekly exon-skipping therapy.

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Sources

• US FDA, Purple Book Database of Licensed Biological Products (snapshot current to July 8, 2026). https://www.fda.gov/vaccines-blood-biologics/purple-book-database-license-biological-products
• US FDA, Elevidys (delandistrogene moxeparvovec-rokl) prescribing information containing Boxed Warning for hepatotoxicity and revised ambulatory indication (revised November 14, 2025). https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/125781s000lbl.pdf
• US FDA, Safety Communication: FDA investigating fatal cases of acute liver failure associated with Sarepta AAVrh74 gene therapies (July 18, 2025). https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/fda-investigating-deaths-due-acute-liver-failure-following-treatment-sareptas-aavrh74-gene-therapies
• US FDA, Elevidys original BLA 125781 approval letter (June 20, 2024 expansion). https://www.fda.gov/media/179484/download
• Parent Project Muscular Dystrophy, FDA Approves New Safety Warning and Revised Indication for Elevidys (November 14, 2025). https://www.parentprojectmd.org/fda-approves-new-safety-warning-and-revised-indication-for-elevidys
• Aetna, Clinical Policy Bulletin 0911: Gonadotropin-Releasing Hormone Analogs and Gene Therapy for Duchenne Muscular Dystrophy (revised April 2026). https://www.aetna.com/cpb/medical/data/900_999/0911.html
• Premera Blue Cross, Medical Policy 5.01.570: Treatment of Duchenne Muscular Dystrophy (revised 2025). https://www.premera.com/medicalpolicies/5.01.570.pdf
• openFDA, FAERS Database API and raw CSV download files (data snapshot current to export dated June 8, 2026; containing 20,328,575 total reports). https://open.fda.gov/data/faers/
• Sarepta Therapeutics, Elevidys Billing and Coding Guide for Healthcare Providers (HCPCS J1413, NDC 60594-0930-01). https://www.elevidyshcp.com/downloads/ELEVIDYS-Billing-and-Coding-Guide.pdf
• BioPharma Dive, Sarepta Prices Duchenne Gene Therapy Elevidys at $3.2 Million (published June 2023). https://www.biopharmadive.com/news/sarepta-duchenne-elevidys-price-million-gene-therapy/653720
• Mendell JR, et al. Longitudinal Effect of Eteplirsen versus Historical Control on Ambulation in Duchenne Muscular Dystrophy. Ann Neurol. 2016;79:257-271. (PMID: 26573217) https://pubmed.ncbi.nlm.nih.gov/26573217
• Mercuri E, et al. Safety and Efficacy of Givinostat in Boys with Duchenne Muscular Dystrophy (EPIDYS): A Double-Blind, Randomized, Placebo-Controlled, Phase 3 Trial. Lancet Neurol. 2024;23:389-399. (PMID: 38442880) https://pubmed.ncbi.nlm.nih.gov/38442880