Amondys 45 (casimersen) — Coverage Criteria for Duchenne Muscular Dystrophy (exon 45 amenable)
Governs coverage criteria and authorization requirements for Amondys 45 (casimersen) for treatment of Duchenne muscular dystrophy in members with DMD mutations amenable to exon 45 skipping under Sierra Health and Life commercial plans.
Revised coverage criteria for initial therapy to add a requirement that the patient either has not previously received gene therapy for DMD or, if previously treated with gene therapy, must have documentation of clinically meaningful functional decline since gene replacement therapy.
Updated Benefit Considerations section to reflect the most current information.
Coverage Criteria for Amondys 45 (casimersen)
Initial Therapy
Covered when ALL of the following are met for Initial Therapy:
Do not flatten — all listed conditions must be met
Continuation Therapy
Covered when ALL of the following are met for Continuation Therapy:
Continuation requires evidence of ongoing ambulatory status
Unproven/Not Medically Necessary Uses
Not covered / Unproven:
Use for non-exon 45 amenable DMD mutations or other muscular dystrophies is excluded; concomitant use with other exon skipping therapies is prohibited.
Use of Amondys 45 (casimersen) is excluded for DMD gene mutations that are not amenable to exon 45 skipping and for other forms of muscular dystrophy. The policy explicitly prohibits concomitant use of Amondys 45 with other exon skipping therapies for DMD (for example, Exondys 51 (eteplirsen), Viltepso (viltolarsen), Vyondys 53 (golodirsen)), and such concurrent therapy will not meet coverage criteria.
Requests for Amondys 45 must document prior gene therapy status. If the member previously received gene replacement therapy (e.g., Elevidys), coverage for casimersen requires submission of medical records documenting a clinically meaningful functional decline (for example, loss of a motor milestone) since receiving gene therapy; absence of this documentation may be a basis for denial.
Amondys 45 is considered not medically necessary for the treatment of other forms of muscular dystrophy such as Becker muscular dystrophy, and use for these indications is unproven and excluded from coverage.
Coding and Measurement Thresholds
| J1426 | Injection, casimersen, 10 mg. |
| G71.01 | Duchenne or Becker muscular dystrophy |
Provider Actions, Authorization, and Documentation
Prior Authorization and Duration
Prior authorization is required. Initial and reauthorization approvals are limited to no more than 12 months and require supporting documentation as described below.
- Initial and reauthorization approvals ≤ 12 months
- Prior authorization required
Concurrent Therapy Restriction
Do not use Amondys 45 concomitantly with other exon skipping therapies for DMD.
- Concurrent use prohibited with Exondys 51 (eteplirsen), Viltepso (viltolarsen), Vyondys 53 (golodirsen) or other exon skipping agents
Required Documentation
Submit complete medical records supporting diagnosis, treatment history, and functional status. Lack of required documentation may result in denial.
- Medical records confirming diagnosis of Duchenne muscular dystrophy (DMD) by or in consultation with a neurologist experienced in DMD
- Documentation that the DMD gene mutation is amenable to exon 45 skipping (genetic test results or genetics consultation notes)
- Baseline functional assessments as applicable: 6-Minute Walk Test (6MWT) result (documented ≥ 300 meters if used), North Star Ambulatory Assessment (NSAA) score, time to rise (TTR) when referenced
- Documentation of ambulatory status (ambulatory without assistive device)
- Treatment history including prior gene therapy (e.g., Elevidys) and, if applicable, documentation of clinically meaningful functional decline since gene therapy
- Prescribing clinician documentation (prescribed by or in consultation with a neurologist experienced in DMD)
- Dosing plan consistent with FDA labeling
- Progress/monitoring notes for reauthorization
Triggers for Denial
Denial may be issued when required criteria or documentation are missing or when clinical criteria are not met.
- Missing or incomplete medical records verifying DMD diagnosis or exon 45 amenability
- Patient is non-ambulatory or does not meet ambulatory functional thresholds required for initiation (e.g., 6MWT < 300 meters and not meeting alternate ambulatory criteria)
- Mutation is not amenable to exon 45 skipping
- Concurrent use of another exon skipping therapy
- Prescribed without neurologist involvement or appropriate consultation
- Dosing not consistent with FDA labeling
- No documentation of clinically meaningful decline following prior gene therapy when applicable
Background
Duchenne muscular dystrophy (DMD) is an X‑linked degenerative neuromuscular disorder characterized by progressive loss of skeletal and cardiac muscle strength. Casimersen (Amondys 45) is an antisense oligonucleotide therapy indicated for patients with a confirmed DMD mutation that is amenable to exon 45 skipping. Coverage under this policy is limited to patients meeting specific clinical and functional criteria, including documentation of the exon 45–amenable mutation, ambulatory function thresholds, and appropriate specialist involvement; dosing must follow FDA labeling and prior authorization requirements, with approvals limited to periods no greater than 12 months.
Definitions and Thresholds
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