Amondys 45 (casimersen) coverage
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Defines medical necessity and prior authorization requirements for Amondys 45 (casimersen) for Geisinger Health Plan across commercial, Medicare, Medicaid, CHIP and exchange lines of business.
No material clinical or coverage changes in this revision.
Coverage Criteria for Amondys 45 (casimersen)
Initial Therapy (Medicare/Medicaid)
Medicare and Medicaid: Covered when ALL of the following are met
Initial approval up to 6 months
Initial Therapy (Commercial/CHIP)
Commercial, exchange, and CHIP: Covered when ALL of the following are met
Initial approval up to 6 months
Continuation Therapy / Renewal
Subsequent approvals (all applicable lines of business): Covered when ALL of the following are met
Subsequent approvals for additional 6 months
Reviewed for continued benefit
Requests for Amondys 45 (casimersen) are ineligible for coverage when there is documentation that the patient has received prior gene therapy (for example, Elevidys). The policy requires medical record documentation that the patient has not received prior treatment with gene therapy as a condition of initial and subsequent approvals. Requests for members who show decline after prior gene therapy will be reviewed on a case‑by‑case basis.
For commercial, exchange, and CHIP lines of business, initiation requests must include evidence of ambulatory status demonstrated by a 6‑Minute Walk Test (6MWT) within the past 3 months. Requests that lack this required baseline ambulatory documentation, or that do not include genetic confirmation of DMD and verification that the mutation is amenable to exon 45 skipping (confirmed by a genetic counselor), do not meet medical necessity criteria and may be denied.
Initial Therapy Requirements
Initial Therapy — Initial coverage requirements
Initial coverage requirements
Prior authorization required; initial approval up to 6 months
Criteria for Continued Coverage
Continuation Therapy — Criteria for continued coverage (renewal)
Criteria for continued coverage (renewal)
Subsequent approvals for 6 months
Used to assess continued benefit
Required Tests and Coding
Provider Actions, Prior Authorization, and Documentation
Prior authorization required; initial approvals up to 6 months
Prior authorization is required and must be obtained from the Medical Director or their designee. Initial approvals will be granted for up to 6 months (or less if the reviewer determines medically appropriate) and require submission of the specified clinical documentation listed in the policy (see genetic testing, motor function assessment, interdisciplinary team documentation, dosing consistent with FDA labeling, and documentation of no prior gene therapy). Subsequent approvals are for additional 6-month periods and require evidence of continued benefit and required follow-up documentation.
- Obtain prior authorization from the Medical Director or designee before initiation.
- Initial authorization duration: up to 6 months (may be shorter if medically appropriate).
- Subsequent approvals: additional 6 months and require documentation of continued benefit and annual/interval assessments as specified.
No specified step therapy; document no prior gene therapy
No specific step therapy sequence is specified in the policy; however, the medical record must document that the patient has not previously received gene therapy (for example, Elevidys) to be eligible.
- Policy does not require trials of alternative agents prior to casimersen.
- Document explicitly that the patient has not had prior gene therapy (e.g., Elevidys).
Required medical record documentation and assessments
Medical record documentation must include interdisciplinary team involvement, genetic confirmation and counseling, baseline and follow-up motor function assessments, corticosteroid use status, dosing consistent with FDA labeling, ambulatory status (for commercial/CHIP), and documentation of no prior gene therapy.
- Interdisciplinary team involvement including at minimum neurology, cardiology, pulmonology, and a genetic specialist (e.g., geneticist or genetic counselor).
- Genetic confirmation of DMD and documentation that the mutation is amenable to exon 45 skipping (confirmed by a genetic counselor).
- Baseline standardized motor function assessment by a neurologist experienced in DMD; for initiation (commercial/CHIP) include a 6MWT within the past 3 months.
- For renewals, annual neurologist evaluation including motor function assessment and, for commercial/CHIP, a follow-up 6MWT within the past 6 months.
- Documentation that Amondys 45 is given concurrently with oral corticosteroids unless contraindicated or intolerant.
- Documentation that dosing will be consistent with FDA labeling (maximum 30 mg/kg infused once weekly).
- Documentation that the patient has not received prior gene therapy (e.g., Elevidys).
Grounds for denial: missing or nonconforming documentation and ineligible mutation/history
Requests may be denied if required documentation is missing or if DMD is not confirmed by genetic testing or the mutation is not amenable to exon 45 skipping; other common denial triggers include absent baseline/renewal motor function assessments, lack of documented concurrent corticosteroid use when applicable, dosing inconsistent with FDA labeling, or prior receipt of gene therapy.
- Missing interdisciplinary team documentation (neurology, cardiology, pulmonology, genetic specialist).
- No genetic confirmation of DMD or no documentation that the mutation is amenable to exon 45 skipping (as confirmed by a genetic counselor).
- Absence of baseline standardized motor function assessment (or required 6MWT for commercial/CHIP) within specified timeframes.
- Failure to document concurrent oral corticosteroid therapy unless contraindicated or intolerant.
- Dosing not consistent with FDA-approved labeling (maximum 30 mg/kg weekly).
- Documentation showing prior treatment with gene therapy (e.g., Elevidys).
Definitions and Key Terms
Background
Casimersen (Amondys 45) is an antisense oligonucleotide designed to bind exon 45 of dystrophin pre‑mRNA to induce exon 45 skipping and enable production of an internally truncated dystrophin protein in patients with Duchenne muscular dystrophy whose mutations are amenable to exon 45 skipping. The agent is approved under accelerated approval based on increased dystrophin production; ongoing coverage requires documentation consistent with the FDA labeling, including dosing not to exceed 30 mg/kg once weekly, and clinical monitoring to verify continued benefit.
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