CurrentCentenePolicy CP.PHAR.470

Casimersen (Amondys 45)

Defines medical necessity criteria, prior authorization requirements, and coverage limits for Amondys 45 (casimersen) for patients with Duchenne muscular dystrophy amenable to exon 45 skipping for Centene-affiliated health plans.

Policy Summary

PayerCentene

PolicyCasimersen (Amondys 45) clinical policy

Policy CodePolicy CP.PHAR.470

Change TypeNo material change

Effective DateFeb 25, 2021

Next Review Date

Key ActionSubmit prior authorization with documentation that the member meets all approval criteria, including genetic confirmation and required functional, pulmonary, and cardiac assessments.

SourceLink

POLICY UPDATE CHANGES

No material clinical or coverage changes in this revision.

30 mg/kg/weekmaximum weekly dose

6 monthsapproval duration

≥300 m6MWT requirement

≥50%FVC requirement

≥40%LVEF requirement

Coverage Criteria for Amondys 45 (casimersen)

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Initial Therapy

Covered when ALL of the following are met:

Initial criteria: 1) Diagnosis of Duchenne muscular dystrophy (DMD) with a mutation amenable to exon 45 skipping confirmed by genetic testing; 2) Patient is < 13 years of age at therapy initiation; 3) Medication is prescribed by or in consultation with a neurologist; 4) Ambulatory function (ability to walk with or without assistive devices, not wheelchair dependent) with 6-minute walk test (6MWT) distance ≥ 300 meters; 5) Stable pulmonary function with predicted forced vital capacity (FVC) ≥ 50%; 6) Stable cardiac function with left ventricular ejection fraction (LVEF) ≥ 40%; 7) Inadequate response to adherent oral corticosteroid therapy (e.g., prednisone, Emflaza, Agamree) for ≥ 6 months, evidenced by significant decline in 6MWT, LVEF, or FVC, unless corticosteroids are contraindicated or not tolerated; 8) Amondys 45 is prescribed concurrently with an oral corticosteroid unless contraindicated or clinically significant adverse effects are experienced; 9) Amondys 45 is not prescribed concurrently with other exon‑skipping therapies (e.g., Exondys 51, Vyondys 53, Viltepso); 10) Member has not previously received gene replacement therapy for DMD (e.g., Elevidys); 11) Requested dose does not exceed 30 mg/kg per week;

Continuation Therapy

Covered when ALL of the following are met:

Continuation criteria: 1) Member is currently receiving medication for DMD with mutation amenable to exon 45 skipping or has previously met initial approval criteria; 2) Member is demonstrating a positive response to therapy as evidenced by ONE of the following: a) ambulatory function with 6MWT distance ≥ 300 meters; OR b) improved or stable LVEF and FVC assessed within the last 6 months (applicable when member received medication via another insurer without documented initial criteria); 3) All of the following assessed within the last 6 months: a neurologist assessment, stable cardiac function with LVEF ≥ 40%, and stable pulmonary function with predicted FVC ≥ 50%; 4) Amondys 45 is not prescribed concurrently with other exon‑skipping therapies (e.g., Exondys 51, Vyondys 53, Viltepso); 5) Member has not previously received gene replacement therapy for DMD (e.g., Elevidys); 6) If a dose increase is requested, the new dose does not exceed 30 mg/kg per week;

Coverage for uses of casimersen (Amondys 45) that are not FDA‑approved is not automatically authorized under this policy. Such requests must include sufficient clinical documentation supporting efficacy and safety in accordance with the Health Plan's applicable off‑label use policies (for example, CP.CPA.09 for commercial, HIM.PA.154 for Health Insurance Marketplace, or CP.PMN.53 for Medicaid) or other evidence of coverage provisions.

Casimersen is contraindicated in patients with a history of serious hypersensitivity to casimersen or to any of the inactive ingredients in Amondys 45. This contraindication is listed in Appendix C and was updated in the policy's recent reviews.

Coverage determinations and the administration of benefits under this clinical policy are subject to all terms, conditions, exclusions, and limitations of the member's coverage documents (for example, evidence of coverage, certificate of coverage, policy, or contract of insurance), as well as applicable state and federal requirements and Health Plan administrative policies and procedures.

Requests that do not meet the policy's clinical criteria are considered not medically necessary and will not be approved. Key required elements include, but are not limited to: confirmed DMD gene mutation amenable to exon 45 skipping, initiation age < 13 years for initial therapy, required functional thresholds (6MWT ≥ 300 m), pulmonary and cardiac thresholds (predicted FVC ≥ 50% and LVEF ≥ 40%), documentation of concurrent or prior corticosteroid therapy (unless contraindicated), absence of concurrent exon‑skipping therapies or prior gene replacement therapy, and dosing not to exceed 30 mg/kg per week. Requests missing these elements or failing the specified thresholds will not meet the clinical criteria for approval.

Coding and Dosing

HCPCS CodesHCPCSCovered

J1426

Injection, casimersen, 10 mg

Maximum dose

Maximum weekly dose30 mg/kg per week

Dosage sourceDosage and Administration: maximum dose listed for DMD = 30 mg/kg per week

Documented in approval criteriaInitial and continued therapy criteria state requests exceeding 30 mg/kg/week are not allowed

6-Minute Walk Test threshold

6MWT threshold for initiation≥ 300 meters

6MWT threshold for continuationAmbulatory function with 6MWT ≥ 300 m (or documentation of improved/stable function per criteria)

Definition reference6MWT defined in Appendix A as 6-minute walk test (functional ambulatory assessment)

Forced Vital Capacity threshold

Predicted FVC threshold≥ 50%

Assessment timingFVC must be assessed within the last 30 days for initial approval and within last 6 months for continuation per criteria

Clinical roleStable pulmonary function with predicted FVC ≥ 50% required for initial and continued therapy

Left Ventricular Ejection Fraction (LVEF) threshold

LVEF threshold≥ 40%

Clinical implicationLVEF below 40% may indicate cardiomyopathy or heart failure (referenced in general information)

Assessment timingLVEF must be assessed within the last 30 days for initial approval and within last 6 months for continuation per criteria

Provider Actions, Prior Authorization, and Documentation

Prior Authorization

Prior Authorization Required

Prior authorization is required for Amondys 45 (casimersen) prior to initiation. Providers should obtain all required prior authorizations as specified by the member's Health Plan to ensure coverage decisions and benefit administration can be completed.

Prior authorization required
Reference HCPCS J1426 (Injection, casimersen, 10 mg) for claims

Documentation Required

Required Clinical Documentation

Provider must submit clinical documentation supporting that the member meets all approval criteria. This includes office/chart notes, genetic testing results confirming a mutation amenable to exon 45 skipping, recent assessments (e.g., 6MWT, FVC, LVEF), and records of corticosteroid use or contraindication.

Submit office notes, lab results, genetic test reports, and recent functional assessments
Document concomitant oral corticosteroid therapy or valid contraindication

Denial Risk

Documentation Insufficiency / Non‑Covered Indications

Requests lacking sufficient documentation or for non‑FDA‑approved (off‑label) indications without adequate evidence may be denied. Providers should reference applicable off‑label use policies when seeking coverage for indications not addressed by this policy.

Insufficient documentation may result in denial
Non‑FDA indications require evidence per off‑label use policies (e.g., CP.CPA.09, HIM.PA.154, CP.PMN.53) or evidence of coverage documents

Note

Follow Health Plan Coverage Documents

Providers must follow the Health Plan's coverage documents, applicable clinical policies, and contract terms when requesting coverage. Coverage decisions are subject to plan terms, exclusions, limitations, and applicable state and federal requirements.

Follow Evidence of Coverage, Certificate of Coverage, policy/contract terms
Coverage subject to plan exclusions, limitations, and applicable laws/regulations

Prior Authorization

Concurrent Corticosteroid Requirement

Amondys 45 must be prescribed with concomitant oral corticosteroid therapy unless there is a documented contraindication or clinically significant adverse effect. Prior authorization submissions should include documentation of corticosteroid therapy or reason for contraindication.

Concurrent oral corticosteroid therapy required unless contraindicated
Include corticosteroid treatment history or contraindication documentation with prior authorization

Background

Duchenne muscular dystrophy (DMD) is a progressive X‑linked neuromuscular disorder. Casimersen (Amondys 45) is an antisense oligonucleotide approved under accelerated approval to increase dystrophin production for patients with a confirmed DMD mutation amenable to exon 45 skipping. This policy defines medical necessity criteria for initiation and continuation of Amondys 45, including genetic confirmation, age limits for initial therapy, neurologist involvement, functional measures (6MWT), and cardiopulmonary stability (predicted FVC and LVEF). The approval durations for both initial and continued therapy are 6 months, and therapy must be prescribed with concomitant oral corticosteroid therapy unless contraindicated. Continued approval may depend on clinical response and available confirmatory evidence; the policy is intended to assist in coverage decisions and does not guarantee payment.

Definitions and Key Terms

Casimersen (Amondys 45) — description and indication

Drug class and nameCasimersen (Amondys 45) — an antisense oligonucleotide

FDA-approved indicationIndicated for treatment of Duchenne muscular dystrophy in patients with a confirmed DMD gene mutation amenable to exon 45 skipping (accelerated approval)

Approval limitationContinued approval may be contingent upon verification of clinical benefit in confirmatory trials

6MWT — definition

Test name6-minute walk test (6MWT)

PurposeFunctional ambulatory assessment measuring distance walked in six minutes

Usage in policyUsed as an ambulatory function requirement (threshold ≥ 300 m) for initial and continued coverage

FVC — definition

TermForced vital capacity (FVC)

DefinitionA pulmonary function measure; policy requires predicted FVC ≥ 50% as a stability threshold

Assessment roleFVC must be documented within required timeframes for initial and continued therapy

LVEF — definition

TermLeft ventricular ejection fraction (LVEF)

DefinitionA cardiac function measure; policy requires LVEF ≥ 40% for initiation and continuation

Clinical noteLVEF below 40% may indicate cardiomyopathy or heart failure

Medical necessity — definition and role

DefinitionMedical necessity: component of guidelines used to assist in making coverage decisions and administering benefits; not a guarantee of payment or a treatment recommendation

ScopePolicy applies to determination of coverage and is subject to terms, conditions, exclusions, and limitations of coverage documents and applicable law

Operational roleUsed by the Health Plan to guide prior authorization and benefit administration, not to dictate clinical care

Provider responsibility

Provider autonomyProviders are independent contractors responsible for medical advice and treatment; the policy does not dictate clinical practice

ExpectationProviders should exercise professional medical judgment and consult treating physicians for diagnosis and treatment decisions

Relationship to Health PlanProviders are not agents or employees of the Health Plan; Health Plan has no control or right of control over provider clinical decisions