CurrentCentenePolicy N/A

Idursulfase (Elaprase) — Clinical Policy (MPS II)

Criteria and coverage rules for Centene-affiliated health plans for use of idursulfase (Elaprase) to treat mucopolysaccharidosis II (Hunter syndrome), including initial and continued therapy requirements and dosing limits; applies to Commercial, HIM, and Medicaid lines of business.

Policy Summary

PayerCentene

PolicyIdursulfase (Elaprase) — Clinical Policy (MPS II)

Policy CodePolicy N/A

Change TypeClarified requirementminor administrative revisions

Effective Date02.16

Next Review Date

Key ActionSubmit prior authorization with documentation of diagnostic confirmation and the member's current weight for dosing.

SourceLink

POLICY UPDATE CHANGES

Added requirement for documentation of member's current weight for dose calculation purposes.

Policy identifier HIMPHAR.21 was revised to HIM.PA.154.

Multiple annual reviews from 2021-2025 noted 'no significant changes' with references reviewed/updated.

0.5 mg/kg/weekmaximum weekly dose

6 monthsinitial approval duration

12 monthscontinued approval (Medicaid/HIM)

35 mmean 6MWT improvement

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Coverage Criteria for Idursulfase (Elaprase)

Initial Therapy

Covered when ALL of the following are met for initial approval:

Initial Approval: Diagnosis and baseline requirements: Diagnosis of MPS II (Hunter syndrome) confirmed by either: (a) enzyme assay demonstrating deficiency of iduronate 2-sulfatase activity OR (b) DNA testing; age > 16 months; documentation of member's current weight (kg)

Provider must submit supporting documentation (e.g., chart notes, lab results) demonstrating diagnostic confirmation and current weight.

Continuation Therapy

Covered when ALL of the following are met for continued therapy:

Continued Therapy Criteria: Member is currently receiving idursulfase via Centene benefit or previously met initial approval; member is responding positively to therapy as evidenced by improvement in the individual's MPS II manifestation profile; if request is for a dose increase, the new dose does not exceed 0.5 mg/kg/week; documentation of member's current weight (kg)<= 0.5 mg/kg/week

See Appendix D for examples of clinical response (e.g., 6MWT, FVC, splenomegaly). Approval duration: Medicaid/HIM 12 months; Commercial 6 months or to member's renewal date, whichever is longer.

Diagnoses/Indications Not Authorized

Not authorized indications: Non‑FDA approved indications that are not addressed in this policy are not authorized unless there is sufficient documentation of efficacy and safety per the applicable off‑label use policy (CP.CPA.09, HIM.PA.154, CP.PMN.53) or evidence of coverage documents.

Requests for non‑FDA approved indications without adequate supporting evidence risk denial.

Non‑FDA approved or off‑label uses of idursulfase (Elaprase) that are not specifically addressed in this policy require additional documentation to be considered for coverage. Such requests must include sufficient evidence of efficacy and safety consistent with the applicable off‑label use policy: CP.CPA.09 (Commercial), HIM.PA.154 (Health Insurance Marketplace), or CP.PMN.53 (Medicaid). Absent this documentation, the indication is not covered under this policy.

Coverage decisions for idursulfase (Elaprase) are made according to the terms of the member's benefit documents and applicable legal and regulatory requirements. This clinical policy is a guide to medical necessity used to assist in coverage decisions and does not guarantee payment. Coverage is subject to all terms, conditions, exclusions, and limitations of the member's evidence of coverage, certificate of coverage, policy, contract of insurance, and any applicable Health Plan administrative policies.

Use of idursulfase for non‑FDA approved indications without adequate supporting evidence per the referenced off‑label policies is considered not authorized (not medically necessary) and will generally be denied. Providers should follow the off‑label use policies listed in this document when submitting requests for such indications.

Coding and Dose Limits

HCPCS CodesHCPCS

J1743

Injection, idursulfase, mg

HCPCS Codes referencedHCPCS

J1743

Injection, idursulfase, mg

Dose limit — maximum weekly dose

Maximum weekly dose0.5 mg/kg per week

Dosing frequencyIntravenous infusion every week

Dose basisDose calculated using member's current weight

Product vial size (single-use)6 mg/3 mL

Member weight documentation — current weight required for dose calculation

Required weight documentationProvider must submit the member's current weight for dose calculation purposes

Provider Actions and Prior Authorization

Prior Authorization

Prior Authorization Required

Prior authorization is required. Provider must submit clinical documentation (e.g., office chart notes, lab results, genetic or enzyme testing) demonstrating diagnosis confirmation of MPS II (Hunter syndrome), age > 16 months, and that dosing is weight‑based. Include documentation of current weight (kg) for dose calculation.

Diagnosis confirmation: enzyme assay showing iduronate 2‑sulfatase deficiency or DNA testing
Age requirement: > 16 months
Weight documentation: current weight in kg must be submitted for dose calculation purposes

Billing Rule

Prior Authorization and Coding

Submit requests using HCPCS code J1743 (Injection, idursulfase, mg) as applicable. Inclusion or exclusion of codes does not guarantee coverage; claims may be denied if coding is incorrect. Providers should reference current professional coding guidance when submitting claims for reimbursement.

Background on MPS II and Treatment

Mucopolysaccharidosis II (Hunter syndrome) is a lysosomal storage disorder caused by deficiency of the enzyme iduronate 2‑sulfatase. Idursulfase (Elaprase) is an enzyme replacement therapy indicated for treatment of patients with MPS II. Clinical trials have demonstrated improvements in functional outcomes, including a mean improvement of approximately 35 meters on the 6‑minute walk test in patients aged ≥5 years, and reductions in spleen volume in younger children.

Definitions and Key Terms

Idursulfase (Elaprase) — key drug definition / mechanism

AgentIdursulfase (Elaprase)

Mechanism / classHydrolytic lysosomal glycosaminoglycan-specific enzyme; enzyme replacement therapy for MPS II

FDA indicationTreatment of patients with Hunter syndrome (mucopolysaccharidosis II)

Clinical effects observedImproved walking capacity in patients ≥5 years and reduction in spleen volume in younger children

Abbreviations — 6MWT, FVC and others

6MWT6-minute walk test

FVC