Currentsierra health and lifePolicy 2025D0071N

Crysvita (burosumab) for X-linked hypophosphatemia and tumor-induced osteomalacia

Defines medical necessity criteria, prescribing specialist requirements, dosing alignment with FDA labeling, and authorization durations for burosumab (Crysvita) in XLH and FGF23-related TIO for Sierra Health and Life members.

Policy Summary

Payersierra health and life

PolicyCrysvita (burosumab) for X-linked hypophosphatemia and tumor-induced osteomalacia

Policy CodePolicy 2025D0071N

Change TypeTemplate update / routine review

Effective DateMay 1, 2025

Next Review DateN/A

Key ActionSubmit prior authorization with diagnostic confirmation, specialist consultation/prescription, fasting serum phosphorus below age-normal, and documentation of prior therapy failure/contraindication when applicable.

SourceLink

POLICY UPDATE CHANGES

Updated Benefit Considerations as part of a template update.

Routine review on 05/01/2025 with no change to coverage guidelines; previous policy version archived.

≤ 12max initial auth (months)

J0584HCPCS code

≥ 6 moXLH min age

≥ 2 yrTIO min age

< 3.0 mg/dL

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Coverage Criteria for Burosumab (Crysvita)

Initial therapy for XLH (children/adults)

Covered when ALL of the following are met:

XLH initial therapy criteria: Diagnosis of XLH confirmed by one of the following: genetic testing (e.g., confirmed PHEX gene mutation in patient or first-degree relative) OR elevated serum FGF23 > 30 pg/mL OR all of the following biochemical findings associated with XLH: serum phosphate < 3.0 mg/dL (0.97 mmol/L) AND serum creatinine below age-adjusted upper limit of normal (ULN) AND serum 25(OH)D ≥ 16 ng/mL; AND prescribed by, or in consultation with, an endocrinologist or specialist experienced in the treatment of metabolic bone disorders; AND patient has experienced a positive clinical response to burosumab (e.g., enhanced height velocity, improvement in skeletal deformities, reduction of fractures, reduction of generalized bone pain); AND dosing is in accordance with the United States Food and Drug Administration approved labeling; AND initial authorization will be for no more than 12 months.

Children and adults included; FDA-indicated minimum age referenced elsewhere.

Initial therapy for TIO (FGF23-related hypophosphatemia)

Covered when ALL of the following are met:

TIO initial therapy criteria: Diagnosis of FGF23-related hypophosphatemia in tumor-induced osteomalacia (TIO) associated with phosphaturic mesenchymal tumors; AND disease cannot be curatively resected or localized; AND patient is age ≥ 2 years; AND prescribed by, or in consultation with, an oncologist, an endocrinologist, or specialist experienced in the treatment of metabolic bone disorders; AND history of failure, contraindication, or intolerance to vitamin D analog therapy (e.g., calcitriol, paricalcitol, doxercalciferol) in combination with an oral phosphate agent (e.g., K-Phos®, K-Phos Neutra®) where specified; AND fasting serum phosphorus is below the normal range for age; AND dosing is in accordance with the United States Food and Drug Administration approved labeling; AND initial authorization will be for no more than 12 months.

Step therapy / prior treatment requirement noted for some reviews and Medicare references.

Continuation / Reauthorization (XLH and TIO)

Covered when ALL of the following are met:

Continuation therapy: Patient has previously received treatment with burosumab; AND prescribed by, or in consultation with, an appropriate specialist (endocrinologist or oncologist as applicable); AND patient has experienced a positive clinical response to burosumab (examples include: enhanced height velocity, improvement in skeletal deformities, reduction of fractures, reduction of generalized bone pain); AND dosing is in accordance with the United States Food and Drug Administration approved labeling; AND reauthorization will be for no more than 12 months.

Continuation criteria explicitly require prior treatment and documented positive clinical response.

The U.S. Food and Drug Administration (FDA) approval status for Crysvita (burosumab) is provided for informational purposes only. FDA labeling indicates indications and minimum ages (XLH: age ≥ 6 months; TIO: age ≥ 2 years), but FDA approval alone is not a basis for coverage. Coverage decisions under this policy rely on the medical necessity criteria and documentation requirements specified below rather than on regulatory approval status alone.

Member-specific benefit plans govern final coverage determinations. Providers and reviewers must consult the member’s benefit plan document and any applicable state or federal mandates when applying this policy. Where a member-specific plan or a statutory mandate conflicts with the standard policy language, the member specific benefit plan or mandate supersedes this policy.

Listing of FDA-approved indications and of procedure/diagnosis codes in this policy is informational only. Inclusion of a code or an indication in the policy does not imply that the service or drug is covered for all members; coverage is determined by meeting the policy’s medical necessity criteria and by the member’s benefit terms.

This document does not contain explicit statements labeling treatments as “not medically necessary.” Instead, coverage determinations are made by applying the medical necessity criteria contained in this policy together with the member’s specific benefit plan. In cases where Medicare Advantage or other plan-specific rules apply, follow the applicable plan determinations when an NCD or LCD is absent.

Billing and Coding

Applicable HCPCSHCPCSCovered

J0584

Injection, burosumab-twza, 1 mg.

Diagnosis Codes (listed)ICD-10

E83.31	Familial hypophosphatemia
M83.8	Other adult osteomalacia

Serum phosphate diagnostic threshold for XLH

Serum phosphate thresholdSerum phosphate < 3.0 mg/dL (0.97 mmol/L)

ContextListed as one of the biochemical findings required to establish XLH when genetic testing or elevated FGF23 is not available.

Associated required labsAlso requires serum creatinine below age-adjusted ULN and serum 25(OH)D ≥ 16 ng/mL as part of the biochemical criteria.

Use for authorizationFasting or non-fasting not specified here; policy cites this numeric cutoff for initial therapy eligibility for XLH.

Provider Actions, Prior Authorization & Documentation

Prior Authorization

Prior Authorization Required

Prior authorization is required for Crysvita (burosumab) under the medical benefit. Submit diagnostic confirmation (genetic testing showing PHEX mutation in the patient or first‑degree relative, or elevated FGF23 > 30 pg/mL, or biochemical findings consistent with XLH/TIO), fasting serum phosphorus results (below age‑normal), serum creatinine and 25(OH)D per criteria, specialist consult or prescription (endocrinologist, oncologist, or other metabolic bone disorder specialist as specified), and documentation of prior treatments. Initial authorizations are limited to no more than 12 months; continuation/reauthorization requires documentation of prior burosumab treatment and objective clinical benefit. For Medicare Advantage members, follow applicable Medicare‑Part‑B step therapy programs where indicated and the MAO’s determinations when no CMS NCD/LCD exists.

Affected codes: J0584 (burosumab-twza)
Initial authorization: ≤ 12 months
Required labs: fasting serum phosphorus, serum creatinine, serum 25(OH)D
Specialist: endocrinologist, oncologist, or metabolic bone disorder specialist

Step Therapy

Medicare Advantage Step Therapy / Preferred Therapy

Background

X-linked hypophosphatemia (XLH) is a heritable disorder of renal phosphate handling driven by increased circulating FGF23, which causes renal phosphate wasting, hypophosphatemia, and defective bone mineralization. Clinical features include rickets and impaired linear growth in children, bone pain, skeletal deformities, and increased fracture risk; biochemical findings commonly demonstrate low serum phosphate and other supportive laboratory abnormalities. Burosumab is an anti-FGF23 monoclonal antibody developed to normalize serum phosphate in patients with XLH.

Definitions

XLH — definition and association with elevated FGF23

DefinitionX-linked hypophosphatemia (XLH) is a heritable disorder of renal phosphate transport associated with hypophosphatemia and abnormal bone mineralization.

PathophysiologyElevated circulating FGF23 levels are observed in patients with XLH and are believed to drive phosphate wasting.

Clinical significanceLeads to rickets/osteomalacia in children and bone pain, fractures, or impaired mobility in adults; burosumab targets excess FGF23 to normalize serum phosphate.

TIO — definition and FGF23-secreting tumors

DefinitionTumor-induced osteomalacia (TIO) is a rare acquired paraneoplastic syndrome in which typically benign phosphaturic mesenchymal tumors ectopically secrete FGF23, causing hypophosphatemia and osteomalacia.

Tumor characteristics

Revision History

2025-07-01template_updateLatest

Template update: Benefit Considerations section updated as part of a template update.

2025-05-01routine_review

Routine review completed; no change to coverage guidelines and previous policy version 2024D0071M archived.