CurrentCareSourcePolicy N/A

Crysvita (burosumab) — coverage criteria for FGF23-related hypophosphatemia

Defines prior authorization criteria, dosing, and exclusions for medical benefit coverage of Crysvita for tumor-induced osteomalacia and X-linked hypophosphatemia for CareSource members; applies to providers requesting authorization.

Policy Summary

PayerCareSource

PolicyCrysvita (burosumab) — coverage criteria for FGF23-related hypophosphatemia

Policy CodePolicy N/A

Change TypeNo material change

Effective DateN/A

Next Review DateN/A

Key ActionSubmit prior authorization with baseline labs showing low serum phosphorus and, for most criteria, low TmP/GFR (or PHEX genetic test for XLH) and documentation of trial of oral phosphate plus calcitriol or contraindication.

SourceLink

POLICY UPDATE CHANGES

No material clinical or coverage changes in this revision.

2FDA indications covered

180 mgTIO max dose

90 mgXLH max dose (adults)

Not recommendedSevere renal impairment/ESRD

RequiredPrior authorization

Coverage Criteria for Crysvita (burosumab)

Tumor-Induced Osteomalacia — FDA indication

Approve Crysvita for TIO when ONE of the following (A or B) is met:

TIO A or B

Initial Therapy criteria (A): i. Patient is ≥ 2 years of age; ii. Patient has a mesenchymal tumor that cannot be curatively resected or identified/localized; iii. Patient is currently exhibiting one or more signs or symptoms of tumor-induced osteomalacia, as determined by the prescriber; iv. Patient has had a baseline serum phosphorus level that was below the normal range for age; v. Patient has had a baseline tubular reabsorption of phosphate corrected for glomerular filtration rate (TmP/GFR) that was below the normal range for age and gender; vi. Patient meets ONE of the following (a or b): (a) Patient has tried oral phosphate and calcitriol therapy; OR (b) Per the prescriber the patient has a contraindication to oral phosphate therapy, calcitriol therapy, or both; vii. The medication is prescribed by or in consultation with an endocrinologist or nephrologist.
Examples of signs/symptoms: bone pain, impaired mobility, muscle weakness, and fatigue.
Continuation criteria (B): Patient is currently receiving Crysvita and is continuing to derive benefit from Crysvita as determined by the prescriber.

Policy Summary

PayerCareSource

PolicyCrysvita (burosumab) — coverage criteria for FGF23-related hypophosphatemia

Policy CodePolicy N/A

Change TypeNo material change

Effective DateN/A

Next Review DateN/A

SourceLink

On This Page

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X-Linked Hypophosphatemia — FDA indication

Approve Crysvita for XLH when ONE of the following (A or B) is met:

XLH A or B

Initial Therapy criteria (A): i. Patient has had a baseline serum phosphorus level that was below the normal range for age; ii. Patient meets ONE of the following (a or b): (a) Patient has had a baseline tubular reabsorption of phosphate corrected for glomerular filtration rate (TmP/GFR) that was below the normal range for age and gender; OR (b) Patient has had a genetic test confirming the diagnosis of X-linked hypophosphatemia via identification of a PHEX pathogenic variant; AND iii. If the patient is ≥ 18 years of age, the patient meets BOTH of the following (a and b): (a) Patient is currently exhibiting one or more signs or symptoms of X-linked hypophosphatemia, as determined by the prescriber (examples in adults include fractures/pseudofractures, bone and joint pain, muscle weakness, and impaired mobility); AND (b) Patient meets ONE of the following (1 or 2): (1) Patient has tried oral phosphate and calcitriol therapy; OR (2) Per the prescriber the patient has a contraindication to oral phosphate therapy, calcitriol therapy, or both; AND iv. The medication is prescribed by or in consultation with an endocrinologist or nephrologist.
Examples of a response to therapy: increased phosphorus levels, radiographic improvement, healing of fractures/pseudofractures.
Continuation criteria (B): Patient is currently receiving Crysvita and is continuing to derive benefit from Crysvita as determined by the prescriber.
Approve for 1 year.

Provider Requirements and Authorization Process

Prior Authorization

Prior Authorization Required

Prior authorization required. Approvals are granted when indication-specific clinical criteria and dosing are met. Initial approval requires the medication to be prescribed by or in consultation with a physician who specializes in the condition being treated (e.g., endocrinologist or nephrologist). Extended approvals allowed if patient continues to meet criteria; duration per indication.

Prior authorization required for Crysvita (medical benefit).
Initial prescriber requirement: prescribed by or in consultation with a specialist (e.g., endocrinologist or nephrologist).
Approvals granted when clinical criteria and dosing in the policy are met; extended approvals allowed if continued benefit is documented.

Step Therapy

Step Therapy: Trial of Conventional Therapy Required

A trial of conventional therapy is required before approval unless contraindicated. Specifically, patients must have tried oral phosphate plus calcitriol therapy, or the prescriber must document a contraindication to one or both agents.

Requirement to try oral phosphate and calcitriol prior to Crysvita, unless contraindicated.
If contraindication claimed, prescriber must document reason(s) for intolerance or contraindication.

Documentation Required

Documentation: Required Baseline Data

Required baseline data must be provided with the prior authorization request. Baseline laboratory evidence of hypophosphatemia and assessment of renal tubular phosphate handling are required; genetic testing is required when applicable.

Baseline serum phosphorus below the normal range for age (drawn prior to any disease-specific treatment such as Crysvita, oral phosphate, or vitamin D).
Baseline TmP/GFR below the normal range for age and gender (drawn prior to any disease-specific treatment).
When applicable (e.g., suspected X-linked hypophosphatemia), genetic testing confirming a PHEX pathogenic variant should be provided.

Denial Risk

Denial Risk: Common Non-Approval Situations

Situations likely to lead to non-approval include contraindications such as severe renal impairment or end-stage renal disease and indications not listed in the authorization criteria. Requests for doses outside established dosing will be reviewed case-by-case and may be denied if not supported.

Crysvita is contraindicated in severe renal impairment or end-stage renal disease — coverage not recommended.
Coverage not recommended for conditions not listed in the Recommended Authorization Criteria (e.g., epidermal nevus syndrome without supporting data).
Requests for non-standard dosing require clinician review and may be denied.

Key Definitions

Tumor-Induced Osteomalacia (TIO) — definition and clinical features

DefinitionA rare condition caused by FGF23‑producing phosphaturic mesenchymal tumors that cause renal phosphate wasting, hypophosphatemia, rickets, and osteomalacia

Typical tumor characteristicsOften small, slow‑growing, benign mesenchymal tumors; complete resection is curative when possible

Common clinical featuresAdults usually present with fatigue, muscle weakness, bone pain, impaired mobility, decreased bone mineral density, and fractures

X‑Linked Hypophosphatemia (XLH) — definition and typical genetic cause

DefinitionA genetic disorder caused by inactivating variants in the PHEX gene leading to increased FGF23, renal phosphate wasting, abnormal vitamin D metabolism, and hypophosphatemic rickets/osteomalacia

Genetic confirmationDiagnosis can be established by identification of a hemizygous (male) or heterozygous (female) PHEX pathogenic variant on molecular genetic testing

Clinical spectrumPediatric patients present with rickets; adults have bone/joint pain, fractures/pseudofractures, muscle weakness, impaired mobility, dental issues, and other manifestations

Baseline — timing and required measurements

Baseline definitionMeasurements obtained prior to receiving any treatment for the condition (e.g., Crysvita, oral phosphate, or vitamin D therapy)

Baseline laboratory examplesBaseline labs referenced include serum phosphorus and tubular reabsorption of phosphate corrected for GFR (TmP/GFR)

Use in criteriaBaseline values are required to be below the normal range for age (serum phosphorus and, for most criteria, TmP/GFR) to meet authorization criteria

Background

Tumor‑induced osteomalacia (TIO) is caused by tumors that secrete FGF23, producing renal phosphate wasting and resultant hypophosphatemia and osteomalacia; tumors are often benign and may be curable with resection but can be unlocalizable or inoperable. Elevated FGF23 leads to decreased renal phosphate reabsorption and impaired activation of vitamin D, driving the clinical consequences of bone pain, muscle weakness, fatigue, decreased bone mineral density, fractures, and impaired mobility.

Because Crysvita (burosumab) targets FGF23, its use is focused on FDA‑approved FGF23‑mediated disorders. However, Crysvita has not been formally studied in patients with significant chronic kidney disease, and patients with severe renal impairment or end stage renal disease often have complex mineral metabolism abnormalities related to FGF23; therefore the policy lists these renal conditions among those for which coverage is not recommended.

The policy emphasizes that indications lacking sufficient evidence (for example, epidermal nevus syndrome / cutaneous skeletal hypophosphatemia syndrome) and any circumstances not included in the Recommended Authorization Criteria are not recommended for approval until more data are available.

OpenPayer

Crysvita (burosumab) — coverage criteria for FGF23-related hypophosphatemia

Coverage Criteria for Crysvita (burosumab)

Dosing Thresholds and Coding-relevant Limits

Provider Requirements and Authorization Process

Key Definitions

Background