Casgevy (exagamglogene autotemcel) Letter of Medical Necessity
Casgevy (exagamglogene autotemcel) is the world's first approved CRISPR/Cas9-based gene therapy, FDA-approved in December 2023 for sickle cell disease and transfusion-dependent beta-thalassemia. At ~$2.2 million per treatment, it is among the most expensive therapies ever approved. PA requires documentation of disease severity, age eligibility, treatment at an authorized center, and coordination with state Medicaid programs for most SCD patients.
FDA-Approved Indications
- ● sickle cell disease (SCD) with recurrent vaso-occlusive crises (VOCs) in patients ≥12 years
- ● transfusion-dependent beta-thalassemia (TDT) in patients ≥12 years
Why Casgevy Prior Authorization Gets Denied
The most common denial reasons across major payers:
- 1. Age criterion not met (≥12 years required)
- 2. SCD indication: recurrent VOC burden not documented (≥2 VOCs per year requiring healthcare intervention)
- 3. TDT indication: transfusion burden not documented (≥100 mL/kg/year pRBCs or ≥8 transfusions/year over 2 years)
- 4. HbS% or hemoglobin profile not provided confirming SCD genotype (HbSS, HbSβ0, HbSβ+)
- 5. Treating center not a qualified Casgevy authorized treatment center (ATC)
- 6. Alternative allogeneic SCT candidacy not assessed
- 7. Medicaid prior authorization pathway: state-level DURB or exception process not followed
What to Include in a Casgevy Letter of Medical Necessity
Document confirmed SCD genotype (HbSS, HbSβ0, or HbSβ+ for SCD; β0/β0 or similar for TDT) with hemoglobin electrophoresis or HPLC, patient age ≥12 years, and severity burden. For SCD: document ≥2 severe VOC episodes per year requiring healthcare visits over the prior 2 years (dates, ED visits, hospitalizations, transfusions). For TDT: document transfusion history (≥100 mL/kg/year or ≥8 transfusions/year for ≥2 years). Confirm treatment at a Casgevy Authorized Treatment Center (ATC). Document discussion of allogeneic SCT as an alternative, prior hydroxyurea use and response (for SCD), and absence of contraindications to myeloablative conditioning (busulfan).
Key clinical evidence to cite:
- ✓ CLIMB SCD-121 Phase 3 — 93.5% of patients free from severe VOC for ≥12 consecutive months (29/31 evaluable)
- ✓ CLIMB THAL-111 Phase 3 — 93% of TDT patients transfusion-independent at 12 months
- ✓ First FDA-approved CRISPR-based gene therapy (December 2023)
- ✓ Durable HbF induction via BCL11A erythroid enhancer editing — potentially curative single treatment
Relevant guidelines:
- 📖 ASH 2023 SCD Gene Therapy Guidance
- 📖 NHLBI SCD Management Guidelines
- 📖 EHA/EBMT Beta-Thalassemia Gene Therapy Recommendations
Casgevy Prior Authorization Criteria
Standard criteria across major US payers for Casgevy. Specific criteria vary by plan — RxCheckUp tailors each LMN to your patient's exact payer policy.
Typical step therapy requirements:
- → Medicaid prior authorization pathway: state-level DURB or exception process not followed
Required documentation:
- ✓ ICD-10 diagnosis code with specificity
- ✓ Prior therapy history with dates, doses, and discontinuation reasons
- ✓ Specialist evaluation (where applicable)
- ✓ Baseline disease activity or biomarker results
- ✓ Clinical rationale citing FDA labeling or guidelines
Approval details:
Initial approval: typically 6 months. Renewal: 12 months with documented clinical response.
Payers Covering Casgevy
RxCheckUp tailors each LMN to the specific payer's medical policy and step therapy requirements:
Casgevy Prior Authorization FAQ
Why was my Casgevy prior authorization denied?
The most common denial reasons for Casgevy are: Age criterion not met (≥12 years required); SCD indication: recurrent VOC burden not documented (≥2 VOCs per year requiring healthcare intervention); TDT indication: transfusion burden not documented (≥100 mL/kg/year pRBCs or ≥8 transfusions/year over 2 years); HbS% or hemoglobin profile not provided confirming SCD genotype (HbSS, HbSβ0, HbSβ+); Treating center not a qualified Casgevy authorized treatment center (ATC); Alternative allogeneic SCT candidacy not assessed; Medicaid prior authorization pathway: state-level DURB or exception process not followed.
What should a Casgevy Letter of Medical Necessity include?
Document confirmed SCD genotype (HbSS, HbSβ0, or HbSβ+ for SCD; β0/β0 or similar for TDT) with hemoglobin electrophoresis or HPLC, patient age ≥12 years, and severity burden. For SCD: document ≥2 severe VOC episodes per year requiring healthcare visits over the prior 2 years (dates, ED visits, hospitalizations, transfusions). For TDT: document transfusion history (≥100 mL/kg/year or ≥8 transfusions/year for ≥2 years). Confirm treatment at a Casgevy Authorized Treatment Center (ATC). Document discussion of allogeneic SCT as an alternative, prior hydroxyurea use and response (for SCD), and absence of contraindications to myeloablative conditioning (busulfan).
Which payers cover Casgevy?
Casgevy is covered by major US payers including Medicaid (state programs — primary payer for most SCD patients), UnitedHealthcare, Aetna, Cigna, Anthem BCBS, Medicare Part B, though formulary tier and prior authorization criteria vary.