CommercialCoverageLow impact
Allogeneic Processed Thymus Tissue–agdc (Rethymic) (CPB 1055, reviewed 2025-12-23)
Aetna·Pediatrics, Allergy & Immunology, General Surgery·Medical Policy
Effective date
Dec 23, 2025
We identified it
Aug 14, 2026
Summary
Aetna has established a new clinical policy (CPB 1055) for Rethymic (allogeneic processed thymus tissue–agdc), an FDA-approved thymus tissue transplant for pediatric patients with congenital athymia. Coverage requires strict criteria including confirmed diagnosis via flow cytometry, pediatric immunologist consultation, surgical implantation in quadriceps muscle, and single-dose limitation (up to 42 slices, max 22,000 mm² per m² BSA). SCID, CMV, HIV, and prior thymus transplant patients are excluded.
Action Required
By December 23, 2025: Billing and prior authorization teams must implement coverage criteria for Rethymic (no specific CPT/HCPCS code assigned). Create internal authorization checklist requiring: (1) verification of congenital athymia diagnosis via flow cytometry documentation (CD4+CD45RA+ <50 cells/mm³ or <5% of total T cells), (2) confirmation of pediatric immunologist as prescriber or consultant, (3) anti-HLA antibody screening results, (4) verification of no prior thymus transplant/Rethymic treatment, (5) documentation of infection control measures capability, (6) confirmation of absence of SCID, CMV, or HIV. Deny claims for patients with excluded diagnoses (B20, B25.9, D81.0-D81.31, D81.9, P35.1, Z21). Billing team must deny all claims submitted with ICD-10 codes B20, B25.9, D81.0, D81.1, D81.2, D81.31, D81.9, P35.1, or Z21. Related labs (CPT 86359, 86360, 86361, 86828-86835) must include prior authorization documentation. Update billing software with one-time-only requirement flag to prevent duplicate billing. Communicate policy to pediatric providers and surgical facilities performing implantations.