Fosdenopterin (Nulibry) (CPB 0991, reviewed 2026-03-27)

By March 27, 2026: Billing and prior authorization teams must implement the following for all Aetna commercial plan claims involving Fosdenopterin (Nulibry, J1809): (1) Require mandatory precertification before claim submission by contacting Aetna at (866) 752-7021 or faxing (888) 267-3277 with Statement of Medical Necessity forms; (2) Verify prescriber is a specialist in enzyme or metabolic disorders before processing; (3) Update billing system to flag claims requiring either genetic testing documentation of MOCS1 pathogenic variants OR both presumed MoCD Type A diagnosis with pending genetic results AND clinical evidence of encephalopathy, seizures, developmental delay, or abnormal amino acid levels; (4) For continuation authorizations, require either genetic confirmation with <12 months cumulative therapy OR ≥12 months therapy with documented clinical benefit (improvement, stabilization, or disease progression slowing); (5) Configure system to associate J1809 with CPT chemotherapy administration codes (96413-96417) and ICD-10 E72.19; (6) Denote all other indications as experimental/investigational. Update encounter forms and specialty pharmacy templates accordingly. Claims submitted without required precertification and documentation will be denied.