Pharmacy Prior Authorization Criteria

Avlayah (tividenofusp alfa-eknm)

For diagnosis of Hunter Syndrome
Indicated for the treatment of neurologic manifestations of Hunter syndrome (Mucopolysaccharidosis type II, MPS II) when initiated in presymptomatic or symptomatic pediatric patients weighing at least 5 kg prior to advanced neurologic impairment. This indication is approved under accelerated approval based on the reduction of cerebrospinal fluid heparan sulfate. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial(s).
Limitations of Use: Avlayah is not recommended for use in combination with other enzyme replacement therapies for the treatment of Hunter syndrome.

Prior Authorization (Initial Authorization)

Length of Approval: 12 Month(s)

AND

Submission of medical records (e.g., chart notes) confirming one of the following [2]:

Enzyme assay demonstrating deficient iduronate 2 sulfatase (I2S) activity
Presence of iduronate-2-sulfatase (IDS) gene mutation as detected by a FDA-approved test or a test performed at a facility approved by Clinical Laboratory Improvement Amendments (CLIA)

AND

Requested medication is initiated prior to advanced neurologic impairment (e.g., progressive cognitive decline, status epilepticus)

AND

AND

AND

Requested medication is not used in combination with other enzyme replacement therapies for the treatment of Hunter syndrome (e.g., Elaprase)

Prior Authorization (Reauthorization)

Length of Approval: 12 Month(s)

Patient demonstrates positive clinical response to therapy (e.g., reductions from baseline in cerebrospinal fluid heparan sulfate [CSF HS)])

AND

Requested medication is not used in combination with other enzyme replacement therapies for the treatment of Hunter syndrome (e.g., Elaprase)

2026-05-20

Avlayah Prescribing Information. Denali Therapeutics Inc. South San Francisco, CA. March 2026.
Burton BK, Giugliani R. Diagnosing Hunter syndrome in pediatric practice: practical considerations and common pitfalls. Eur J Pediatr. 2012 Apr;171(4):631-9.

Patients treated with enzyme replacement therapies, including AVLAYAH, have experienced life-threatening hypersensitivity reactions, including anaphylaxis. Anaphylaxis has occurred during the early course of enzyme replacement therapy and after extended duration of therapy. Administer AVLAYAH under the supervision of a healthcare provider knowledgeable in the management of hypersensitivity reactions including anaphylaxis. Initiate AVLAYAH in a healthcare setting with appropriate medical monitoring and support measures, including access to cardiopulmonary resuscitation equipment. [1]