Palynziq clinic: One year and 43 patients later

Pegvaliase-pqpz (Palynziq) is an enzyme substitution therapy FDA approved May 2018 to treat phenylketonuria in adults with blood phenylalanine levels greater than 600 μmol/L (10 mg/dL). Pegvaliase is administered via subcutaneous injection and carries a high risk of side effects including anaphylaxis. A consensus statement on its use recommends careful education and monitoring of patients. We established a dedicated Palynziq Clinic in October 2018 with detailed protocols to minimize these risks. In the first year, we evaluated 43 patients, initiated Palynziq in 37 and transitioned two trial patients to commercial drug. 13/37 patients (35.1%) have sustained blood phenylalanine levels <360 μmol/L (6 mg/dL) without adjunct sapropterin dihydrochloride treatment or medical food. The timing and dosage needed to achieve a response did not correlate with patient weight, starting phenylalanine level, starting diet, or co-treatment with sapropterin dihydrochloride. Some patients had consistently low phenylalanine levels <30 μmol/L (0.5 mg/dL) and required doses as low as 20 mg weekly. Anaphylactic episodes were reported by 21.6% (8/37 patients) versus 10% seen in the clinical trial. Rates of other side effects were similar to or less than those in the trial. Adverse reactions commonly occurred shortly after dosage increases. We provide a model for safely introducing and managing pegvaliase in adult patients with PKU.