2. Evidence that the patient is a non responder to Kuvan® treatment (ie, 4 weeks of treatment with 20 mg/kg/day of Kuvan, insufficient response per investigator determination, unsuitable for Kuvan® per Investigator determination, and treatment end date ≥ 2 days prior to Day 1 [ie, first dose]). Patients who have had a previous response to Kuvan® treatment but are not currently taking Kuvan® because of noncompliance and have been off treatment for ≥ 4 months prior to Screening are eligible for participation.