Efficacy and Safety of Pegzilarginase in Patients With Arginase 1 Deficiency

Inclusion criteria

• ✓. The subject and/or parent/guardian provides written informed consent/assent, which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol
• ✓. A current diagnosis of ARG1 D as documented in medical records, which must include 1 of the following: elevated plasma arginine levels, a mutation analysis that results in a pathogenic variant, or reduced RBC arginase activity. For entry into this study, subjects must also fulfill the following plasma arginine criteria:
• ✓. The average of all measured values of plasma arginine during the screening period prior to the randomization visit (Visit 1, Study Day 1) is ≥ 250 µmol/L
• ✓. If a subject is re-screened, the only values that are considered for eligibility assessment are those in the current screening period
• ✓. Subjects must be ≥ 2 years of age on the date of informed consent/assent
• ✓. The subject must be assessable for clinically meaningful within-subject change (clinical response) on at least one component of one assessment included in the key secondary/other secondary endpoints. To be considered assessable, the subject must be able to complete the assessment, and must have a baseline deficit in at least one component as defined in the protocol
• ✓. Have received documented confirmation from the investigator and/or dietician that the subject can maintain their diet in accordance with dietary information presented in the protocol, ie, can maintain the current level of protein consumption, including natural protein and EAA supplementation
• ✓. Subjects receiving ammonia scavenger therapy, anti-epileptic drugs, and/or medications for spasticity (eg, baclofen) must be on a stable dose of the medication for at least 4 weeks prior to randomization and be willing to remain on a stable dose during the double-blind portion and blinded follow-up portions of the study