The purpose of this study is to measure efficacy and safety of pegtibatinase treatment compared with placebo in participants with classical HCU receiving standard of care. Study details include:
* Total Study duration: up to 38 weeks * Screening:
* Initial Screening duration: up to 4 weeks * Pre-treatment Diet Standardization Period duration: up to 6 weeks * Blinded Treatment Duration: 24 weeks
* 2-week blinded dose titration period * 22-week blinded assessment period * Safety Follow-Up: 4 weeks after last dose (as applicable for those not enrolling in the long term extension study, ENSEMBLE)
Must be ≥12 to ≤65 years of age, at the time of signing the informed consent
Must have a diagnosis of classical HCU based on clinical, biochemical, and/or molecular genetic testing
Plasma tHcy ≥80 µM at Screening visit, with allowance for up to 18 participants who may be enrolled with a Screening plasma tHcy ≥50 to <80 µM
Participants who can become pregnant must have a negative pregnancy test before starting the study and must use a highly effective form of birth control (less than 1% risk of pregnancy per year) during the study and for at least 4 weeks after the last dose.
Diagnosis of Marfan syndrome, methylenetetrahydrofolate reductase (MTHFR) deficiency, or disorder of cobalamin metabolism
Concurrent disease or condition (eg, history or presence of clinically significant cardiovascular, pulmonary, hepatic, renal, hematologic, gastrointestinal, endocrine, immunologic, dermatologic, neurological, oncologic, or psychiatric disease) that would interfere with study participation or safety (excluding complications of HCU).
History of major thrombotic event (eg, cerebrovascular accident, myocardial infarction, pulmonary embolism) in the previous 6 months.
Body weight ≥160 kg.