A Phase 3, Parallel-Group Treatment, Blinded, Randomized, Placebo-Controlled Study To Assess The Efficacy And Safety Of Pegtibatinase Administered Subcutaneously In Addition To Standard Of Care In Participants With Classical Homocystinuria Due To Cystathionine Beta Synthase Deficiency (HARMONY)
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.
• Willing to maintain a generally stable diet for the duration of the study (unless changes are required based on medical/safety reasons)
• Willing to maintain generally stable intake and doses of betaine, pyridoxine, and medical food for the duration of the study (unless changes are required based on medical/safety reasons)