RZ358 Treatment for Congenital Hyperinsulinism

Inclusion Criteria: At screening, aged ≥ 3 months and ≤ 45 years old. An established clinical diagnosis of congenital HI (hyperinsulinism), with or without identification of a known monogenic variant by genetic testing. Participant has failed to achieve adequate glycemic control with appropriate and reasonable trials of locally accepted and available Standard of Care (SOC) medical therapies (e.g., diazoxide and somatostatin analogs (SSAs)) per the judgment of the investigator. Experiencing ≥ 3 hypoglycemia events per week by screening Self-Monitoring Blood Glucose (SMBG) and average daily percent time with hypoglycemia of ≥ 8% of the monitored screening Continuous Glucose Monitor (CGM) time. Exclusion Criteria: Alanine aminotransaminase (ALT), aspartate aminotransaminase (AST), total bilirubin (TB), alkaline phosphatase (ALP), and gamma-glutamyl transferase (GGT) ≥ 1.5 × the upper limit of normal for the age-specific reference range, regardless of assessed significance. Body mass index (BMI) ≥ 35 kg/m2 for participants aged 18 years and above, or BMI ≥ 99% (percentile) per Centers for Disease Control and Prevention growth charts for participants \> 12 and \< 18 years of age (no BMI exclusion for participants ≤ 12 years of age). A known clinical diagnosis of diabetes or pre-diabetes, or a history of insulin dependency within 3 months of screening. Average daily percent time with hyperglycemia ≥ 5% of the monitored screening continuous glucose monitoring (CGM) time. Known allergy or sensitivity to RZ358 or any component of the drug.