Congenital hyperinsulinism (cHI) is a rare, primarily pediatric disease characterized by dysregulated insulin secretion resulting in severe, persistent hypoglycemia, frequently leading to lifelong neurologic impairments. The safety, pharmacokinetics, and glycemic efficacy of ersodetug, a fully human monoclonal antibody that allosterically and reversibly binds the insulin receptor (INSR) and reduces excess insulin action, are being evaluated for the treatment of cHI-related hypoglycemia.A global, open-label, phase 2b study (ClinicalTrials.gov: NCT04538989) was conducted in 23 patients with cHI with persistent hypoglycemia on standard-of-care (SOC) therapies. Eligible participants (age ≥2 years) received add-on ersodetug at dose levels between 3 and 9 mg/kg intravenously (i.v.) bi-weekly for 8 weeks in 4 sequential dose cohorts.Enrolled participants (average age = 6.7 years) on SOC (87% medications; 17% previous pancreatectomy) experienced 13 events/week and 23% time in hypoglycemia at baseline. Ersodetug resulted in predictable, dose-proportional pharmacokinetics. No deaths, adverse drug reactions, study withdrawals, or dose-limiting toxicities occurred. Hypoglycemia (