A Dose REgimen-Finding Study of AGA2115 in Chinese Patients With Osteogenesis ImpeRfecta (EIR)

Inclusion Criteria: * Adults (18-75 years) or adolescents (12-17 years) with a confirmed diagnosis of Osteogenesis Imperfecta (OI) Type I, III, or IV with genetic confirmation of pathogenic variants in COL1A1 or COL1A2 genes * BMD T-score of ≤-1.0 at the lumbar spine, total hip, or femoral neck (adults) or BMD Z-score of ≤-1.0 at the lumbar spine, total hip, or femoral neck (adolescents) * Capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in the protocol Exclusion Criteria: * Vitamin D deficiency * Concomitant uncontrolled diseases or conditions that could affect bone metabolism such as hypo-/hyperparathyroidism, hypo-/hyperthyroidism, abnormal thyroid function or thyroid disease, or other endocrine disorders. * Current hyper- or hypocalcemia. * History of rickets, osteomalacia, or other significant skeletal disorders (excluding OI) leading to long-bone deformities and/or increased risk of fractures. * Use of bisphosphonates within the past 6 months. * Use of teriparatide, abaloparatide, strontium ranelate, or hormone replacement therapy within the past 12 months. * Use of denosumab (or denosumab biosimilars) within the past 2 years. * Use of anti-sclerostin antibody medications (romosozumab, setrusumab, blosozumab) at any time. * History of myocardial infarction or stroke (or other cardiovascular associated event deemed significant) within the past 12 months. * Malignancy within the last 5 years. * Pregnant or breastfeeding women, or women planning to become pregnant during the study or within 4 months after the last dose of IP.