A Study of JR-141 in Patients With Mucopolysaccharidosis Type II

Inclusion Criteria: * Patients aged 6 years or older at the time of informed consent. * Patients diagnosed with MPS II. * Patients who have received idursulfase (0.5 mg/kg/week) continuously for at least 12 weeks until the initial dose of JR-141. Exclusion Criteria: * Patients with a history of hematopoietic stem cell transplantation, excluding those who need enzyme replacement therapy even after hematopoietic stem cell transplantation. * Patients in whom lumbar puncture cannot be performed. * Patients who have developed serious drug allergy or hypersensitivity that is inappropriate for participation in the study. * Patients who have received other investigational products within 4 months before enrollment in the study.