GC Pharma (formerly known as Green Cross Corporation) and Clinigen K.K. (“Clinigen”), has received on January 22, 2021, Japan manufacturing and marketing approval for Hunterase ICV (intracerebroventricular) Injection 15 mg (generic name: idursulfase-beta (recombinant)) as a treatment for mucopolysaccharidosis type II (Hunter syndrome). An enzyme-replacement therapy drug for intravenous injection is already in use in Japan and other countries as a treatment for systemic symptoms of mucopolysaccharidosis type II. However, there is no therapeutical drug targeting the central nervous system symptoms, from which approximately 70% of patients suffer. The newly approved Hunterase ICV Injection 15 mg, developed by GC Pharma, is delivered directly to the cerebral ventricles, allowing it to reach the cells of the brain and central nervous system. It is expected to alleviate aspects of the disease such as delayed psychomotor development. In the result of the phase I/II study conducted by Dr. Torayuki Okuyama, principal investigator of the study, Department Head of Clinical Laboratory Medicine of the National Center for Child Health Development, Hunterase demonstrated a significant decrease of heparan sulfate in cerebrospinal fluid, which is regarded as the key factor for delayed cognitive development. The approval in Japan is ahead of the world, being the first approval of Hunterase ICV Injection in any country worldwide. Hunterase ICV Injection 15 mg is also the world’s first and only drug for the treatment of central nervous system symptoms of mucopolysaccharidosis type II.