A scientific conference marking the five-year anniversary of the use of the drug Hunterase Neuro for the treatment of Hunter syndrome was held in Tokyo. Hunter syndrome is a rare inherited disease from the group of mucopolysaccharidoses that occurs in approximately one in 100,000–150,000 newborns. Russian clinical practice was presented at the event by specialists from the Russian Children’s Clinical Hospital (RCCH), who delivered reports on the results of treating the first patients with the innovative therapy.

Three RCCH experts spoke at the conference: neurologist Svetlana Mikhailova, MD, PhD, neurosurgeon Dmitry Reshchikov, and clinical psychologist Olga Mendelevich. They presented treatment outcomes for three patients receiving therapy with Hunterase Neuro and shared their experience in the multidisciplinary management of such patients.

According to RCCH specialists, the experience of using the therapy in Russia to date has been assessed as positive: patients have demonstrated clinical improvement, and no adverse reactions have been recorded during treatment. “Our initial experience with the drug shows that the therapy is well tolerated by patients and may contribute to stabilizing the condition in severe forms of the disease. Importantly, we now have a tool that allows us to address the neurological manifestations of Hunter syndrome,” said neurologist Svetlana Mikhailova, MD, PhD.

The first use of Hunterase Neuro in Russia took place in December 2025. Russia became the second country in the world where this innovative therapy became available to patients. Treatment is provided within the framework of the Circle of Kindness Foundation program, which ensures access to modern medicines for children with rare diseases. In the near future, the treatment program is expected to expand, with three additional patients set to receive therapy with Hunterase Neuro.

The availability of this therapy for Russian patients became possible thanks to a long-term partnership between the Russian biopharmaceutical company Nanolek and the South Korean company GC Biopharma.

Enzyme replacement therapy (ERT) with recombinant human idursulfase has been used to treat mucopolysaccharidosis type II (MPS II) since 2006. Patients receive the drug intravenously once a week; however, this route of administration does not allow the medicine to cross the blood–brain barrier and affect the brain. As a result, patients with the neuropathic form of the disease continue to experience progression of central nervous system damage.

Hunterase® Neuro (idursulfase beta)* is the first and only registered ERT drug in the world that delivers the enzyme directly into the brain ventricles. Intracerebroventricular administration via an Ommaya reservoir allows the therapy to bypass the blood–brain barrier and target the neurological manifestations of MPS II.

Clinical trial data** show that the use of Hunterase Neuro in combination with standard intravenous ERT can stabilize or improve the neurological condition of patients with the neuropathic form of the disease.

*https://grls.minzdrav.gov.ru/Grls_View_v2.aspx?routingGuid=a92a7222-c0b4-4c22-bcdf-0049154c3105

** Seo JH, Kosuga M, Hamazaki T, Shintaku H, Okuyama T. Impact of intracerebroventricular enzyme replacement therapy in patients with neuronopathic mucopolysaccharidosis type II. Mol Ther Methods Clin Dev. 2021

** Joo-Hyun Seo, et al Intracerebroventricular enzyme replacement therapy in patients with neuronopathic mucopolysacchar idosis type II: Final report of 5-year results from a Japanese open-label phase 1/2 study2023