YONGIN, South Korea, Aug. 21, 2025 -- GC Biopharma, a leading global pharmaceutical company based in South Korea, announced today that it has revealed the delivery mechanism of Hunterase (idursulfase beta), a recombinant enzyme replacement therapy for Hunter syndrome (MPS II). The research findings, detailing the role of N-glycosylation in lysosomal targeting, have been published in the International Journal of Biological Macromolecules, a prestigious SCIE-indexed journal.

Hunter syndrome (MPS II) is a rare genetic disorder caused by mutations in the iduronate-2-sulfatase (IDS) gene, resulting in a deficiency of the IDS enzyme, which is essential for the degradation of glycosaminoglycans (GAGs). This deficiency leads to the progressive accumulation of GAG within lysosomes, causing a range of symptoms. Thus, effective treatment relies on delivering the therapeutic enzyme to lysosomes to facilitate GAG breakdown.

For effective lysosomal targeting, the N-glycan structures of the therapeutic enzyme must contain mannose-6-phosphate (M6P). M6P acts as a targeting signal, guiding the enzyme to bind to cells, facilitating its uptake and delivery into lysosomes to degrade GAGs.

The research utilized high-resolution Orbitrap mass spectrometry to analyze the site-specific N-glycan structures of idursulfase beta (Hunterase). A total of 42 N-glycan structures were identified, with two sites, Asn221 and Asn255, found to be predominantly modified with bis-mannose-6-phosphate (bis-M6P), a structure containing two phosphate groups. The research team explains that this bis-M6P structure ensures the efficient and stable delivery of idursulfase beta (Hunterase) to lysosomes.

The research team also demonstrated idursulfase beta's high-affinity binding to the M6P receptors using surface plasmon resonance. Additionally, fluorescence-labeled cellular studies confirmed efficient uptake and lysosomal delivery of idursulfase beta (Hunterase).

Moreover, several N-glycan structures of idursulfase beta (Hunterase) were found to be modified with sialic acid, which is known to prolong the enzyme's circulation in the blood, extending its half-life.

Hunterase (idursulfase beta), according to GC Biopharma, is highly effective for treating Hunter syndrome due to its targeted lysosomal delivery, driven by N-glycan structures modified with M6P and prolonged circulation enabled by sialic acid modifications.

"This study analyzed the lysosomal delivery mechanism of Hunterase (idursulfase beta), supported by robust scientific evidence," said Jae Uk Jeong, Head of R&D at GC Biopharma. "With clear evidence of its therapeutic effectiveness, patients with Hunter syndrome can have greater confidence in using Hunterase throughout their treatment journey."

About GC Biopharma

GC Biopharma (formerly known as Green Cross Corporation) is a biopharmaceutical company headquartered in Yong-in, South Korea. The company has over half a century of experience in the development and manufacturing of plasma derivatives and vaccines, and is expanding its global presence with successful US market entry of Alyglo^®(intravenous immunoglobulin G) in 2024. In line with its mission to meet the demands of future healthcare, GC Biopharma continues to drive innovation by leveraging its core R&D capabilities in engineering of proteins, mRNAs, and lipid nanoparticle (LNP) drug delivery platform to develop therapeutics for the field of rare disease as well as I&I (Immunology & Inflammation). To learn more about the company, visit https://www.gcbiopharma.com/eng/

This press release may contain biopharmaceuticals in forward-looking statements, which express the current beliefs and expectations of GC Biopharma's management. Such statements do not represent any guarantee by GC Biopharma or its management of future performance and involve known and unknown risks, uncertainties, and other factors. GC Biopharma undertakes no obligation to update or revise any forward-looking statement contained in this press release or any other forward-looking statements it may make, except as required by law or stock exchange rule.

GC Biopharma Contacts (Media)

Sohee Kim
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Yoonjae Na
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