Biochemical evaluation of intracerebroventricular rhNAGLU-IGF2 enzyme replacement therapy in neonatal mice with Sanfilippo B syndrome

Mol Genet Metab. 2021 Jun;133(2):185-192. doi: 10.1016/j.ymgme.2021.03.013. Epub 2021 Mar 31.


Mucopolysaccharidosis IIIB (MPS IIIB, Sanfilippo syndrome type B) is caused by a deficiency in α-N-acetylglucosaminidase (NAGLU) activity, which leads to the accumulation of heparan sulfate (HS). MPS IIIB causes progressive neurological decline, with affected patients having an expected lifespan of approximately 20 years. No effective treatment is available. Recent pre-clinical studies have shown that intracerebroventricular (ICV) ERT with a fusion protein of rhNAGLU-IGF2 is a feasible treatment for MPS IIIB in both canine and mouse models. In this study, we evaluated the biochemical efficacy of a single dose of rhNAGLU-IGF2 via ICV-ERT in brain and liver tissue from Naglu-/- neonatal mice. Twelve weeks after treatment, NAGLU activity levels in brain were 0.75-fold those of controls. HS and β-hexosaminidase activity, which are elevated in MPS IIIB, decreased to normal levels. This effect persisted for at least 4 weeks after treatment. Elevated NAGLU and reduced β-hexosaminidase activity levels were detected in liver; these effects persisted for up to 4 weeks after treatment. The overall therapeutic effects of single dose ICV-ERT with rhNAGLU-IGF2 in Naglu-/- neonatal mice were long-lasting. These results suggest a potential benefit of early treatment, followed by less-frequent ICV-ERT dosing, in patients diagnosed with MPS IIIB.

Keywords: Heparan sulfate; Intracerebroventricular enzyme replacement therapy (ICV-ERT); Mucopolysaccharidosis IIIB; Neonatal mice; Sanfilippo syndrome type B.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acetylglucosaminidase / genetics*
  • Animals
  • Animals, Newborn
  • Disease Models, Animal
  • Dogs
  • Enzyme Replacement Therapy*
  • Heparitin Sulfate / metabolism
  • Humans
  • Infusions, Intraventricular
  • Insulin-Like Growth Factor II / genetics*
  • Mice
  • Mice, Knockout
  • Mucopolysaccharidosis III / enzymology
  • Mucopolysaccharidosis III / genetics
  • Mucopolysaccharidosis III / pathology
  • Mucopolysaccharidosis III / therapy*
  • Nervous System Diseases
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / pharmacology


  • IGF2 protein, mouse
  • Recombinant Fusion Proteins
  • Insulin-Like Growth Factor II
  • Heparitin Sulfate
  • alpha-N-acetyl-D-glucosaminidase
  • Acetylglucosaminidase