A phase I/II study on intracerebroventricular tralesinidase alfa in patients with Sanfilippo syndrome type B

Nicole Muschol, Anja Koehn, Katharina von Cossel, Ilyas Okur, Fatih Ezgu, Paul Harmatz, Maria J. de Castro Lopez, Maria Luz Couce, Shuan Pei Lin, Spyros Batzios, Maureen Cleary, Martha Solano, Igor Nestrasil, Brian Kaufman, Adam J. Shaywitz, Stephen M. Maricich, Bernice Kuca, Joseph Kovalchin, Eric Zanelli

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4 Scopus citations


BACKGROUND. Sanfilippo type B is a mucopolysaccharidosis (MPS) with a major neuronopathic component characterized by heparan sulfate (HS) accumulation due to mutations in the NAGLU gene encoding alfa-N-acetyl-glucosaminidase. Enzyme replacement therapy for neuronopathic MPS requires efficient enzyme delivery throughout the brain in order to normalize HS levels, prevent brain atrophy, and potentially delay cognitive decline. METHODS. In this phase I/II open-label study, patients with MPS type IIIB (n = 22) were treated with tralesinidase alfa administered i.c.v. The patients were monitored for drug exposure; total HS and HS nonreducing end (HS-NRE) levels in both cerebrospinal fluid (CSF) and plasma; anti-drug antibody response; brain, spleen, and liver volumes as measured by MRI; and cognitive development as measured by age-equivalent (AEq) scores. RESULTS. In the Part 1 dose escalation (30, 100, and 300 mg) phase, a 300 mg dose of tralesinidase alfa was necessary to achieve normalization of HS and HS-NRE levels in the CSF and plasma. In Part 2, 300 mg tralesinidase alfa sustained HS and HS-NRE normalization in the CSF and stabilized cortical gray matter volume (CGMV) over 48 weeks of treatment. Resolution of hepatomegaly and a reduction in spleen volume were observed in most patients. Significant correlations were also established between the change in cognitive AEq score and plasma drug exposure, plasma HS-NRE levels, and CGMV. CONCLUSION. Administration of tralesinidase alfa i.c.v. effectively normalized HS and HS-NRE levels as a prerequisite for clinical efficacy. Peripheral drug exposure data suggest a role for the glymphatic system in altering tralesinidase alfa efficacy.

Original languageEnglish (US)
Article numbere165076
JournalJournal of Clinical Investigation
Issue number2
StatePublished - Jan 17 2023

Bibliographical note

Funding Information:
BioMarin Pharmaceutical Inc. and Allievex Corporation. We owe an immense debt of gratitude to the participants and their parents/caregivers for participating in this study, and we thank all the clinical staff, neuropsychologists, and supporting individuals essential to the study’s implementation and execution. Allievex also expresses their gratitude to the individual clinical and research institutions and study staff of each of our authors for their support and commitment to the tralesinidase alfa program.

Publisher Copyright:
© 2023, Muschol et al.

PubMed: MeSH publication types

  • Clinical Trial, Phase II
  • Clinical Trial, Phase I
  • Journal Article


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