Intravenous delivery of a chemically modified sulfamidase efficiently reduces heparan sulfate storage and brain pathology in mucopolysaccharidosis IIIA mice

Abstract

Mucopolysaccharidosis type IIIA (MPS IIIA) is a lysosomal storage disorder (LSD) characterized by severe central nervous system (CNS) degeneration. The disease is caused by mutations in the SGSH gene coding for the lysosomal enzyme sulfamidase. Sulfamidase deficiency leads to accumulation of heparan sulfate (HS), which triggers aberrant cellular function, inflammation and eventually cell death. There is currently no available treatment against MPS IIIA. In the present study, a chemically modified recombinant human sulfamidase (CM-rhSulfamidase) with disrupted glycans showed reduced glycan receptor mediated endocytosis, indicating a non-receptor mediated uptake in MPS IIIA patient fibroblasts. Intracellular enzymatic activity and stability was not affected by chemical modification. After intravenous (i.v.) administration in mice, CM-rhSulfamidase showed a prolonged exposure in plasma and distributed to the brain, present both in vascular profiles and in brain parenchyma. Repeated weekly i.v. administration resulted in a dose- and time-dependent reduction of HS in CNS compartments in a mouse model of MPS IIIA. The reduction in HS was paralleled by improvements in lysosomal pathology and neuroinflammation. Behavioral deficits in the MPS IIIA mouse model were apparent in the domains of exploratory behavior, neuromuscular function, social- and learning abilities. CM-rhSulfamidase treatment improved activity in the open field test, endurance in the wire hanging test, sociability in the three-chamber test, whereas other test parameters trended towards improvements. The unique properties of CM-rhSulfamidase described here strongly support the normalization of clinical symptoms, and this candidate drug is therefore currently undergoing clinical studies evaluating safety and efficacy in patients with MPS IIIA.

Impact of chemical modification of sulfamidase on distribution to brain interstitial fluid and to CSF after an intravenous administration in awake, freely-moving rats

“…The cloning, expression and purification of rhSulfamidase and for CM-rhSulfamidase the additional chemical modification are described in Gustavsson et al [6]. Per compound, 7 male Sprague Dawley rats received a single 30 mg/kg i.v.…”

“…The concentrations of rhSulfamidase or CM-rhSulfamidase were determined by a Meso Scale Discovery electrochemiluminescence (MSD-ECL) based method [6]. In short, MSD multi-array streptavidin coated plates were blocked with 5% Blocker A in Phosphate-Buffered Saline (PBS) for >1 h on a shaker at 500 rpm.…”

“…rhSulfamidase has an unglycosylated calculated molecular weight of 55 kDa, has four N-glycosylation sites and forms dimers in solution [16]. The chemical modification procedure used to generate CM-rhSulfamidase results in a modification of its glycans, which strongly reduces uptake of the enzyme into peripheral tissues by reducing the affinity of CM-rhSulfamidase to the cation-independent mannose-6-phosphate receptor [6]. The modification conditions are mild to maintain the structure and activity of the enzyme in the resulting drug substance.…”

“…Using this chemical modification protocol, repeated i.v. administration of CM-rhSulfamidase reduced biomarkers HS, the disaccharide GlcNS-UA and the tetrasaccharide, GlcNS-UA-GlcNAc-UA (+1S) in brain of MPS IIIA mice [6,12].…”

Pre-clinical Mouse Models of Neurodegenerative Lysosomal Storage Diseases

“…et al, 2010), ERT(Lee et al, 2011(Lee et al, , 2014Higuchi et al, 2012;Hong et al, 2012;Sohn et al, 2018 Sohn et al, ) et al, 2007Haurigot et al, 2013), AI(Arfi et al, 2011), BMT(Lau et al, 2012),LV (McIntyre et al, 2008), SRT(Roberts et al, 2010) Mgat3 (D31N)(Bhattacharyya et al, 2001) + + AAV(Ruzo et al, 2012;Haurigot et al, 2013), ERT(Gustavsson et al, 2019), GT(Quiviger et al, 2014), SRT(Roberts et al, 2007) Mgat3(CKO) (Lau et al, 2017(Lau et al, ) et al, 2004Ribera et al, 2015), ERT(Kan et al, 2014),LV (Di Natale et al, 2005Blanz et al, 2008;Damme et al, 2011) NEU1 Sialidosis, Type I & II Neu1 (−/−) (de Geest et al, 2002) + < Neu1 (V54M) (Bonten et al, 2013) + + Chaperone-AAV (Bonten et al, 2013)(Continued)…”