Engineering and Characterization of an Enzyme Replacement Therapy for Classical Homocystinuria.

Abstract

Homocystinuria due to loss of cystathionine beta-synthase (CBS) causes accumulation of homocysteine and depletion of cysteine. Current treatments are suboptimal, and thus the development of an enzyme replacement therapy based on PEGylated human truncated CBS (PEG-CBS) has been initiated. Attenuation of potency was observed, which necessitated a screen of several PEG-CBS conjugates for their efficacy to correct and maintain the plasma metabolite profile of murine homocystinuria after repeated administrations interrupted with washouts. We found that CBS coupling with maleimide PEG inconsistently modified the enzyme. In contrast, the PEG-CBS conjugate with 20 kDa N-hydroxysuccinimide-PEG showed very little loss of potency likely due to a reproducible PEGylation resulting in species modified with five PEGs per subunit on average. We developed assays suitable for monitoring the extent of CBS PEGylation and demonstrated a sustainable partial normalization of homocystinuria upon continuous PEG-CBS administration via osmotic pumps. Taken together, we identified the PEG-CBS conjugate suitable for manufacturing and clinical development.

• Authors: Tomas Majtan, Insun Park, Richard S Carrillo, Erez M Bublil, Jan P Kraus
• Journal: Biomacromolecules (Biomacromolecules) Vol. 18 Issue 6 Pg. 1747-1761 (Jun 12 2017) ISSN: 1526-4602 [Electronic] United States
• PMID: 28431470 (Publication Type: Journal Article)

Chemical References

• Cross-Linking Reagents
• Delayed-Action Preparations
• Maleimides
• Succinimides
• Homocysteine
• maleimide
• Polyethylene Glycols
• Cystathionine beta-Synthase
• Cysteine
• N-hydroxysuccinimide

Topics

• Amino Acid Sequence
• Animals
• Cross-Linking Reagents (chemistry)
• Cystathionine beta-Synthase (chemistry, pharmacokinetics, pharmacology)
• Cysteine (blood)
• Delayed-Action Preparations (chemical synthesis, pharmacokinetics, pharmacology)
• Disease Models, Animal
• Enzyme Replacement Therapy (methods)
• Homocysteine (blood)
• Homocystinuria (blood, physiopathology, therapy)
• Humans
• Maleimides (chemistry)
• Mice
• Polyethylene Glycols (chemistry)
• Succinimides (chemistry)