Process Development for the GMP Production of N-Acetylgalactosamine-6-Sulfate Sulfatase (GALNS) Expressed by CHO Cells

The enzyme N-acetylgalactosamine-6-sulfate sulfatase (GALNS) is intended to be used as an Enzyme Replacement Therapy to treat the disorder Mucopolysaccharidosis IV A (MPS IVA or Morbus Morquio) caused by a deficiency of GALNS. GALNS is a lysosomal enzyme required to degrade glycosaminoglycans (GAGs), keratin sulphate (KS) and chondroitin-6-sulfate (C6S). The human GALNS cDNA encodes a polypeptide of 522 amino acid residues, whereas the GALNS protein is a 120 kDa homodimer with a molecular mass of 60 kDa for the monomer that is processed to polypeptides of 40 and 15 kDa. The aim of the study is to establish a stable CHO cell line overexpressing the recombinant human GALNS enzyme (rhGALNS), tagged with specific acidic oligopeptides to improve the delivery of GALNS to bone (to treat bone-related pathology and symptoms). The expressed rhGALNS is unstable at the generally used cultivation temperature and therefore requires a continuous perfusion process using micro carriers in protein and serum-free media for the GMP production.