Using PASylation®, a proprietary process of XL-protein GmbH, XL-protein has modified Coversin by adding a 600 amino acid proline/alanine/ serine (PAS) N-terminal fusion tag to generate PAS-Coversin (68kDa). The unstructured and uncharged PAS polypeptide increases the apparent molecular size to approximately 700kDa, slowing kidney clearance and extending the half-life.
Data from mouse and rat studies of PAS-Coversin demonstrated that the expected terminal half-life in humans should be approximately 4 days. Based on these data, PK modeling supports that a once weekly dosing regimen is feasible. We intend to conduct a Phase I clinical study of PAS Coversin in the future based on our availability of resources.