15 - Site-specific PEGylation of interferon beta-1b: from bench to clinic

Abstract

Incorporation of non-natural amino acids during recombinant protein expression allows site-specific conjugation at predetermined site(s). A variant of interferon beta-1b was PEGylated using this technology, where azidohomoalanine and copper-catalyzed azide-alkyne cycloaddition (CuAAC) were used to enable half-life extension of this therapeutic protein for multiple sclerosis. The use of PEG diol and cysteine in the reaction mixture enabled efficient PEGylation and protected the protein from degradation. The optimal 40kDa branched PEG configuration was identified and scalable processes for robust cGMP production were established. In Phase I clinical studies, an extended pharmacokinetic profile with detectable serum levels up to 28days and a concomitant neopterin biomarker response was observed. Preexisting and treatment emergent anti-PEG antibodies were detected in some subjects and have important implications for immunogenicity and clinical utility of PEGylated proteins. The importance of controlling residual host cell protein levels and of avoiding polysorbate in anti-PEG ELISAs is also highlighted.