Safety and Efficacy of Avaren-Fc Lectibody Targeting HCV High-Mannose Glycans in a Human Liver Chimeric Mouse Model

Infection with hepatitis C virus (HCV) remains to be a major cause of morbidity and mortality worldwide despite the recent advent of highly effective direct-acting antivirals. The envelope glycoproteins of HCV are heavily glycosylated with a high proportion of high-mannose glycans (HMGs), which serve as a shield against neutralizing antibodies and assist in the interaction with cell-entry receptors. However, currently there is no approved therapeutic targeting this potentially druggable biomarker. Here, we investigated the therapeutic potential of the lectibody Avaren-Fc (AvFc), a HMG-binding lectin-Fc fusion protein. In vitro assays showed AvFc9s capacity to neutralize cell culture-derived HCV in a genotype independent manner with IC50 values in the low nanomolar range. A histidine buffer-based AvFc formulation was developed for in vivo studies using the PXB human liver chimeric mouse model. Systemic administration of AvFc was well tolerated; after 11 consecutive doses every other day at 25 mg/kg, there were no significant changes in body or liver weights, nor any impact noted in blood human albumin levels or serum alanine aminotransferase activity. Gross necropsy and liver pathology further confirmed the lack of discernible toxicity. This treatment regimen successfully prevented genotype 1a HCV infection in all animals, while an AvFc mutant lacking HMG binding activity failed to block the infection. These results suggest that targeting envelope HMGs is a promising therapeutic approach against HCV infection. In particular, AvFc may provide a safe and efficacious means to prevent recurrent infection upon liver transplantation in HCV-related end-stage liver disease patients.