Macrocycle-based PROTACs selectively degrade cyclophilin A and inhibit HIV-1 and HCV
Lydia S. Newton, Clara Gathmann, Sophie Ridewood, Robert J. Smith, Andre J. Wijaya, Thomas W. Hornsby, Kate L. Morling, Dara Annett, Riccardo Zenezini Chiozzi, Ann‐Kathrin Reuschl, Morten L. Govasli, Ying Ying Tan, Lucy Thorne, Clare Jolly, Konstantinos Thalassinos, Alessio Ciulli, Greg J. Towers, David L. Selwood
Abstract
Targeting host proteins that are crucial for viral replication offers a promising antiviral strategy. We have designed and characterised antiviral PROteolysis TArgeting Chimeras (PROTACs) targeting the human protein cyclophilin A (CypA), a host cofactor for unrelated viruses including human immunodeficiency virus (HIV) and hepatitis C virus (HCV). The PROTAC warheads are based on fully synthetic macrocycles derived from sanglifehrin A, which are structurally different from the classical Cyp inhibitor, cyclosporine A. Our Cyp-PROTACs decrease CypA levels in cell lines and primary human cells and have high specificity for CypA confirmed by proteomics experiments. Critically, CypA degradation facilitates improved antiviral activity against HIV-1 in primary human CD4+ T cells compared to the non-PROTAC parental inhibitor, at limiting inhibitor concentrations. Similarly, we observe antiviral activity against HCV replicon in a hepatoma cell line. We propose that CypA-targeting PROTACs inhibit viral replication potently and anticipate reduced evolution of viral resistance and broad efficacy against unrelated viruses. Furthermore, they provide powerful tools for probing cyclophilin biology.