A novel highly potent inhibitor of TMPRSS2-like proteases blocks SARS-CoV-2 variants of concern and is broadly protective against infection and mortality in mice

Shapira, Tirosh; Monreal, I. Abrrey; Dion, Sébastien P.; Jager, Mason; Désilets, Antoine; Olmstead, Andrea D.; Vandal, Thierry; Buchholz, David W.; Imbiakha, Brian; Gao, Guang; Chin, Aaleigha; Rees, William D.; Steiner, Theodore; Nabi, Ivan Robert; Marsault, Eric; Sahler, Julie; August, Avery; Van de Walle, Gerlinde; Whittaker, Gary R.; Boudreault, Pierre-Luc; Aguilar, Hector C.; Leduc, Richard; Jean, François

The COVID-19 pandemic caused by the SARS-CoV-2 virus remains a global public health crisis. Although widespread vaccination campaigns are underway, their efficacy is reduced against emerging variants of concern (VOCs) 1,2. Development of host-directed therapeutics and prophylactics could limit such resistance and offer urgently needed protection against VOCs 3,4. Attractive pharmacological targets to impede viral entry include type-II transmembrane serine proteases (TTSPs), such as TMPRSS2, whose essential role in the virus lifecycle is responsible for the cleavage and priming of the viral spike protein 5–7. Here, we identify and characterize a small-molecule compound, N-0385, as the most potent inhibitor of TMPRSS2 reported to date. N-0385 exhibited low nanomolar potency and a selectivity index of >106 at inhibiting SARS-CoV-2 infection in human lung cells and in donor-derived colonoids 8. Importantly, N-0385 acted as a broad-spectrum coronavirus inhibitor of two SARS-CoV-2 VOCs, B.1.1.7 and B.1.351. Strikingly, single daily intranasal administration of N-0385 early in infection significantly improved weight loss and clinical outcomes, and yielded 100% survival in the severe K18-human ACE2 transgenic mouse model of SARS-CoV-2 disease. This demonstrates that TTSP-mediated proteolytic maturation of spike is critical for SARS-CoV-2 infection in vivo and suggests that N-0385 provides a novel effective early treatment option against COVID-19 and emerging SARS-CoV-2 VOCs.