An Oral Antiviral Combination Against Severe COVID‐19 Enabled by the Synergistic Mechanisms of Action of Auranofin and Remdesivir
Oyahida Khatun, Rohan Narayan, Santhosh Kambaiah Nagaraj, Rishad Shiraz, Abinaya Kaliappan, Sumandeep Kaur, Ankur Singh, Siva Shanmugam Selvaraj, Gudepalya Renukaiah Rudramurthy, Chakenahalli Naveenkumar, Shridhar Narayanan, Radha Krishan Shandil, Shailly Tomar, Shashank TripathiABSTRACT
Auranofin, an FDA‐approved oral anti‐rheumatic drug, was previously shown by our group to restrict Severe Acute Respiratory Syndrome Coronavirus‐2 (SARS‐CoV‐2) replication and pathology in preclinical models. Here, we systematically characterized its mechanism of action (MOA) through biochemical drug‐protein interactions, cell‐based mechanistic assays, and preclinical efficacy studies. Auranofin directly binds and inhibits SARS‐CoV‐2 MPro while simultaneously targeting multiple stages of the viral life cycle, disrupting endosomal trafficking, suppressing Spike S1/S2 proteolytic processing, impairing syncytia formation, and attenuating NF‐κB‐driven proinflammatory signaling. In cell culture, Auranofin demonstrated robust synergy with Remdesivir but competed with the MPro inhibitor Nirmatrelvir, informing rational combination design. In mice infected with the SARS‐CoV‐2 Delta variant, the oral combination of Auranofin and the Remdesivir prodrug GS‐621763 outperformed monotherapy, markedly reducing viral replication, inflammatory cytokine responses, and lung pathology, and improving clinical outcomes. These findings establish a multi‐target antiviral MOA of Auranofin and provide a mechanistic rationale for an all‐oral antiviral combination regimen against COVID‐19.