Discovery and development of INNA-051, a TLR2/6 agonist for the prevention of complications resulting from viral respiratory infections.

Viral respiratory infection is associated with significant morbidity and mortality. The diversity of viruses implicated, coupled with their propensity for mutation, ignited an interest in host-directed antiviral therapies effective across a wide range of viral variants. Toll-like receptors (TLRs) are potential targets for the development of broad-spectrum antivirals given their central role in host immune defenses. Synthetic agonists of TLRs have been shown to boost protective innate immune responses against respiratory viruses. However, clinical success was hindered by short duration of benefit and/or induction of systemic adverse effects. INNA-051, a TLR2/6 agonist, is in development as an intranasal innate immune enhancer for prophylactic treatment in individuals at risk of complications resulting from respiratory viral infections. In vivo animal studies demonstrated the efficacy as prophylaxis against multiple viruses including SARS-CoV-2, influenza, and rhinovirus. Early clinical trials demonstrated an acceptable safety and tolerability profile. Intranasal delivery to the primary site of infection in humans induced a local innate host defense response characterized by innate immune cell infiltration into the nasal epithelium and activation and antiviral response genes. Taken together, the preclinical and clinical data on INNA-051 support further investigation of its use in community infection settings.