Safety, tolerability, and efficacy of intranasally-administered detoxified LTh(αK) in mild-to-moderate COVID-19 patients: A randomized, double-blinded, placebo-controlled phase 2 study

The objective of the study was to assess the safety, tolerability, and potential efficacy of intranasally administered AD17002, a detoxified form of <i>Escherichia coli</i> heat-labile enterotoxin, in treating individuals with mild-to-moderate coronavirus disease of 2019 (COVID-19). In this randomized, double-blinded, and placebo-controlled phase 2a study, a total of 30 adults aged 20-70 years with mild-to-moderate COVID-19 were recruited from three medical centers in Taiwan in 2022-2023. The trial comprised two cohorts, and participants were randomly assigned to receive intranasal administrations of either three doses of AD17002 immunomodulator or a placebo formulation buffer. Outcome analyses were conducted on the intention-to-treat set, and the safety set that included all randomized participants exposed to the AD17002. The proportion of cycle threshold (C<i>t</i>) ≥30 and time to the recovery of key symptoms were assessed. An exploratory study was conducted to analyze the integrity of the viral genome after treatment. Administering 20 μg of AD17002 three times, either at 1-week or 1-day intervals, proved to be safe and well tolerated in subjects with mild-to-moderate COVID-19. AD17002 demonstrated a rapid and positive outcome in reducing the viral load in patients receiving the treatment. Impact of AD17002 treatment was further supported by the analysis of viral genome integrity following the treatment. The enhancement in clinical recovery by AD17002 within 5 days after symptom onset was observed but did not achieve statistical significance. According to the results, intranasal administration of AD17002 was safe, well-tolerated, and potentially effective for treating mild-to-moderate COVID-19.