COVID-19 drug repurposing: Summary statistics on current clinical trials and promising untested candidates

Repurposing of existing anti-viral drugs, immunological modulators and supportive therapies represents a promising path towards rapidly developing new control strategies to mitigate the devastating public health consequences of the COVID-19 pandemic. A comprehensive text-mining and manual curation approach was used to comb and summarize the most pertinent information from existing clinical trials and previous efforts to develop therapies against related betacoronaviruses, particularly SARS and MERS. In contrast to drugs in current trials, which have been derived overwhelmingly from studies on taxonomically unrelated RNA viruses, a number of untested small molecule anti-virals had previously demonstrated remarkable in vitro specificity for SARS-CoV or MERS-CoV, with high selectivity indices, EC₅₀ and/or IC₅₀ . Due to the rapid containment of the prior epidemics, however, these were generally not followed up with in vivo animal studies or clinical investigations and thus largely overlooked as treatment prospects in the current COVID-19 trials. This brief review summarizes and tabulates core information on recent or ongoing drug repurposing-focused clinical trials, while detailing the most promising untested candidates with prior documented success against the aetiologic agents of SARS and/or MERS.