In light of this, a randomized, phase II, placebo-controlled clinical trial (ClinicalTrials.gov; Identifier: NCT04578236) for assessing the efficacy of aerosol combination therapy of 13- cis retinoic acid and captopril for treating COVID-19 patients via indirect inhibition of TMPRSS2 is currently ongoing. The gene discussed is TMPRSS2; the disease is COVID-19.