In a recent paper on why hydroxychloroquine doesn't really work against Covid-19, it's been demonstrated that SARS-CoV-2 is much better at taking advantage of TMPRSS2 at the cell membrane surface, so that the cathepsin-mediated endosomal-entry pathway (which hydroxychloroquine inhibits) is basically irrelevant most of the time for SARS-CoV-2 infections in the cells it actually infects in humans.
There is one inhibitor of TMPRSS2 mentioned in that paper namely camostat, but it seems it's only approved as a drug in Japan and for other diseases: pancreatitis etc. Wikipedia does cite one small-scale retrospective study of camostat for Covid-19 (but actually conducted in Germany). That paper ends with the predictable suggestion that "Camostat mesylate thus warrants further evaluation within randomized clinical trials."
I also found an older (2017) review on other TMPRSS2 inhibitors, but it's not exactly clear if any of the [other] compounds mentioned (aprotinin, nafamostat, AEBSF, leupeptin, bromhexine hydrochloride, and a few more which only have [long] chemical names) has been tested in any way against Covid-19, although some of these compounds were previously tested against influenzas. So, has any RCTs for a TMPRSS2 inhibitor been even started for Covid-19? Or is there some (other) reason to think such drugs would likely not be useful against Covid-19, so it makes no sense to test them?
