Monoclonal antibody therapy (the same treatment President Trump got in the hospital) works pretty well. It’s just expensive and it’s not a magic cure-all.
A lot of different possible treatments have been tried. Some have been found to have some value. Most have been found to have little or no value. Nearly all have no value once the person is at the stage of being hospitalized. And no treatment has yet been found that’s nearly as effective at saving lives and keeping people out of the hospital as the vaccines are. When it’s trained in recognizing and responding to the particular threat, even a fairly unhealthy person’s immune system can win the fight. An ounce of prevention really is worth a pound of cure.
Well therein lies the rub. There has been a lot of study, but all very small and scattered around the world by clinicians. There has been a lack of uniformity in the studies. The trials that show lack of statistical meaningful results often don't use the same protocols as the studies that seem to show benefits. Nearly all of these potential treatments (and I stress potential, recognizing few if any were large randomized studies) need to be given as early in the disease cycle as possible - e.g. upon positive test and/or onset of first symptoms even before PCR test confirms.
So again my point is, no interest in actually enrolling a 10,000-30,000 person study for anything that would be fast and cheap to produce to help those who are actively infected. This thing is rampaging throughout the world and little hope to produce enough vaccines in any meaningful quantities to stop it.