The point of going slowly is that we make sure something works, even if it has these bad side affects. Do we try experimental drugs with worse effects so that we can find effective ones faster? There are brave souls out there who will participate in clinical trials or experimental exceptions
Typically what happens is that the new treatments with bad side effects are given to the sickest patients (who have exhausted all other mechanisms), rather than to the bravest souls with less dire current circumstances.
This makes some sense in terms of compassion and matching new experimental techniques with patients with no hope, but it skews the results highly negative because the patients are already very close to death's door. It does not provide an accurate signal for what the results would be if we gave them to less sick people.
I don't think any of this can be changed without large-scale social acceptance of greater risk in clinical trials and significant support from the government.
> It does not provide an accurate signal for what the results would be if we gave them to less sick people.
It provides an excellent signal because we want to prove that these drugs are doing something that the standard of care is unable to.
There's this sense that medicine is easy and some evil cabal are limiting health to their cronies. Most medications never get to trial for their intended indications, and most fail trials. There's no reason to believe oncology medications are somehow uniquely unlikely to go through this well-described process of failure.