"yet it doesn’t seem to be important for normal development"
Gene space is huge. My cancer is cured, but now I'm dying of mange. So that's why that mouse kept licking itself. Big ask for someone else. They have trouble getting blood thinners, statins and beta blockers right. And there's no genetics there. It's stuff people ate out in the woods for hundreds of thousands of years.
> There are so many people close to dying in cancer finding volunteers for a Phase 1 test should be easy
I take the opposite approach. These people have few days left. It's a time to make things nice. It can get much worse quick. Cancer, which can be managed, is nowhere near as bad as it can get.
Disease tends to hit all at once. It's really just dying. Cancer, strokes, heart attacks and infections all tend to gang up at once. The trial will kill these people no doubt. If you have a ticket out of the hospital, take it! Don't squander it trying to wash mud.
Also the patient pays a lot for clinical trials. Hundreds of thousands of dollars.