Typically in Stage 1 trials, they test safety effectiveness by giving doses of varying size, often times below the level of clinical effectiveness. They also gi

Typically in Stage 1 trials, they test safety effectiveness by giving doses of varying size, often times below the level of clinical effectiveness. They also give these to much smaller populations, usually fewer than 25 people. The main goal of these trials is to figure out "safety and dosage" -- so they measure side effects at each dosage and try to discern interactions with the body. They'll be especially careful with the CRISPR drugs due to the disasters that Gene Therapy trials have previously undergone. Most notably, TGN1412 was given at a dosage about 500x smaller than the safe dosage in animals but caused almost immediate cytokine storms that nearly killed all 6 participants in the trial.