On Nov. 21, shares of CRISPR Therapeutics (CRSP 3.44%) were down 47% from a peak they reached in March. This might be a little surprising to folks who have been following this developer of gene therapies. After all, it's been less than a year since regulators in the U.S. and E.U. approved its first therapy, Casgevy, to treat two blood-based disorders.Casgevy's initial launch hasn't been as exciting as investors and its partner, Vertex Pharmaceuticals (VRTX 0.13%), had hoped. Less than a year into the launch ...