From “Experimental CRISPR technique has promise against aggressive leukaemia,” Michael Le Page, NewScientist (17 December 2022):
The 13-year-old girl, called Alyssa, hadn’t responded to other treatments. As part of a trial, she received a dose of immune cells from a donor that had been modified to attack the cancer. Twenty-eight days later, tests revealed she was in remission.
Tough on the donor, I’m tellin’ you. Generally, they just modify the immune cells.