What happened next would have been unthinkable just a few years ago and has been made possible by incredible advances in genetics.- The first base edit disabled the T-cells targeting mechanism so they would not assault Alyssa's body - The second removed a chemical marking, called CD7, which is on all T-cells - The third edit was an invisibility cloak that prevented the cells being killed by a chemotherapy drug The final stage of genetic modification instructed the T-cells to go hunting for anything with the CD7 marking on it so that it would destroy every T-cell in her body - including the cancerous ones.Alyssa was left vulnerable to infection, as the designer cells attacked both the cancerous T-cells in her body and those that protect her from disease.It's just amazing I've been able to have this opportunity, I'm very thankful for it and it's going to help other children, as well, in the future."Dr David Liu, one of the inventors of base editing at the Broad Institute, told me it was "a bit surreal" that people were being treated just six years after the technology was invented."