“…TCR sequences used in these trials originated from healthy human donors, TILs of cancer patients or vaccinated HLA transgenic mice. Some of the TCRs were ex vivo engineered, high-affinity variants with improved anti-tumor function [ 4 , 5 , 6 , 73 , 77 , 78 , 79 , 84 , 87 , 88 , 91 , 92 ]. Of these affinity-engineered TCRs, unfortunately only the HLA-A*02:01-restricted NY-ESO-1 1G4-a95:LY or c259 TCR proved safe [ 4 , 5 ], while the other three TCRs produced significant, and in some cases lethal, toxicities [ 9 , 77 , 79 , 83 , 84 ].…”