Finally, in one case, a patient with CLL treated with CAR T cells was reported to display the proliferation of an identified population of clonal CD8+ CAR T cells carrying 1) a TET2 gene interrupted by the chimeric antigen receptor transgene and 2) a preexisting TET2 mutation in the second allele [35]. Here, TET2 is linked to B-cell chronic lymphocytic leukemia.