GPT and Autoimmunity: In addition, the increased PTPN2‐deficient CAR T cells did not result in autoimmunity as reflected by the absence of circulating anti‐nuclear antibodies (Fig EV4D) and the lack of any overt tissue damage, including liver damage, as assessed by measuring the liver enzymes alanine transaminase (ALT) and aspartate transaminase (AST) in serum (Fig EV4E).