CTLA4 and neoplasm: Interestingly, it was observed that distant untreated lesions also had increased TILs, particularly of KLRG1hi CD8+ effector T cells, a population that can differentiate into a memory T cell subset capable of mounting highly effective anti-tumor responses with improved resistance to T cell exhaustion by PD-1 and CTLA-4 immune checkpoints [142,159].