CTLA4 and rectal cancer: To determine predictive and prognostic effects of tumor immune microenvironment, Teng et al. investigated the subset densities of tumor-infiltrating lymphocytes (TILs), as well as programmed cell death ligand 1 (PD-L1) and cytotoxic T-lymphocyte protein 4 (CTLA4) expression before and after nCRT in 62 rectal cancer.