CD4 and neoplasm: In studies on rectal cancer before nCRT combined with PD-L1 inhibitor therapy, it has been observed that higher densities of CD4+ TILs, CD8+ TILs, and CD56+ TILs in tumor tissues correlate with an increased proportion of patients achieving TRG0, 1, or 2 (complete or partial tumor regression) and a relative decrease in the number of TRG3 (no regression).