Brain tumor volumes ranged from 0 to 300 mm3 and were found to be inversely correlated to the density of intratumoral PD-1+ TILs (P < .05; Figure 2A), and, although not statistically significant, a trend toward correlation for ICOS+ TILs was observed (P = 0.058; Figure 2B). This evidence concerns the gene ICOS and brain neoplasm.