After comparing the expression levels of common immune checkpoints between high- and low-LMI groups in breast cancer, we found that expressions of PD-1, CTLA4, CD96, VSIR, and TIGIT except PD-L1 were significantly upregulated in the low-LMI group, which hinted that breast cancer patients with lower LMI value might have had a better immunotherapy response. This evidence concerns the gene CTLA4 and breast cancer.