ERBB2 and breast cancer: Moreover, compared with the low-risk group, the high-risk group showed a lower expression of the immune checkpoint molecule BTLA among patients with HER2+, HER2−, and TNBC and a lower expression of B7H3 among patients with HER2+ BC, indicating that patients with BC in the high-risk group may tend to be immunologically “cold” and may gain little benefit from immunotherapy.