Prognostic value of immune checkpoint molecules in breast cancer

Immune checkpoint blockade treatments bring remarkable clinical benefits to fighting several solid malignancies. However, the efficacy of immune checkpoint blockade in breast cancer remains controversial. Several clinical trials of immune checkpoint blockades focused on the effect of CTLA4 and PD1/PDL1 checkpoint inhibitors on breast cancer. Only a small portion of patients benefited from these therapies. Here we systematically investigated the expression of 50 immune checkpoint genes, including ADORA2A, LAG-3, TIM-3, PD1, PDL1, PDL2, CTLA-4, IDO1, B7-H3, B7-H4, CD244, BTLA, TIGIT, CD80, CD86, VISTA, CD28, ICOS, ICOSLG, HVEM, CD160, LIGHT, CD137, CD137L, OX40, CD70, CD27, CD40, CD40LG, LGALS9, GITRL, CEACAM1, CD47, SIRPA, DNAM1, CD155, 2B4, CD48, TMIGD2, HHLA2, BTN2A1, DC-SIGN, BTN2A2, BTN3A1, BTNL3, BTNL9, CD96, TDO, CD200 and CD200R, in different subtypes of breast cancer and assessed their prognostic value. The results showed that the expression patterns of these 50 immune checkpoint genes were distinct in breast cancer. High expression of B7-H3 mRNA was significantly associated with worse overall survival (OS), especially in patients with luminal A and luminal B breast cancer. The mRNA expression levels of TIM-3, ADORA2A, LAG3, CD86, CD80, PD1 and IDO1 had no relationship with OS in breast cancer. High expression levels of CTLA-4 and TIGIT were correlated with favorable prognosis in breast cancer. Interestingly, we observed that B7-H3 expression was negatively correlated with the efficacy of cyclophosphamide (CTX). In summary, our study suggested that B7-H3 has potential prognostic value in breast cancer and is a promising target for immune therapy.