e12566 Background: The adhesion molecule CD44 is expressed in cancer stem-like cells (CSCs). CD44 variant 9 (CD44v9), a splicing variant of CD44, has emerged as a novel marker of cancer stemness. CD44v9 was reported to be associated with the resistance to chemotherapy in several malignancies. We recently reported that the high expression of CD44v9 is associated with the poor prognosis of the patients with triple negative breast cancer (TNBC), who received neoadjuvant chemotherapy (NAC). In this study, we investigated the clinical impact of the expression of CD44v9 in early TNBC who underwent surgery without NAC. Methods: Among 2257 primary breast cancer patients at clinical stage I-III who underwent surgery without NAC form 2002 to 2015, 201 patients with TNBC were included in this study. The expression of CD44v9 was analyzed immunohistochemistry (IHC). The associations between the CD44v9 expression and the clinicopathological characteristics and the prognosis were investigated. The tumors with the positive staining in more than two third of the cancer cells were regarded to be high expression of CD44v9. Results: CD44v9 high expression was observed in 62 cases (30.8%) and the low expression was in 139 cases (69.2%). Many of the CD44v9 high tumors were low grade than the tumors with low CD44v9. There were no significant associations between the expression levels of CD44v9 and the tumor size, lymph node metastasis and the pathological stage (pStage). There were no differences in the prognosis between the high and low CD44v9 expression in pStage I. However, in the patients with the tumors with pT1c or more (pT2, pT3) and the patients with pStage 2 and more, the high CD44v9 expression was significantly associated with the poor prognosis in terms of distant recurrence-free survival (DRFS) and overall survival (OS). In addition, high CD44v9 was associated with significantly shorter survival after recurrence. Many of these patients received various chemotherapy in the adjuvant setting and after recurrence. Therefore, CD44v9 high expression is considered to be associated with the poor prognosis due to the resistance to various chemotherapeutic agents. Conclusions: The prognosis of the TNBC patients with the high expression of CD44v9 is poor, which might be induced by the resistance to various chemotherapeutic agents. These results suggest that CD44v9 might be a novel therapeutic target for TNBC.
High expression of UBD correlates with epirubicin resistance and indicates poor prognosis in triple-negative breast cancer