Impact of IMP3 Expression on Chemotherapy Response and Prognosis in Triple-Negative Breast Cancer: A Retrospective Cohort Study

Although advances in neoadjuvant chemotherapy (NAC) are improving the rate of pathological complete response (pCR) and outcomes for triple-negative breast cancer (TNBC) patients, the prognosis remains poor. Insulin-like growth factor II mRNA-binding protein 3 (IMP3) expression was recently reported to be associated with chemotherapy resistance and poor prognosis in TNBC. We evaluated IMP3 expression in 40 female TNBC patients to assess its association with NAC sensitivity and outcome. Among the cohort, 11 patients (27.5%) had IMP3-positive TNBC, which was associated with a higher Ki-67 labeling index (p = 0.119), indicating greater malignancy. However, IMP3 positivity showed no significant correlation with NAC resistance or differences in disease-free survival (DFS) as compared with IMP3-negative patients. Patients receiving effective immunotherapy or high-dose chemotherapy achieved pCR regardless of IMP3 status, which suggests that the NAC regimen is more important than IMP3 status for pCR. Even in IMP3-positive TNBC, NAC may improve prognosis by achieving pCR. Thus, while IMP3 might predict poor prognosis, it may not serve as a definitive marker in the context of NAC. Because IMP3 is involved in cancer stem cell (CSC) function, further research is necessary to understand its complex role in CSCs and TNBC.