-Original-

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

Mio Yagi¹, Koji Nagata², Megumi Sano¹, Keiko Yanagihara¹, Ryuji Ohashi³ and Hiroyuki Takei⁴

¹Department of Breast Surgery and Oncology, Nippon Medical School Tama Nagayama Hospital, Tokyo, Japan
²Department of Diagnostic Pathology, Nippon Medical School Tama Nagayama Hospital, Tokyo, Japan
³Department of Integrated Diagnostic Pathology, Nippon Medical School, Tokyo, Japan
⁴Department of Breast Surgery and Oncology, Nippon Medical School Hospital, Tokyo, Japan

Background: 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.
Methods: We evaluated IMP3 expression in 40 female TNBC patients to assess its association with NAC sensitivity and outcome.
Results: 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.
Conclusions: 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.

J Nippon Med Sch 2025; 92: 44-51

Keywords
triple-negative breast cancer, neoadjuvant chemotherapy, IMP3, pathological complete response, prognosis

Correspondence to
Mio Yagi, Department of Breast Surgery and Oncology, Nippon Medical School Tama Nagayama Hospital, 1-7-1 Nagayama, Tama, Tokyo 206-0021, Japan
m-yagi@nms.ac.jp

Received, July 18, 2024
Accepted, September 30, 2024