Evaluation of therapeutic target gene expression based on residual cancer burden classification after neoadjuvant chemotherapy for HER2-negative breast cancer

Abstract Purpose Patients with residual diseases (RD) usually have poor prognoses after neoadjuvant chemotherapy for breast cancer. The aim of this study was to explore therapeutic targets and potential additional adjuvant treatments for patients with RD after standard neoadjuvant chemotherapy. Materials and Methods We retrieved publicly available cDNA microarray data from 399 human epidermal growth factor 2 negative primary breast cancer samples from patients undergone standard neoadjuvant chemotherapy. We analyzed the mRNA expression levels of key breast cancer markers and therapeutic target genes based on residual cancer burden (RCB) classification: RCB-0/I, RCB-II, and RCB-III. Results Among hormone receptor (HR) -positive samples, there were more luminal A tumors by PAM50 in RCB-III than in RCB-0/I and RCB-II (P Conclusion In HR-positive breast cancer, biological features such as luminal A were associated with RCB; this trend was not observed in TN breast cancer. Further, some targeted therapies should be tested as new strategies after standard neoadjuvant chemotherapy in future clinical trials.