Predicting the response of neoadjuvant chemotherapy in hormone receptor- positive and HER2-negative breast cancer with axillary lymph node metastasis by a multigene assay (GenesWell™ BCT)

The GenesWell™ BCT (BCT score) is a recently developed multigene assay that predicts the risk of distant recurrence in patients with hormone receptor-positive (HR+) and HER2 negative (HER2-) early breast cancer (BC). The ability of the assay to predict the response to neoadjuvant chemotherapy (NACT) has not been established to date. Biopsy specimens of HR+/HER2- BC patients with axillary lymph node (LN) metastasis who underwent NACT were analyzed using the BCT score. The modified breast cancer test (BCT) score was developed and classified into high-and low-response groups. A total of 88 patients were available for the BCT score among 108 eligible patients. The median follow-up duration was 35.9 (7.8-128.5) months. Among these, 61 (65.1%) had cN1 and 53 (60.2%) had cT1 or T2. The BCT score was low in 25 (28.4%) patients and high in 63 (71.6%) patients. Among 50 patients with pathologic complete response or partial response, 41 (82.0%) were in the high-response group, and 9 (18.0%) were in the low-response group. Among 38 patients with stable disease or progressive disease, 22 (57.9%) patients were in the high-response group, and 16 (42.1%) were in the low-response group (p = 0.025). Ki-67 before NACT was a significant factor for predicting tumor response (p = 0.006; 3.81 [1.50-10.16]). The BCT score showed a significant response to NACT (p = 0.016; 4.18 [1.34–14.28]). A significant difference was found in distant metastasis-free survival between the high and low response groups (p = 0.004). We demonstrated that the BCT score predicts NACT responsiveness of HR+/HER2- BC with LN metastasis and might help determine whether to undergo NACT or not. Further studies are warranted to validate these findings.