Prognostic implications of HER2 changes after neoadjuvant chemotherapy in patients with HER2-zero and HER2-low breast cancer
Sora Kang, So Heun Lee, Hee Jin Lee, Hyehyun Jeong, Jae Ho Jeong, Jeong Eun Kim, Jin‐Hee Ahn, Kyung Hae Jung, Gyungyub Gong, Hak Hee Kim, Saebyeol Lee, Jongwon Lee, Sung‐Bae Kim
Abstract
BACKGROUND: The transition of human epidermal growth factor receptor 2 (HER2) status after neoadjuvant chemotherapy (NAC) in HER2-low breast cancer has not been thoroughly evaluated. Here, we evaluated the HER2 transition among HER2-zero and HER2-low breast cancer cases post-NAC and its impact on clinical outcomes. METHODS: We included 1288 patients with HER2-low or zero breast cancer who underwent NAC and surgery between 2014 and 2018 and had paired pre- and post-therapeutic HER2 status results. RESULTS: Among patients who were HER2-zero pre-NAC (n = 650), 68% and 29% were HER2-zero and HER2-low, respectively, post-NAC. Among patients who were HER2-low pre-NAC (n = 638), 32% of patients showed HER2 changes (low to zero), and 59% of patients had a constant HER2-low status post-NAC. Patients with constant HER2-low or transitions from HER2-low to zero had a higher proportion of hormone receptor positivity (84% and 79%) than those with changes from HER2-zero to low (77%) or with constant HER2-zero (56%), respectively. Multivariable logistic regression analysis revealed that patients with oestrogen receptor positivity had a higher probability of gaining HER2-low expression than those with oestrogen receptor negativity (odds ratio 2.48). No significant differences were observed in terms of overall survival or disease-free survival between patients with and without HER2-changes according to their hormone receptor status, except in the post-therapeutic HER2-low, hormone receptor-negativity subset. CONCLUSION: Temporal heterogeneity of HER2-low expression is observed in substantial numbers of post-NAC breast cancer patients. Clinical outcomes show no significant associations, except in the post-therapeutic HER2-low, hormone receptor negativity subset. The prognostic implications of HER2 transition in HER2-low breast cancer require further investigation.