Hormone Receptor Status as a Predictive Factor for Pathological Complete Response to Neoadjuvant Dual HER2 Blockade...

Area of Science:

• Oncology
• Medical Research
• Clinical Trials

Background:

• Neoadjuvant dual human epidermal growth factor receptor 2 (HER2) blockade with trastuzumab, pertuzumab, and chemotherapy is standard for locally advanced HER2-positive breast cancer.
• Patient responses to this therapy vary, with hormone receptor (HR) status being a key differentiator.

Purpose of the Study:

• To evaluate the predictive value of HR status for achieving pathological complete response (pCR) in patients undergoing neoadjuvant dual HER2 blockade.
• To identify predictors of pCR and assess event-free survival (EFS) based on HR status.

Main Methods:

• Retrospective cohort study of 293 patients with stage II-III HER2-positive breast cancer treated between January 2018 and December 2022.
• Primary endpoint: pCR rate (ypT0/is ypN0). Secondary endpoints: breast conservation surgery (BCS) rate, objective response rate, safety, and EFS.
• Multivariate logistic regression and Kaplan-Meier analyses were used to identify predictors of pCR and analyze EFS.

Main Results:

• The overall pCR rate was 48.1%. Hormone receptor-negative (HR-) patients had a significantly higher pCR rate (65.0%) compared to HR-positive (HR+) patients (35.9%; p < 0.001).
• Independent predictors of pCR included HR- status (OR = 3.10), Ki-67 index >20% (OR = 2.01), and negative nodal status (OR = 1.85).
• The HR- group showed a trend toward better EFS (p = 0.043) at a median follow-up of 36 months.

Conclusions:

• HR status is a significant independent predictor of pCR in HER2-positive breast cancer treated with neoadjuvant dual blockade.
• HR-negative disease is associated with superior response rates and a trend towards better EFS.
• Tailored therapeutic strategies are needed to optimize outcomes for the HR+ subgroup.