This retrospective, single-center study evaluated the HER2DX genomic assay in 156 patients with stage I–III HER2-positive early breast cancer treated with dual HER2 blockade (trastuzumab + pertuzumab)-based neoadjuvant therapy between February 2015 and May 2022, examining associations with pathological complete response (pCR) and invasive disease-free survival (IDFS).
Overall pCR rate was 51.3% (n=156). Medium-high HER2DX pCR category had significantly higher pCR than the low category (OR 4.83, 95% CI 1.72–14.65; p=0.004). The continuous HER2DX risk score was independently associated with IDFS (HR 2.84, 95% CI 1.24–6.48; p=0.010). Hormone receptor-positive disease was strongly associated with lower pCR (OR 0.25, 95% CI 0.11–0.50; p<0.001) but better IDFS (HR 3.67 for HR-negative vs. HR-positive; p=0.004).
- Single-center, retrospective design with modest sample size (n=111 with HER2DX data), limiting generalizability. - HER2DX pCR score lost significance in multivariable analysis, suggesting possible confounding or limited independent predictive value in this cohort. - Median IDFS was not reached, making long-term survival conclusions preliminary.
The HER2DX risk score may help identify HER2-positive early breast cancer patients at higher risk of recurrence after dual HER2 blockade-based neoadjuvant therapy, supporting its potential role in treatment stratification. Clinicians should note that hormone receptor status remains a key modifier of both pCR and survival outcomes in this setting.
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