A Novel Biological Index for Predicting Neoadjuvant Treatment Response in HER2-Positive Breast Cancer: The...

Objective: To evaluate the Tumor-Immune-Proliferation-Inflammation (TIPI) score as a composite biomarker for predicting pathological complete response (pCR) in human epidermal growth factor receptor 2 (HER2)-positive breast cancer treated with neoadjuvant therapy. Methods: This retrospective single-center study included 75 patients with HER2-positive invasive breast cancer treated with neoadjuvant chemotherapy plus dual anti-HER2 blockade (trastuzumab and pertuzumab). The association between the TIPI score and pCR was assessed using receiver operating characteristic (ROC) analysis and logistic regression. Results: pCR was achieved in 34 patients (45.3%). The optimal TIPI cut-off was 11.41. Patients with high TIPI scores had a higher pCR rate than those with low TIPI scores (56.3% vs. 25.9%, p = 0.016). However, the discriminative performance of the score was modest (AUC 0.598, 95% CI: 0.467-0.730; p = 0.145). In the adjusted analysis, hormone receptor negativity remained the most consistent factor associated with pCR. Conclusions: The TIPI score was developed as a preliminary composite model integrating selected tumor- and host-related biological variables and showed an exploratory association with pCR in this single-center HER2-positive cohort. Given the modest discriminative performance and lack of external validation, these findings should be interpreted cautiously. Further validation in larger independent cohorts is required before the score can be considered for clinical stratification or implementation.