Identifying Predictors of Pathological Complete Response in Moroccan Patients With HER2-Positive Breast Cancer
Boutaina Atmane1, Jihad El Afeya1, Safae Toumi1
1Department of Medical Oncology, Institut National d'Oncologie, Mohammed V University, Rabat, MAR.
Abstract:
Background The prognosis of human epidermal growth factor receptor 2 (HER2)-positive breast cancer has significantly improved with the use of neoadjuvant chemotherapy combined with anti-HER2 therapy. Achieving pathological complete response (pCR) is commonly associated with favorable long-term outcomes. However, real-world data on predictive factors influencing pCR remain limited, particularly in Morocco and North Africa, where evidence is scarce. Generating region-specific evidence is therefore essential to complement findings from other populations. This study aimed to assess pCR rates and identify predictors of response in Moroccan patients with HER2-positive breast cancer treated with neoadjuvant systemic therapy. Methods We retrospectively included 203 patients with stage I-III HER2-positive breast cancer treated with neoadjuvant chemotherapy plus trastuzumab, with or without pertuzumab, followed by surgery between October 2019 and April 2023. Predictors of pCR were assessed using logistic regression. Disease-free survival (DFS) was compared between patients achieving pCR and those without pCR using Cox proportional hazards regression analysis. Results Among 203 patients, 44.3% achieved pCR. Higher pCR rates were independently associated with hormone receptor-negative tumors (odds ratio (OR) = 2.20, 95% confidence interval (CI): 1.08-4.47), HER2 (score 3) status (OR = 4.80, 95% CI: 1.73-13.30), and the use of dual HER2 blockade (OR = 2.05, 95% CI: 1.03-4.07) compared with triple-positive tumors and HER2 (score 2) fluorescence in situ hybridization (FISH)-amplified tumors treated with trastuzumab alone. In contrast, lower pCR rates were observed in T3-T4 tumors (OR = 0.45, 95% CI: 0.23-0.92). After a median follow-up of 51.3 months, achieving pCR was significantly associated with improved DFS (HR = 0.07, 95% CI: 0.02-0.28; p < 0.001). Conclusions Tumor stage, hormone receptor status, HER2 expression, and neoadjuvant pertuzumab use were independently associated with pCR, emphasizing the importance of tailored neoadjuvant strategies in HER2-positive breast cancer.
