Neoadjuvant SHR-A1811 Combined With Pertuzumab in HER2-Positive Breast Cancer: An Exploratory Clinical Study.

This is a multicenter, two-arm, exploratory clinical study designed to evaluate the efficacy and safety of a response-guided neoadjuvant treatment strategy in patients with HER2-positive early or locally advanced breast cancer.

Breast cancer is the most common malignancy in women worldwide, and HER2-positive disease accounts for approximately 15-20% of cases and is associated with aggressive tumor biology and a higher risk of recurrence. The introduction of HER2-targeted therapies, including trastuzumab and pertuzumab, has significantly improved patient outcomes. However, a proportion of patients exhibit suboptimal response to standard neoadjuvant therapy, highlighting the need for more effective treatment strategies.

In this study, approximately 100 eligible patients will be enrolled. All patients will initially receive 2 cycles of standard neoadjuvant therapy with trastuzumab, pertuzumab, and chemotherapy (THP or TCbHP). Tumor response will be assessed according to RECIST version 1.1 criteria. Patients with tumor reduction greater than 40% will continue the same regimen for an additional 4 cycles. Patients with tumor reduction of 40% or less will switch to an alternative regimen consisting of SHR-A1811, a novel HER2-targeted antibody-drug conjugate, in combination with pertuzumab for 4 cycles.

SHR-A1811 is an investigational HER2-targeted antibody-drug conjugate designed to deliver a cytotoxic payload directly to tumor cells, potentially overcoming resistance to prior HER2-targeted therapies. Emerging clinical data have demonstrated promising anti-tumor activity and manageable safety in HER2-positive breast cancer.

Clinical data, including baseline characteristics, imaging findings, and pathological markers such as Ki-67, will be collected throughout the study. Efficacy will be evaluated based on imaging assessments according to RECIST 1.1 criteria and pathological response at surgery, while safety will be monitored during treatment.

The primary objective of this study is to explore whether switching to SHR-A1811 in combination with pertuzumab in patients with suboptimal early response can improve pathological complete response (pCR) rates. Secondary objectives include evaluation of safety and tolerability of the treatment strategies.

This study aims to provide evidence for an individualized, response-adapted neoadjuvant treatment approach in HER2-positive breast cancer, and to optimize treatment outcomes for patients with inadequate response to standard therapy.