Clinical Evaluation of the HER2 Extracellular Domain in Breast Cancer Patients by Herceptin-Encapsulated Gold Nanocluster Probe-Based Electrochemiluminescence Immunoassay

The extracellular domain (ECD) of human epidermal growth factor receptor 2 (HER2) serves as a promising biomarker for the early diagnosis and treatment of breast cancer (BC). However, due to the heterogeneity of tumors, assessing HER2 status through a core needle biopsy presents significant challenges. In this study, we propose a facile and high-performance electrochemiluminescence immunoassay (ECLIA) platform utilizing a herceptin-encapsulated gold nanoclusters (HER-AuNCs)/(diisopropylamino)ethanol (DIPEA-OH) ECL system for the clinical evaluation of HER2 ECD in BC patients. The two-in-one HER-AuNCs ECL probes integrate the immunological recognition capabilities of HER with the ECL performance of AuNCs. Coupled with the low-potential and high ECL intensity of the HER-AuNCs/DIPEA-OH system, this ECL biosensing platform offers advantages in simplicity, high sensitivity, specificity, and sample saving. Consequently, the proposed ECLIA method enables ultrasensitive detection of HER2 in the range of 0.05-10 ng/mL with a detection limit of 11 pg/mL. Notably, the serum HER2 (sHER2) ECD ECLIA analytical strategy demonstrates strong correlation with tissue HER2 expression in clinical specimens. Furthermore, the sHER2 ECD ECLIA method effectively identifies individuals with HER2-negative status within the low HER2 expression population, thereby providing enhanced guidance for treatment decisions involving antibody-drug conjugates (ADC) in BC patients. Thus, the combined diagnostic approach proposed in this work accurately differentiates between HER2-positive, HER2-negative, and low-expression BC patients, facilitating informed, clinically personalized treatment decisions.