Precision Delineation of Surgical Margins across Breast Cancer Subtypes with a Novel KIAA1363-Targeted NIR Fluorescent Probe

Surgical resection remains the first-line treatment for breast cancer, underscoring the need for precision tools for intraoperative margin delineation. Due to high heterogeneity, accurate identification of tumor margins poses a significant challenge in breast cancer. Herein, we report a rapid-clearance near-infrared fluorescent probe, Cy-JW (λ_ab = 775 nm, λ_em = 808 nm, compatible with current clinical intraoperative fluorescence imaging devices), which can target the tumor-overexpressed enzyme KIAA1363. Cy-JW exhibited high aqueous solubility and potent affinity for KIAA1363 (IC₅₀ = 36.90 nM) and enabled clear visualization in three representative breast cancer cell lines. In mouse xenograft models, both intratumoral and intravenous administration yielded high tumor-to-background ratios (TBR > 5), supporting complete and precise tumor resection. Biodistribution and safety evaluations indicated rapid plasma clearance (<i>t</i>_1/2 < 0.5 h) and predominant renal excretion within 48 h, suggesting a favorable safety profile with a reduced risk of systemic toxicity. Furthermore, preclinical assessment of freshly resected specimens from breast cancer patients (across three subtypes) using a clinical fluorescence imaging device showed strong agreement between fluorescence-guided demarcation and histopathological analysis. Collectively, these results establish Cy-JW as a promising agent for fluorescence-guided surgery (FGS) applications across diverse breast cancer subtypes.