Assembly of Nanocatalyst As a Noninvasive Tool for Breast Cancer Diagnosis and Immunotherapy Surveillance Designed by Visually Tracking Tumor-Derived Exosomal PD-L1

Immunotherapy has reshaped the therapeutic landscape of many advanced tumors; however, its effectiveness is seriously hampered due to the limitations of existing predictors and diagnostic tools. In response, we have fabricated a noninvasive tool for the diagnosis and immunotherapy surveillance of breast cancer (BC). The diagnostic tool functions by performing dual-aptamer-activated tandem assembly of a nanocatalyst for visually tracking tumor-derived exosomal programmed death-ligand 1 (PD-L1). By accurately identifying serum exosomal PD-L1 derived from BC, the diagnostic tool can rival immunohistochemistry (IHC) in the early classification of PD-L1-positive groups, PD-L1-negative groups, and healthy donors. Furthermore, real-time monitoring of the response to immunotherapy in 6 BC patients treated with anti-PD-L1 antibodies has been successfully achieved with the naked eye or a mobile phone camera by virtue of this diagnostic tool, which is highly consistent with computed tomography. Together, our work offers an unprecedented diagnostic tool for identifying potential beneficiaries and monitoring the response to immunotherapy, which highlights the significance of exosomal PD-L1 derived from tumors as a potential tumor prognostic and diagnostic factor including but not limited to BC.