A Tandem‐Locked Fluorescent NETosis Reporter for the Prognosis Assessment of Cancer Immunotherapy

Abstract

NETosis, the peculiar type of neutrophil death, plays important roles in pro‐tumorigenic functions and inhibits cancer immunotherapy. Non‐invasive real‐time imaging is thus imperative for prognosis of cancer immunotherapy yet remains challenging. Herein, we report a Tandem‐locked NETosis Reporter 1 (TNR1) that activates fluorescence signals only in the presence of both neutrophil elastase (NE) and cathepsin G (CTSG) for the specific imaging of NETosis. In the aspect of molecular design, the sequence of biomarker‐specific tandem peptide blocks can largely affect the detection specificity towards NETosis. In live cell imaging, the tandem‐locked design allows TNR1 to differentiate NETosis from neutrophil activation, while single‐locked reporters fail to do so. The near‐infrared signals from activated TNR1 in tumor from living mice were consistent with the intratumoral NETosis levels from histological results. Moreover, the near‐infrared signals from activated TNR1 negatively correlated with tumor inhibition effect after immunotherapy, thereby providing prognosis for cancer immunotherapy. Thus, our study not only demonstrates the first sensitive optical reporter for noninvasive monitoring of NETosis levels and evaluation of cancer immunotherapeutic efficacy in tumor‐bearing living mice, but also proposes a generic approach for tandem‐locked probe design.

Bienzyme-Locked Activatable Fluorescent Probes for Specific Imaging of Tumor-Associated Mast Cells

“…The tandem-locked optical probes have been developed for real-time tracking and noninvasive interpretation of the profiles, distribution, and functions of immune cells in tumors during cancer immunotherapy. − It has been revealed that the immunotherapy efficacy varies with the infiltration of different immune cells, and detection of tumor-infiltrated immune cells could be applied for prognostic stratification and targeted therapy. , Mast cells, a prominent subset of tissue-resident immune cells, play a crucial role in allergic and other inflammatory diseases . However, their functions in modulation of the tumor immune microenvironment have been less understood.…”

Organic fluorophore-based fluorescent probes for abnormal immune response diagnosis and treatment evaluation

“…20,21 Therefore, a large number of smallmolecule fluorescent probes with distinct photophysical properties have been developed to date for in vivo study of the immune system. [22][23][24][25][26] Furthermore, researchers have also constructed some small-molecule fluorescent probes with excellent photodynamic and photothermal properties, which display great potential for the early diagnosis and intervention in immune abnormalities.…”