Abstract 2602: Near-infrared light-triggered pyroptosis boosts anti-tumor immunity via a novel antibody-drug conjugate
Authors: Chen Fan , Tian Xue-Fei , Lu Ye , Guo Peng , Tan Wei-Hong 
Published: March 2024

Background: Cancer remains a significant health challenge, driving advancements in therapies. Despite progress in chemotherapy and radiotherapy, the quest for more precise, immunostimulatory interventions continues. Photodynamic therapy (PDT)/photothermal therapy (PTT) has utilized various photosensitizers to induce programmed cell death in tumors. The mechanism of action (MoA) solely relies on apoptosis. Among these, indocyanine green (ICG), a clinically approved photosensitizer, has shown efficacy in PDT/PTT. Meanwhile, pyroptosis, a newly discovered programmed cell death, holds promise in boosting anti-tumor immunity by generating pro-inflammatory factors. However, there remains a lack of therapeutic agents for facilitating precise and controllable pyroptosis of cancer cells.

Methods: In this study, ICAM1-ICG was developed as a novel near-infrared (NIR) pyroptosis agent for anaplastic thyroid carcinoma (ATC). The in vitro cytotoxicity on ATC cells under NIR light was determined by flow cytometry. Morphological changes were confirmed under both light microscopy and transmission electron microscopy (TEM). Western blot evaluated the impact of ICAM1-ICG under NIR light on pyroptosis-related proteins. Considering that the NIR radiation product of ICG is mainly reactive oxygen species (ROS), we next investigated the role of ROS in ICAM1-ICG-mediated pyroptosis using the ROS scavenger n-acetyl-l-cysteine (NAC). Anti-tumor activity and biosafety were determined using animal models with different immune backgrounds. In addition, we assessed its impact on the anti-tumor immune response through RNA-seq and evaluated the synergistic effect of NIR-pyroptosis and PD-1 combination therapy.

Results: ICAM1-ICG exhibits a NIR light dose-dependent cytotoxicity on ATC cells under a serial dose of NIR light irradiation, along with pyroptosis-like morphological changes that are directly visualized under both microscopy and TEM. Western blot further revealed that ICAM1-ICG can induce tumor-specific pyroptosis under NIR light, evidenced by NLRP1 activation, Caspase1 tetramer formation, and GSDMD cleavage, indicating that ICAM1-ICG induces tumor-specific pyroptosis under NIR light through a ROS/NLRP1/Caspase1/GSDMD signaling cascade by using NAC. Animal models’ dates validated the anti-tumor efficacy of NIR-pyroptosis and enhanced anti-tumor immune responses. Additionally, NIR-pyroptosis synergizes with PD-1 immunotherapy to boost anti-tumor immunity in naïve and immune-rechallenged tumor models.

Conclusions: Overall, we discovered that antibody-conjugated ICG can work as a novel tumor-specific NIR-pyroptosis agent and explored its potential in boosting anti-tumor immunity, providing a viable approach for the clinical translation of pyroptosis-based therapy.

Citation Format: Fan Chen, Xue-Fei Tian, Ye Lu, Peng Guo, Wei-Hong Tan. Near-infrared light-triggered pyroptosis boosts anti-tumor immunity via a novel antibody-drug conjugate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2602.