Abstract 4118: Near infrared photoimmunotherapy for lung metastases

Abstract

Abstract Introduction and Purpose Lung metastases are a leading cause of cancer related deaths. Current therapies include surgery, chemotherapy and radiotherapy but cause considerable side effects in the remaining normal lung, chest wall and heart. Therefore, a new-targeted therapy for lung metastases that results in minimal damage to adjacent structures, yet effectively treats lung metastases, is needed. Since one interesting property of the lung is that it transmits light better than other organs, light therapy is a viable alternative therapy. Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of intravenously injected antibodies that target tumors with the toxicity induced by photosensitizers activated by NIR light. Herein, we demonstrate the efficacy of NIR-PIT in a mouse model of lung metastases. Experimental Design In vitro and in vivo experiments were conducted with a HER2, luciferase and GFP expressing cell line (3T3/HER2-luc-GFP). An antibody-photosensitizer conjugate (APC) consisting of trastuzumab and a phthalocyanine dye, IRDye-700DX, was synthesized. In vitro NIR-PIT cytotoxicity was assessed with dead staining, luciferase activity, and GFP fluorescence intensity. In vivo NIR-PIT was performed in a mouse model of lung metastases as well as a flank model, and assessed by tumor volume and/or bioluminescence (BLI). Results In vitro NIR-PIT-induced cytotoxicity was light dose dependent. In vivo anti-tumor effects of NIR-PIT included significant reductions in both tumor volume (p = 0.0141 vs. APC) and BLI (p = 0.0086 vs. APC) in the flank model, and prolonged survival (p < 0.0001). BLI demonstrated a significant reduction in lung metastases volume (p = 0.0117 vs. APC). Multiple NIR-PIT doses significantly prolonged survival in the lung metastases model (p < 0.0001). Conclusions NIR-PIT prolonged survival suggesting that NIR-PIT is a potential new therapy for the local control of lung metastases. Citation Format: Kazuhide Sato, Tadanobu Nagaya, Peter L. Choyke, Hisataka Kobayashi. Near infrared photoimmunotherapy for lung metastases. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4118. doi:10.1158/1538-7445.AM2015-4118