Abstract 4166: TSPO-targeted near-infrared optical probe for early identification and localization of high-risk premalignant pancreatic lesions

Abstract

Abstract Background: Pancreatic cancer is the third most prevalent cause of cancer death in the U.S. with a ~10% survival rate. Surgery represents one of the best opportunities for extending survival and potential cures. Fluorescence-guided surgery (FGS) employing near-infrared (NIR) fluorescence-based targeting agents improves resection margins, allowing removal of small lesions not visible under white light. We previously reported a targeted NIR tracer (V-1520) of translocator protein (TSPO) expression that demonstrated proof-of-principle utility in high-grade pancreatic lesions arising in Ptf1a-Cre; LSL-KrasG12D/+; Smad4flox/flox (KCS) of pancreatic cancer. The purpose of the present study is to evaluate the utility of V-1520 to identify low-grade, premalignant yet high risk lesions in KCS mice; in this scenario we attempted to model use of V-1520 to remove lesions likely to manifest as future recurrence. We compared the uptake of the tracer in these mice from weaning to adulthood to systematically evaluate the efficacy of FGS as a function of lesion grade. Experimental: The tracer, V-1520, was synthesized and KCS mice were generated as reported.1 Mice were injected with 30μg of V-1520 intravenously 24 hours before imaging. Images were acquired using the 800nm channel. KCS and WT mice were imaged as a function of from 4 to 11 weeks age. After imaging, tumor tissues and major organs were harvested for ex-vivo imaging, histopathology and Cryo-Fluorescent Tomography (CFT). Summary: We found, V-1520 prominently localized in low-grade, premalignant PanIN cystic lesions with malignancy potential, as well as pancreatic tumors with and without local invasion. In contrast, V-1520 did not accumulate in healthy pancreata of KCS or WT mice. Mice as young as 4 weeks exhibited localized accumulation of the tracer with low grade PanIN and early dysplasia. The fluorescence intensity was further enhanced in mice with higher grade disease, whereby the pathology was characterized by high-grade cyst formation, increased nuclear/cytoplasm ratio, acinar to ductal metaplasia and invasion. Low and high-grade neoplasia was characterized by high TSPO immunoreactivity, consistent with in-vivo imaging. Confocal microscopy was used to colocalize V-1520 accumulation and TSPO immunoreactivity; V-1520 was found to prominently localized to premalignant epithelia pancreatic cancer cells. CFT illustrated that the primary localization of V-1520 included the liver, kidneys, and pancreatic diseases. Conclusion: These studies suggest the utility of V-1520 to identify high-risk pancreatic lesions that could be removed with surgery. Encouragingly, the V-1520 was capable of differentiating tumors from surrounding non-tumor tissue at an early stage, which could lead to better resections and delay and/or prevent recurrence in the future. 1. Clinical Cancer Research 26(22), 15 Nov. 2020 5914-5925 Citation Format: Shilpa Sharma, Denise Hernandez, Xiaoxia Wen, Jianbo Wang, Cong-Dat Pham, Beibei Huang, Henry Charles Manning. TSPO-targeted near-infrared optical probe for early identification and localization of high-risk premalignant pancreatic lesions [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 4166.