Novel Tools for Colon Cancer Detection and Therapy

Colorectal cancer (CRC) is the third major cancer in the USA and accounts for 9.5% of all the cancers among the Veterans. Polypectomy during screening colonoscopy has significantly reduced both the CRC incidence and associated patient mortality. However, despite the significant progress, the CRC risk reduction remains suboptimal and specifically worse in relation to CRC arising in the right colon. Although quality metrics in endoscopy have focused on improving detection of standard adenomas, there is a lack of concordance between the conventional adenoma detection rate and ability to visualize sessile serrated polyps underscoring the need for adjuvant approaches. Also, despite high R0 resection rates in patients with CRC, local and distant recurrence is still a significant problem and has been cited as high as 40%. The complete resection of tumor is critical to patient outcomes. We and others have shown that Claudin-1(CLDN-1), a tight junction (TJ) protein, expression increases in colorectal cancer (CRC) in stage specific manner, and is highly upregulated during colon cancer progression and metastasis. Several studies have further validated a causal role of Claudin-1 colon cancer progression and metastasis in vitro and in vivo. In brief, CLDN1 expression increases in a stage specific manner and an upregulated CLDN1 expression characterizes both, pre-malignant SSA/P adenomas and CRC metastasis. Notably, in our study, 8 out of 9 metastatic patients derived orthotopic xenografts (PDOX) demonstrated high CLDN1 expression. We further demonstrated that using antibody-guided imaging anti-CLDN1 antibodies conjugated to NIR fluorophores clearly labeled tumor and liver metastases enabling successful fluorescence-guided surgery (FGS). Similar ability of CLDN1 fluorescent peptides for detection of CRC adenomas was reported by another lab. Taken together, we hypothesize that intraoperative use of CLDN-1-targeted near- Infrared fluorescent (NIRF) imaging probes will improve the detection of high-risk pre-malignant adenomas and CRC metastasis, and also improve their resection. To this hypothesis, we propose following specific studies: SPECIFIC AIM 1: To synthesize, characterize, and perform the pre- clinical safety evaluation of CLDN-1 antibodies-conjugated to NIR fluorophores. The antibody-dye conjugate ratio providing maximum tumor signal, minimum short and long-term tissue retention, and lowest toxicity will be established for pre-clinical studies. SPECIFIC AIM 2: Assessment of the pre-clinical and clinical efficacy of CLDN-1-targeted imaging probes in polyps and CRC metastasis. The clinical-guiding efficacy of CLDN-1-NIRF probes will also be validated in surgical samples from adenomas and metastatic tumor tissues using ex vivo imaging of patient tissues. Characterization of the key molecules involved in the processes critical for CRC progression to develop novel early detection and therapeutic approaches would not only decrease patient mortality among VA-CRC patients but will also help reduce associated financial burden for the Veterans Administration. The outcome from the preclinical studies using the imaging technology for accurate detection/resection of premalignant polyps and CRC will strongly impact the management of CRC patients. Successful accomplishment of the study goals will pave the path for a Phase-I clinical trial for urgently needed novel imaging probes for improved detection, resection, and management of the CRC and its high-risk precursor lesions.