Harnessing Molecular Imaging for the Delineation of Sessile Serrated Adenomas

/ABSTRACT Colorectal cancer is the third most commonly diagnosed and third most deadly cancer in the United States. In 2023, for example, over 150,000 Americans were diagnosed with the disease, and over 50,000 succumbed to the malignancy. While colonoscopies are a powerful tool for the prevention and diagnosis of colon cancer, these exams typically rely upon white light visualization, which complicates the differentiation between healthy colonic epithelium, non-cancerous polyps, and precancerous adenomas. The visualization of one type of pre- cancerous lesion ¾ sessile serrated adenomas (SSAs) ¾ is particularly difficult, particularly in patients with colorectal comorbidities such as ulcerative colitis. Thus, the development of new approaches to the non-invasive identification of these lesions is an urgent clinical need. In this proposal, we describe the synthesis, characterization, in vitro validation, and in vivo evaluation of a fluorophore-labeled molecular imaging agent for non-invasive delineation of sessile serrated adenomas. The target for this probe is MUC5AC, a member of the mucin family of proteins that are found throughout the body and are typically involved in cell signaling or barrier protection. Critically, we have already validated the abundant expression of MUC5AC by sessile serrated adenomas and confirmed the concomitant lack of expression by healthy colonic epithelium using tissue isolated from patients and a MUC5AC-targeted mAb, RA96. In Specific Aim 1 (SA1) of this investigation, we plan to use a thiol-directed site-specific bioconjugation strategy to attach a fluorophore ¾ IR800CW ¾ to the MUC5AC-targeting mAb RA96; characterize this fluorescence immunoconjugate via gel electrophoresis, MALDI-ToF mass spectrometry, and surface plasmon resonance; and interrogate the specificity of the probes via the immunofluorescence staining of sessile serrated adenoma, hyperplastic polyp, colorectal carcinoma, and healthy colonic epithelium tissue samples collected from patients. Subsequently, in Specific Aim 2, we will use in vivo near-infrared fluorescence (NIRF) imaging and ex vivo biodistribution experiments to study the pharmacokinetic profile of RA96-IR800CW in healthy athymic nude mice, mice bearing orthotopic MUC5AC-expressing LS174T colorectal carcinoma xenografts, and a murine model of spontaneous sessile serrated adenoma formation. To the best of our knowledge, there are no extant molecular imaging agents that target sessile serrated adenomas, making the immunoconjugate described herein a first-in-class probe. In the short term, this work could produce imaging agents that could be useful tools for the preclinical study of pre-cancerous lesions within the colon. In the long term, this investigation could yield novel molecular imaging agents that could aid physicians in the identification of sessile serrated adenomas during coloscopies, thereby increasing the rate at which these lesions are safely resected and decreasing the overall incidence of colorectal carcinoma. Project Number: 1F31CA305957-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Cancer Institute (NCI) | Principal Investigator: Camilla Grimaldi | Institution: HUNTER COLLEGE, NEW YORK, NY | Award Amount: $35,814 | Activity Code: F31 | Study Section: Special Emphasis Panel[ZRG1 F10C-B (20)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11386116