Abstract
Abstract Introduction and Objectives: Current diagnosis of bladder cancer is by white light cystoscopy, which has suboptimal specificity for differentiating non-papillary cancer from inflammation. Probe-based confocal laser endomicroscopy (pCLE) provides dynamic in vivo imaging of the endoluminal tracts with micron-scale resolution. Real-time analysis of confocal images remains challenging with non-specific contrast agents such as intravesical fluorescein. Tumor imaging specificity may be enhanced by coupling pCLE with fluorescently labeled tumor-specific antibodies or peptides. We report our preliminarily efforts of ex vivo bladder tumor imaging by pCLE using a mouse antibody against a known human tumor-specific surface biomarker and a dodecapeptide that binds human epidermal growth factor receptor (EGFR) as contrast. Studies have shown that both the antibody and peptide bind surface markers abundant in cancer but not present on the superficial layer of normal urothelium. METHODS: The antibody or peptide was instilled intravesically into a fresh cystectomy specimen (n=4 for antibody; n=1 for peptide). Excess antibody or peptide was drained, and the bladder was opened for pCLE. Imaging was performed of normal-appearing, tumor, and suspicious areas, followed by excision of imaged tissues for histopathology with H&E. Tumor-specific staining of the antibody was further confirmed with anti-mouse IgG. RESULTS: All bladders had high-grade urothelial carcinoma on pathology. The tumor-specific antibody consistently showed greater fluorescent staining on pCLE in areas of tumor, compared to normal urothelium, in all 4 bladders. A suspicious area was not stained by the antibody and was confirmed to be inflammation by pathology. Immunostaining showed tumor-specific antibody on the most superficial layer of tumor but not on normal urothelium. Similarly, preferential staining of tumor over normal urothelium was also observed when using the EGFR peptide as a contrast agent. CONCLUSIONS: Both the known tumor-specific antibody and EGFR-specific peptide show specificity for bladder cancer by pCLE ex vivo. Our study shows the feasibility of optical imaging of bladder cancer with pCLE and tumor-specific contrast agents. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4146. doi:10.1158/1538-7445.AM2011-4146
Published Version
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