Optical Imaging of Bladder Cancer with Molecular Contrast Agents

Stanford University, Stanford CA

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Abstract

DESCRIPTION (provided by applicant): Our long-term objective is to improve the outcomes of patients with high-grade bladder cancer through better diagnostics based on optical imaging. Bladder cancer is the fifth most common cancer in the United States, with 70,980 new cases and 14,330 attributable deaths in 2009. In addition to the associated morbidity of surveillance and treatment, the enormous healthcare burden imposed by bladder cancer makes it the most expensive cancer to treat from diagnosis to death. The current standard for bladder cancer diagnosis relies on white light cystoscopy (WLC) and cystoscopic excisional biopsy for pathologic confirmation and local staging. The quality of optical imaging directly impacts the diagnosis, surveillance, surgery, and consequently the outcome of bladder cancer. WLC has suboptimal diagnostic accuracy for nonpapillary and flat cancerous tumors, which are challenging to differentiate from co-existing inflammatory lesions or scars from prior treatments. Notably, it is these tumors that are more likely to be high-grade, recurrence-prone, and progressive to muscle-invasive disease, which typically require removal of bladder (i.e. radical cystectomy). Our overall hypothesis is that real-time molecular imaging of bladder cancer will lead to improved diagnosis and therapy of high grade bladder cancer. By coupling cancer-specific molecular contrast agents with optical imaging tools, we aim to improve detection of high-grade bladder cancer at an early stage to effect better local cancer control and promote bladder sparing. Towards this goal, we have preliminarily: 1) performed the first clinical application of intravital microscopy in the bladder using confocal laser endomicroscopy; 2) applied phage display technology and whole organ biopanning to identify bladder cancer-binding peptides; and 3) identified CD47 as a promising therapeutic and imaging target for bladder cancer. We propose three specific aims: (1) identification and preliminary validation of peptides and CD47 antibody as bladder cancer-specific molecular contrast agents; (2) in vivo validation of the molecular contrast agents in a mouse orthotopic bladder cancer model using confocal laser endomicroscopy; and (3) ex vivo validation of the molecular contrast agents in intact human bladders using confocal laser endomicrocopy. To achieve these aims, we have assembled a multidisciplinary team with complementary expertise in bladder cancer, molecular imaging, small animal cancer models, and optical diagnostics. The team is consisted of an urologic surgeon-scientist, a cancer biologist and an urologic pathologist. We anticipate that at the conclusion of this highly translational project, we will have formed the necessary foundation to begin in vivo validation of these molecular contrast agents for application in human subjects.