Intraoperative Guidance of Pancreatic Cancer Resection Using a Toll-like Receptor 2-Targeted Fluorescence Molecular Imaging Agent

To increase the achievement of negative R0 surgical margins and increase the low survival rates of pancreatic cancer, improvements in assessing tumor margins during surgical resections are needed. This can be accomplished by using pancreatic cancer-targeted fluorescence molecular imaging agents to intraoperatively detect tumor margins in real time. Because Toll-like receptor 2 (TLR2) is broadly expressed among many cancer types including pancreatic adenocarcinomas, a high-affinity TLR2-targeted fluorescence molecular imaging agent (TLR2L-800) was developed. We investigate the potential for increased survival by employing real-time intraoperative tumor detection in a preclinical orthotopic human pancreatic xenograft tumor model using TLR2L-800. Three cohorts of nude mice bearing orthotopic human pancreatic xenograft tumors were intravenously injected with TLR2L-800. At 24 hours postinjection, one cohort underwent in vivo fluorescence-guided surgical removal of tumors using a real-time fluorescence imaging platform, a second cohort underwent visible light surgery (VLS), and a third cohort did not undergo surgery. A fourth, nontumor-bearing cohort was administered TLR2L-800 with no surgery. At 41 days postsurgery, the survival rates were 53% for the fluorescence-guided surgery (FGS) group and 0% for both the VLS and the tumor-bearing no-surgery group. The overall 200-day survival rate of 35% for the FGS group was significant compared with 0% for the VLS group (P value = 0.0018). This study demonstrates the potential of increasing disease-free survival for patients with pancreatic cancer by increasing the attainment of R0 margins using a novel tumor-targeted lipopeptide ligand-based fluorescence molecular imaging agent, TLR2L-800, during real-time FGS.

Significance: Human TLR2 is broadly expressed among pancreatic adenocarcinomas, and the highly specific TLR2L-800 fluorescence molecular imaging agent has potential for use in fluorescence-guided surgery to increase R0 margins and improve patient survival.