Comparison of a targeted anti-αvβ3 integrin NIR fluorescent probe and Indocyanin green for precision resection of naturally occurring soft tissue sarcomas in dogs and cats.

• Mirja Nolff
• Clinic of Small Animal Surgery, Vetsuisse Faculty Zürich, University of Zürich Winterthurerstrasse 260 8057 Zürich Zürich Switzerland

Soft Tissue Sarcomas (STS) represent a group of mesenchymal neoplasms with poorly defined tumor boundaries, marked local tissue invasion and moderate to low metastatic potential in dogs and cats. The mainstay of therapy is complete surgical resection and the most important prognostic factors for local recurrence and survival are completeness of resection, tumor size and tumor grade. As direct visualization of the tumor borders during surgery is currently impossible, the highly infiltrative growth of STS unfortunately leads to incomplete resections in up to 60% of dogs and cats. Near Infrared (NIR) imaging might be a tool to allow improved visualization of tumor margins during surgery to improve resection accuracy. A preliminary study at our institution demonstrated that the use of Angiostamp reduced R1 resection rate from 40 to 10%.. Unfortunately, targeted dyes are expensive and currently not available as a licensed drug. As we lack comparative studies that evaluate performance of different type of fluorophores for NIR tumor imaging, it is also not clear if they outperform untargeted fluorophores. The aim of this pilot study is to validate if the targeted dye Angiostamp^TM is superior to the untargeted indocyanine green (ICG) to guide sarcoma resection in cats and dogs with naturally occurring disease. Our hypothesis is that Angiostamp^TM will result in more specific tumor visualization compared to ICG, translating into improved resection outcomes.