ABSTRACT SiNc-NP, an innovative tumor-specific nano medicine for treatment of canine cancers Canines are prone to the development of cutaneous/subcutaneous cancers with mast cell tumors (MCT) being the most common skin malignancy. Surgical resection is the conventional treatment for canine MCT, but tumor-positive resection margins remain a challenge; resulting in high tumor recurrence rates especially for high-grade MCT. What is needed is an effective intraoperative strategy that would not only aid the veterinary surgeon with margin delineation and metastatic lymph node detection, but also offer an adjuvant therapy that can be performed immediately following tumor resection to eliminate any residual cancer left in the surgical bed. Such an intraoperative strategy would improve long-term survival rates for dogs at a significant cost savings to pet owners by reducing the need for expensive follow-up procedures. Towards this goal, TheraFluor is focused on the development and commercialization of our patented tumor-activatable near infrared (NIR) theranostic nanomedicine. This smart “all-in-one” nanomedicine comprises imaging and therapeutic functions, which are integrated into a formulation based on a single agent, silicon naphthalocyanine (SiNc), encapsulated in biodegradable PEG-PCL (poly (ethylene glycol)-b-poly(ɛ-caprolactone)) nanoparticles (SiNc-NP). SiNc-NP offers a number of advantages over established NIR fluorescent imaging agents, including: low background because it fluoresces in the NIR and is formulated to remain “off” until it accumulates in tumor cells, it has enhanced photo-stability, no significant toxicity or phototoxicity, and possesses dual PT properties (photodynamic and photothermal therapies). The goal for this Phase I application is to determine the proper dose for SiNc-NP to target MCT both in the mouse syngeneic P815 mastocytoma tumor model and in canines. Furthermore, the efficacy of SiNc-enabled PT treatment will be tested in the mouse P815 model. The results of these Phase I studies will determine extended canine clinical studies, treatment paradigms, and toxicology assessments to pursue during Phase II with the goal of filing an Investigational New Animal Drug (INAD) with the FDA/CVM for the treatment of canine MCT.