2016 ACVIM Forum Research Abstract Program

Toceranib appears to be well-tolerated in feline patients with mast cell neoplasia. Biologic activity of this drug is evident in the studied cats, however further prospective studies are needed to fully elucidate its role in treatment of this condition. Gastrointestinal is the most common anatomical form of lymphoma in cats and systemic chemotherapy is indicated for the treatment. Although most of cats can achieve a complete remission with chemotherapy, relapse can occurs and may be associated to the multidrug resistance (MDR). Cell mechanisms of MDR include activation of transmembrane proteins, that reduce intracellular concentrations of different chemical compounds, and alterations in drug target. The main protein related to MDR phenotype is P-glycoprotein. Its overexpression results in reduced concentration of certain drugs within the cell, which is linked to the resistance. The aim of this study was to investigate P glycoprotein (P-gp) expression in cats with T-cell lymphocytic gastrointestinal lymphoma. Immunohistochemistry was performed in 40 samples using the monoclonal antibodies mouse anti-PAX-5 (PAX5-Invitrogen), polyclonal rabbit anti-CD3 (DAKO) and mouse anti-P-glycoprotein (clone C494-Enzo Life Sciences). P-gp immunoreactivity was analysed by degree of staining intensity, between 0 (no expression) to 3 (strong expression). Lymphoma was considered to be positive for P-gp when more than 10% of the neoplastic population expressed the protein. Three cats had a strong and 7 had a moderate expression, comprising 25% of the cases. The median of overall survival time was 24 months for these 10 cats; 60% had complete and 40% partial response to the treatment, and it was the same median observed for all cats studied. In conclusion, the expression of P-gp was observed in 25% of the cats with T-cell lymphocytic gastrointestinal lymphoma and this expression was not related to the treatment response or overall survival time. The purpose of this study was to describe initial experiences with a stereotactic radiation therapy (SRT) protocol (10 Gy x 3 daily fractions delivered with 6 MV photons via a linear accelerator) used as treatment for non-lymphomatous nasal tumors in dogs. A retrospective analysis of cases treated from August 2013 to October 2015 at NC State Veterinary Hospital was performed. Dogs were included if they had biopsy-confirmed nonlymphomatous nasal tumors. Dogs treated with chemotherapy were excluded. The gross tumor volume (GTV) was contoured using pre-and post-contrast 1-2 mm slice thickness CT image sets.