LAUSR

Histiocytic sarcoma (HS) is an orphan hematological malignancy with an incidence of less than 1% of all non-Hodgkin9s lymphoma, affecting both children and adults. It is a highly metastatic disease, and can affect any organ in the body including spleen, lungs, bone marrow, liver and lymph nodes. It is associated with a poor prognosis as treatment options are scarce and responses are short lived. Dogs spontaneously develop a similar form of HS with an appreciable frequency, and therefore present a unique translational model to investigate better treatments. Preliminary data from in vitro studies identified dasatinib, a multi tyrosine kinase inhibitor, as a highly potent drug against HS cell lines derived from tumors in dogs, but non-toxic to normal normal tissue surrogate fibroblasts. The current study was undertaken to evaluate if the efficacy of dasatinib could be re-capitulated in an in vivo orthotopic xenograft model of HS. The mouse model was generated in NOD-SCID mice by surgical injection of HS cells, transfected with a luciferase reporter construct, into their spleen. Tumor growth was monitored using In Vivo Imaging System. Mice were treated with 30 mg/kg of dasatinib intraperitoneally once a day or vehicle control, with five mice in each group. Dasatinib treated mice had a significantly decreased tumor growth rate in comparison to untreated mice. Most importantly, treatment with dasatinib significantly increased their survival time. All mice from the vehicle control group reached humane endpoints for euthanasia by day 27, while treated mice were clinically stable at day 53, with the difference in survival being highly significant (p Citation Format: Marilia Takada, Lauren Smyth, Vilma Yuzbasiyan-Gurkan. Dasatinib displays antitumor efficacy in an orthotopic xenograft mouse model of histiocytic sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2166.