A novel xenograft model of gastrointestinal stromal tumors.

202 Background: GIST treatment with imatinib has served as the prototype for targeted molecular therapy. However, patients frequently acquire drug resistance to imatinib and this has prompted the development of additional multi-kinase inhibitors. To date, preclinical testing of novel agents has predominantly been performed using cell line based subcutaneous xenografts that may overestimate drug activity in the clinic. This suggests that novel in vivo models are needed to improve prediction of clinical efficacy. We hypothesized that human GISTs could be intra-peritoneally xenografted into immunodeficient mice in order to better recapitulate the microenvironment and biology of GIST. Methods: Tumor acquisition was performed under an IRB-approved protocol. Following tumor resection, we anesthetized NOD-scid (NS) or NS gamma (NSG) mice and performed a midline laparotomy. 2′2 mm tumor fragments were sutured into the abdominal viscera of NS (N=10) or NSG (N=15) mice. Tumors were imaged every 3-4 wks with ultraso...