Abstract 1090: Preclinical evaluation of combination therapy with dasatinib and sorafenib for the treatment of brain metastases

Brain metastases, the most common type of intracranial tumors in adults, carry a dismal prognosis with a median survival of less than 18 months regardless of primary status or treatment given. As part of an ongoing project, this study is concerned with the preclinical evaluation of targeted combination therapy for the treatment of brain metastases. The cell line used in this study was the H1915 (ATCC® CRL-5904 TM ) human lung cancer cell line, which was originally derived from a brain metastasis from primary lung adenocarcinoma. The cell line was stably transfected with a plasmid that allows expression of firefly luciferase (i.e., H1915-luc) so that the tumor growth in a mouse orthotopic model of brain metastases can be assessed in real time using the Xenogen in vivo bioluminescence imaging (BLI). Our previous study has demonstrated that the synergistic effect of combined dasatinib and sorafenib treatment was cell-line dependent. In this study, the cytotoxicity of dasatinib and sorafenib, when used alone or in combination at the fixed molar ratios of 3:1, 1:1 and 1:3 (dasatinib:sorafenib), was further examined in H1915-luc cells using the MTT assay. The results demonstrated that simultaneous and continuous exposure of H1915-luc cells to dasatinib and sorafenib at the fixed concentration ratio of 1:1 and 1:3 for 72 h showed synergism (the combination index value between 0.7 and 0.8) at effect levels of 40 and 80% inhibition of cell viability. For the in vivo study, an orthotopic mouse model of brain metastases was established by injecting H1915-luc cells into the right general carotid artery of individual athymic nude mice followed by permanent ligation. The preliminary study showed that following the intracarotid injection of H1915-luc cells, brain metastases were formed and readily to be detected by BLI. The obtained whole brain samples were fixed in OCT and stored at -80 o C. The brain sections are to be subjected to the immunofluorescence double staining of CD31 and firefly luciferase to assess the potential effect of the dasatinib-sorafenib combination on microscopic brain metastasis formation and progression and vessel co-option. Given the fact that brain metastases usually have a poor response to chemotherapeutic agents in part due to the presence of blood-brain barrier, a pharmacokinetic study is underway to characterize the distribution of sorafenib and dasatinib in normal brain tissues and brain metastases using the serial blood sampling and brain microdialysis technique. Overall, results from the in vitro cytotoxicity study demonstrated the synergistic effect of dasatinib and sorafenib on H1915-luc human lung cancer cells, providing a rationale for the in vivo evaluation the potential of this combination for the treatment of brain metastases from lung carcinomas. Citation Format: Qingyu Stephanie Zhou, Xiaofang Guo. Preclinical evaluation of combination therapy with dasatinib and sorafenib for the treatment of brain metastases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1090. doi:10.1158/1538-7445.AM2017-1090