Abstract A84: Stereotactic injections of primary medulloblastomas as a representative model of the different subgroups for preclinical drug screening

Established tumor cell lines are extensively used for screening of novel therapeutic compounds. However, during long-term culturing cells adjust to the conditions and acquire additional genetic aberrations, which may cause them to differ significantly from the original tumor. In vitro conditions may also fail to recapitulate aspects of the tumor microenvironment that may have an impact on cell fate, for example, drug clearance by the circulation, which would lead to renewed cell cycling and the heterogeneity of the tumor cell population versus the homogenous population of cells in culture. Predisposed genetic mouse models more closely recapitulate most aspects of human disease but they usually require complex breeding schemes and may suffer from incomplete tumor penetrance and a variable age of tumor onset. In order to establish a new medulloblastoma model for therapeutic studies, we have acquired primary cultures of medulloblastoma tumors representing the four different subtypes of medulloblastomas (Wnt, Shh, group 3 and group 4). Cells were grown as neurospheres and characterized regarding stem cell markers and immunological status. Early passages were collected and for each primary line, two NOD scid mice were orthotopically injected with 20.000 and 200.000 cells, respectively. Mice were closely monitored for symptoms of brain tumor burden (weight loss, hunched posture, uncoordinated movement, lethargy, poor balance and/or paralysis) during six months. Mice injected with cells from the SHH subgroup and group 3 medulloblastomas developed symptoms of brain tumors with a latency of 13-25 weeks. A positive correlation was observed between tumor latency and number of injected cells. Brains were collected and processed for histopathological confirmation of tumor prevalence, whole genome sequencing and gene expression analysis. Neurosphere cultures were also re-established to create a reproducible model for pre-clinical therapeutic trials on human medulloblastoma by serial orthotopic transplantation. Citation Format: Cecilia Krona, Cecilia Dyberg, Emma Sanden, Anna Darabi, Malin Wickstrom, Paul Northcott, John Inge Johnsen, Peter Siesjo. Stereotactic injections of primary medulloblastomas as a representative model of the different subgroups for preclinical drug screening. [abstract]. In: Proceedings of the AACR Special Conference on Pediatric Cancer at the Crossroads: Translating Discovery into Improved Outcomes; Nov 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;74(20 Suppl):Abstract nr A84.