Abstract 1121: Profiling patient-specific glioblastoma drug response in vitro using complex 3D microtumors
Authors: Smith Ashley M. , Millard Melissa , Holmes Lillia , Lewis Michael T. , Dobrolecki Lacey E. , Kanos Charles , Gardner Stephen , Hodge Philip , Nelson Fred , Lynn Michael , Edenfield Jeff , Corless Christopher , Schammel David , Crosswell Howland E. , DesRochers Teresa M. 
Published: August 2018

Glioblastoma (GBM) has a median survival of less than 2 years due to intra-tumoral heterogeneity, diffuse infiltrations of adjacent brain tissue, and a lack of effective therapies. Development of more efficacious therapies will require better GBM models for the testing and identification of novel agents. Towards this end, we have successfully developed a GBM 3D tissue model that can provide in vitro, patient-specific compound screening. Stable populations of glioma stem cells (GSC) from 24 of 41 patient samples have been successfully established and cultured long-term with minimal changes. To confirm stemness of the GSC population, we have successfully established a limiting-dilution series within SCID/Bg mice and characterized the resultant tumors. 4 of these lines have been used to establish patient-derived xenograft (PDX) models in mice. The original, primary patient tissue established GSC populations, and the resultant PDX tissues have been characterized by flow cytometry, IHC, RNA expression, NGS, and MGMT methylation status. With the goal of better modeling the patient tumor tissue in vitro, our GSC populations have also been used to establish complex microtumors within the KIYATEC 3DKUBE™ perfusion system, consisting of monoculture GSCs, GSCs co-cultured with human brain endothelial cells (HBECs), and GSCs co-cultured with HBECs and CD14+ peripheral blood mononuclear cells. Our monoculture microtumors consisting of only GSCs show a maintenance of GSC markers Nestin and Sox2 by both IHC and mRNA. Interestingly, when these cells are used to produce PDX, they up-regulate GFAP as a marker of differentiation that is not observed in the neurosphere or monoculture microtumor cultures. We have shown these 3D models to be viable for more than 1 month in perfusion and to be effective models for drug compound screening by dosing the microtumors on a weekly basis with temozolomide (TMZ). We have correlated TMZ response to MGMT methylation as reported both clinically and measured in vitro. Finally, In vitro drug response has been compared to both matched PDX in vivo drug response and the patient's clinical response to TMZ and MGMT methylation. Our data supports that this complex, 3D, patient-derived GBM model can be used to effectively screen, identify and characterize novel treatments of GBM.

Citation Format: Ashley M. Smith, Melissa Millard, Lillia Holmes, Michael T. Lewis, Lacey E. Dobrolecki, Charles Kanos, Stephen Gardner, Philip Hodge, Fred Nelson, Michael Lynn, Jeff Edenfield, Christopher Corless, David Schammel, Howland E. Crosswell, Teresa M. DesRochers. Profiling patient-specific glioblastoma drug response in vitro using complex 3D microtumors [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 1121.