Abstract LB-034: Development and characterization of PDX-derived 3D tumor microtissues as platform for screening targeted molecular therapeutics
Authors: Chiovaro Francesca , Agarkova Irina , Maier Armin , Messner Simon , Schueler Julia , Guye Patrick 
Published: August 2018

Abstract
Background A major issue for improving the overall success rate in drug development is the lack of accurate experimental human in-vitro models. While there is a significant and increasing need for such better ex-vivo cell-based models, the question on how closely these systems resemble and recapitulate the original tumors is of great importance. Patient-derived xenograft (PDX) models act as vehicle systems to propagate human tumor specimens, faithfully preserving the biological features and the genetic expression profile. The retainment of such criteria in in vitro 3D InSightTM Tumor Microtissues derived from PDX lines is crucial to provide a relevant physiological environment and strategy to assess candidate drugs for novel therapeutic approaches.
Aim Development and characterization of in vitro 3D InSightTM Tumor Microtissues from patient-derived xenograft models.
Material & Methods and Results PDX cell suspensions of Lung, Breast and Melanoma origin were successfully used to assess 3D aggregation in 96 well format and characterized over 10 days in culture. After careful removal of mouse cell contaminants in each in vitro 3D PDX sample, PDX cell cultures were supplied with exogenous normal human dermal fibroblasts (nHDF). The morphology, biomarker phenotype (IHC) as well as cell proliferation were assessed by histological analysis. In addition to screening for standard diagnostic marker such as proliferating vs. dead cells (e.g. Ki67, ClCasp3) and stromal vs. epithelial-tumor cells (e.g. FAP, pan-CK, E-Cadherin), we also assessed the expression of cancer type-specific biomarkers. Moreover, to monitor the dynamics of cancer phenotypic alterations, epithelial-to-mesenchymal transition (EMT) marker were evaluated and scored. Immunohistochemistry assessment of 3D microtumors validated the resemblance with their respective PDX tumor models. The viability and growth rate of PDX-derived microtumors were assessed by size analysis (cell scanner) and ATP assay. 3D tumor growth rate and cell behavior observations reflected the diversity of disease progression in vivo. Further efforts will focus on employing this platform to investigate the efficacy of specific targeted therapies based on the distinct molecular signatures of PDX tumor models.
Conclusion Development and characterization of In vitro 3D InSightTM Tumor Microtissues from patient-derived xenograft (PDX) lines demonstrated that the morphological and molecular features of the parental tumors are well retained. We suggest that in vitro 3D PDX models offer a more suitable and robust approach to expedite faithful efficacy assessment and approval of optimal drug candidates.
Citation Format: Francesca Chiovaro, Irina Agarkova, Armin Maier, Simon Messner, Julia Schueler, Patrick Guye. Development and characterization of PDX-derived 3D tumor microtissues as platform for screening targeted molecular therapeutics [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 LB-034.