LAUSR

Introduction In vitro cell based drug testing tools have been widely used in drug discovery and early development to evaluate novel drug entities for further evaluation in preclinical in vivo models. However, the question on how closely these systems resemble and recapitulate the original tumours has prompted researchers and clinical oncologists to seek complementary in vitro strategies. Patient-derived xenograft (PDX) mouse models are a widely accepted tool for propagation of primary human tumour specimens, faithfully preserving the biological features and the genetic expression profiles. In order to increase accessibility of these physiological relevant tumour surrogates in drug development, we investigated whether ex-vivo culturing of PDX-derived tumours as 3D Microtissues retain the in-vivotumour characteristics. The resulting 3D PDX Tumour Microtissues will increase throughput and compatibility with existing platforms while reducing costs and animal testing. Material and methods To this end, PDX cell suspensions of Lung, Breast and Melanoma origin were used to aggregated in Akura 96 plates and characterised over 10 days in culture. The 3D tumour microtissues were monitored for growth characteristics, phenotype, cancer biomarkers and drug efficacy. In addition to screening for standard diagnostic marker for proliferating (Ki67), apoptotic cells (cleaved Caspase 3), stromal (FAP) and epithelial-tumour cells (pan-CK, E-Cadherin), we also assessed the expression of cancer type specific biomarkers. Immunohistochemistry assessment of 3D tumour microtissues demonstrated the resemblance with the respective in-vivo PDX tumour model. The viability and growth rate of PDX-derived tumour microtissues was assessed by size analysis and ATP assay. 3D tumour growth rate reflected the diversity of tumour growth progression in vivo. Subsequently, these tumour microtissues were assessed using either non-specific cytotoxic drugs or molecular-targeted drug therapy in a single agent treatment regimen. The efficacy of specific targeted therapies was based on the distinct molecular signatures of PDX tumour models. Results and discussions In conclusion, in vitro 3D InSight Tumour Microtissues from patient-derived xenograft (PDX) lines demonstrated retention of morphological and molecular features of the parental tumours. Conclusion We suggest that 3D PDX Tumour Microtissues are physiological relevant and higher throughput compatible in vitro models for efficacy assessment and drug candidate screenings.