Jaklin, M. | Search bioRxiv

bioRxiv2021

Optimization of the TeraTox assay for preclinical teratogenicity assessment

Current animal-free methods to assess teratogenicity of drugs under development still deliver high numbers of false negatives, and more sensitive approaches of toxicity prediction are required. To address this issue, we characterized the TeraTox test, a newly developed multi-lineage differentiation assay for human teratogenicity prediction using 3D human induced pluripotent stem cells. TeraTox produces as primary output concentration-dependent data sets for each test compound on cytotoxicity and altered gene expression. These data are then fed into a prediction model based on an interpretable machine-learning approach. The final information obtained relates to the concentration-dependent human teratogenicity potential of drug candidates. We applied TeraTox to profile 33 approved pharmaceuticals and 12 proprietary drug candidates with known in vivo data. This way, it was possible to relate the test predictions to known human or animal toxicity. The TeraTox had an accuracy of 69% (specificity: 53%, sensitivity: 79%). It clearly performed better than two quantitative structure-activity relationship (QSAR) models and it had a higher sensitivity than the murine embryonic stem cell test (mEST) run in the same laboratory. By combining TeraTox and mEST data, the overall prediction accuracy was further improved. The knowledge on the pattern of altered gene expression may provide additional value in grouping toxicologically similar compounds and possibly deducing common modes of action. The assay will thus be a helpful additional tool in drug discovery, and the dataset provided here will be a valuable resource for the field of stem cell-based drug profiling.

pharmacology and toxicology↗

bioRxiv2021

In vitro teratogenicity testing using a 3D, embryo-like gastruloid system

Pharmaceuticals that are intended for use in patients of childbearing potential need to be tested for teratogenicity before marketing. Several pharmaceutical companies use animal-free in vitro models which allow a more rapid selection of lead compounds and contribute to 3Rs principles ( replace, reduce and refine) by streamlining the selection of promising compounds that are submitted to further regulatory studies in animals. Currently available in vitro models typically rely on adherent monolayer cultures or disorganized 3D structures, both of which lack the spatiotemporal and morphological context of the developing embryo. A newly developed 3D gastruloid model has the potential to achieve a more reliable prediction of teratogenicity by providing a robust recapitulation of gastrulation-like events alongside morphological coordination at relatively high-throughput. In this first proof-of-concept study, we used both mouse and human gastruloids to examine a panel of seven reference compounds, with associated in vivo data and known teratogenic risk, to quantitatively assess in vitro teratogenicity. We observed several gross morphological effects, including significantly reduced elongation or decreased size of the gastruloids, upon exposure to several of the reference compounds. We also observed aberrant gene expression using fluorescent reporters, including SOX2, BRA, and SOX17, suggestive of multi-lineage differentiation defects and disrupted axial patterning. Finally, we saw that gastruloids recapitulated some of the known in vivo species-specific susceptibilities between their mouse and human counterparts. We therefore suggest that gastruloids represent a powerful tool for teratogenicity assessment by enabling relevant physiological recapitulation of early embryonic development, demonstrating their use as a novel in vitro teratogenic model system.

pharmacology and toxicology↗