Hazard Screening for Human Developmental Toxicity in the DevTox Germ Layer Reporter Assay

: Key provisions in TSCA legislation promote the use of non-animal, new approach methods (NAMs), to identify chemical risks to susceptible populations including infants, children, and pregnant women. Regulatory decisions regarding developmental toxicity currently rely on animal testing, but there is recognition that the reduction, refinement, and replacement of in vivo testing requires application of human cell-based NAMs to enhance throughput capabilities for data-poor chemicals, reduce the time and cost of testing, and improve hazard identification to protect human health. The objective of this product is to screen data-poor TSCA-relevant chemicals for potential developmental hazard using the stem cell-based DevTox Germ Layer Reporter (GLR) assay. The assay is an adaptation of the human pluripotent stem cell test (hPST) which is a rapid, high-throughput method that measures perturbations to mesendoderm differentiation to identify potential teratogens (doi:10.1093/toxsci/kft239). The DevTox GLR assay increases screening throughput, shortens the assay duration time, and expands the conceptual capability to identify perturbations across all three gastrulation germ layer lineages. Assay performance evaluation for the endoderm lineage of a benchmark training set of 66 chemicals yielded a balanced accuracy of 72% (79% sensitivity, 65% specificity). The impact should enable more robust assessment of potential human developmental toxicants and support Agency efforts to integrate NAMs into new chemical evaluations.