Developmental and Reproductive Toxicology (DART) Committee
Developmental and Reproductive Toxicology (DART) Committee
The DART committee provides a forum where scientists from industry, government and academia can exchange information and initiate activities to advance science related to DART, and to develop consensus on the appropriate use of experimental data for human health risk assessment.
Thyroid hormone assessment survey and historical control data collection
The Health and Environmental Sciences Institute (HESI) Developmental and Reproductive Toxicology (DART) Technical Committee Thyroid Hormone Workgroup, in collaboration with the European Teratology Society (ETS) Thyroid Hormone Task Force, has initiated a comprehensive effort to survey and collect historical data for thyroid hormones measurements from nonclinical studies. Regulatory test guideline requirements for the measurement of thyroid hormones are already in place for several study types, and deliberations continue for other guidelines. This HESI DART-ETS joint effort aims to provide clarification and guidance regarding the collection, assessment and interpretation of thyroid hormone data for regulatory toxicology and risk assessment. The data collected will be anonymously archived in a database that will ultimately be available for public use and incorporated into a workshop planned for Spring 2019. The facility/laboratory, assay and strain-specific data collected will ultimately contribute to improved data interpretation, the establishment of biologically relevant ranges for each assessment and recommendations for best practices for thyroid assessment.
If your organization conducts these assays and you are interested participating in the survey and contributing to the data collection effort, please contact Connie Chen () for more information.
Susan Makris, MS
US Environmental Protection Agency
Kary Thompson, PhD
Members and Fact Sheet
This satellite workshop to the 45th Annual Meeting of the European Teratology Society is addressed to participants working in industries or regulatory bodies who are involved in testing and assessment of the potential developmental toxicity of chemicals.
This workshop will consider new strategies to identify developmental hazards taking into account the current state of science which may include alternative possibilities or improvements to the current Segment 2 design. These considerations could include the use of new technology to overcome some of the limitations in predicting human response with current animal models or completely new radical approach to developmental toxicity hazard identification. These may range from having a critical paradigm to deciding when non-clinical studies are needed to the use of biotechnology and computational models or hazard characterization. Working groups can consider either strategy, or combinations of the two.
This satellite workshop was held in conjunction with the European Teratology Society Annual Meeting.
The recently finalized Pregnancy Labeling and Lactation Labeling Rule changes the organization of the current Pregnancy and Nursing Mothers section of the US package insert of prescription drugs. In response to these changes in prescription drug labeling, the HESI Developmental and Reproductive Toxicology (DART) Technical committee sponsored a two-day workshop on this topic.
The HESI Developmental and Reproductive Toxicology (DART) Committee launched a multisector collaborative research effort to increase the knowledge base in the nonclinical neonatal space to better inform decisions made in the clinic.
This review is part of a multisector collaborative research effort coordinated by the HESI Developmental and Reproductive Toxicology (DART) Committee to increase the knowledge base in the nonclinical neonatal space to better inform clinical treatment decisions made for the newborn patient population (De Schaepdrijver et al., 2018).
Summary from the HESI workshop on embryo‐fetal development testing, considers how we might design developmental toxicity testing if we started over with 21st century knowledge and techniques. The paper considers what might make current protocols more predictive for human risk.
A database of embryo-fetal developmental toxicity (EFDT) studies of 379 pharmaceutical compounds in rat and rabbit was analyzed for species differences based on toxicokinetic parameters of area under the curve (AUC) and maximum concentration (Cmax) at the developmental lowest adverse effect level (dLOAEL). For the vast majority of cases (83% based on AUC of n = 283), dLOAELs in rats and rabbits were within the same order of magnitude (less than 10-fold different) when compared based on available data on AUC and Cmax exposures. For 13.5% of the compounds the rabbit was more sensitive and for 3.5% of compounds the rat was more sensitive when compared based on AUC exposures. For 12% of the compounds the rabbit was more sensitive and for 1.3% of compounds the rat was more sensitive based on Cmax exposures. When evaluated based on human equivalent dose (HED) conversion using standard factors, the rat and rabbit were equally sensitive. The relative extent of embryo-fetal toxicity in the presence of maternal toxicity was not different between species. Overall effect severity incidences were distributed similarly in rat and rabbit studies. Individual rat and rabbit strains did not show a different general distribution of systemic exposure LOAELs as compared to all strains combined for each species. There were no apparent species differences in the occurrence of embryo-fetal variations. Based on power of detection and given differences in the nature of developmental effects between rat and rabbit study outcomes for individual compounds, EFDT studies in two species have added value over single studies.
Regulatory non-clinical safety testing of human pharmaceuticals typically requires embryo–fetal developmental toxicity (EFDT) testing in two species (one rodent and one non-rodent). The question has been raised whether under some conditions EFDT testing could be limited to one species, or whether the testing in a second species could be decided on a case-by-case basis. As part of a consortium initiative, we built and queried a database of 379 compounds with EFDT studies (in both rat and rabbit animal models) conducted for marketed and non-marketed pharmaceuticals for their potential for adverse developmental and maternal outcomes, including EFDT incidence and the nature and severity of adverse findings. Manifestation of EFDT in either one or both species was demonstrated for 282 compounds (74%). EFDT was detected in only one species (rat or rabbit) in almost a third (31%, 118 compounds), with 58% (68 compounds) of rat studies and 42% (50 compounds) of rabbit studies identifying an EFDT signal. For 24 compounds (6%), fetal malformations were observed in one species (rat or rabbit) in the absence of any EFDT in the second species. In general, growth retardation, fetal variations, and malformations were more prominent in the rat, whereas embryo–fetal death was observed more often in the rabbit. Discordance across species may be attributed to factors such as maternal toxicity, study design differences, pharmacokinetic differences, and pharmacologic relevance of species. The current analysis suggests that in general both species are equally sensitive on the basis of an overall EFDT LOAEL comparison, but selective EFDT toxicity in one species is not uncommon. Also, there appear to be species differences in the prevalence of various EFDT manifestations (i.e. embryo–fetal death, growth retardation, and dysmorphogenesis) between rat and rabbit, suggesting that the use of both species has a higher probability of detecting developmental toxicants than either one alone.