New approach methodologies for assessing developmental toxicity of pharmaceuticals: Case examples and future directions.

Several new approach methodologies (NAMs) for developmental toxicity (Dev Tox) testing are being used by pharmaceutical companies for derisking or for exploring Dev Tox mechanisms. Regulatory adoption of these NAMs-based approaches as being adequate for Dev Tox risk assessment has been more challenging, due, in part, to dynamic changes in the conceptus and placenta throughout development and the impact of the pharmaceutical on the mother's physiology, which may also have an embryo-fetal impact. Still, there is currently a recognition by Health Authorities that there are certain contexts-of-use under which Dev Tox NAMs can provide information that is adequate to inform risk. This has been adopted in the 3rd revision of the ICH S5 guideline, which provides a path to qualify Dev Tox NAMs for regulatory decision making. Despite this opportunity, pharmaceutical companies rarely submit Dev Tox NAMs to Health Authorities for qualification or with intent to support regulatory decision making. This may be in part due to the need for a greater understanding of the biological relationship between currently available Dev Tox NAMs and in vivo outcome, applicability domain, translatability, predictivity, and that these NAMs do not cover the complete scope of embryo-fetal development. Furthermore, there is a lack of Dev Tox NAMs data visibility to Health Authorities. To use Dev Tox NAMs for regulatory decision making, more data sharing with Health Authorities and further understanding the applicability domain of these methodologies are needed.