Exposure assessments in reproductive and developmental toxicity testing: An IQ-DruSafe industry survey on current practices and experiences in support of exposure-based high dose selection.

The draft ICH S5(R3) guideline includes an exposure-based endpoint as an option for selecting the high dose in developmental and reproductive toxicity (DART) studies. In 2016, IQ DruSafe conducted an anonymous survey to identify industry practices and experiences related to pharmacokinetic assessments in DART studies in order to facilitate a pragmatic data-driven approach to development of an acceptable multiple of the clinical exposure to be proposed for dose selection in the guideline. Questions in the survey were designed to explore pharmacokinetic differences in pregnant versus non-pregnant animals, and to assess exposure levels attained in the absence of maternal toxicity as well as DART outcomes in animal studies associated with those exposures. Small molecule and therapeutic proteins were analyzed separately. The key findings for small molecules were: a) differences in exposures between pregnant and non-pregnant animals were generally ≤3-fold, b) C or AUC exposures ≥25-fold the clinical exposure were achieved in the absence of maternal toxicity for 31% and 23% of rat and rabbit developmental toxicity studies, respectively, and c) only 3.3% (5/153) and 1.6% (2/128) of the developmental toxicity studies were positive for malformations or embryofetal lethality in rats and rabbits, respectively, that were not observed until exposure margins were ≥25-fold.