Review of embryo-fetal developmental toxicity studies performed for pharmaceuticals approved by FDA in 2020 and 2021.

103 novel drugs were approved by the FDA in 2020–2021. Embryofetal development (EFD) studies were conducted for 76 % of these approvals. For the majority of drugs, EFD studies were conducted in rats and rabbits. Both species were equally sensitive to developmental toxicity, but the rabbit was slightly more sensitive to maternal toxicity at the same systemic exposure level. Nonetheless, 68 % of drugs showed more than a 2-fold difference in the low adverse effect level for developmental toxicity between the rat and rabbit. Previous reviews in this series compiled information on EFD studies for all small molecule pharmaceuticals approved since 2014 and for all therapeutic monoclonal antibodies approved to date. The use of non-human primates for the developmental toxicity testing of biopharmaceuticals has fallen over recent years (22 % of biologics license applications (BLAs) for 2020–2021, compared with 62 % for 2002–2015), with more biopharmaceuticals now tested in rodents (37 % of BLAs for 2020–2021). While the Pregnancy and Lactation Labeling Rule (PLLR), adopted in 2014, has brought consistency to the presentation of EFD data in drug labels, prescribers complain that the pregnancy section of current drug labels is neither concise nor clear. The FDA has pledged to address the concerns of clinicians in a future revision of the PLLR rule. The recommendations on risk assessment in the recently revised ICHS5(R3) guideline could be incorporated into the PLLR rule to remove extraneous nonclinical details from the label with the aim of facilitating rapid understanding by the practitioner.