Alternatives to Monkey Reproductive Toxicology Testing for Biotherapeutics

Embryofetal toxicity studies are conducted to support inclusion of women of childbearing potential in clinical trials and to support labeling for the marketed pharmaceutical product. For biopharmaceuticals, which frequently lack activity in the rodent or rabbit, the nonhuman primate is the standard model to evaluate embryofetal toxicity. These studies have become increasingly challenging to conduct due to the small number of facilities capable of performing them and a shortage of sexually mature monkeys. The low number of animals per group and the high rate of spontaneous abortion in cynomolgus monkeys further complicate interpretation of the data. Recent FDA guidance has proposed a weight of evidence (WoE) approach to support product labeling for reproductive toxicity of products intended to be used for the treatment of cancer (Oncology Pharmaceuticals: Reproductive Toxicity Testing and Labeling Recommendations), an approach that has also supported the approval of biotherapeutics for non-cancer indications. Considerations to determine the appropriateness and content of a WoE approach to support product labeling for embryofetal risk include known class effects in humans; findings from genetically modified animals with or without drug administration; information from surrogate compounds; literature-based assessments about the developmental role of the pharmaceutical target; and the anticipated exposure during embryofetal development. This paper summarizes the content of a session presented at the 42nd annual meeting at the American College of Toxicology, which explored the conditions under which alternative approaches may be appropriate to support product labeling for reproductive risk, and how sponsors can best justify the use of this approach.