Assessment of menstrual cycle length in cynomolgus monkeys as a female fertility endpoint of a biopharmaceutical in a 6 month toxicity study.

According to ICH S6(R1), mating studies are not practical for assessing effects on female fertility of biopharmaceuticals that are pharmacologically active only in non-human primates (NHPs). Instead, fertility should be assessed by evaluating histopathology and organ weights of the reproductive tract in studies of at least 3 months dosing duration using sexually mature NHPs. An assessment of the menstrual cycle in females can be included if there is cause for concern based on pharmacological mode of action or relevant findings in previous studies.