Bioequivalence Study Designs for Generic Solid Oral Anticancer Drug Products: Scientific and Regulatory Considerations

The demonstration of bioequivalence (BE) between the test and reference products is an integral part of generic drug approval process. A sound BE study design is pivotal to the successful demonstration of BE of generic drugs to their corresponding reference listed drug product. Generally, BE of systemically acting oral dosage forms is demonstrated in a crossover, single-dose in vivo study in healthy subjects. The determination of BE of solid oral anticancer drug products is associated with its own unique challenges due to the serious safety risks involved. Unlike typical BE study in healthy subjects, the safety issues often necessitate conducting BE studies in cancer patients. Such BE studies of an anticancer drug should be conducted without disturbing the patients' therapeutic dosing regimen. Attributes such as drug permeability and solubility, pharmacokinetics, dosing regimen, and approved therapeutic indication(s) are considered in the BE study design of solid anticancer drug products. To streamline the drug approval process, the Division of Bioequivalence posts the Bioequivalence Recommendations for Specific Products guidances on the FDA public website. The objective of this article is to illustrate the scientific and regulatory considerations in the design of BE studies for generic solid oral anticancer drug products through examples.