Back to: FDA Second Annual Animal Drug User Fee Educational Conference – July 2025
Lesson Content:
Adaptive Study Designs
Anthony Parker
Office of New Animal Drug Evaluation
Center for Veterinary Medicine, FDA
Q&A Session
Walt Ellenberg & CVM Q&A Panel Table
Closing Remarks
Walt Ellenberg, Moderator
Special Advisor
Office of New Animal Drug Evaluation
Center for Veterinary Medicine, FDA
Abstract
This webinar introduces adaptive study designs for effectiveness studies of new animal drugs, drawing from Guidance for Industry 268. An adaptive design is a clinical effectiveness study design that allows for prospectively planned modifications based on accumulating data from subjects in the study. This approach offers practical advantages by saving resources like time and money, and ethical benefits by potentially reducing the number of animals needed through early stopping for effectiveness or futility. For regulatory acceptance, any proposed adaptive design must be well-defined and prespecified, consistent with requirements for substantial evidence, and adequately control the chance of erroneous conclusions while minimizing statistical and operational bias. Early and consistent communication with the Center for Veterinary Medicine (CVM) is strongly encouraged throughout the process. The protocol should clearly explain the process for evaluating interim data, justifying decisions, and detailing how results are communicated to protect study integrity and mask personnel. Common adaptive designs include group sequential designs, which allow for early stopping, and sample size reestimation, which adjusts the planned sample size based on interim results to avoid underpowering. Due to unique features of animal clinical studies, established statistical methods may not always be directly applicable; in such cases, simulations may be required to demonstrate the statistical properties of the proposal, including the control of the overall type one error rate. Obtaining protocol concurrence from CVM prior to beginning the study is strongly recommended.