Considerations for Master Protocols Using External Controls

Abstract

There has been an increasing use of master protocols in oncology clinical trials because of its efficiency and flexibility to accelerate cancer drug development. Depending on the study objective and design, a master protocol trial can be a basket trial, an umbrella trial, a platform trial, or any other form of trials in which multiple drugs and/or multiple subpopulations are studied in parallel under a single protocol. External data and evidence (EDE) can be used in the design and analysis of master protocols such as external controls for treatment effect estimation, which can further improve efficiency of the master protocol trial. This paper provides an overview of different types of external controls and their unique features when used in master protocols. Some key considerations in master protocols with external controls are discussed including construction of estimands and assessment of fit-for-use real-world data. A targeted learning-based causal roadmap is presented which constitutes three key steps: (1) define a target statistical estimand that aligns with the causal estimand for the study objective, (2) use an efficient estimator to estimate the target statistical estimand and its uncertainty, and (3) evaluate the impact of causal assumptions on the study conclusion by performing a sensitivity analysis. Two illustrative examples are provided for master protocols using external controls