ABSTRACT

Biomarkers offer the potential to improve patient care by directing therapies to specific patients for whom they are most likely to work. This is especially true in the era of targeted therapies, for which it is thought that an understanding of the characteristics of a patient’s tumor and how a targeted agent interacts with those characteristics should help personalize therapy for patients. How to incorporate biomarkers into the clinical trials used to develop and establish the benefit of a new agent (possibly in a subset of patients defined by their biomarker status) is not completely straightforward. The outline of this chapter is as follows. The chapter begins with a brief discussion of assessing the analytic performance of biomarker; before using a biomarker clinically, one would want to ensure that the biomarker is accurately measuring what it is supposed to be measuring. Next, we consider the distinction between prognostic versus predictive biomarkers. Prognostic and predictive biomarkers would be used in different ways in patient care, and so the careful assessment of the prognostic and predictive ability of a biomarker in clinical trials is important. We then discuss biomarkers and their potential roles in phase I, II, and III trials in successive sections. We end with a brief summary.