Table 2.

FDA biomarker classification based on contexts of use

Biomarker type	When biomarker is measured	What biomarker indicates
Prognostic	Prior to treatment	Indicates (estimates) the risk or likelihood that a patient who receives no further cancer-directed therapy will experience a specified clinical outcome, such as recurrence, progression, or death
Predictive	Prior to treatment	Interpreted with defined criteria to identify patients who are likely to benefit from a specific treatment compared to patients who do not meet the specified criteria
Response indicator	During or after treatment	Demonstrates a pharmacological or physiological response to the treatment, but does not necessarily signify patient benefit. Examples are declines in prostate-specific antigen, measures of tumor shrinkage, or pharmacodynamic changes in a parameter to show the on-target effect of a drug as proof of mechanism or to optimize dosing
Efficacy response (surrogate)	After treatment	Provides an early and accurate prediction of both a clinical end point, and the effects of the treatment on that end point