Surrogate endpoint

A biomarker that is intended to substitute for a clinical endpoint. A surrogate endpoint is expected to predict clinical benefit (or harm or lack of benefit or harm) based on epidemiological, therapeutic, pathophysiologic, or other scientific evidence.
Surrogate endpoints are a subset of biomarkers. Although all surrogate endpoints can be considered biomarkers, it is likely that only a few biomarkers will achieve surrogate endpoint status. The term surrogate endpoint applies primarily to endpoints in therapeutic intervention trials; however, it may sometimes apply in natural history or epidemiological studies.
It is important to point out that the same biomarkers used as surrogate endpoints in clinical trials are often extended to clinical practice in which disease responses are similarly measured. The use of biomarkers as surrogate endpoints in a clinical trial requires the specification of the clinical endpoints that are being substituted, class of therapeutic intervention being applied, and characteristics of population and disease state in which the substitution is being made.
The term surrogate literally means “to substitute for”; therefore use of the term surrogate marker is discouraged because the term suggests that the substitution is for a marker rather than for a clinical endpoint.
Synonyms: biological marker, clinical endpoint

Last update: 30 June 2023

Source: Biomarkers Definitions Working Group, updated by PPRI