Surrogate Endpoint — What It Means in Clinical Trials
Plain English Definition
A surrogate endpoint is a measurement used as a stand-in for a clinical outcome that takes a long time to measure. For example, tumor shrinkage (which can be measured in weeks) may be used as a surrogate for overall survival (which takes years to measure). Surrogate endpoints allow researchers to get faster answers.
Why It Matters
Surrogate endpoints can speed up drug development, but they are not perfect substitutes. A drug that shrinks tumors (surrogate) may not always extend life (actual outcome). Regulators sometimes grant accelerated approval based on surrogate endpoints.
Example
A trial might use: "Blood pressure reduction as a surrogate endpoint for cardiovascular mortality." Lowering blood pressure is assumed to reduce heart-related deaths.
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