Brief · Use case · Medical Affairs
Surrogate Endpoint Assessment.
LiveAssessmentJudge whether a surrogate endpoint is adequate evidence of clinical benefit, how well that is supported and where the position fails.
Surrogate Endpoint Assessment is a ready-made use case for Medical Affairs. It ships under the Assessment template.
For medical affairs and clinical leaders deciding how far an endpoint can be relied on. You get a position with its confidence, the evidence graded, the strongest objection answered and the weaknesses named with their cause. Claims are cited or marked as gaps.
Add it to your library to reuse from New → From template. Edit the saved copy in your library on the service form.
The decision
How well supported is the position that a surrogate endpoint is adequate evidence of clinical benefit for a chronic disease therapy?
What the assessment examines
A surrogate endpoint stands in for how a patient feels, functions or survives. The assessment asks whether this one earns that role, using the tests the literature and the regulators use.
| Part of the position | What the assessment examines | Where it looks |
|---|---|---|
| Correlation is not enough | Whether the effect of the intervention on the surrogate predicts its effect on the clinical outcome, and not merely whether the two move together.1 | Fleming and DeMets (1996), who set out why a correlate does not make a surrogate. |
| What the regulator has accepted | Whether FDA lists the surrogate as validated, which supports traditional approval, or as reasonably likely, which supports accelerated approval but rests on less clinical data.2 | FDA’s table of surrogate endpoints that were the basis of drug approval or licensure. |
| What a surrogate is | The standard definition, which separates a biomarker from an endpoint and a surrogate from a direct measure of how a patient feels, functions or survives.3 | The FDA-NIH BEST glossary. |
What the assessment does
The central test. Fleming and DeMets argue that a surrogate is valid only if the intervention’s effect on it predicts the intervention’s effect on the clinical outcome. They list how a surrogate fails: it may sit outside the causal pathway of the disease, or the intervention may act through mechanisms independent of that pathway. The assessment applies both tests to the surrogate in question.1
Two levels of regulatory acceptance. FDA’s table separates validated surrogates, which can support traditional approval, from reasonably likely surrogates, which rest on a strong mechanistic or epidemiologic rationale and a smaller body of clinical data. The assessment says which level applies and what that means for the position.2
A chronic disease changes the stakes. In a chronic disease a therapy is taken for years, so a surrogate that fails to track clinical benefit exposes patients to long-term risk without long-term gain. The assessment says what follow-up evidence the position needs.
The strongest objection. The objection is that surrogates have misled before. The assessment restates it fairly, names the cases in which it applies, and says whether this surrogate resembles them.1
Recommended length
Comprehensive
The position will be challenged by people who hold another view. Comprehensive adds the alternatives considered and the reasoning behind the support, which is what a challenger asks for.
You can pick another length on the form. The other two stay available.
Assumptions the assessment checks
The assessment states the assumptions the position rests on and says which one would hurt most if it failed. Examples for this position:
- The surrogate sits on the causal pathway between the intervention and the clinical outcome.
- The intervention does not act through other pathways that affect the clinical outcome.
- Evidence linking surrogate and outcome comes from trials of the same class of therapy.
Standards, guidance and sources
Validity of surrogates
Terms
- FDA-NIH BEST (Biomarkers, EndpointS, and other Tools) glossary.3
The decision practice behind the memo itself is on the template page.
What gets flagged
Any claim that a surrogate is validated when FDA lists it as reasonably likely, any evidence from a different class of therapy, and any mechanism by which the intervention could act outside the pathway.
What arrives
- The position
- The basis
- Why the evidence supports it
- The strongest objection, answered
- Other views considered
- Where it is weak
What it will not do
It does not recommend an action. A Decision Memo takes the assessment as its starting point.
It does not say whether a regulator would accept the surrogate in a particular submission.
It does not recommend an action. An assessment says how well a position is supported; a Decision Memo recommends what to do.
Certainty ratings are analyst judgment from an AI specialist, not measurements, and the reason for each is on the page so you can disagree with it.
It does not settle a question the evidence leaves open. Where the evidence is thin, the assessment says so and says what would settle it.
References
- [1] Fleming, T. R. and DeMets, D. L. Surrogate end points in clinical trials: are we being misled? Annals of Internal Medicine, 1996;125:605–613. DOI 10.7326/0003-4819-125-7-199610010-00011. Read from the abstract as summarized in search excerpts; the link is a university course copy of the paper.
- [2] U.S. Food and Drug Administration. Table of Surrogate Endpoints That Were the Basis of Drug Approval or Licensure. Described from FDA’s page as summarized in search excerpts; the table is updated periodically, so check the current version.
- [3] FDA-NIH Biomarker Working Group. BEST (Biomarkers, EndpointS, and other Tools) Resource: glossary. The page could not be opened from our tools; the definitions are from search excerpts.
Links checked 9 October 2026
These are the sources the template drew on. None of their authors or issuers has reviewed it.
About the Brief service
A Brief is a written answer from one specialist, at the depth you asked for. It arrives with its sources, and it closes by saying plainly what would change the conclusion. Nothing is hidden behind a summary, and anything the expert could not source is marked as a gap rather than filled in.
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