RE:Validating surrogate end pointsFrom FDA 2023 - A surrogate endpoint used for accelerated approval is a marker - a laboratory measurement, radiographic image, physical sign or other measure that is thought to predict clinical benefit, but is not itself a measure of clinical benefit.
The FDA instituted its Accelerated Approval Program to allow for earlier approval of drugs that treat serious conditions, and fill an unmet medical need based on a surrogate endpoint.
To qualify as a surrogate endpoint, a biomarker needs to demonstrate significant ability to predict a clinically relevant outcome as well as the effect of treatment on this outcome, as ONCYs PFS Bracelet-1 data demonstrates.
Validated surrogate endpoint allows prediction of a clinically important outcome, the surrogate itself does not measure a clinical benefit.
The use of surrogates also enables shorter and less expensive trials as it is generally less expensive and takes less time to see the effect of the intervention on the surrogate rather than on the true clinical endpoint.
https://www.fda.gov/drugs/nda-and-bla-approvals/accelerated-approval-program