Figure 2

Participant answers to the question: "The following sentences may characterize a surrogate endpoint. Which one or which ones (maximum 3) seem important for you to remember?". Proposition 1: "A surrogate endpoint is a variable known to be a prognostic factor" Proposition 2: "A surrogate endpoint is a variable correlated with overall survival" Proposition 3: "A surrogate endpoint is a biomarker¹ 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 epidemiologic, therapeutic, pathophysiologic, or other scientific evidence" (ref. [3]) ¹ A biomarker is "a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention" Proposition 4: "A surrogate endpoint is an intermediate endpoint, reliably and reproducibly measurable (imaging, biology...), which allows to predict the effect of the treatment on the clinical endpoint" (ref. [13]) Proposition 5: "A surrogate endpoint is a variable which is accepted as primary endpoint in clinical trials by medical agencies (e.g. FDA, EMEA, AFSSAPS, etc.)²" ² FDA, (United State) Food and Drug Administration; EMEA, European Medicines Agency; AFSSAPS, Agence Française de Sécurité Sanitaire des Produits de Santé Proposition 6: "A surrogate endpoint is a response variable for which a test of the null hypothesis of no relationship to the treatment groups under comparison is also a valid test of the corresponding null hypothesis based on the true endpoint" (ref. [14])