Review Note

Last Update: 02/18/2024 05:30 AM

Current Deck: Part 2::6. High Yield Questions::Clinonc

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What is the definition of a surrogate end point? Give three examples of surrogate endpoints. What are the advantages and disadvantages of using surrogate end points in oncology clinical trials? 4 marks
Back
A surrogate endpoint is defined as a measure of effect of a specific treatment that may correlate with a real critical endpoint (of intrinsic value to the patient such as overall survival or QOL) but not necessarily have a guaranteed relationship. Or simply a biomarker intended to substitute for a clinical endpoint.
Examples:
1.      Progression free survival
2.      Metastasis free survival
3.      Ipsilateral invasive breast cancer occurrence in DCIS
4.      RANO/Resist criteria for tumour response post treatment.

Advantages
-        Easier and quicker to measure than the hard endpoints (eg overall survival)
-        Enables trials to be conducted quickly at a reduced cost
-        Enables trials to be run when there is a small number of events or long time to event hence making it impractical to conduct a clinical trial in that setting to reach a clinically significant outcome
-        Speeds up treatment approval process, keeping up with new knowledge and medical developments.

Disadvantages
-        Surrogate endpoints may not be inherently meaningful to patients or intrinsically valuable to patients such as overall survival or improved quality of life
-        Many surrogates used in clinical practice are not clinically validated to prove a correlation to the hard outcome.
-        Speeding up drug or treatment approval is uncertain and may lead to unintended consequences.
-        Measuring surrogate endpoints may be complex – measurement error, evaluation bias, attrition bias or informative censoring which weakens the association between the surrogate and hard endpoint, hence loss of predictive value.
Further information, not for memorising (no card)
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