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confirmatory clinical trial

(kun-FIR-muh-TOR-ee KLIH-nih-kul TRY-ul)
A study that confirms how well a new treatment works after it was shown in early-phase clinical trials that it might be beneficial for patients. New drugs that are given an accelerated approval by the U.S. Food and Drug Administration (FDA) to treat a serious or life-threatening disease, such as cancer, are required to be tested in a confirmatory clinical trial. This is done to verify that they really work when they are tested on many more people in a randomized study. The FDA may remove a drug from the market if a confirmatory clinical trial shows that the drug is not beneficial for patients.
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