The Mechanisms of a Controlled Trial

Phase I, an initial study in a small group, establishes whether a treatment is safe and at what dosage.

Phase II, in a larger group, evaluates the effectiveness of the drug and determines common short-term side effects and risks.

Phase IIIexpands the evaluation, usually through acontrolled trialwhere the drug is tested against standard treatments to evaluate benefits and risks, differences in response rates, and toxicity. One group of participants gets the experimental drug, and the control group receives a placebo or standard treatment (in the trial for themelanomadrug PLX4032, the control waschemotherapy). Participants are randomly assigned to a treatment group.

In a typical“blind” study, neither patients nor researchers know which participants are receiving the experimental drug. The trial of PLX4032 wasunblinded, meaning doctors told patients whether they were assigned to the control arm.

Phase IVtakes place after the drug has been licensed and marketed, to determine optimal use.

SOURCE:ClinicalTrials.gov

Source