ABSTRACT
Prognostic biomarkers measure disease prognosis or are associated with the disease outcome without consideration to treatment. A companion diagnostic test for a drug is a test for a predictive biomarker of the response of the drug in a patient. Predictive biomarkers are measured in subjects at the baseline, that is, on entry to a clinical trial of a particular drug, sponsored by a pharmaceutical company. A prognostic biomarker may be of interest to a company making a pharmaceutical product, in order to screen patients who will qualify for entry into a clinical trial. In the stratified design, the biomarker cut point is known and subjects in both BM+ and BM- subgroups are randomized to either treatment or control regimen. The reason BM- subgroup is included because they may derive treatment benefit as well or the treatment effect in the overall population may be acceptable.
