sentences:  A prognostic biomarker could be indirectly associated with a disease if it is related to a change caused by the exposure, or related to an unknown factor connected with the exposure or disease.Predictive biomarkers measure the effect of a drug and tell if the drug is having its expected activity, but do not offer any direct information on the disease.Predictive biomarkers are highly sensitive and specific; therefore they increase diagnostic validity of a drug or toxin's site-specific effect by eliminating recall bias and subjectivity from those exposed.