Figure 2. Diagram of types of biomarkers.

Direct biomarkers are in the disease pathway and are therefore mechanistic biomarkers that reflect disease activity and contribute to disease pathogenesis. Changes in direct biomarkers would have the potential to reflect changes in disease state over time or in response to a drug. Indirect biomarkers report on some aspect of the disease but are not directly in the disease pathway. Created with BioRender.com (paid license)