Biomarkers in Drug Discovery and Development: From Target Identification to Drug Marketing

The role of biomarkers in drug discovery and development has gained precedence over the years. Biomarkers play an important role in medicine and have begun to assume a greater role in drug discovery and development. Biomarkers are central to the future of medicine. By providing a measure of a biological state, they can indicate normal biological processes, pathogenic processes, or responses to an intervention or perturbation in the environment. They can be used to monitor the on-target and off-target effects of medical interventions, including treatments for disease and also in diagnostic and prognostic tests; and they can define the individuals and populations most likely to respond to therapy. At the broadest level, they can provide insight into biological pathways and networks. Biomarkers need to be taken into account while the therapeutic target is still being identified and the concept is being formulated. They need to be incorporated into a continuous cycle that takes what is learned from the discovery and development of one series of biomarkers and translates it into the next series of biomarkers. Optimum biomarker development and application requires a team approach because of the multifaceted nature of biomarker selection, validation, and application, using such techniques as pharmacoepidemiology, pharmacogenetics, pharmacogenomics, and functional proteomics; bioanalytical method development and validation; disease process and therapeutic intervention assessments; and pharmacokinetic / pharmacodynamic modeling and simulation to improve and refine drug development. The potential for biomarkers in medicine and drug development is limited by the least effective component of the processes. As scientific/ regulatory foundations for biomarkers in medicine and drug development begin to be established, its applications must be effectively communicated with all of the stakeholders, including not only internal and external drug developers and regulators but also the medical community, to ensure that biomarkers are totally integrated into drug discovery and development as well as the practice of medicine.