Biomarkers can also be used to evaluate the effectiveness of particular therapies in treating a disease. By measuring drug response rate or toxic effects associated with the drug, specific biomarkers can be used to monitor a patient's reaction to a particular drug, checking whether the treatment is effective and facilitating earlier detection of adverse drug response. Biomarkers also play an important role in the development of new drugs with the discovery of druggable targets. Alterations in the progression markers can be used to understand whether and how a disease is slowed or reversed by a new therapy, which allows researchers to focus efforts and resources on the most effective ones. Finally, biomarkers can be used to evaluate the progression of a disease or the susceptibility of a disease to a given treatment and hold great promise for personalized medicine.