Biomarkers are substances that differentiate one individual from another and can help selecting good candidates for specific highly selective therapies. The example of PLX4032 for metastatic melanoma and a response rate over 80% is one of the few examples of the use of biomarkers for diagnostic and treatment purposes because general screening methods are very challenging. Metabolomics, the study of chemical processes involving metabolites, could be a valuable tool to overcome the challenges posed by the search of new biomarkers.