Predictive biomarkers in clinical practice: State of the art and perspectives in solid tumors.

The discovery of molecular alterations that play key functions in pathways of tumor growth and survival have changed the treatment approach of several solid tumors. A number of biomarkers are now approved in clinical practice for the selection of patients to be treated with the specific targeted drug, and others are currently under study. None of these biomarkers are perfect and they have a number of biases. Novel treatment approaches, such as immunotherapy, require the development of more complex biomarker combinations as the mechanism of action of these drugs involves multiple parameters. In this short communication the principal approved biomarkers in solid tumors are discussed, with attention to the novel promising biomarkers that will be developed in the future.