Tumor mRNA Expression Profiles Predict Responses to Chemotherapy

The development of prognostic and diagnostic markers suchastumorstagingandmorerecentlymolecularfactorshavegreatlycontributed to identifying lung cancer patients that can benefitfrom adjuvant or neoadjuvant chemotherapy. However, the pre-dictingefficienciesvaryconsiderably,andmanytherapiesfailwhilesurviving patients often experience severe toxicities. Moreover,patients displaying similar clinical characteristics often responddifferently to therapy, and this is likely a result of heterogeneity ofthe tumors’ genetic and epigenetic characteristics. The advent ofthe human genome sequencing project and the concurrent devel-opment of many genomic-based technologies, including expres-sion microarrays, have allowed scientists to explore the possibilityof using expression profiles to predict tumor drug sensitivity orresistance before treatment, and thereby select the best possibletherapies while decreasing the risk of toxicities for the patients.To this end, various gene signatures and sequence alterationintargetgeneshavebeenobtainedforpredictionofdrugresponsein patients. Examples include signatures for taxane/doxorubicinsensitivity in breast cancer,