EML4-ALK translocation identification in RNA exosomal cargo (ExoALK) in NSCLC patients: a novel role for liquid biopsy

The introduction of druggable targets has significantly improved the outcomes of non-small cell lung cancer patients (NSCLC). EML4-ALK translocation represents 4–6% of the druggable alterations in NSCLC. With the approval of Crizotinib, first discovered drug for the EML4-ALK translocation, on first line treatment for patients with detected mutation meant a complete change on the treatment landscape. The current standard method for EML4-ALK identification is immunohistochemistry or FISH in a tumor biopsy. However, a big number of NSCLC patients have not tissue available for analysis and others are not suitable for biopsy due to their physical condition or the location of the tumor. Liquid biopsy seems the best alternative for identification in these patients that have no tissue available. Circulating free RNA has not been validated for the identification of this mutation. As a complementary tool, exosomes might represent a good tool for predictive biomarkers study, and due to their stability, they preserve the genetic material contained in them. Our group has described for the first time the translocation EML4-ALK in RNA isolated from exosomes derived from NSCLC patients using next generation sequencing.