Finally, in a large prospective cohort study involving ALK and ROS1 positive NSCLC patients treated with first to third generation TKIs, a targeted amplicon-based NGS assay revealed the presence of cfDNA alterations potentially correlated with resistance, both in ALK or ROS1 genes and in other genes (i.e., KRAS, PI3KCA, and PTEN). The gene discussed is KRAS; the disease is non-small cell lung carcinoma.