Lineage plasticity – where adenocarcinomas develop resistance through epithelial-to-mesenchymal transition, seen in some cases of NSCLC treated with EGFR inhibitors (Schoenfeld et al. 2020) – has been reported in two recent cases of resistance to RET inhibition (Gazeu et al. 2023, Peng et al. 2023) although this mechanism of resistance does not appear to be common (Lin et al. 2020, Rosen et al. 2022). This evidence concerns the gene RET and non-small cell lung carcinoma.