ALK and metastatic neoplasm: As cellular heterogeneity along this spectrum is a paramount feature in most tumors including ALK-rearranged NSCLC, forthcoming studies should evaluate whether the utilization of the so-called EMT scores, which have been developed based on pan-cancer signatures of EMT identified from preclinical and/or clinical data [70,71,72,73,74], in a primary/metastatic tumor can be used to predict resistance to ALK–TKIs.