Are all ALK rearrangements created equal?

The discovery of ALK rearrangements in non-small cell lung cancer (NSCLC) and their oncogenic properties by Soda et al. in 2007 gave the start to one of the most famous stories in the treatment of lung cancer (1). Diagnosed in around 5% of patients with NSCLC, ALK rearrangements are effectively treated with the ALK-directed tyrosine kinase inhibitor (ALK-TKI) crizotinib (2,3).