cDNA sequencing of ALK kinase domain revealed activating mutations—I1171T in Karpas299CR and F1174C in Karpas299CHR....AUY922 potently suppressed growth of Karpas299 parental cells as well as both resistant cell lines, albeit it had slightly weaker effect on Karpas299CHR cells, particularly at a dose of 41 nM (p ≤ 0.001).