Insights into ALK-driven cancers revealed through development of novel ALK tyrosine kinase inhibitors

Cancer Res. 2011 Jul 15;71(14):4920-31. doi: 10.1158/0008-5472.CAN-10-3879. Epub 2011 May 25.


Aberrant forms of the anaplastic lymphoma kinase (ALK) have been implicated in the pathogenesis of multiple human cancers, where ALK represents a rational therapeutic target in these settings. In this study, we report the identification and biological characterization of X-376 and X-396, two potent and highly specific ALK small molecule tyrosine kinase inhibitors (TKIs). In Ambit kinome screens, cell growth inhibition studies, and surrogate kinase assays, X-376 and X-396 were more potent inhibitors of ALK but less potent inhibitors of MET compared to PF-02341066 (PF-1066), an ALK/MET dual TKI currently in clinical trials. Both X-376 and X-396 displayed potent antitumor activity in vivo with favorable pharmacokinetic and toxicity profiles. Similar levels of drug sensitivity were displayed by the three most common ALK fusion proteins in lung cancer (EML4-ALK variants E13;A20, E20;A20, and E6b;A20) as well as a KIF5B-ALK fusion protein. Moreover, X-396 could potently inhibit ALK kinases engineered with two point mutations associated with acquired resistance to PF-1066, L1196M, and C1156Y, when engineered into an E13;A20 fusion variant. Finally, X-396 displayed synergistic growth inhibitory activity when combined with the mTOR inhibitor rapamycin. Our findings offer preclinical proof-of-concept for use of these novel agents to improve therapeutic outcomes of patients with mutant ALK-driven malignancies.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anaplastic Lymphoma Kinase
  • Animals
  • Brain / metabolism
  • Cell Line, Tumor
  • Drug Synergism
  • Female
  • Humans
  • Isoenzymes
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Nude
  • Models, Molecular
  • Neoplasms / drug therapy*
  • Neoplasms / enzymology*
  • Neoplasms / metabolism
  • Point Mutation
  • Protein Kinase Inhibitors / chemistry
  • Protein Kinase Inhibitors / pharmacokinetics
  • Protein Kinase Inhibitors / pharmacology*
  • Pyridazines / chemistry
  • Pyridazines / pharmacokinetics
  • Pyridazines / pharmacology
  • Receptor Protein-Tyrosine Kinases / antagonists & inhibitors*
  • Receptor Protein-Tyrosine Kinases / chemistry
  • Receptor Protein-Tyrosine Kinases / genetics
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases / antagonists & inhibitors


  • Isoenzymes
  • Protein Kinase Inhibitors
  • Pyridazines
  • MTOR protein, human
  • ALK protein, human
  • Alk protein, mouse
  • Anaplastic Lymphoma Kinase
  • Receptor Protein-Tyrosine Kinases
  • TOR Serine-Threonine Kinases
  • Sirolimus