Sequential inhibitor therapy in CML: in vitro simulation elucidates the pattern of resistance mutations after second- and third-line treatment

Clin Cancer Res. 2013 Jun 1;19(11):2962-72. doi: 10.1158/1078-0432.CCR-13-0052. Epub 2013 Apr 2.


Purpose: Dasatinib and nilotinib are active in imatinib-resistant chronic myelocytic leukemia (CML) and many patients undergo sequential treatment. We aimed at modeling sequential tyrosine kinase inhibitor (TKI) resistance in vitro to compare the sequences imatinib-nilotinib-dasatinib and imatinib-dasatinib-nilotinib.

Experimental design: We designed an in vitro model for sequential TKI resistance in CML. Replicates of imatinib-resistant cell lines were treated with dasatinib or nilotinib. Second-line resistant replicates were exposed to third-line treatment.

Results: Growth of all replicates in all three lines of treatment was associated with T315I. However, T315I occurred with low abundance and did not increase during sequential treatment. Nilotinib second-line more often gave rise to sequential resistance compared with dasatinib due to pre-existing P-loop mutations, especially at suboptimal drug concentration. In contrast, mutations predisposing to dasatinib resistance such as F317C/V and V299L did not occur before dasatinib exposure. Nilotinib third-line did not overcome imatinib-dasatinib resistance due to pre-existing T315I or P-loop/V299L or P-loop/F317 exchanges. Dasatinib third-line suppressed imatinib-nilotinib-resistant replicates with residual sensitivity.

Conclusions: Sequential acquisition of BCR-ABL drug resistance mutations in CML might be underestimated. Resistance to sequential TKI monotherapy in vitro more often was associated with stepwise acquisition of drug-specific compound mutations compared with T315I. Pre-existing mutations strongly limited the activity of both third-line treatments, and the activity of nilotinib second-line in vitro critically depended on drug concentration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Antineoplastic Agents / therapeutic use
  • Benzamides / pharmacology
  • Benzamides / therapeutic use
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Drug Resistance, Neoplasm / genetics*
  • Fusion Proteins, bcr-abl / genetics*
  • Humans
  • Imatinib Mesylate
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / drug therapy
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / genetics*
  • Mutation*
  • Piperazines / pharmacology
  • Piperazines / therapeutic use
  • Protein Kinase Inhibitors / pharmacology*
  • Protein Kinase Inhibitors / therapeutic use
  • Pyrimidines / pharmacology
  • Pyrimidines / therapeutic use


  • 4-methyl-N-(3-(4-methylimidazol-1-yl)-5-(trifluoromethyl)phenyl)-3-((4-pyridin-3-ylpyrimidin-2-yl)amino)benzamide
  • Antineoplastic Agents
  • Benzamides
  • Piperazines
  • Protein Kinase Inhibitors
  • Pyrimidines
  • Imatinib Mesylate
  • Fusion Proteins, bcr-abl