The BCR-ABL35INS insertion/truncation mutant is kinase-inactive and does not contribute to tyrosine kinase inhibitor resistance in chronic myeloid leukemia.

Division of Hematology and Medical Oncology, Oregon Health & Science University Knight Cancer Institute, Portland, USA.
Blood (Impact Factor: 9.78). 09/2011; 118(19):5250-4. DOI: 10.1182/blood-2011-05-349191
Source: PubMed

ABSTRACT Chronic myeloid leukemia is effectively treated with imatinib, but reactivation of BCR-ABL frequently occurs through acquisition of kinase domain mutations. The additional approved ABL tyrosine kinase inhibitors (TKIs) nilotinib and dasatinib, along with investigational TKIs such as ponatinib (AP24534) and DCC-2036, support the possibility that mutation-mediated resistance in chronic myeloid leukemia can be fully controlled; however, the molecular events underlying resistance in patients lacking BCR-ABL point mutations are largely unknown. We previously reported on an insertion/truncation mutant, BCR-ABL(35INS), in which structural integrity of the kinase domain is compromised and all ABL sequence beyond the kinase domain is eliminated. Although we speculated that BCR-ABL(35INS) is kinase-inactive, recent reports propose this mutant contributes to ABL TKI resistance. We present cell-based and biochemical evidence establishing that BCR-ABL(35INS) is kinase-inactive and does not contribute to TKI resistance, and we find that detection of BCR-ABL(35INS) does not consistently track with or explain resistance in clinical samples from chronic myeloid leukemia patients.

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