A gene expression signature of primary resistance to imatinib in chronic myeloid leukemia.

Using gene expression profiling we show that the expression of 105-probe sets in mononuclear cells collected from chronic myeloid leukemia (CML) chronic phase (CP) patients with raised leukocyte counts who subsequently achieved complete cytogenetic response after 12 months on imatinib, differed substantially from that of patients who failed to achieve any degree of cytogenetic response. In the non-responder cohort, 9 of the 50 overexpressed genes were involved in DNA repair by homologous recombination, whereas 36 genes, including PTEN, were downregulated. This pattern of altered gene expression in responders and non-responders was validated in another independent dataset. These findings may prove useful for identifying at the time of diagnosis a subset of CP-CML patients who are likely to be resistant to imatinib and require an alternative treatment.