Emergence of BCR-ABL kinase domain mutations associated with newly diagnosed chronic myeloid leukemia: a meta-analysis of clinical trials of tyrosine kinase inhibitors.

backgroundTyrosine kinase inhibitors (TKIs) are a mainstay of treatment for patients suffering from chronic myeloid leukemia (CML). Testing for various mutations in the BCR-ABL gene may help predict lack of response to specific TKIs where resistance has developed.

objectiveTo estimate the emergence of BCR-ABL kinase domain mutations associated with newly diagnosed CML patients exposed to first-line TKI treatment.

methodsPublished studies were identified using a structured search of online databases. Original research studies were included if they reported the incidence of specific BCR-ABL kinase domain point mutations after first-line TKI treatment failure or baseline mutations for second-line TKI treatment following first-line treatment failure. Meta-analysis of mutation rates across studies was based on DerSimonian and Laird's random-effects model.

resultsOf 1,323 citations, 12 studies met the inclusion criteria, involving a total of 1,698 patients. Overall mutation rates (95% CI) were imatinib 9.7% (6.2%-13.3%); dasatanib 1.7% (0.0%-4.3%); and nilotinib 3.3% (0.0%-7.7%). The most common specific mutations were T315I, E255K, and M351T. T315I mutations constituted 58% (7 of 12) of dasatinib-related mutations and 13% (15 of 117) of imatinib-related mutations.

conclusionsLack of response to TKIs associated with mutation in the BCR-ABL gene was significantly higher in imatinib-treated patients, and all mutations arose after treatment. T315I was a common treatment-emergent mutation. Further research is needed to assess the prognostic value of testing for mutations and the economic implications of treatment-emergent mutations.