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Medline ® Abstract for Reference 21

of 'Treatment of chronic myeloid leukemia in chronic phase after failure of initial therapy'

Long-term outcome of patients with chronic myeloid leukemia treated with second-generation tyrosine kinase inhibitors after imatinib failure is predicted by the in vitro sensitivity of BCR-ABL kinase domain mutations.
Jabbour E, Jones D, Kantarjian HM, O'Brien S, Tam C, Koller C, Burger JA, Borthakur G, Wierda WG, Cortes J
Blood. 2009;114(10):2037. Epub 2009 Jun 30.
Secondary imatinib resistance in chronic myeloid leukemia (CML) is associated in approximately 50% of cases with mutations in the BCR-ABL kinase domain, necessitating switch to one of several new tyrosine kinase inhibitors (TKIs) that act differentially on mutated BCR-ABL. We assess here whether scoring mutation based on in vitro inhibitory concentration of each TKI-mutation pair can predict long-term clinical outcome. Among 169 patients with CML after imatinib failure, mutations were detected before TKI switch in 41 (48%) treated with dasatinib and 45 (52%) treated with nilotinib. Inhibitory concentration values for each TKI-mutation pair were stratified into high (n = 42), intermediate (n = 25), low (T315I, n = 9), or unknown sensitivity (n = 10). Hematologic and cytogenetic response rates were similar for patients with or without mutations. For patients in chronic phase, hematologic and cytogenetic responses correlated with mutation score; tumors with low and intermediate scores had lower response rates than those with highly sensitive mutations, and worse event-free and overall survival. These correlations with overall survival were not seen for advanced phases. Mutation scoring canpredict outcome in CML-chronic phase with imatinib failure treated with second-generation TKIs and can help in therapy selection. More complex prognostic models will be required for advanced stages of disease.
Department of Leukemia, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA.