Molecular analysis and the characterization of imatinib-resistant mutations can aid timely therapeutic decisions.

(A) A 3-fold rise in BCR-ABL prompted mutation analysis. Imatinib failure was confirmed by the detection of the highly imatinib-resistant Y253H mutation, which became detectable after F317L. Y253H is one of the least sensitive mutations to nilotinib and F317L has been identified in dasatinib resistance screens. Dasatinib was commenced prior to matched unrelated donor (MUD) transplantation to maintain response. (B) The corresponding bone marrow (BM) cytogenetic analyses indicated maintenance of complete cytogenetic response (CCR), and these analyses did not contribute to early warning of imatinib failure that was evident by molecular analysis.