Incidence and outcome of BCR-ABL mutated chronic myeloid leukemia patients who failed to tyrosine kinase inhibitors.

Purpose: To assess the incidence of BCR-ABL kinase domain (KD) mutation detection and its prognostic significance in chronic phase chronic myeloid leukemia (CP-CML) patients treated with tyrosine kinase inhibitors (TKIs).

Patients And Methods: We analyzed characteristics and outcome of 253 CP-CML patients who had at least one mutation analysis performed using direct sequencing. Of them, 187 patients were early CP (ECP) and 66 were late CP late chronic phase (LCP) and 88% were treated with Imatinib as first-line TKI.

Impact of second decline rate of BCR-ABL1 transcript on clinical outcome of chronic phase chronic myeloid leukemia patients on imatinib first-line.

Early molecular response has been associated with clinical outcome in chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors. The BCR-ABL1 transcript rate decline from baseline to 3 months has been demonstrated to be more predictive than a single BCR-ABL1 level at 3 months (M3). However, it cannot be used routinely because ABL1, as an internal gene control, is not reliable for BCR-ABL1 quantification above 10%.

α-defensin 1-3 and α-defensin 4 as predictive markers of imatinib resistance and relapse in CML patients.

Objective: Imatinib mesylate is a tyrosine kinase inhibitor used as first line treatment in chronic myeloid leukaemia. Despite a remarkable effectiveness, treatment failure cases have been reported in 20 percent of CML patients. The identification of biomarkers which can predict the response to imatinib is our point of interest.

Molecular remission in chronic myeloid leukemia patients with sustained complete cytogenetic remission after imatinib mesylate treatment.

Background And Objectives: Imatinib mesylate induces a complete cytogenetic response (CCR) in many patients with chronic myeloid leukemia (CML). However, the ultimate goal of therapy for CML is complete elimination of Philadelphia chromosome positive cells or BCR-ABL rearrangements. We studied molecular responses in CML patients in CCR after imatinib treatment.

Rapid detection of phosphotyrosine proteins by flow cytometric analysis in Bcr-Abl-positive cells.

Background: Constitutive tyrosine phosphorylation derived from Bcr-Abl kinase activity is the major characteristic of Bcr-Abl positive cells. In this study, we developed a method to detect the phosphotyrosine proteins by flow cytometry and we asked whether phosphorylation was affected by imatinib mesylate treatment.

Methods: Cells were treated or not with imatinib mesylate, fixed and permeabilized by PFA followed by saponin, then stained with anti-phosphotyrosine (p-tyr) monoclonal antibody and analyzed by flow cytometry.

MDR1 gene overexpression confers resistance to imatinib mesylate in leukemia cell line models.

Inappropriate expression of the multidrug resistance (MDR1) gene encoding the P-glycoprotein (Pgp) has been frequently implicated in resistance to different chemotherapeutic drugs. We have previously generated chronic myeloid leukemia (CML) cell lines resistant to the tyrosine kinase inhibitor imatinib mesylate (STI571), and one line (LAMA84-r) showed overexpression not only of the Bcr-Abl protein but also of Pgp. In the present study, we investigated this phenomenon in other cell lines overexpressing exclusively Pgp.

Mutation in the ATP-binding site of BCR-ABL in a patient with chronic myeloid leukaemia with increasing resistance to STI571.

The Abl kinase inhibitor STI571 (imatinib mesylate) induces haematological remissions in many patients with chronic myeloid leukaemia (CML) but advanced stage CML usually becomes resistant to STI571. We describe a patient in whom progressive resistance to STI571 correlated with the appearance of a mutation in the Bcr-Abl kinase domain. This was a G to A transition that resulted in a glutamic acid to lysine substitution at position 255 (E255K) in the Abl type 1a protein.