Search

Objective: To evaluate hematological, cytogenetic and molecular responses as well as the overall, progression-free and event-free survivals of chronic myeloid leukemia patients treated with a third tyrosine kinase inhibitor after failing to respond to imatinib and nilotinib/dasatinib., Methods: Bone marrow karyotyping and real-time quantitative polymerase chain reaction were performed at baseline and at 3, 6, 12 and 18 months after the initiation of treatment with a third tyrosine kinase inhibitor. Hematologic, cytogenetic and molecular responses were defined according to the European LeukemiaNet recommendations. BCR-ABL1 mutations were analyzed by Sanger sequencing., Results: We evaluated 25 chronic myeloid leukemia patients who had been previously treated with imatinib and a second tyrosine kinase inhibitor. Nine patients were switched to dasatinib, and 16 patients were switched to nilotinib as a third-line therapy. Of the chronic phase patients (n=18), 89% achieved a complete hematologic response, 13% achieved a complete cytogenetic response and 24% achieved a major molecular response. The following BCR-ABL1 mutations were detected in 6/14 (43%) chronic phase patients: E255V, Y253H, M244V, F317L (2) and F359V. M351T mutation was found in one patient in the accelerated phase of the disease. The five-year overall, progression-free and event-free survivals were 86, 54 and 22% (p<0.0001), respectively, for chronic phase patients and 66%, 66% and 0% (p<0.0001), respectively, for accelerated phase patients. All blast crisis patients died within 6 months of treatment. Fifty-six percent of the chronic phase patients lost their hematologic response within a median of 23 months., Conclusions: Although the responses achieved by the third tyrosine kinase inhibitor were not sustainable, a third tyrosine kinase inhibitor may be an option for improving patient status until a donor becomes available for transplant. Because the long-term outcome for these patients is poor, the development of new therapies for resistant chronic myeloid leukemia patients is necessary.

The introduction of oral tyrosine kinase inhibitors (TKIs) has dramatically improved outcomes in chronic myeloid leukemia (CML) patients. However, treatment success is directly related to good long-term adherence. Adherence to TKI therapy was evaluated in 137 CML patients over a period of 1 year. Three different methods were used to evaluate adherence: the Morisky questionnaire, a medication diary and the medication possession ratio (MPR). MPR was the most effective method of assessing adherence (median adherence 96.5%; p = 0.0001), duration of TKI treatment was the variable that most impacted adherence (p = 0.03), and the MPR was inversely correlated to the duration of therapy. Additionally, participation in clinical trials, better quality of life as reported by patients and higher socioeconomic status were all related to better compliance (p = 0.02, 0.007 and 0.01, respectively). For patients treated with imatinib for 24-48 months (n = 22), individuals with major molecular response (MMR) had a significantly better MPR than those who failed to achieve MMR (p = 0.04). In this group, the mean MPR was 87% for the population without apparent molecular response and 96% for those achieving MMR; however, only 24% of the patients were completely adherent to TKI treatment., (Copyright © 2013 S. Karger AG, Basel.)

PURPOSE Patients with chronic myelogenous leukemia in accelerated phase (CML-AP) that is resistant or intolerant to imatinib have limited therapeutic options. Dasatinib, a potent inhibitor of BCR-ABL and SRC-family kinases, has efficacy in patients with CML-AP who have experienced treatment failure with imatinib. We now report follow-up data from the full patient cohort of 174 patients enrolled onto a phase II trial to provide a more complete assessment of the efficacy and safety of dasatinib in this population. PATIENTS AND METHODS Patients with imatinib-resistant (n = 161) or -intolerant (n = 13) CML-AP received dasatinib 70 mg orally twice daily. Results At a median follow-up of 14.1 months (treatment duration, 0.1 to 21.7 months), major and complete hematologic responses were attained by 64% and 45% of patients, respectively, and major and complete cytogenetic responses were achieved in 39% and 32% of patients, respectively. Responses were achieved irrespective of imatinib status (resistant or intolerant), prior stem-cell transplantation, or the presence of prior BCR-ABL mutation. The 12-month progression-free survival and overall survival rates were 66% and 82%, respectively. Dasatinib was generally well tolerated; the most frequent nonhematologic severe treatment-related adverse event was diarrhea (52%; grade 3 to 4, 8%). Cytopenias were common, including grade 3 to 4 neutropenia (76%) and thrombocytopenia (82%). Pleural effusion occurred in 27% of patients (grade 3 to 4, 5%). CONCLUSION Dasatinib is effective in patients with CML-AP after imatinib treatment failure.

Point mutations within the ABL kinase domain are the most frequent mechanism for reactivation of kinase activity of the BCR-ABL gene and have been associated with clinical resistance to tyrosine kinase (TK) inhibitors in patients with CML, conferring a poor prognosis. T315I (Treonine-->Isoleucine) is a mutation in the exon 6 of BCR-ABL gene that makes the protein resistant to kinase inhibitors currently used for treating CML. Denaturing High-performance liquid chromatography (D-HPLC) allows for high throughput mutation screening. In this study, we screened mutations in exon 6 of the BCR-ABL gene in patients presenting failure or sub optimal response according to Leukemia Net criteria and correlated the presence of mutations with clinical outcome. Genomic DNA was extracted from peripheral blood samples from 93 patients with CML (5 intolerant and 88 resistant). The PCR product was analysed by D-HPLC, and the patients samples with abnormal D-HLPC profiles were submitted to automated sequencing, using specific primers. Overall survival (OS) was calculated from the date of mutation analysis, for the whole group and for both groups (mutation versus no mutation). We screened mutations in exon 6 of the BCR-ABL gene in 93 CML TKI - resistant patients. Twenty-three out of 93 samples (25%) showed an abnormal elution profile. Automated sequencing confirmed the presence of a nucleotide change in 19 out of 23 cases: one polymorphism, T315T, seven known point mutations: T315I, F317L, V339L, M351T, E355G and F359V and three novel mutations: C305R, D325D and I360S. OS for the whole group was 80% in a median observation time of 30 months. OS for patients without the mutation was 87% and with the mutation was 56%, in a median observation time of 37 and 10 months, respectively (p < 0.0001, RR = 68). D-HPLC is a practical and sensitive method for routine clinical monitoring for emergence of kinase domain mutations and may be useful for optimising therapy in CML. The screening of mutations in exon 6 is clinically relevant, once the presence of mutations confers a poor outcome. Early detection of emerging mutant clones may help in decision-making for alternative treatment.

Treatment options are limited for patients with imatinib-resistant or -intolerant accelerated phase chronic myeloid leukemia (CML-AP). Dasatinib is a novel, potent, oral, multitargeted kinase inhibitor of BCR-ABL and SRC-family kinases that showed marked efficacy in a phase 1 trial of patients with imatinib-resistant CML. Results are presented for 107 patients with CML-AP with imatinib-resistance or -intolerance from a phase 2, open-label study further evaluating dasatinib efficacy and safety. At 8 months' minimum follow-up, 81%, 64%, and 39% of patients achieved overall, major (MaHR), and complete hematologic responses, respectively, whereas 33% and 24% attained major and complete cytogenetic remission. Of 69 patients who achieved MaHR, 7 progressed. Seventy-six percent of patients are estimated to be alive and progression-free at 10 months. Response rates for the 60% of patients with baseline BCR-ABL mutations did not differ from the total population. Dasatinib was well tolerated: most nonhematologic adverse events (AEs) were mild to moderate; no imatinib-intolerant patients discontinued dasatinib because of AEs. Although common (76% of patients with severe neutropenia), cytopenias were manageable through dose modification. In summary, dasatinib induced significant hematologic and cytogenetic responses in patients with imatinib resistance or intolerance, was well tolerated, and may represent a potent new therapeutic option for CML-AP. Further follow-up is warranted. This trial was registered at www.clinicaltrials.gov as #CA180005.