Chronic myeloid leukemia patients with the e13a2 BCR-ABL fusion transcript have inferior responses to imatinib compared to patients with the e14a2 transcript.

BACKGROUND: Chronic myeloid leukemia is characterized by a reciprocal translocation between chromosomes 9 and 22, creating the fusion gene BCR-ABL. The clinical significance of the type of BCR-ABL transcript in newly diagnosed patients in chronic phase treated with imatinib 400 mg from initial diagnosis remains unknown. DESIGN AND METHODS: We analyzed the clinical outcome of 78 newly diagnosed chronic phase patients, aged 16 or over, treated with imatinib 400 mg. Of these, 71 expressed either e13a2 or e14a2 transcripts. BCR-ABL transcripts were assayed by quantitative real-time polymerase chain reaction. RESULTS: After 12 months of treatment, 54% of the e14a2 patients had achieved a complete cytogenetic response, compared to 25% of the e13a2 patients (p=0.01). Kaplan-Meier analysis of the time to achieve complete cytogenetic response revealed that e14a2 patients had more rapid response rates, compared to e13a2 patients (p=0.006). e14a2 patients had a higher event-free survival rate in the first 12 months of treatment, although overall survival did not differ significantly between the patients with the two types of transcript. Human organic cation transporter protein 1 mRNA levels did not differ between the patients with the two types of transcript. The pre-treatment pCrKL/CrKL ratio (a surrogate marker of BCR-ABL tyrosine kinase activity) was higher in patients with e13a2 transcripts than in those with e14a2 (p=0.017). CONCLUSIONS: Patients expressing the e14a2 transcript type have a higher rate and more rapid complete cytogenetic responses than e13a2-expressing patients, which may be due to higher BCR-ABL tyrosine kinase activity. Knowledge of the transcript type may yield additional prognostic information, although this requires testing on larger datasets.

The role of serial BCR-ABL transcript monitoring in predicting the emergence of BCR-ABL kinase mutations in imatinib-treated patients with chronic myeloid leukemia.

BCR-ABL kinase mutations may confer resistance to imatinib in patients with chronic myeloid leukemia (CML), and may predict a poor outcome. We investigated whether rises in BCR-ABL transcript levels predicted mutation development in 82 CML patients receiving imatinib. Eleven mutations were detected in 10 patients. A single 2-fold or greater rise in BCR-ABL transcript did not predict mutations. However, a mutation was detectable in five of six cases with progressively rising levels of transcripts. In contrast, consecutive rises were not seen in any of 33 stable responders. Rising BCR-ABL transcript levels can identify patients who developBCR-ABLmutations. A serial rise is more reliable than a single rise.

A population study showing that the advent of second generation tyrosine kinase inhibitors has improved progression-free survival in chronic myeloid leukaemia.

BACKGROUND: Population based data suggest the proportion of patients failing imatinib in chronic myeloid leukaemia (CML) is higher than the reported one-third of patients in clinical trials. Clinical trials have demonstrated second generation tyrosine kinase inhibitors (TKI) dasatinib and nilotinib can restore complete cytogenetic remission (CCR) and major molecular response (MMR) to many patients failing imatinib, but their impact in the general population is not clear. DESIGN AND METHODS: We report CML outcome in a population of 2.3 million people in a geographically contiguous area of North West England and North Wales. RESULTS: Between 2003 and 2009, 192 new CML cases were diagnosed, of whom 184 were in chronic phase and 160 started on imatinib. The maximal CCR rate was 65% at 24 months and the maximal MMR rate was 50% at 36 months. Patients diagnosed since second generation TKI became available for imatinib failure had a more rapid cumulative CCR and MMR rate and a significantly improved progression free survival (p=0.022) than those diagnosed before this time. CONCLUSION: The study indicates that second generation TKI have improved CML outcome in the general population.

A prospective evaluation of cardiac function in patients with chronic myeloid leukaemia treated with imatinib.

In vitro studies have suggested that imatinib may be toxic to cardiac myocytes. Though retrospective studies have not shown clinical heart failure, these did not look for subtle cardiac damage. We have carried out a prospective cardiac assessment in 59 chronic myeloid leukaemia (CML) patients treated with imatinib for a median of 3.4 years, using echocardiography and MUGA scanning, with the latter repeated after a further year. We report no evidence of myocardial deterioration, either at baseline or over 12 months of imatinib treatment. Imatinib cardiotoxicity is not an important clinical consideration for CML patients or their advisors.

BCR-ABL peptide vaccination in healthy subjects: immunological responses are equivalent to those in chronic myeloid leukaemia patients.

We and others have reported that vaccination of chronic myeloid leukaemia (CML) patients with e14a2 BCR-ABL junctional peptides can elicit moderate but transient T cell responses. To determine whether CML patients may be tolerised to BCR-ABL, here we used the same schedule to vaccinate 5 healthy subjects. Although IFN-γ and granzyme-B production, and proliferative responses to the vaccine peptides were detected in all 5 cases, responses were statistically similar to CML patients. CML patients are therefore not appreciably tolerised to BCR-ABL, and junctional peptides may only be moderately immunogenic, underlining the importance of antigen immunogenicity when designing vaccination strategies.

Naturally occurring CD4+ CD25+ FOXP3+ T-regulatory cells are increased in chronic myeloid leukemia patients not in complete cytogenetic remission and can be immunosuppressive.

OBJECTIVE: Clinical presentation of chronic myeloid leukemia (CML) requires not only the deregulated tyrosine kinase BCR-ABL, but also the failure of an immune response against BCR-ABL-expressing cells. T-cell responses against BCR-ABL and other antigens are well-described, but their relevance to the in vivo control of CML is unclear. The suppressive role of naturally occurring T regulatory (T-reg) cells in antitumor immunity is well-established, although little is known about their role in modulating the T-cell response to BCR-ABL. MATERIALS AND METHODS: Naturally occurring T-reg cells were characterized and quantified by flow cytometry in 39 CML patients and 10 healthy donors. Their function was studied by observing their effect on responses to purified protein derivative, a recall antigen, and on the response of an autologous T-cell line recognizing BCR-ABL. RESULTS: T-reg cells were CD4(+), CD25(+), FOXP3(+), CD127(low), and CD62L(high). T-reg numbers in patients in complete cytogenetic remission were significantly lower than in patients not in complete cytogenetic remission (p < 0.01). T-reg cell depletion using anti-CD25 selection enhanced proliferative responses to purified protein derivative. Furthermore, the interferon-γ and/or granzyme-B production of effector cells specific for viral peptides or a BCR-ABL HLA-A3-restricted peptide was inhibited when autologous T-reg cells were present. CONCLUSIONS: Taken together, these data suggest a role for T-reg cells in limiting immune responses in CML patients and this may include immune responses to BCR-ABL. The increased frequency of T-reg cells in patients with high levels of BCR-ABL transcripts indicates that an immune mechanism may be important in the control of CML.

Simultaneous determination of nilotinib, imatinib and its main metabolite (CGP-74588) in human plasma by ultra-violet high performance liquid chromatography.

We describe a high performance liquid chromatography (HPLC) method that separates two of the currently licenced tyrosine kinase inhibitors (TKIs); nilotinib (AMN107, Tasigna) and imatinib (STI571, Glivec), together with its main metabolite, CGP-74588, from human plasma. After solid phase extraction the drug mix was separated through a Gemini C6-phenyl column (150 mm x 4.6mm, i.d.; 5 microm) (Phenomenex), UK) under isocratic mobile phase conditions of methanol:50mM ammonium acetate (pH 8) (65:35, v/v) with ultra-violet (UV) detection at 260 nm wavelength. For all compounds the intra-day coefficient of variation and bias were <3% and <5% respectively; and inter-day were <4% and <9%. This simple and novel method may be used to quantify levels of TKIs when used alone or in combination with drug treatments for clinical samples.