'Real-life' study of imatinib therapy in chronic phase-chronic myeloid leukemia: A novel retrospective observational longitudinal analysis

OBJECTIVES

Imatinib is a cornerstone of treatment of chronic myeloid leukemia. It remains unclear whether transient treatment discontinuation or dose changes affect outcome and this approach has not yet been approved for use outside clinical trials.

METHODS

We conducted a retrospective single-institution observational study to evaluate factors affecting response in 'real-life' clinical practice in 138 chronic myeloid leukemia patients in chronic phase treated with imatinib. We used a novel longitudinal data analytical model, with a generalized estimating equation model, to study BCR-ABL variation according to continuous standard dose, change in dose or discontinuation; BCR-ABL transcript levels were recorded. Treatment history was subdivided into time periods for which treatment was given at constant dosage (total 483 time periods). Molecular and cytogenetic complete response was observed after 154 (32%) and 358 (74%) time periods, respectively.

RESULTS

After adjusting for length of time period, no association between dose and cytogenetic complete response rate was observed. There was a significantly lower molecular complete response rate after time periods at a high imatinib dosage.

DISCUSSION

This statistical approach can identify individual patient variation in longitudinal data collected over time and suggests that changes in dose or discontinuation of therapy could be considered in patients with appropriate biological characteristics.

Induction of heme oxygenase-1 by Na+-H+ exchanger 1 protein plays a crucial role in imatinib-resistant chronic myeloid leukemia cells

Resistance toward imatinib (IM) and other BCR/ABL tyrosine kinase inhibitors remains troublesome in the treatment of advanced stage chronic myeloid leukemia (CML). The aim of this study was to estimate the reversal effects of down-regulation of Na(+)/H(+) exchanger 1 (NHE1) on the chemoresistance of BCR-ABL-positive leukemia patients' cells and cell lines. After treatment with the specific NHE1 inhibitor cariporide to decrease intracellular pH (pHi), the heme oxygenase-1 (HO-1) levels of the K562R cell line and cells from IM-insensitive CML patients decreased. HO-1, as a Bcr/Abl-dependent survival molecule in CML cells, is important for the resistance to tyrosine kinase inhibitors in patients with newly diagnosed CML or IM-resistant CML. Silencing PKC-β and Nrf-2 or treatment with inhibitors of p38 pathways obviously blocked NHE1-induced HO-1 expression. Furthermore, treatment with HO-1 or p38 inhibitor plus IM increased the apoptosis of the K562R cell line and IM-insensitive CML patients' cells. Inhibiting HO-1 enhanced the activation of caspase-3 and poly(ADP-ribose) polymerase-1. Hence, the results support the anti-apoptotic role of HO-1 induced by NHE1 in the K562R cell line and IM-insensitive CML patients and provide a mechanism by which inducing HO-1 expression via the PKC-β/p38-MAPK pathway may promote tumor resistance to oxidative stress.

How I treat newly diagnosed chronic myeloid leukemia in 2015

The initial treatment for chronic myeloid leukemia in chronic phase (CP-CML) represents a complex process, which includes a prompt and precise diagnosis, the choice among three available tyrosine kinase inhibitors (TKIs), and the initial management of care for these patients, which will protract over a very long period of time. This manuscript summarizes different data on activity, side effects, and supportive measures available for each TKI, the need for particular care in the logistical organization of CML management, the scenario which will be opened by the future availability of generic imatinib. The opinion of the authors is that imatinib remains the first-line treatment for CP-CML; this strategy, accompanied by intensive monitoring and possible dose modification/drug switch after the initial 3-12 months of treatment presently assures a normal life expectancy to the population of newly diagnosed patients with CP-CML.

Practical issues surrounding the explosion of tyrosine kinase inhibitors for the management of chronic myeloid leukemia

The advent of tyrosine kinase inhibitors (TKIs) has drastically changed the treatment outcome of chronic myeloid leukemia (CML). Imatinib was the first TKI approved, and has been considered the standard of care for more than a decade. Second generation compounds, namely dasatinib and nilotinib, are highly effective in newly diagnosed patients as well as those who fail imatinib. Bosutinib and ponatinib have also become available as second line options. With five agents from which to choose, selecting a TKI has become a challenge. Multiple tests are now available to determine a patient's disease status, making the ideal monitoring strategy unclear. The gold standard for response to TKI therapy remains the achievement of complete cytogenetic response. This review will discuss the practical aspects of selecting a TKI and monitoring a patient once on therapy, including when to consider a treatment change. Other relevant issues, including cost, compliance, role of allogeneic hematopoietic cell transplantation, and discontinuation of TKIs will also be covered.

Should persons with acute myeloid leukemia have a transplant in first remission?

Despite more than 40 years of extensive study, it remains uncertain which individuals, if any, with acute myelogenous leukemia (AML) in first remission should receive a blood cell or bone marrow transplant versus post-remission chemotherapy (or both). Nevertheless, there is a recent trend toward recommending more transplants in this setting. We consider four myths underlying this recommendation: (1) only individuals achieving second remission benefit from a transplant; (2) there is no effective therapy for relapse other than an allotransplant; (3) we can accurately predict which individuals with AML in first remission need a transplant; and (4) detection of minimal residual disease in first remission will resolve this controversy. We discuss these misconceptions and suggest approaches to resolve this issue.