Screens, iron, and leukemia

Hepcidin expression in patients with acute leukaemia

BACKGROUND

Hepcidin plays a central role in iron homeostasis, which is regulated by iron stores, the rate of erythropoiesis, inflammation, and hypoxia. Aberrant expression of hepcidin was found in many diseases, however, there is scant information on hepcidin expression in acute leukemia (AL).

MATERIALS AND METHODS

32 patients with AL which diagnosis according to FAB criteria were studied. Serum hepcidin levels, erythropoietin (EPO), interleukin-6 (IL-6), hematological parameters, intracellular and extracellular iron store were evaluated.

RESULTS

Hepcidin was elevated significantly with increased iron storage in patients at onset of AL when erythropoiesis was depressed by blast cells, then decreased significantly with AL remission, while soluble transferrin receptor (sTfR) concentration was elevated. Negative correlations were found between serum hepcidin and erythropoietic markers including RBC, Hb, Ret and sTfR. Positive correlations were shown between hepcidin and ferritin, between hepcidin and ratio of sideroblasts, as well as between hepcidin and IL-6.

CONCLUSIONS

Hepcidin production was regulated by iron stores, inflammation and erythropoietic activity in AL patients. Erythropoietic activity may play the main role among the regulators of hepcidin expresssion.

Tyrosine kinase inhibitors in acute and chronic leukemias

INTRODUCTION

Since the initial approval of imatinib much has been learned about its resistance mechanisms, and efforts have continued to improve upon BCR-ABL tyrosine kinase inhibitor therapy. Targeted therapy with TKIs has continued to be an area of active research and development in the care of acute and chronic leukemia patients.

AREAS COVERED

This article reviews current approved and investigational TKI treatments for chronic myelogenous leukemia (CML), Philadelphia-chromosome positive acute lymphoblastic leukemia (Ph + ALL) and acute myelogenous leukemia (AML).

EXPERT OPINION

There are now more potent BCR-ABL TKIs approved, which allow for additional options when determining front-line and second-line CML and Ph + ALL treatments. The T315I mutation is an ever-present challenge. Ponatinib, a pan BCR-ABL TKI, while still under investigation, is very hopeful with its ability to overcome T315I mutations in resistant CML and Ph + ALL patients. Because nilotinib and dasatinib have not been directly compared, at present we recommend selecting one or the other based on the side-effect profile, drug interactions, patient comorbidities, and mutational status. FLT-3 inhibition is of particular interest in AML patients with FLT-3 internal tandem duplication mutations; this type of targeted therapy continues to be studied.

Targeting the FMS-like tyrosine kinase 3 in acute myeloid leukemia

Acute myeloid leukemia (AML) is a highly heterogenous disease with multiple signaling pathways contributing to its pathogenesis. A key driver of AML is the FMS-like tyrosine kinase receptor-3 (FLT3). Activating mutations in FLT3, primarily the FLT3-internal tandem duplication (FLT3-ITD), are associated with decreased progression-free and overall survival. Identification of the importance of FLT3-ITD and the FLT3 pathway in the prognosis of patients with AML has stimulated efforts to develop therapeutic inhibitors of FLT3. Although these inhibitors have shown promising antileukemic activity, they have had limited efficacy to date as single agents and may require use in combination with cytotoxic chemotherapies. Here, we review clinical and preclinical results for the clinically mature FLT3 inhibitors currently in development. We conclude that multitargeted FLT3 inhibitors may have more utility earlier in the course of disease, when in vitro evidence suggests that AML cells are less dependent on FLT3 signaling, perhaps because of upregulation of multiple other signaling pathways. More potent agents may have greater utility in relapsed and heavily pretreated patients, in whom high levels of circulating FLT3 ligand may necessitate use of an agent with a very favorable pharmacokinetic/pharmacodynamic profile. Novel combination regimens are also discussed.

[Current treatment options in acute myeloid leukemia]

Genetic aberrations form the basis for diagnostic classification of patients with acute myeloid leukemia (AML) according to the World Health Organization (WHO) classification. Moreover, these aberrations predict response to induction chemotherapy, relapse-free survival, and overall survival of patients with AML. Understanding the pathogenetic role of cytogenetic and molecular changes has led to the development of targeted treatment strategies that require rapid diagnostic assessment of the genetic profile of each patient to select the best treatment available.

Emerging FMS-like tyrosine kinase 3 inhibitors for the treatment of acute myelogenous leukemia

INTRODUCTION

The FMS-like tyrosine kinase 3 (FLT3) is highly expressed in acute leukemias. Mutations involving FLT3 are among the most common molecular abnormalities in acute myelogenous leukemia (AML). Available evidence suggests that these molecular lesions confer a shorter disease-free survival and overall survival in patients with intermediate-risk cytogenetics. Therefore, substantial interest in FLT3 as a therapeutic target has led to the development of several promising inhibitors that target this tyrosine kinase.

AREAS COVERED

This review covers the molecular pathways associated with FLT3 activation in patients with AML, the biological rationale for inhibiting FLT3 and recent clinical progress with FLT3 inhibitors for the treatment of AML. Six FLT3 inhibitors undergoing clinical evaluation are discussed. A review of selected published manuscripts on the subject of FLT3 inhibition in AML and a search of the English language manuscripts in PubMed using the index words FLT3 and AML were conducted and articles of interest selected.

EXPERT OPINION

Mutated forms of FLT3, specifically FLT3-internal tandem duplication, have a significant impact on the prognosis of AML patients, particularly those with a normal karyotype. Inhibiting FLT3 may lead to clinical benefit for patients with AML. Newly developed FLT3 inhibitors have shown encouraging activity as monotherapy and in combination with other therapeutic agents.