Clinical and prognostic significance of histamine monitoring in patients with CML during treatment with imatinib (STI571)

Identification of CD203c as a New Basophil-Specific Flow-Marker in Ph+ Chronic Myeloid Leukemia

Basophilia is a crucial prognostic variable in Ph-chromosome-positive chronic myeloid leukemia (CML). The ectoenzyme CD203c is an activation-linked surface antigen that is expressed specifically on basophil-committed progenitor cells and mature basophils. We examined the expression of CD203c on progenitors and/or basophils in 21 healthy donors and 44 patients with CML. As expected, the numbers of CD203c+ blood leukocytes were significantly higher in CML patients compared to controls (percentage of CD203c+ cells among viable cells in CML at diagnosis: 4.19 ± 3.68% vs. controls: 0.53 ± 0.23%, p < 0.05). Moreover, CML basophils expressed higher levels of CD203c compared to normal basophils (median staining-index in CML at diagnosis: 29.41 ± 19.14 versus controls: 20.44 ± 13.45). We also found that the numbers and percentage of circulating CD203c+ cells at diagnosis correlate with the disease-related risk-profile. Incubation of CML basophils with an anti-IgE-antibody resulted in further upregulation of CD203c. After successful treatment with imatinib and/or other BCR::ABL1 inhibitors leading to major or complete molecular responses, the numbers of CD203c+ basophils decreased substantially in our CML patients compared to pre-treatment values. Together, CD203c is overexpressed on CML basophils, is further upregulated by IgE receptor cross-linking, and may serve as a biomarker to quantify basophilia in patients with CML at diagnosis and during therapy.

[The basophil: From control of immunity to control of leukemias]

The basophils, first described by Paul Ehlrich in 1879, are rare circulating cells, representing approximately 0.01 to 0.3% of the blood leukocytes. Until recently, these cells have been neglected because of their minority status among immune cells and because they show some similarities to mast cells residing in tissues. However, basophils and mast cells are now recognized as distinct cell lines and it appears that basophils have important and non-redundant functions, distinct from those of mast cells. On the one hand, basophils have beneficial contribution to protective immunity, in particular against parasitic infections. On the other hand, basophils are involved in the development of various benign and malignant pathologies, ranging from allergy to certain leukemias. Basophils interact with other immune cells or neoplastic cells through direct contacts or soluble mediators, such as cytokines and proteases, thus contributing to the regulation of the immune system but also to allergic responses, and probably to the process of neoplastic transformation. In this review, we will develop recent knowledge on the involvement of basophils in the modulation of innate and adaptive immunity. We will then describe the benign or malignant circumstances in which an elevation of circulating basophils can be observed. Finally, we will discuss the role played by these cells in the pathophysiology of certain leukemias, particularly during chronic myeloid leukemia.

The underestimated role of basophils in Ph+ chronic myeloid leukaemia

Chronic myeloid leukaemia (CML) is a hematopoietic neoplasm defined by the chromosome translocation t(9;22) and the related oncogene, BCR-ABL1. In most patients, leukaemic cells can be kept under control using BCR-ABL1-targeting drugs. However, many patients relapse which remains a clinical challenge. In particular, patients with advanced (accelerated or blast phase) CML have a poor prognosis. So far, little is known about molecular and cellular interactions and features that contribute to disease progression and drug resistance in CML. One key prognostic factor at diagnosis is marked basophilia. However, although basophils are well-known multifunctional effector cells, their impact in CML remains uncertain. In this article, we discuss the potential role of basophils as active contributors to disease evolution and progression in CML. In particular, basophils serve as a unique source of inflammatory, angiogenic and fibrogenic molecules, such as vascular endothelial growth factor or hepatocyte growth factor. In addition, basophils provide vasoactive substances, like histamine as well as the cytokine-degrading enzyme dipeptidyl-peptidase IV which may promote stem cell mobilization and the extramedullary spread of stem and progenitor cells. Finally, basophils may produce autocrine growth factors for myeloid cells. Understanding the role of basophils in CML evolution and progression may support the development of more effective treatment concepts.

Standard treatment of Ph+ CML in 2010: how, when and where not to use what BCR/ABL1 kinase inhibitor?

Chronic myeloid leukaemia (CML) is a haematopoietic neoplasm characterised by the BCR/ABL1 oncoprotein. In chronic phase CML, the neoplastic clone exhibits multilineage differentiation and maturation capacity. The BCR/ABL1 kinase blocker imatinib shows major antileukaemic effects in most patients and is considered standard frontline therapy. However, not all patients have a long-lasting response to imatinib. Notably, resistance to imatinib has been recognised as an emerging problem and challenge in CML. Whereas CML stem cells are considered to exhibit intrinsic resistance, acquired resistance may, in addition, develop in subclones over time, resulting in an overt relapse. A key trigger of resistance in subclones are BCR/ABL1 mutations. For such patients, novel multikinase inhibitors such as nilotinib, dasatinib, bosutinib or bafetinib, which block the kinase activity of various BCR/ABL1 mutants, have been developed and reportedly exert antileukaemic effects in drug-resistant cells. For highly resistant patients, haematopoietic stem cell transplantation is an alternative option. Treatment decisions and the selection of drugs are based on the presence and type of BCR/ABL1 mutation(s), phase of disease, other disease-related variables and patient-related factors including age, compliance and co-morbidity. The current review provides an overview on standards in the diagnosis and therapy in CML, with special reference to novel BCR/ABL1 inhibitors.

Mean cell volume can be an early predictor for the cytogenetic response of chronic myeloid leukemia patients treated with imatinib?

Imatinib-induced macrocytic anemia was known to result from c-kit inhibition in chronic myeloid leukemia (CML). However, recent studies showed that the prevalence of anemia is increased with high trough imatinib level and increased doses of imatinib influence decreased proliferation of burst forming units-erythroids (BFU-Es). The aim of this study was to evaluate the continuously increased mean cell volume (MCV) level's correlation with cytogenetic response and the favorable outcome in early chronic phase (CP)-CML patients. Clinical importance of MCV level was evaluated to correlate with cytogenetic response and compared with Sokal score, a known excellent prognostic parameter of cytogenetic response (CCR) in 84 early CP-CML patients. The patients with early and continuously increased MCV level irrespective of anemia achieved higher CCR after 12 months of imatinib therapy than patients with non-CCR (p=0.011). When the value was compared with low Sokal score, elevated MCV was independent predictor of CCR (RR=12.925, p=0.002 vs. RR=35.445, p<0.001). Furthermore, the patients with early and continuously increased MCV level had a higher probability of maintaining CCR than non-increased level (p=0.019). Increased MCV level was surrogate marker of achievement and durability to CCR for early CP-CML patients in the present study.

Diagnostic and prognostic value of new biochemical and immunohistochemical parameters in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a stem-cell disease characterized by multilineage expansion of clonal BCR/ABL+ cells. Transformation from chronic into accelerated and blast phase of CML is usually associated with drug resistance and is accompanied by typical clinical and/or laboratory features, such as splenomegaly, increase in precursor cells, disturbed megakaryopoiesis, basophilia or marrow fibrosis. Because of new treatment options, early recognition of disease-acceleration is of importance. In this article, we review most recent developments in diagnostic procedures employing basophil-related biochemical and histopathological markers. These tests are useful to quantitate basophil-lineage cells in the peripheral blood in CML, to determine and quantify basophilia in the bone marrow, and to detect focal accumulations of blast cells and megakaryocytes as well as increased angiogenesis and fibrosis in bone marrow sections. Application of these markers may assist in determining the phase of disease and may help to better predict the prognosis in individual patients.