A review of the therapeutic agents used in the management of polycythaemia vera

Simply red: A novel spectrophotometric erythroid proliferation assay as a tool for erythropoiesis and erythrotoxicity studies

Most mammalian cell proliferation assays rely on manual or automated cell counting or the assessment of metabolic activity in colorimetric assays, with the former being either labor and time intensive or expensive and the latter being multistep procedures requiring the addition of several reagents. The proliferation of erythroid cells from hematopoietic stem cells and their differentiation into mature red blood cells is characterized by the accumulation of large amounts of hemoglobin. Hemoglobin concentrations are easily quantifiable using spectrophotometric methods due to the specific absorbance peak of the molecule’s heme moiety between 400 and 420 nm. Erythroid proliferation can therefore be readily assessed using spectrophotometric measurement in this range. We have used this feature of erythroid cells to develop a simple erythroid proliferation assay that is minimally labor/time- and reagent-intensive and could easily be automated for use in high-throughput screening. Such an assay can be a valuable tool for investigations into hematological disorders where erythropoiesis is dysregulated, i.e., either inhibited or enhanced, into the development of anemia as a side-effect of primary diseases such as parasitic infections and into cyto-(particularly erythro-) toxicity of chemical agents or drugs.

Treatment-related risk factors for transformation to acute myeloid leukemia and myelodysplastic syndromes in myeloproliferative neoplasms

PURPOSE

Patients with myeloproliferative neoplasms (MPNs), including polycythemia vera, essential thrombocythemia, and primary myelofibrosis, have a propensity to develop acute myeloid leukemia (AML) and myelodysplastic syndromes (MDSs). Using population-based data from Sweden, we assessed the role of MPN treatment and subsequent AML/MDS risk with special focus on the leukemogenic potential of hydroxyurea (HU).

METHODS

On the basis of a nationwide MPN cohort (N = 11,039), we conducted a nested case-control study, including 162 patients (153 and nine with subsequent AML and MDS diagnosis, respectively) and 242 matched controls. We obtained clinical and MPN treatment data for all patients. Using logistic regression, we calculated odds ratios (ORs) as measures of AML/MDS risk.

RESULTS

Forty-one (25%) of 162 patients with MPNs with AML/MDS development were never exposed to alkylating agents, radioactive phosphorous (P(32)), or HU. Compared with patients with who were not exposed to HU, the ORs for 1 to 499 g, 500 to 999 g, more than 1,000 g of HU were 1.5 (95% CI, 0.6 to 2.4), 1.4 (95% CI, 0.6 to 3.4), and 1.3 (95% CI, 0.5 to 3.3), respectively, for AML/MDS development (not significant). Patients with MPNs who received P(32) greater than 1,000 MBq and alkylators greater than 1 g had a 4.6-fold (95% CI, 2.1 to 9.8; P = .002) and 3.4-fold (95% CI, 1.1 to 10.6; P = .015) increased risk of AML/MDS, respectively. Patients receiving two or more cytoreductive treatments had a 2.9-fold (95% CI, 1.4 to 5.9) increased risk of transformation.

CONCLUSION

The risk of AML/MDS development after MPN diagnosis was significantly associated with high exposures of P(32) and alkylators but not with HU treatment. Twenty-five percent of patients with MPNs who developed AML/MDS were not exposed to cytotoxic therapy, supporting a major role for nontreatment-related factors.

Hematological Oncology: further ahead

This editorial presents the new editorial structure of Hematological Oncology and summarizes the topics of interest of the journal. Authors are strongly encouraged to submit quality manuscripts regarding all the aspects of haematologic cancers via the Hematological Oncology website at http://mc.manuscriptcentral.com/hon.

Congenital and acquired polycythemias

INTRODUCTION

Polycythemias are characterized by an increased concentration of red blood cells. Because blood cell counts are a routine investigation, these disorders present to non-hematologic physicians. Polycythemia vera (PV), an acquired stem cell disease, is the most important variant.

METHODS

Selective literature review and the authors' own clinical experiences.

RESULTS AND DISCUSSION

Erythropoietin, which is produced in the kidneys, and its receptor system in the bone marrow, are of critical importance in polycythemia. Congenital polycythemias are caused by mutations of the Erythropoietin-receptor gene, hemoglobin variants, 2,3-bisphosphoglycerate mutase deficiency or by disturbances of renal oxygen sensing. Acquired polycythemias can occur secondary to hypoxia at high altitudes, or primarily through acquired mutations in the EPO-receptor signaling system (JAK2 mutations). Alternatively they may be caused by pulmonary or renal disease. An artificial erythrocytosis is induced by athletes through doping. Differential diagnosis comprises erythropoietin determination, JAK2 mutation analysis and if necessary hemoglobin electrophoresis. Only PV requires immediate treatment, because of a high thromboembolic risk. Epidemiological studies on polycythemias in German speaking countries are urgently needed.