Risk of thrombosis according to need of phlebotomies in patients with polycythemia vera treated with hydroxyurea.

Hematocrit control below 45% is associated with a lower rate of thrombosis in polycythemia vera. In patients receiving hydroxyurea, this target can be achieved with hydroxyurea alone or with the combination of hydroxyurea plus phlebotomies. However, the clinical implications of phlebotomy requirement under hydroxyurea therapy are unknown. The aim of this study was to evaluate the need for additional phlebotomies during the first five years of hydroxyurea therapy in 533 patients with polycythemia vera. Patients requiring 3 or more phlebotomies per year (n=85, 16%) showed a worse hematocrit control than those requiring 2 or less phlebotomies per year (n=448, 84%). There were no significant differences between the two study groups regarding leukocyte and platelet counts. Patients requiring 3 or more phlebotomies per year received significantly higher doses of hydroxyurea than the remaining patients. A significant higher rate of thrombosis was found in patients treated with hydroxyurea plus 3 or more phlebotomies per year compared to hydroxyurea with 0-2 phlebotomies per year (20.5% vs. 5.3% at 3 years; P<0.0001). In multivariate analysis, independent risk factors for thrombosis were phlebotomy dependency (HR: 3.3, 95%CI: 1.5-6.9; P=0.002) and thrombosis at diagnosis (HR: 4.7, 95%CI: 2.3-9.8; P<0.0001). The proportion of patients fulfilling the European LeukemiaNet criteria of resistance/intolerance to hydroxyurea was significantly higher in the group requiring 3 or more phlebotomies per year (18.7% vs. 7.1%; P=0.001) mainly due to extrahematologic toxicity. In conclusion, phlebotomy requirement under hydroxyurea therapy identifies a subset of patients with increased proliferation of polycythemia vera and higher risk of thrombosis.

Predictive factors for anemia response to erythropoiesis-stimulating agents in myelofibrosis.

OBJECTIVE: Erythropoiesis-stimulating agents (ESAs) are commonly used to treat the anemia of myelofibrosis (MF), but information on the predictors of response is limited. METHODS: Results of ESA therapy were analyzed in 163 MF patients with severe anemia, most of whom had inadequate erythropoietin (EPO) levels (<125 U/L) at treatment start. RESULTS: According to the revised criteria of the International Working Group for Myelofibrosis Treatment and Research, anemia response was achieved in 86 patients (53%). Median response duration was 19.3 months. In multivariate analysis, baseline factors associated with a higher response rate were female sex (P=.007), leukocyte count ≥10×109 /L (P=.033), and serum ferritin <200 ng/mL (P=.002). Patients with 2 or 3 of the above features had a significantly higher response rate than the remainder (73% vs 28%, respectively; P<.001). Over the 373 patient-years of follow-up on ESA treatment, nine patients developed thrombotic complications (six arterial, three venous), accounting for 2.41 events per 100 patient-years. Survival time from ESA start was longer in anemia responders than in non-responders (P=.011). CONCLUSION: Besides the already established predictive value of EPO levels, these data can help to identify which MF patients are more likely to benefit from ESA treatment.

The proliferation index of specific bone marrow cell compartments from myelodysplastic syndromes is associated with the diagnostic and patient outcome.

Myelodysplastic syndromes (MDS) are clonal stem cell disorders which frequently show a hypercellular dysplastic bone marrow (BM) associated with inefficient hematopoiesis and peripheral cytopenias due to increased apoptosis and maturation blockades. Currently, little is known about the role of cell proliferation in compensating for the BM failure syndrome and in determining patient outcome. Here, we analyzed the proliferation index (PI) of different compartments of BM hematopoietic cells in 106 MDS patients compared to both normal/reactive BM (n = 94) and acute myeloid leukemia (AML; n = 30 cases) using multiparameter flow cytometry. Our results show abnormally increased overall BM proliferation profiles in MDS which significantly differ between early/low-risk and advanced/high-risk cases. Early/low-risk patients showed increased proliferation of non-lymphoid CD34(+) precursors, maturing neutrophils and nucleated red blood cells (NRBC), while the PI of these compartments of BM precursors progressively fell below normal values towards AML levels in advanced/high-risk MDS. Decreased proliferation of non-lymphoid CD34(+) and NRBC precursors was significantly associated with adverse disease features, shorter overall survival (OS) and transformation to AML, both in the whole series and when low- and high-risk MDS patients were separately considered, the PI of NRBC emerging as the most powerful independent predictor for OS and progression to AML. In conclusion, assessment of the PI of NRBC, and potentially also of other compartments of BM precursors (e.g.: myeloid CD34(+) HPC), could significantly contribute to a better management of MDS.

Cell-cycle distribution of different cell compartments in normal versus reactive bone marrow: a frame of reference for the study of dysplastic hematopoiesis.

Limited information is currently available about the proliferation activity and cell-cycle distribution of different bone marrow (BM) cell subsets defined according to their lineage and maturation stage in normal versus cytopenia-associated reactive BM samples. Here, we report a three-color flow cytometry approach to investigate the cell-cycle distribution of different BM cell compartments-CD34(+) hematopoietic progenitor and precursor cells (HPC), maturing neutrophils and monocytic cells, mature lymphocytes, eosinophils, and nucleated red blood cell precursors (NRBC)-from normal (n = 47) versus cytopenia-associated reactive (n = 47) BM samples. Highly similar proliferation profiles were detected in normal versus reactive BM, with a higher proliferation index (PI) for the more immature CD34(+) HPC, CD11b(-) maturing neutrophils and NRBC versus other BM cell compartments. The only differences observed between normal and reactive BM were restricted to the more mature (CD13(hi) /CD11b(+) ) bands/neutrophils and to monocytic cells, which showed an increased PI (0.9% ± 0.8% vs. 0.6% ± 0.5% and 6 ± 3.6 vs. 4.6 ± 4.5, respectively) at the expense of a lower PI of CD34(+) HPC in reactive conditions. Of note, bands/mature neutrophils and mature lymphocytes showed either residual numbers or absence of S + G2 /M-phase cells in both normal and reactive BM. Our results suggest that a slight shift of proliferation from the early precursors to the more mature granulomonocytic compartment occurs in reactive BM, which could reflect an attempt of the hematopoietic system to rapidly produce functional neutrophils and monocytes, at the expense of a lower expansion of the minor compartments of CD34(+) HPC.