Impact of white blood cells on thrombotic risk in patients with optimized platelet count in essential thrombocythemia.

OBJECTIVES: Risk of thrombosis is significantly enhanced by both elevated platelet (PLT) and white blood cell (WBC) counts according to a retrospective analysis of a large anagrelide registry in thrombocythemic MPN patients. We were interested in the impact of elevated WBC counts on thrombosis risk in patients where PLT counts were reduced below the calculated cutoff of 574.5 G/L by treatment with anagrelide. METHODS: Cox regression analysis and Kaplan-Meier plot were applied on all patients in the registry with optimized PLT counts. RESULTS: Using the calculated cutoff of 9.66 G/L for WBC, Cox regression analysis revealed a clear influence of elevated WBC counts on the occurrence of a major thrombotic event (P = .012). A Kaplan-Meier plot revealed a markedly shorter time to a major thrombotic event for patients with WBC counts above the cutoff (P = .001). CONCLUSIONS: These data suggest that additional correction of elevated WBC counts is mandatory in patients with optimally managed PLT counts to reduce thrombotic risk. This study is the first investigation in a prospectively observed large patient cohort which was treated homogenously allowing for evaluation of single parameters for an effect on thrombophilia.

Influence of platelet and white blood cell counts on major thrombosis - analysis from a patient registry in essential thrombocythemia.

OBJECTIVES: Although guidelines recommend normalization of platelet counts as an appropriate endpoint for treatment in high-risk essential thrombocythemia (ET), retrospective studies could not prove a correlation of diagnostic platelet counts with an increased thrombotic rate. There is, however, an increasing evidence that leukocytosis is an important risk factor for arterial thrombosis in myeloproliferative neoplasms. METHODS: This study considers the Austrian cohort of a European registry regarding the platelet-lowering therapeutic anagrelide. Influence of platelet and white blood cell (WBC) counts on thrombotic risk was assessed. RESULTS: Using the calculated cutoffs of 574.5 G/L for platelets and 8.48 G/L for WBC counts, respectively, the Cox regression analysis revealed a clear influence of elevated platelets (P = 0.008) and WBC counts (P = 0.011) on the occurrence of major thrombotic events. The time to a major thrombotic event was shortest (P < 0.001) and the frequency related to 100 patient-years was highest (P = <0.001) when both platelet and WBC counts ranged above the calculated cutoffs. CONCLUSION: Our data add evidence to the impact of platelet and WBC counts on thrombosis in ET. We suspect a particular interaction between platelets and WBC which might be based on a biological interplay depending on particular cell counts.

Ropeginterferon alfa-2b, a novel IFNα-2b, induces high response rates with low toxicity in patients with polycythemia vera.

In this prospective, open-label, multicenter phase 1/2 dose escalation study, we used a next-generation, mono-pegylated interferon (IFN) α-2b isoform, ropeginterferon alfa-2b. The unique feature of ropeginterferon alfa-2b is a longer elimination half-life, which allows administration every 2 weeks. We present data from 51 polycythemia vera patients. The main goal was to define the maximum tolerated dose and to assess safety and efficacy. A dose range of 50 to 540 µg was tested without the appearance of dose-limiting toxicities. All drug-related adverse events were known toxicities associated with IFN-α. The cumulative overall response rate was 90%, comprising complete response in 47% and partial response in 43% of patients; the best individual molecular response level was a complete response in 21% of patients and partial response in 47%. Notably, we did not observe any correlation between the dose level and the response rate or response duration, suggesting that already low levels of ropeginterferon alfa-2b are sufficient to induce significant hematologic and molecular responses. These data suggest promising efficacy and safety of ropeginterferon alfa-2b and support the development of the drug in a randomized phase 3 clinical trial. The study was disclosed at www.clinicaltrials.gov as #NCT01193699 before including the first patient.

Molecular responses and chromosomal aberrations in patients with polycythemia vera treated with peg-proline-interferon alpha-2b.

Fifty-one polycythemia vera (PV) patients were enrolled in the phase I/II clinical study PEGINVERA to receive a new formulation of pegylated interferon alpha (peg-proline-IFNα-2b, AOP2014/P1101). Peg-proline-IFNα-2b treatment led to high response rates on both hematologic and molecular levels. Hematologic and molecular responses were achieved for 46 and 18 patients (90 and 35% of the whole cohort), respectively. Although interferon alpha (IFNα) is known to be an effective antineoplastic therapy for a long time, it is currently not well understood which genetic alterations influence therapeutic outcomes. Apart from somatic changes in specific genes, large chromosomal aberrations could impact responses to IFNα. Therefore, we evaluated the interplay of cytogenetic changes and IFNα responses in the PEGINVERA cohort. We performed high-resolution SNP microarrays to analyze chromosomal aberrations prior and during peg-proline-IFNα-2b therapy. Similar numbers and types of chromosomal aberrations in responding and non-responding patients were observed, suggesting that peg-proline-IFNα-2b responses are achieved independently of chromosomal aberrations. Furthermore, complete cytogenetic remissions were accomplished in three patients, of which two showed more than one chromosomal aberration. These results imply that peg-proline-IFNα-2b therapy is an effective drug for PV patients, possibly including patients with complex cytogenetic changes.

Plerixafor and granulocyte-colony-stimulating factor (G-CSF) in patients with lymphoma and multiple myeloma previously failing mobilization with G-CSF with or without chemotherapy for autologous hematopoietic stem cell mobilization: the Austrian experience on a named patient program.

BACKGROUND: Plerixafor in combination with granulocyte-colony-stimulating factor (G-CSF) has been shown to enhance stem cell mobilization in patients with multiple myeloma, non-Hodgkin's lymphoma, and Hodgkin's disease who demonstrated with previous mobilization failure. In this named patient program we report the Austrian experience in insufficiently mobilizing patients. STUDY DESIGN AND METHODS: Twenty-seven patients from eight Austrian centers with a median (range) age of 58 (19-70) years (18 female, nine male) were included in the study. Plerixafor was limited to patients with previous stem cell mobilization failure and was given in the evening of Day 4 of G-CSF application. RESULTS: A median increase of circulating CD34+ cells within 10 to 11 hours from administration of plerixafor by a factor of 4.7 over baseline was noted. Overall, 20 (74%) patients reached more than 10 × 10(6) CD34+ cells/L in the peripheral blood, resulting in 17 (63%) patients collecting at least 2 × 10(6) CD34+ cells/kg body weight (b.w.; median, 2.6 × 10(6) CD34+ cells/kg b.w.; range, 0.08 × 10(6) -8.07 × 10(6) ). Adverse events of plerixafor were mild to moderate and consisted of gastrointestinal side effects and local reactions at the injection site. Thirteen (48%) patients underwent autologous transplantation receiving a median of 2.93 × 10(6) CD34+ cells/kg (range, 1.46 × 10(6) -5.6 × 10(6) ) and showed a trilinear engraftment with a median neutrophil recovery on Day 12 and a platelet recovery on Day 14. CONCLUSION: Our study confirms previous investigations showing that plerixafor in combination with G-CSF is an effective and well-tolerated mobilization regimen with the potential of successful stem cell collection in patients with previous mobilization failure.