Study on activated protein C resistance and disordered coagulation in patients with myeloproliferative neoplasms / 中华血液学杂志

<p><b>OBJECTIVE</b>To study the correlation of activated protein C (APC) resistance, coagulation factors and inhibitors abnormality and JAK2V617F mutation burden in patients with myeloproliferative neoplasms (MPN).</p><p><b>METHODS</b>The APC resistance was defined as the ratio of activated partial thromboplastin time (APTT) in the presence and absence of APC, i.e. APC sensitivity ratio (APCsr). Plasma protein C (PC), protein S (PS), prothrombin (FII), factor V (FV), factor VIII levels and CD11b expression on neutrophils were measured. The percentage of mutated JAK2V617F allele (V617F%) was evaluated by real time polymerase chain reaction (qRT-PCR).</p><p><b>RESULTS</b>Expression of CD11b on neutrophils was significantly elevated in MPN patients compared with that of the control group. APCsr, PS and FV levels were reduced in patients with MPN. The APCsr level was decreased mainly in patients with thrombosis and JAK2V617F mutant burden higher than 75%. APCsr was not only positively correlated with PS levels but also inversely correlated with JAK2V617F allele burden in JAK2V617F mutant gene carriers.</p><p><b>CONCLUSION</b>The neutrophil was activated and PS, FV level were reduced in MPN patients. The APCsr level was decreased and the occurrence of relatively acquired APC resistance was found in MPN patients with thrombosis. The APCsr is correlated with the PS level and JAK2V617F mutational furden.</p>

Interferon-alpha-2b induces molecular responses of patients with polycythemia vera and its post-polycythemic myelofibrosis / 中国实验血液学杂志

To evaluate the efficacy and safety of interferon-alpha-2b (IFN-α-2b) in polycythemia vera patients(PV patient) with or without post-polycythemic myelofibrosis (post-PV MF), 30 patients with mutated JAK2V617F were enrolled in this study, from which 29 patients were evaluable. The percentage of mutated JAK2V617F allele (V617F%) was evaluated by real-time polymerase chain reaction (RT-PCR) before and after treatment with IFN-α-2b. The correlation of V617F allele burden with the major clinical outcomes was studied. Adverse effects appeared in patients was observed. The results showed that the median follow-up was 24 (12 - 42) months for 29 evaluable patients. Complete hematologic response was achieved in 10%, 48%, 72% and 78% of patients after treatment for 6, 12, 24 and 36 months respectively. The detection of V617F allele burden revealed that the molecular remission of patients (V617F%) was achieved in 41%, 76%, 89% and 89% after treatment for 6, 12, 24 and 36 months respectively. Molecular complete remission (JAK2V617F undetectable) was achieved in 4 patients, lasted from 6 to 12 months after IFN-α-2b discontinuation. The decrease of V617F% in patients with post-PV MF was significantly higher than that in patients without post-PV MF (53 ± 18% vs 32 ± 22%, respectively; p = 0.031) after treatment for 12 months. PV patients had a good tolerance to IFN-α-2b. It is concluded that IFN-α-2b can decrease the mutated V617F allele burden. Patients with PV, especially with post-PV MF, can achieve molecular remission after treatment with IFN-α-2b.

The risk factors for thrombosis, myelofibrosis and leukemia transformation in patients with polycythemia vera / 中华血液学杂志

<p><b>OBJECTIVE</b>To reassess the natural history of polycythemia vera (PV) in Chinese and evaluate the relationship between the incidence of thrombosis, post-polycythaemic myelofibrosis with myeloid metaplasia( PPMM) , leukemia transformation and the therapeutic outcome and prognostic factors.</p><p><b>METHODS</b>The clinical manifestations, laboratory parameters and treatment were retrospectively analyzed in 287 patients with PV. Univariate analysis of prognostic factors was performed using Log-rank model and multivariate analysis using COX model in term of the incidence of thrombosis, PPMM, hematologic or non hematologic cancers and mortality.</p><p><b>RESULTS</b>Of the 287 patients, the median follow-up time was 46 (8-360) months. 208 thromboses were recorded in 115 patients. Twice or more thrombotic events occurred on 59 patients (51.34%). Most of these episodes occurred either at presentation or in the 2 years before diagnosis. Elder patients, prior thrombosis, poor response to therapy were associated with poor prognosis. With these three adverse prognostic factors, the patients could be separated into different risk groups. The incidence of thrombosis was higher in high risk group. 36 patients progressed to PPMM, the median time to PPMM was 80 (7-190) months. Higher WBC count, splenomegaly and treatment with alkylating agent and hydroxy-carbamide (HU) were associated with poor prognosis. 2 cases progressed to AML. 1 to lymphoma and 1 to nonhematologic cancer. 13 patients died, the cause of death was fatal thrombosis in 9 and AML in 2.</p><p><b>CONCLUSION</b>The incidence of thromboembolism is higher and the time to myelofibrosis was shorter in Chinese PV patients than in western PV patients. The main factors that influence the survival of PV patients are thromboembolism and leukemia transformation.</p>