Hydroxyurea dose impacts hematologic parameters in polycythemia vera and essential thrombocythemia but does not appreciably affect JAK2-V617F allele burden

IRF4 and IRF8 expression are associated with clinical phenotype and clinico-hematological response to hydroxyurea in essential thrombocythemia

The morbidity and mortality of myeloproliferative neoplasms (MPNs) are primarily caused by arterial and venous complications, progression to myelofibrosis, and transformation to acute leukemia. However, identifying molecular-based biomarkers for risk stratification of patients with MPNs remains a challenge. We have previously shown that interferon regulatory factor-8 (IRF8) and IRF4 serve as tumor suppressors in myeloid cells. In this study, we evaluated the expression of IRF4 and IRF8 and the JAK2V617F mutant allele burden in patients with MPNs. Patients with decreased IRF4 expression were correlated with a more developed MPN phenotype in myelofibrosis (MF) and secondary AML (sAML) transformed from MPNs versus essential thrombocythemia (ET). Negative correlations between the JAK2V617F allele burden and the expression of IRF8 (P < 0.05) and IRF4 (P < 0.001) and between white blood cell (WBC) count and IRF4 expression (P < 0.05) were found in ET patients. IRF8 expression was negatively correlated with the JAK2V617F allele burden (P < 0.05) in polycythemia vera patients. Complete response (CR), partial response (PR), and no response (NR) were observed in 67.5%,10%, and 22.5% of ET patients treated with hydroxyurea (HU), respectively, in 12 months. At 3 months, patients in the CR group showed high IRF4 and IRF8 expression compared with patients in the PR and NR groups. In the 12-month therapy period, low IRF4 and IRF8 expression were independently associated with the unfavorable response to HU and high WBC count. Our data indicate that the expression of IRF4 and IRF8 was associated with the MPN phenotype, which may serve as biomarkers for the response to HU in ET.

A case of JAK2V617F-positive essential thrombocythemia where allele burden was reduced by a PD-1 inhibitor

The Janus kinase/signal transducers and activators of transcription signaling pathway induces programmed death ligand-1 (PD-L1) expression. JAK2 mutation at position 617 (JAK2V617) is a frequent driver of myeloproliferative neoplasms (MPN) through PD-L1 expression. Although PD-1 inhibitors should be effective against MPN with JAK2V617F mutation, this has not yet been reported in humans. Thus, we assessed the efficacy of a PD-1 inhibitor in a lung cancer patient with JAK2V617F-positive essential thrombocythemia (ET). A 71-year-old man was diagnosed with ET, and with lung carcinoma 3 years later. After right lobectomy and postoperative chemotherapy, pembrolizumab [a PD-1 inhibitor (200 mg, every 3 weeks)] was initiated for refractory lung carcinoma. Lung cancer progression did not occur for 1.5 years under treatment. Most megakaryocytes were PD-L1-positive, and after pembrolizumab initiation, platelet count remained below 45 × 10⁴/μL without the need for other cytoreductive therapies for ET. The JAK2V617F allele burden gradually decreased from 11.5% at diagnosis to 2.9% after 17 months of pembrolizumab treatment. Other peripheral blood lineages did not decrease, and pembrolizumab treatment was continued without any adverse events. This is the first report demonstrating the effectiveness of pembrolizumab in an MPN patient with JAK2V617F mutation.

Treatment outcome of Philadelphia chromosome negative myeloproliferative neoplasms: experience of a single developing country's hematology-oncology centre

BACKGROUND

Myeloproliferative neoplasms (MPNs) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) are characterized by excessive production of blood cells. Treatment of MPNs patients has an important effect thereby reducing morbidity and mortality.

OBJECTIVE

To evaluate the effect of cytoreductive treatment on some hematological and biochemical parameters in MPNs patients treated at a hemato-oncology Centre in Erbil, Iraq.

METHODS

A total of 185 patients diagnosed with PV, ET, and PMF (111 males and 74 females with a mean age of 50.8±3.2 years, range: 46-73) were assigned to receive MPNs treatment. Laboratory tests were performed before and after a median period from the initiation of MPNs treatment of 9.3 months (range 5-10 months).

RESULTS

Significant differences were noted in Hemoglobin (P<0.003), Hematocrit (P<0.004), Neutrophil (P<0.001) and glutamate pyruvate transferase levels (P<0.01) in PV patients, Platelet count (P<0.002) in ET patients, and both white blood cell count (P<0.004) and Lactate dehydrogenase level (P<0.001) in PMF patients, while no significant differences were found in other parameters at the time of diagnosis and during therapy.

CONCLUSION

Clinical and laboratory improvements were presented in MPNs patients. Regular follow up of patients are essential to ensure prescribed treatment in addition to the continual and long-lasting response to therapy and to prevent thrombosis.

A remarkable hematological and molecular response pattern in a patient with polycythemia vera during combination therapy with simvastatin and alendronate

We report a 57-year old man with polycythemia vera, who had a remarkable hematological and molecular response during treatment with simvastatin and alendronate. The patient was treated with this combination for 56 months, and during this period the patient has been in complete hematological remission. The JAK2-V617F allele burden has dropped from 64% to sustained values below 20%, and follow-up bone marrow biopsies have revealed no change in PV features, without any regular cytoreductive treatment.

JAK2V617F Allele Burden Measurement in Peripheral Blood of Iranian Patients with Myeloproliferative Neoplasms and Effect of Hydroxyurea on JAK2V617F Allele Burden

BACKGROUND

Myeloproliferative neoplasms (MPNs) are clonal malignant diseases that represent a group of conditions including polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The aim of this study was to evaluate possible correlations between JAK2V617F allele burden and clinicohematologic characteristics in Iranian patients with MPNs. We also aimed at determining the correlation between JAK2V617F allele burden and use of cyto reductive treatment (hydroxyurea).

MATERIALS AND METHODS

We performed ARMS-PCR for all MPNs samples and subsequently performed real-time quantitative polymerase chain reaction (qRT-PCR) for JAK2V617F allele burden measurement using DNA from peripheral blood leukocytes.

RESULTS

Two distinct groups of patients were examined at a single time point: group A (n=40; 20 PV, 20 ET) was examined at the time of diagnosis; group B (n=85; 40 PV, 30 ET and 15 PMF) while under treatment with hydroxyurea (HU). The median allele burden of the JAK2 V617F was 72% for PV and 49% for ET patients at the time of diagnosis (p=0.01). For patients with HU treatment, we determined the median JAK2V617F allele burden to be 43%, 40%, and 46.5 % in PV, ET and PMF patients; respectively. HU-treated PV patients had a significant lower %JAK2V617F than PV patients at the time of diagnosis (43% vs. 72%, p=0.005). In ET group, the relationship between the JAK2 V617F allele burden and leukocyte count was significant (p=0.02 and p=0.01 in untreated and treated patients, respectively).

CONCLUSIONS

Our results showed that patients with PV have a higher JAK2V617F allele burden. Moreover, our study demonstrated that the JAK2V617F allele burden correlates with clinical features in ET group. We also showed hydroxyurea can affect the JAK2V617F allele burden in PV patients.

Pharmacological management of essential thrombocythemia

INTRODUCTION

Two factors have deeply influenced the area of essential thrombocythemia (ET). A gain-of-function mutation in the pseudokinase region of the JAK2 gene, which partly explains the pathophysiology of myeloproliferative neoplasms (MPNs), was discovered in 2005 and is present in 50 - 60% of ET patients. Furthermore, the 2008 WHO MPN classification outlined criteria for the separation of ET and early or prefibrotic primary myelofibrosis (PMF). However, these and other new findings have not yet changed the pharmacotherapy of ET, which is based on risk stratification for thrombohemorrhagic risk and aims to reduce thrombosis and bleeding.

AREAS COVERED

Studies on the basis for and the validation of the WHO classification as well as studies on possible new risk factors are covered. The most important drugs for ET treatment and consensus recommendations for management of ET are also presented.

EXPERT OPINION

The new WHO classification should be used for both ET studies and clinical practice, since true ET has a different prognosis than early PMF. The management of patients should be based on risk stratification. Age > 60 years or previous throbosis (high risk) and platelet counts > 1500 × 10(9)/l warrant cytoreductive treatment, and high risk patients and selected low risk patients should be given anti-aggregation therapy.

JAK2 V617F allele burden quantified by real time quantitative polymerase chain reaction and competitive polymerase chain reaction in patients with chronic myeloproliferative neoplasia

Assessing the clinical significance of JAK2 V617F mutant allele burden is complicated by a myriad of techniques reported to detect and quantify the mutation. As a consequence, the level of sensitivity and how the data is reported vary. Harmonization of well-defined molecular studies would permit evaluation of the clinical significance of measuring allele burden and rapid determination of the efficacy of novel agents for the treatment of chronic myeloproliferative neoplasia via multicenter clinical trials, at the subclinical level. Here we report a comparison between the widely available TaqMan quantitative real time polymerase chain reaction (Q-PCR) and competitive PCR (C-PCR) assays. We found that the tumor load was invariably greater when measured by C-PCR compared to that recorded by Q-PCR. Furthermore, none of the samples converted from undetectable to detectable when the enriched granulocyte (GR) fraction was tested. While a difference in the V617F allele levels was detected between GR fraction and whole blood, this was not statistically significant.

Differential effects of hydroxyurea and INC424 on mutant allele burden and myeloproliferative phenotype in a JAK2-V617F polycythemia vera mouse model

JAK2-V617F cells show a competitive advantage over wild-type cells in BM transplantation assays. A preclinical mouse model allows the examination of the effects of therapeutic agents on blood parameters and JAK2-V617F mutant allele burden.