Respective clustering of unfavorable and favorable cytogenetic clones in myelofibrosis with myeloid metaplasia with homozygosity for JAK2(V617F) and response to erythropoietin therapy

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.

Establishing optimal quantitative-polymerase chain reaction assays for routine diagnosis and tracking of minimal residual disease in JAK2-V617F-associated myeloproliferative neoplasms: a joint European LeukemiaNet/MPN&MPNr-EuroNet (COST action BM0902) study

Reliable detection of JAK2-V617F is critical for accurate diagnosis of myeloproliferative neoplasms (MPNs); in addition, sensitive mutation-specific assays can be applied to monitor disease response. However, there has been no consistent approach to JAK2-V617F detection, with assays varying markedly in performance, affecting clinical utility. Therefore, we established a network of 12 laboratories from seven countries to systematically evaluate nine different DNA-based quantitative PCR (qPCR) assays, including those in widespread clinical use. Seven quality control rounds involving over 21 500 qPCR reactions were undertaken using centrally distributed cell line dilutions and plasmid controls. The two best-performing assays were tested on normal blood samples (n=100) to evaluate assay specificity, followed by analysis of serial samples from 28 patients transplanted for JAK2-V617F-positive disease. The most sensitive assay, which performed consistently across a range of qPCR platforms, predicted outcome following transplant, with the mutant allele detected a median of 22 weeks (range 6–85 weeks) before relapse. Four of seven patients achieved molecular remission following donor lymphocyte infusion, indicative of a graft vs MPN effect. This study has established a robust, reliable assay for sensitive JAK2-V617F detection, suitable for assessing response in clinical trials, predicting outcome and guiding management of patients undergoing allogeneic transplant.

Karyotype complements the International Prognostic Scoring System for primary myelofibrosis

OBJECTIVES

The International Prognostic Scoring System (IPSS) for primary myelofibrosis (PMF) is based on five independent predictors of inferior survival: age >65 yr, hemoglobin <10 g/dL, leukocyte count >25 x 10(9)/L, circulating blasts > or =1%, and presence of constitutional symptoms. The presence of 0, 1, 2, and > or =3 adverse factors defines low, intermediate-1, intermediate-2, and high risk disease, respectively. We examined the additional prognostic relevance of karyotype.

METHODS

World Health Organization criteria were used for PMF diagnosis. Only patients with bone marrow cytogenetic studies at the time or within 1 yr of diagnosis and a minimum of 20 evaluable metaphases were considered. Cytogenetic findings were categorized as 'normal' vs. 'abnormal' or 'favorable' (normal or with sole abnormalities of 13q- or 20q-) vs. 'unfavorable' (all other abnormalities).

RESULTS

A total of 109 patients were studied (median age 63 yr). Numbers of patients in the above-listed four IPSS risk groups were 26, 31, 28, and 24, respectively. Cytogenetic results were abnormal in 33% of the patients and unfavorable in 21%. At a median follow-up of 35 months, 45 (41%) deaths were recorded. 'Unfavorable' (P = 0.008) but not 'abnormal' (P = 0.19) karyotype predicted shortened survival and its significance remained on multivariable analysis that included the IPSS or other prognostic tools as covariates. JAK2V617F, detected in 63 (58%) patients, was inconsequential to survival.

CONCLUSIONS

In PMF, specific cytogenetic abnormalities and not the mere presence of an abnormal karyotype provide important prognostic information that is not accounted for by the IPSS or other established risk factors.

From palliation to epigenetic therapy in myelofibrosis

Myelofibrosis shows a progressive clinical course and usually a poor, lethal prognosis. The molecular pathogenesis of this disease largely remains to be fully understood but the identification of the JAK2V617F mutation in more than half of patients was a major improvement in our understanding of the disease biology and may represent the first biologic marker useful for risk stratification, independently from conventional clinical predictors. After many elusive efforts, new effective treatment strategies are becoming available for this disease. Allogeneic transplantation following reduced-intensity conditioning programs, at least in some patients, may induce not only a hematologic response but also a molecular remission, thus supporting the hope of a possible, definitive eradication of the disease. Moreover, new innovative drugs, targeting either the JAK2V617F mutation or more general oncogenic mechanisms, may provide widely applicable, effective treatments to many patients for whom allogeneic transplantation is not feasible.

Advances in molecular diagnostics of myeloproliferative disorders

Incremental advances in the molecular pathogenesis of myeloproliferative disorders (MPDs) have had a substantial impact on clinical practice in terms of both diagnosis and treatment. An array of novel molecular methods are being developed and integrated into the current battery of tests for diagnosis and monitoring of treatment response. Primarily, subjective clinico-histologic approaches to diagnosis are being replaced by more objective semimolecular diagnostic algorithms. Furthermore, identification of disease-specific molecular markers has facilitated the development of small-molecule drugs for targeted therapy. This review provides an overview of MPDs with emphasis on molecular diagnostic tests and their incorporation into contemporary diagnostic and therapeutic algorithms.

Cytogenetic and molecular aspects of Philadelphia negative chronic myeloproliferative disorders: clinical implications

Chronic myeloproliferative disorders (CMPD) are clonal disorders of the hematopoietic stem cell. The myeloid lineage shows increased proliferation with effective maturation, while peripheral leukocytosis, thrombocytosis or elevated red blood cell mass are found. In Philadelphia negative CMPD recurrent cytogenetic abnormalities occur, but no specific abnormality has been defined to date. The spectrum of cytogenetic aberrations is heterogeneous ranging from numerical gains and losses to structural changes including unbalanced translocations. The most common chromosomal abnormalities are 20q-, 13q-, 12p-, +8, +9, partial duplication of 1q, balanced translocations involving 8p11 and gains in 9p. Cytogenetic analysis of CMPD by conventional or molecular techniques has an important role in establishing the diagnosis of a malignant disease, adding also more information for disease outcome. Molecular studies may detect the possible role of candidate genes implicated in the neoplastic process, addressing new molecular target therapies. FIP1L1/PDGFRalpha rearrangements, as well as alterations of PDGFRbeta or FGFR1 gene have been found to be associated with specific types of CMPD. Recently, a novel somatic mutation, JAK2V617F, has been reported in most of the polycthemia vera (PV) patients, as well as in a lower percentage in essential thrombocythemia (ET) or idiopathic myelofibrosis (IMF) patients. This finding represents the most important advance in understanding of the molecular mechanisms underlined the pathogenesis of CMPD, contributing to the classification and management of patients.

Experimental therapy in myelofibrosis with myeloid metaplasia

Myelofibrosis with myeloid metaplasia (MMM) is a Philadelphia chromosome-negative myeloproliferative disorder that is characterised by constitutional symptoms, progressive anaemia and extramedullary haematopoiesis. There are no curative therapies available for patients with MMM apart from stem cell transplantation, which is associated with significant morbidity and mortality, and for which most patients are not suitable candidates. Traditional pharmacological therapy of MMM has focused on the palliation of symptoms associated with myeloproliferation and correction of cytopoenias. Recently, new findings regarding the molecular basis of MMM and the pathogenesis of the associated bone marrow stromal reaction have provided both basic and clinical researchers with invaluable tools to develop effective targeted therapies for patients with MMM. Several novel treatment strategies are being investigated including antiangiogenic agents, signal transduction inhibitors, inhibitors of fibrogenesis and small-molecule inhibitors of the JAK2(V617F )mutation. This article reviews the current status of experimental novel therapies for MMM.

Cytogénétique et génétique moléculaire dans la myélofibrose avec métaplasie myéloïde et dans la polyglobulie de Vaquez

Myelofibrosis with myeloid metaplasia (MMM) is a rare myeloproliferative disorder (MPD) characterized by clonal proliferation of hematopoietic progenitors. 40-50% of karyotypes on blood (or more rarely on bone marrow) revealed at least one abnormality: 30% at diagnosis and 90% in blastic transformation phase. A minority of patients with newly diagnosed polycythemia vera (PV) presented chromosomal abnormalities in their myeloid cells. The most frequent visible alteration in MMM and PV is a 20q deletion, also characterized in other MPDs and myeloid malignancies. Among other chromosomal changes, deletion 13q is more common in MMM than in other MPDs, trisomy 9 and 9p alterations appear more frequent in PV. Cytogenetic studies have disclosed cryptic anomalies and pointed out the high frequency of 9p alterations. JAK2 (V617F) mutation was found in almost all PV patients and near half of MMM patients. This molecular abnormality takes an increased importance in the knowledge of the physiopathology of MPDs, particularly in PV and also in prognosis of MMM patients.

Biology and Treatment of Primary Myelofibrosis

Primary myelofibrosis (PMF) is a chronic myeloproliferative disorder associated with an average survival of less than 5 years. Therapy for PMF has used chemotherapeutic agents, immunomodulatory drugs, or biological-response modifiers that have not always been directed at the biological processes that underlie the origins of PMF. Such strategies are palliative and have an uncertain effect on survival. At present, allogeneic stem cell transplantation (ASCT) is the only means of altering the natural history of patients with PMF and provides the only hope for cure of this disorder. Enthusiasm for ASCT in PMF has been muted due to an unacceptable transplantation-related morbidity and mortality in patients receiving fully myeloablative conditioning regimens. Recently, a variety of reduced-intensity conditioning regimens have been utilized in older patients with PMF with significant comorbidities with promising results. Greater understanding of the cellular and molecular events that lead to the development of PMF have provided the opportunity for targeted therapies for PMF. Such therapies must be first evaluated in phase 1/2 trials using a variety of endpoints to assess their efficacy and their potential associated toxicities. The performance of randomized clinical trials comparing these agents to the present standard of care would permit for the first time evidence-based therapeutic decisions to be made for patients with PMF.

Advances in the therapy of chronic idiopathic myelofibrosis

The molecular basis of chronic idiopathic myelofibrosis (CIMF) has remained elusive, thus hampering the development of effective targeted therapies. However, significant progress regarding the molecular mechanisms involved in the pathogenes is of this disease has been made in recent years that will likely provide ample opportunity for the investigation of novel therapeutic approaches. At the fore front of these advances is the discovery that 35%-55% of patients with CIMF harbor mutations in the Janus kinase 2 tyrosine kinase gene. Until very recently, the management of patients with CIMF involved the use of supportive measures, including growth factors, transfusions, or interferon, and the administration of cyto-reductive agents, such as hydroxyurea and anagrelide. However, several trials have demonstrated the efficacy of antiangiogenic agents alone or in combination with corticosteroids. In addition, the use of reduced-intensity conditioning allogeneic stem cell transplantation has resulted in prolonged survival and lower transplant-related mortality.