Pomalidomide is active in the treatment of anemia associated with myelofibrosis

A Validated Chiral Chromatography Method for Enantiomeric Separation of Pomalidomide in Human Plasma

In the present work, new chiral stationary phase high-performance liquid chromatography (CSP-HPLC) method was established and validated for the quantification of pomalidomide (PMD) enantiomers in human plasma. The chromatographic enantiomeric separation was achieved on a Daicel-CSP, Chiralpack IA 4.6 × 250 mm, 5 μm; because of its advantages of high degree of retention, high resolution capacity, better reproducibility, ability to produce lower back pressure and low degree of tailing. The mobile phase was maintained as methanol: glacial acetic acid (499.50 ml:50 μL). Ultraviolet wavelength for detection was 220 nm. PMD enantiomer-I and enantiomer-II were separated at 8.83 and 15.34 min, respectively. Limit of detection and limit of quantification for each enantiomer and the calibration curve of standard PMD was linear in range between 10-5,000 ng mL-1. The method was validated according to The International Council for Harmonisation of Technical Requirements of Pharmaceuticals for Human Use (ICH(Q2R1)) specific guidelines. We found no interference peak with PMD chromatogram obtained. This is a simple, reliable and specific method for detection and quantification of enantiomer of PMD in human plasma sample.

Extramedullary hematopoiesis in myeloproliferative neoplasms: Pathophysiology and treatment strategies

Extramedullary hematopoiesis (EMH) is often a physiologic response to ineffective marrow production of hematologic cells. While this can be found incidentally in various physiologic and pathophysiologic states, the myeloproliferative neoplasms (MPNs) are some of the most common underlying conditions found in patients with EMH. Although this process can assist with hematologic production in defective states, the burden of EMH can lead to symptomatic discomfort and mechanical obstructive complications, most commonly in the spleen and liver. Here we describe the pathophysiology of EMH, treatment options, including medical, surgical and radiation-based approaches.

HRI depletion cooperates with pharmacologic inducers to elevate fetal hemoglobin and reduce sickle cell formation

Increasing fetal hemoglobin (HbF) provides clinical benefit in patients with sickle cell disease (SCD). We recently identified heme-regulated inhibitor (HRI, EIF2AK1), as a novel HbF regulator. Because HRI is an erythroid-specific protein kinase, it presents a potential target for pharmacologic intervention. We found that maximal HbF induction required >80% to 85% HRI depletion. Because it remains unclear whether this degree of HRI inhibition can be achieved pharmacologically, we explored whether HRI knockdown can be combined with pharmacologic HbF inducers to achieve greater HbF production and minimize potential adverse effects associated with treatments. Strongly cooperative HbF induction was observed when HRI depletion was combined with exposure to pomalidomide or the EHMT1/2 inhibitor UNC0638, but not to hydroxyurea. Mechanistically, reduction in the levels of the HbF repressor BCL11A reflected the cooperativity of HRI loss and pomalidomide treatment, whereas UNC0638 did not modulate BCL11A levels. In conjunction with HRI loss, pomalidomide maintained its HbF-inducing activity at 10-fold lower concentrations, in which condition there were minimal observed detrimental effects on erythroid cell maturation and viability, as well as fewer alterations in the erythroid transcriptome. When tested in cells from patients with SCD, combining HRI depletion with pomalidomide or UNC0638 achieved up to 50% to 60% HbF and 45% to 50% HbF, respectively, as measured by high-performance liquid chromatography, and markedly counteracted cell sickling. In summary, this study provides a foundation for the exploration of combining future small-molecule HRI inhibitors with additional pharmacologic HbF inducers to maximize HbF production and preserve erythroid cell functionality for the treatment of SCD and other hemoglobinopathies.

Immunotherapy and Immunomodulation in Myeloproliferative Neoplasms

Myeloproliferative neoplasms are characterized by chronic inflammation. The discovery of constitutively active JAK-STAT signaling associated with driver mutations has led to clinical and translational breakthroughs. Insights into the other pathways and novel factors of potential importance are being actively investigated. Various classes of agents with immunomodulating or immunosuppressive properties have been used with varying degrees of success in treating myeloproliferative neoplasms. Early clinical trials are investigating the feasibility, effectiveness, and safety of immune checkpoint inhibitors, cell-based immunotherapies, and SMAC mimetics. The dynamic landscape of immunotherapy and immunomodulation in myeloproliferative neoplasms is the topic of the present review.

Finding a Jill for JAK: Assessing Past, Present, and Future JAK Inhibitor Combination Approaches in Myelofibrosis

Myelofibrosis (MF) is a myeloproliferative neoplasm hallmarked by the upregulation of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway with associated extramedullary hematopoiesis and a high burden of disease-related symptoms. While JAK inhibitor therapy is central to the management of MF, it is not without limitations. In an effort to improve treatment for MF patients, there have been significant efforts to identify combination strategies that build upon the substantial benefits of JAK inhibition. Early efforts to combine agents with additive therapeutic profiles have given way to rationally designed combinations hoping to demonstrate clinical synergism and modify the underlying disease. In this article, we review the preclinical basis and existing clinical data for JAK inhibitor combination strategies while highlighting emerging strategies of particular interest.

The Rationale for Immunotherapy in Myeloproliferative Neoplasms

PURPOSE OF REVIEW

The classic, chronic Philadelphia chromosome negative myeloproliferative neoplasms (MPN)-essential thrombocythemia (ET), polycythemia vera (PV), and myelofibrosis (MF)-are clonal malignancies of hematopoietic stem cells and are associated with myeloproliferation, organomegaly, and constitutional symptoms. Expanding knowledge that chronic inflammation and a dysregulated immune system are central to the pathogenesis and progression of MPNs serves as a driving force for the development of agents affecting the immune system as therapy for MPN. This review describes the rationale and potential impact of anti-inflammatory, immunomodulatory, and targeted agents in MPNs.

RECENT FINDINGS

The advances in molecular insights, especially the discovery of the Janus kinase 2 (JAK2) V617F mutation and its role in JAK-STAT pathway dysregulation, led to the development of the JAK inhibitor ruxolitinib, which currently represents the cornerstone of medical therapy in MF and hydroxyurea-resistant/intolerant PV. However, there remain significant unmet needs in the treatment of these patients, and many agents continue to be investigated. Novel, more selective JAK inhibitors might offer reduced myelosuppression or even improvement of blood counts. The recent approval of a novel, long-acting interferon for PV patients in Europe, might eventually lead to its broader clinical use in all MPNs. Targeted immunotherapy involving monoclonal antibodies, checkpoint inhibitors, or therapeutic vaccines against selected MPN epitopes could further enhance tumor-specific immune responses. Immunotherapeutic approaches are expanding and hopefully will extend the therapeutic armamentarium in patients with myeloproliferative neoplasms.

Current and future therapies for myelofibrosis

Myelofibrosis is classified as a 'Philadelphia-chromosome negative' clonal myeloproliferative disorder. The heterogeneity of this condition and patient population and array of often challenging clinical manifestations can frequently make therapeutic decisions challenging. Despite many advances in therapy with targeted and combination approaches, following an enhanced understanding of underlying disease pathogenesis, cure only remains achievable with allogeneic stem cell transplant. This option is often limited to a small group of younger transplant-eligible patients with more advanced disease who have both a suitable donor and no or few co-morbidities. In this article, we will discuss up-to-date disease prognostication, common clinical challenges associated with myelofibrosis and both standard and novel therapeutic approaches. Increasingly complex prognostic modelling utilises patient-specific, haematological and genomic parameters to improve the accuracy of risk assessment and predict disease progression. We will also focus on difficult clinical scenarios such as disease-associated anaemia, thrombocytopenia and extremes of age. Future and evolving therapies within this field are highly anticipated and novel JAK inhibitor and non-JAK inhibitor-based therapy will also be discussed, including the new challenge of how to switch from one JAK inhibitor therapy to another.

A provider's guide to primary myelofibrosis: pathophysiology, diagnosis, and management

Although understanding of the pathogenesis and molecular biology of primary myelofibrosis continues to improve, treatment options are limited, and several biological features remain unexplained. With an appropriate clinical history, exam, laboratory evaluation, and bone marrow biopsy, the diagnosis can often be established. Recent studies have better characterized prognostic factors and driver mutations in myelofibrosis, facilitated by use of next-generation sequencing. These advances have facilitated development of a management strategy that is based on both risk factors and clinical phenotype. For low-risk patients, treatment will depend on symptom severity. For patients with higher-risk disease, several treatments are available including JAK inhibitors, allogeneic hematopoietic stem cell transplant, and clinical trials using novel molecularly targeted therapies and rational drug combinations. In this review, we outline what is known about the disease pathogenesis, discuss an approach to reaching the diagnosis, review the prognosis of myelofibrosis, and detail current therapeutic strategies.

Beyond Ruxolitinib: Fedratinib and Other Emergent Treatment Options for Myelofibrosis

Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by clonal proliferation of differentiated myeloid cells leading to bone marrow fibrosis, cytopenias and extramedullary hematopoiesis. In late 2019, the FDA approved the highly selective JAK2 inhibitor, fedratinib, for intermediate-2 or high-risk primary or secondary MF, making it the second drug approved for MF after ruxolitinib, a JAK1/2 inhibitor, which was approved for MF in 2011. The approval of fedratinib was based on phase II trials and the phase III JAKARTA trial, in which the drug significantly reduced splenomegaly and symptom burden compared to placebo, including some patients previously treated with ruxolitinib. The main side effects of fedratinib include anemia, gastrointestinal symptoms, and elevations in liver transaminases. Fedratinib also has ablack box warning for encephalopathy, although this occurred only in about 1% of the treated patients, most of which were ultimately felt not to represent Wernicke’s encephalopathy. Nonetheless, monitoring of thiamine levels and supplementation are recommended especially in high-risk patients. This concern has led to a prolonged clinical hold and delayed the drug approval by several years during which the drug exchanged manufacturers, highlighting the need for meticulous investigation and adjudication of serious, but rare, adverse events in drug development that could end up preventing drugs with favorable risk/benefit ratio from being approved. In this review, we discuss the pharmacokinetic data and efficacy, as well as the toxicity results of clinical trials of fedratinib. We also review ongoing trials of JAK inhibitors in MF and explore future treatment options for MF patients who are refractory to ruxolitinib.

Standard care and investigational drugs in the treatment of myelofibrosis

Myelofibrosis (MF) is a heterogeneous disorder characterized by splenomegaly, constitutional symptoms, ineffective hematopoiesis, and an increased risk of leukemic transformation. The ongoing research in understanding the pathophysiology of the disease has allowed for the development of targeted drugs optimizing patient management. Furthermore, disease prognostication has significantly improved. Current therapeutic interventions are only partially effective with only allogeneic stem cell transplant potentially curative. Ruxolitinib is the only approved therapy for MF by the US Food and Drug Administration. However, despite efficacy in reducing splenomegaly and controlling symptomatology, it is not associated with consistent molecular or pathologic responses. Drug discontinuation is associated with a dismal outcome. The therapeutic landscape in MF has significantly improved, and emerging drugs with different target pathways, alone or in combination with ruxolitinib, seem promising.

Pharmacotherapy of Myelofibrosis

Myelofibrosis (MF) is a myeloproliferative neoplasm that is pathologically characterized by bone marrow myeloproliferation, reticulin and collagen fibrosis, and extramedullary hematopoiesis. Constitutive activation of the Janus associated kinase (JAK)-signal transducers and activators of transcription signaling pathway with resultant elevation in pro-inflammatory cytokine levels is the pathogenic hallmark of MF. JAK inhibitors, namely ruxolitinib, have been successful in alleviating symptoms and reducing splenomegaly, but therapy-related myelosuppression has led to the further development of highly selective JAK2 inhibitors. Additionally, ruxolitinib does not appear to affect the malignant hematopoietic clone substantially, evidenced by lack of molecular remissions, bone marrow histopathologic responses, and a proportion of treated patients developing progressive disease and leukemic transformation while receiving therapy. A number of other pharmacotherapeutic strategies are currently being explored in the clinic. Non-JAK inhibitor strategies being evaluated in MF include non-JAK signaling pathway inhibitors, epigenetic-directed therapies, immune-modulating agents, anti-fibrotic agents, and telomerase inhibitors. This review highlights the current landscape of MF pharmacotherapy and explores therapeutic advances underway.

Management of Myelofibrosis-Related Cytopenias

PURPOSE OF REVIEW

Cytopenias, particularly anemia, are frequently encountered in patients with myelofibrosis. Management of cytopenias in myelofibrosis can be very challenging because current therapeutic interventions are only of modest efficacy and ruxolitinib, the only approved drug for myelofibrosis, is myelosuppressive. Yet, dose optimization of ruxolitinib is important for its survival benefit in patients with advanced disease. We sought to summarize the data on treatments for cytopenias available at present and review promising agents in development and emerging strategies.

RECENT FINDINGS

The activin receptor ligand traps hold considerable promise for the treatment of anemia and could represent an attractive combination strategy with ruxolitinib. Low-dose thalidomide, which could offset both anemia and thrombocytopenia caused by ruxolitinib, represents another potential partner for ruxolitinib. The anti-fibrotic agent PRM-151 produced sustained improvements in cytopenias in some patients, and further data on this drug are eagerly awaited. Finally, several preclinical leads with translational potential are worthy of clinical investigation as strategies to halt/reverse bone marrow fibrosis and thereby improve cytopenias. Cytopenias remain a significant hurdle in myelofibrosis management, but several novel investigational agents hold considerable promise for the future.

Chronic myeloproliferative neoplasms in the elderly

This review focuses on the management of elderly patients with chronic myeloid leukemia and chronic myeloproliferative neoplasms, including polycythemia vera, essential thrombocythemia and primary myelofibrosis. Median age in these neoplasms is within the 6th decades of age. All new therapies can be done at any age without absolute contraindication. However, the selection of the precise therapy for the single patient is mandatory. For these reasons, an accurate definition of diagnosis and prognostication is necessary. Precision in disease definition and prognostication is definitively helpful for personalizing therapeutic approach.

Erythropoiesis: insights into pathophysiology and treatments in 2017

Erythropoiesis is a tightly-regulated and complex process originating in the bone marrow from a multipotent stem cell and terminating in a mature, enucleated erythrocyte.Altered red cell production can result from the direct impairment of medullary erythropoiesis, as seen in the thalassemia syndromes, inherited bone marrow failure as well as in the anemia of chronic disease. Alternatively, in disorders such as sickle cell disease (SCD) as well as enzymopathies and membrane defects, medullary erythropoiesis is not, or only minimally, directly impaired. Despite these differences in pathophysiology, therapies have traditionally been non-specific, limited to symptomatic control of anemia via packed red blood cell (pRBC) transfusion, resulting in iron overload and the eventual need for iron chelation or splenectomy to reduce defective red cell destruction. Likewise, in polycythemia vera overproduction of red cells has historically been dealt with by non-specific myelosuppression or phlebotomy. With a deeper understanding of the molecular mechanisms underlying disease pathophysiology, new therapeutic targets have been identified including induction of fetal hemoglobin, interference with aberrant signaling pathways and gene therapy for definitive cure. This review, utilizing some representative disorders of erythropoiesis, will highlight novel therapeutic modalities currently in development for treatment of red cell disorders.

Myelofibrosis-Related Anemia: Current and Emerging Therapeutic Strategies

Myelofibrosis (MF) is a clonal hematopoietic stem cell disorder characterized by pathological myeloproliferation and aberrant cytokine production resulting in progressive fibrosis, inflammation, and functional compromise of the bone marrow niche. Patients with MF develop splenomegaly (due to extramedullary hematopoiesis), hypercatabolic symptoms (due to overexpression of inflammatory cytokines), and anemia (due to bone marrow failure and splenic sequestration). MF remains curable only with allogeneic hematopoietic stem cell transplantation (ASCT), a therapy that few MF patients are deemed fit to undergo. The goals of treatment are thus often palliative. The approval of the JAK inhibitor ruxolitinib has done much to address the burden of splenomegaly and constitutional symptoms of patients with MF; however, therapy-related anemia is often an anticipated downside. Anemia thus remains a challenge in the management of MF and represents a major unmet need. Intractable anemia depresses quality of life, portends poor outcomes, and can act to restrict access to palliative JAK inhibition in some patients. While therapies for MF-related anemia do exist, they are limited in their efficacy, durability, and tolerability. Therapies currently in development promise improved anemia-specific outcomes; however, are still early in the pathway to regulatory approval and regular clinical use. In this review, we will discuss established and emerging treatments for MF-related anemia. We will give particular attention to developmental therapies which herald significant progress in the understanding and management of MF-related anemia.

Developmental Therapeutics in Myeloproliferative Neoplasms

The unprecedented success of the Janus kinase (JAK) 1/2 inhibitor ruxolitinib in myelofibrosis (MF) provided much-needed impetus for clinical drug development for the Philadelphia chromosome-negative myeloproliferative neoplasms. The survival benefit conferred by this agent, along with its marked efficacy with regard to spleen volume and symptom reduction, have made ruxolitinib the cornerstone of drug therapy in MF. However, there remain significant unmet needs in the treatment of patients with MF, and many novel classes of agents continue to be investigated in efforts to build on the progress made with ruxolitinib. These include inhibitors of histone deacetylases (HDACs) and DNA methyltransferases, phosphatidylinositol-3-kinase isoforms, heat shock protein 90, cyclin-dependent kinases 4/6, and Hedgehog signaling, among others. In parallel, other JAK inhibitors with potential for less myelosuppression or even improvement of anemia, greater selectivity for JAK1 or JAK2, and the ability to overcome JAK inhibitor persistence are in various stages of development. First-in-class agents such as the activin receptor IIA ligand trap sotatercept (for anemia of MF), the telomerase inhibitor imetelstat, and the antifibrotic agent PRM-151 (recombinant human pentraxin-2) are also in clinical trials. In polycythemia vera, a novel interferon administered every 2 weeks is being developed for front-line therapy in high-risk individuals, and inhibitors of human double minute 2 (HDM2) have shown promise in preclinical studies, as have HDAC inhibitors such as givinostat (both in the laboratory and in the clinic). Ruxolitinib is approved for second-line therapy of polycythemia vera and is being developed for essential thrombocythemia.

Fibroblast dynamics as an in vitro screening platform for anti-fibrotic drugs in primary myelofibrosis

Although the cause for bone marrow fibrosis in patients with myelofibrosis remains controversial, it has been hypothesized that it is caused by extensive fibroblast proliferation under the influence of cytokines generated by the malignant megakaryocytes. Moreover, there is no known drug therapy which could reverse the process. We studied the fibroblasts in a novel system using the hanging drop method, evaluated whether the fibroblasts obtain from patients are part of the malignant clone of not and, using this system, we screen a large library of FDA-approved drugs to identify potential drugs candidates that might be useful in the treatment of this disease, specifically which would inhibit fibroblast proliferation and the development of bone marrow fibrosis. We have found that the BM fibroblasts are not part of the malignant clone, as previously suspected and two immunosuppressive medications-cyclosporine and mycophenolate mophetil, as most potent suppressors of the fibroblast collagen production thus potentially inhibitors of bone marrow fibrosis production in myelofibrosis.

Emerging treatments for classical myeloproliferative neoplasms

There has been a major revolution in the management of patients with myeloproliferative neoplasms (MPN), and in particular those with myelofibrosis and extensive splenomegaly and symptomatic burden, after the introduction of the JAK1 and JAK2 inhibitor ruxolitinib. The drug also has been approved as second-line therapy for polycythemia vera (PV). However, the therapeutic armamentarium for MPN is still largely inadequate for coping with patients' major unmet needs, which include normalization of life span (myelofibrosis and some patients with PV), reduction of cardiovascular complications (mainly PV and essential thrombocythemia), prevention of hematological progression, and improved quality of life (all MPN). In fact, none of the available drugs has shown clear evidence of disease-modifying activity, even if some patients treated with interferon and ruxolitinib showed reduction of mutated allele burden, and ruxolitinib might extend survival of patients with higher-risk myelofibrosis. Raised awareness of the molecular abnormalities and cellular pathways involved in the pathogenesis of MPN is facilitating the development of clinical trials with novel target drugs, either alone or in combination with ruxolitinib. Although for most of these molecules a convincing preclinical rationale was provided, the results of early phase 1 and 2 clinical trials have been quite disappointing to date, and toxicities sometimes have been limiting. In this review, we critically illustrate the current landscape of novel therapies that are under evaluation for patients with MPN on the basis of current guidelines, patient risk stratification criteria, and previous experience, looking ahead to the chance of a cure for these disorders.

Austrian recommendations for the management of primary myelofibrosis, post-polycythemia vera myelofibrosis and post-essential thrombocythemia myelofibrosis: an expert statement

The entity "myelofibrosis" represents a subgroup of the Philadelphia chromosome-negative myeloproliferative neoplasms. It comprises primary myelofibrosis, post-polycythemia vera myelofibrosis and post-essential thrombocythemia myelofibrosis. This heterogeneous disease is characterized by clonal myeloproliferation, dysregulated kinase signalling and the abnormal expression of several proinflammatory cytokines. Clinically, patients present with symptoms related to thrombocytosis/leukocytosis, anemia and/or progressive splenomegaly. Mutations in Janus kinase 2, an enzyme that is essential for the normal development of erythrocytes, granulocytes, and platelets, notably the V617F mutation, have been identified in approximately 60% of patients with primary myelofibrosis. Recent molecular advances have not only elucidated critical pathways in the pathogenesis of the disease, but also contributed to a more precise assessment of a patient's individual risk. While allogeneic stem cell transplantation remains the only curative treatment, the natural course of the disease and the patient's survival and quality of life may be improved by new treatments, notably ruxolitinib, the first Janus kinase 1/2 inhibitor approved for the management of myelofibrosis. Additional treatment options are being explored.

Update from the latest WHO classification of MPNs: a user's manual

The 2016 multiparameter World Health Organization (WHO) classification for Philadelphia-negative myeloproliferative neoplasms (MPNs) integrates clinical features, morphology, and genetic data to diagnose polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The main novelties are: (1) the reduction of the hemoglobin (Hb) level threshold to diagnose PV, now established at 16.5 g/dL for men and 16 g/dL for women (based on the identification of MPN patients with PV-consistent bone marrow [BM] features and a Hb level lower than that established in the 2008 WHO classification for PV); (2) the recognition of prefibrotic/early PMF, distinguishable from ET on the basis of BM morphology, an entity having a higher tendency to develop overt myelofibrosis or acute leukemia, and characterized by inferior survival; (3) the central role of BM morphology in the diagnosis of ET, prefibrotic/early PMF, PMF, and PV with borderline Hb values; megakaryocyte number and morphology (typical in ET, atypical in both PMF forms) accompanied by a new distinction of reticulin fibrosis grade in PMF (grade 1 in prefibrotic/early PMF and grade 2-3 in PMF) constitute diagnostic criteria; and (4) the inclusion of all mutually exclusive MPN driver mutations (JAK2, CALR, and MPL) as major diagnostic criteria in ET and PMF; 10% to 15% of these patients are triple negative, and in these cases the search for an additional clonal marker (eg, mutations in ASXL1, EZH2, TET2, IDH1/IDH2, SRSF2, and SF3B1) is warranted.

Myelofibrosis: an update on drug therapy in 2016

INTRODUCTION

Primary myelofibrosis (PMF) is the least common but the most aggressive of the classic Philadelphia chromosome-negative myeloproliferative neoplasms. Survival is much shorter in PMF than in polycythemia vera (PV) or essential thrombocythemia (ET). Post-PV/ET myelofibrosis (MF) is clinically indistinguishable from PMF and approached similarly. Areas covered: Current pharmacologic therapy of MF revolves around the Janus kinase 1/2 (JAK1/2) inhibitor ruxolitinib, which dramatically improves constitutional symptoms and splenomegaly in the majority of patients, and improves overall survival (OS). However, allogeneic stem cell transplantation remains the only potential cure. Other JAK inhibitors continue to be developed for MF, and momelotinib and pacritinib are in phase III clinical trials. Anemia is common in MF, and initially worsened by ruxolitinib. Momelotinib and pacritinib may prove advantageous in this regard. Current strategies for managing anemia of MF include danazol, immunomodulatory drugs and erythroid stimulating agents, either alone or in combination with ruxolitinib. Expert opinion: A number of other agents, representing diverse drug classes, are in various stages of development for MF. These include newer JAK inhibitors, other signaling inhibitors, epigenetic modifiers, anti-fibrotic agents, telomerase inhibitors, and activin receptor ligand traps (for anemia). Hopefully, these novel therapies will further extend the clinical benefits of ruxolitinib.

Treatment of Myelofibrosis: A Moving Target

Myelofibrosis (MF) is a myeloproliferative neoplasm that presents either as a primary disease or evolves secondarily from polycythemia vera or essential thrombocythemia to post-polycythemia vera MF or post-essential thrombocythemia MF, respectively. Myelofibrosis is characterized by stem cell-derived clonal myeloproliferation, abnormal cytokine expression, bone marrow fibrosis, anemia, splenomegaly, extramedullary hematopoiesis, constitutional symptoms, cachexia, leukemic progression, and shortened survival. Therapeutic options for patients with MF have been limited to the use of cytoreductive agents, predominantly hydroxyurea; splenectomy and splenic irradiation for treatment of splenomegaly; and management of anemia with transfusions, erythropoiesis-stimulating agents, androgens, and immunomodulatory agents along with steroids. The only curative option is allogeneic stem cell transplantation (ASCT), which is associated with high morbidity and mortality risks. Recently, JAK (Janus kinase) inhibitor therapies have become available and proven to be palliative in primary MF patients with hydroxyurea-refractory splenomegaly and severe constitutional symptoms. The purpose of this article is to review the clinical features of MF; discuss different treatment strategies, including ASCT; and discuss the potential danger and benefit of using JAK inhibitors prior to ASCT.

Momelotinib in myelofibrosis: JAK1/2 inhibitor with a role in treating and understanding the anemia

Myelofibrosis (MF) is a chronic malignancy of the blood-forming system caused by hyperactivation of JAK2/STAT signaling pathway. Small-molecule inhibitors of JAK2 can variably ameliorate MF-related symptoms caused by chronic inflammation and hepatosplenomegaly. Anemia is a significant problem and adverse prognostic factor in over a third of MF patients and is often worsened by JAK2 inhibitors. The JAK1/2 inhibitor momelotinib unexpectedly resulted in reduction of anemia in MF patients during Phase I/II trials. Current Phase III trials will be the basis for seeking regulatory approval of momelotinib during 2017. Studies to determine how momelotinib improves anemia are underway, potentially leading to expanded momelotinib use and/or development of other targeted therapies for treating anemia in MF and related diseases.

Pomalidomide in myeloproliferative neoplasm-associated myelofibrosis

Myeloproliferative neoplasm (MPN)-associated myelofibrosis is a MPN characterized by bone marrow fibrosis, cytopenias, splenomegaly and constitutional symptoms. Pomalidomide, an immune-modifying drug, is reported to improve anaemia and thrombocytopenia in some patients with MPN-associated myelofibrosis. We designed a phase 2 study of pomalidomide in patients with MPN-associated myelofibrosis and anaemia and/or thrombocytopenia and/or neutropenia. Subjects received pomalidomide 2.0 mg/day in cohort 1 (n=38) or 0.5 mg/day in cohort 2 (n=58). Prednisolone was added if there was no response after 3 months in cohort 1 and based on up-front randomization in cohort 2 if there was no response at 3 or 6 months. Response rates were 39% (95% confidence interval (CI), 26-55%) in cohort 1 and 24% (95% CI, 15-37%) in cohort 2. In a multivariable logistic regression model pomalidomide at 2.0 mg/day (odds ratio (OR), 2.62; 95% CI, 1.00-6.87; P=0.05) and mutated TET2 (OR, 5.07; 95% CI, 1.16-22.17; P=0.03) were significantly associated with responses. Median duration of responses was 13.0 months (range 0.9-52.7). There was no significant difference in response rates or duration in subjects receiving or not receiving prednisolone. Clinical trial MPNSG 01-09 is registered at ClinicalTrials.gov (NCT00949364) and clinicaltrialsregister.eu (EudraCT Number: 2009-010738-23).

A randomized study of pomalidomide vs placebo in persons with myeloproliferative neoplasm-associated myelofibrosis and RBC-transfusion dependence

RBC-transfusion dependence is common in persons with myeloproliferative neoplasm (MPN)-associated myelofibrosis. The objective of this study was to determine the rates of RBC-transfusion independence after therapy with pomalidomide vs placebo in persons with MPN-associated myelofibrosis and RBC-transfusion dependence. Two hundred and fifty-two subjects (intent-to-treat (ITT) population) including 229 subjects confirmed by central review (modified ITT population) were randomly assigned (2:1) to pomalidomide or placebo. Trialists and subjects were blinded to treatment allocation. Primary end point was proportion of subjects achieving RBC-transfusion independence within 6 months. One hundred and fifty-two subjects received pomalidomide and 77 placebo. Response rates were 16% (95% confidence interval (CI), 11, 23%) vs 16% (8, 26% P=0.87). Response in the pomalidomide cohort was associated with ⩽4 U RBC/28 days (odds ratio (OR)=3.1; 0.9, 11.1), age ⩽65 (OR=2.3; 0.9, 5.5) and type of MPN-associated myelofibrosis (OR=2.6; 0.7, 9.5). Responses in the placebo cohort were associated with ⩽4 U RBC/28 days (OR=8.6; 0.9, 82.3), white blood cell at randomization >25 × 10⁹/l (OR=4.9; 0.8, 28.9) and interval from diagnosis to randomization >2 years (OR=4.9; 1.1, 21.9). Pomalidomide was associated with increased rates of oedema and neutropenia but these adverse effects were manageable. Pomalidomide and placebo had similar RBC-transfusion-independence response rates in persons with MPN-associated RBC-transfusion dependence.

Pharmacologic management of myelofibrosis

Myelofibrosis is a BCR-ABL-negative myeloproliferative neoplasm characterized by abnormal hematopoiesis. Alterations to the Janus kinase-signal transducer and activator of transcription pathway result in dysregulation of gene transcription and cell proliferation. Patients with symptomatic myelofibrosis present with a variety of signs and symptoms including, but not limited to myelosuppression, marked splenomegaly, abdominal discomfort, fatigue, and blood transfusion-dependence. Traditional myelosuppressive therapies including hydroxyurea, azacitidine, and cladribine aim to reduce constitutional symptoms and control the burden of disease. Immunomodulators can potentially reverse anemia associated with myelofibrosis, but are poorly tolerated by most patients. The novel Janus kinase 2 (JAK2) inhibitor, ruxolitinib, has demonstrated marked improvements to constitutional symptoms and splenomegaly. While survival benefit has not yet been demonstrated, continued research into pharmacologic management of myelofibrosis offers the promise of altering the course of disease progression.

Role of tyrosine-kinase inhibitors in myeloproliferative neoplasms: comparative lessons learned

An important pathogenetic distinction in the classification of myeloproliferative neoplasms (MPNs) is the presence or absence of the BCR–ABL fusion gene, which encodes a unique oncogenic tyrosine kinase. The BCR–ABL fusion, caused by the formation of the Philadelphia chromosome (Ph) through translocation, constitutes the disease-initiating event in chronic myeloid leukemia. The development of successive BCR–ABL-targeted tyrosine-kinase inhibitors has led to greatly improved outcomes in patients with chronic myeloid leukemia, including high rates of complete hematologic, cytogenetic, and molecular responses. Such levels of treatment success have long been elusive for patients with Ph-negative MPNs, because of the difficulties in identifying specific driver proteins suitable as drug targets. However, in recent years an improved understanding of the complex pathobiology of classic Ph-negative MPNs, characterized by variable, overlapping multimutation profiles, has prompted the development of better and more broadly targeted (to pathway rather than protein) treatment options, particularly JAK inhibitors. In classic Ph-negative MPNs, overactivation of JAK-dependent signaling pathways is a central pathogenic mechanism, and mutually exclusive mutations in JAK2, MPL, and CALR linked to aberrant JAK activation are now recognized as key drivers of disease progression in myelofibrosis (MF). In clinical trials, the JAK1/JAK2 inhibitor ruxolitinib – the first therapy approved for MF worldwide – improved disease-related splenomegaly and symptoms independent of JAK2^V617F mutational status, and prolonged survival compared with placebo or standard therapy in patients with advanced MF. In separate trials, ruxolitinib also provided comprehensive hematologic control in patients with another Ph-negative MPN – polycythemia vera. However, complete cytogenetic or molecular responses with JAK inhibitors alone are normally not observed, underscoring the need for novel combination therapies of JAK inhibitors and complementary agents that better address the complexity of the pathobiology of classic Ph-negative MPNs. Here, we discuss the role of tyrosine-kinase inhibitors in the current MPN-treatment landscape.

Long-term results of a phase II trial of lenalidomide plus prednisone therapy for patients with myelofibrosis

Lenalidomide, with or without prednisone, is an active therapy for patients with myelofibrosis (MF). We provide an update of a phase II study of lenalidomide plus prednisone in patients with MF, after median follow up of 9 years. Forty patients were enrolled in the study and all patients were evaluable for response. Response to the treatment was reevaluated using IWG response criteria published in 2013: quality of response improved over time and overall response rate was 35%. Response in splenomegaly was seen in 39% of patients and anemia response in 32%. The median time to treatment failure (TTF) in all patients was 8.2 months and the median duration of response was 34.6 months. Response was highly durable in some patients: six patients (15%) had TTF for more than 60 months (5 years) and three patients are still on the treatment beyond 109 months (9 years). Complete and partial responses were seen in one and five patients, respectively, but achieving deeper response was not necessary for the response to be durable. New clinical studies are needed to explore safe and well tolerated lenalidomide-based combination strategies for patients with MF.

Managing patients with myelofibrosis and low platelet counts

Myelofibrosis (MF) is a chronic myeloproliferative neoplasm characterized by bone marrow fibrosis, ineffective hematopoiesis, splenomegaly, constitutional symptoms, and shortened survival. Patients often experience multiple disease-associated, as well as treatment-emergent, cytopenias, including thrombocytopenia. However, patients with MF with thrombocytopenia have few therapeutic options, and there is little information on the management of these patients. Several Janus kinase (JAK) inhibitors have been developed for the treatment of MF, with one (ruxolitinib) having been approved. However, given their mechanism of action, JAK inhibitors are associated with high rates of thrombocytopenia. Patients can be successfully managed with dose modifications, but little is known about the safety and efficacy of these agents in patients with thrombocytopenia. Recent studies of JAK inhibitors in patients with MF who have low platelet counts have had mixed results. This review discusses the prevalence, prognostic implications, and management of thrombocytopenia in MF and the different therapeutic options available for this patient population, with an emphasis on current clinical experience with targeted therapies, as well as recent findings from several clinical studies currently underway.

Primary myelofibrosis: current therapeutic options

Primary myelofibrosis is a Philadelphia-negative myeloproliferative neoplasm characterized by clonal myeloid expansion, followed by progressive fibrous connective tissue deposition in the bone marrow, resulting in bone marrow failure. Clonal evolution can also occur, with an increased risk of transformation to acute myeloid leukemia. In addition, disabling constitutional symptoms secondary to the high circulating levels of proinflammatory cytokines and hepatosplenomegaly frequently impair quality of life. Herein the main current treatment options for primary myelofibrosis patients are discussed, contemplating disease-modifying therapeutics in addition to palliative measures, in an individualized patient-based approach.

Tumour necrosis factor-α inhibits hepatic lipid deposition through GSK-3β/β-catenin signaling in juvenile turbot (Scophthalmus maximus L.)

In this study, the mechanism that TNFα inhibits lipid deposition through GSK-3β/β-catenin signaling was investigated in the liver of juvenile turbot (Scophthalmus maximus L.) by injection of TNFα or TNFα inhibitor pomalidomide (POM). It was found that TNFα inhibited the expression of GSK-3β and induced β-catenin expression. TNFα inhibited the expression of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα), as well as the activity of lipoprotein lipase (LPL) and fatty acid synthetase (FAS). In addition, the level of triglyceride (TG), total cholesterol (TC), nonesterified fatty acid (NEFA), and glycerol was decreased by TNFα treatment in the liver. In the plasma, the level of TG, TC, low density lipoprotein cholesterol (LDL-C), NEFA, and glycerol was decreased, but high density lipoprotein cholesterol (HDL-C) was increased by TNFα treatment. However, compared to TNFα, POM had the opposite effect on the biochemical indexes and genes related to lipid deposition in the liver. The results indicated that TNFα may regulate hepatic lipid metabolism and fat distribution through GSK-3β/β-catenin signaling as well as transcription factors PPARγ and C/EBPα in juvenile turbot.

Myeloproliferative neoplasms: A decade of discoveries and treatment advances

Myeloproliferative neoplasms (MPN) are clonal stem cell diseases, first conceptualized in 1951 by William Dameshek, and historically included chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). In 1960, Nowell and Hungerford discovered an invariable association between the Philadelphia chromosome (subsequently shown to harbor the causal BCR-ABL1 mutation) and CML; accordingly, the term MPN is primarily reserved for PV, ET, and PMF, although it includes other related clinicopathologic entities, according to the World Health Organization (WHO) classification system. In 2005, William Vainchenker and others described a Janus kinase 2 mutation (JAK2V617F) in MPN and this was followed by a series of additional descriptions of mutations that directly or indirectly activate JAK-STAT: JAK2 exon 12, myeloproliferative leukemia virus oncogene (MPL) and calreticulin (CALR) mutations. The discovery of these, mostly mutually exclusive, "driver" mutations has contributed to revisions of the WHO diagnostic criteria and risk stratification in MPN. Mutations other than JAK2, CALR and MPL have also been described in MPN and shown to provide additional prognostic information. From the standpoint of treatment, over the last 50 years, Louis Wasserman from the Unites States and Tiziano Barbui from Italy had skillfully organized and led a number of important clinical trials, whose results form the basis for current treatment strategies in MPN. More recently, allogeneic stem cell transplant, as a potentially curative treatment modality, and JAK inhibitors, as palliative drugs, have been added to the overall therapeutic armamentarium in myelofibrosis. In the current review, I will summarize the important advances made in the last 10 years regarding the science and practice of MPN.

Evolving Therapeutic Strategies for the Classic Philadelphia-Negative Myeloproliferative Neoplasms

Despite the emergence of JAK inhibitors, there is a need for disease-modifying treatments for Philadelphia-negative myeloproliferative neoplasms (MPNs). JAK inhibitors ameliorate symptoms and address splenomegaly, but because of the heterogeneous contributors to the disease process, JAK inhibitor monotherapy incompletely addresses the burden of disease. The ever-growing understanding of MPN pathogenesis has provided the rationale for testing novel and targeted therapeutic agents, as monotherapies or in combination, in preclinical and clinical settings. A number of intriguing options have emerged, and it is hoped that further progress will lead to significant changes in the natural history of MPNs.

A case of simultaneous occurrence of acute myeloid leukemia and multiple myeloma

Background

Although the occurrence of acute myeloid leukemia (AML) after chemotherapy for multiple myeloma (MM) is common in clinical settings, the simultaneous occurrence of these malignancies in patients without previous exposure to chemotherapy is a rare event. Etiology, disease management, and clinical treatment remain unclear for this particular occurrence. To the best of our knowledge, this study is the first to report a case of simultaneous presentation of AML and MM after exposure to ultraviolet irradiation.

Case presentation

We reported the case of a 73-year-old man (Han Chinese ethnicity) without previous medical history of AML and MM. The morphology and immunology of bone marrow cells confirmed the co-existence of AML and MM. Fluorescent in situ hybridization analysis of immunomagnetically separated abnormal plasma cells showed abnormal expression of the amplified RB-1, TP53, and CDKN2C (1p32). Cytogenetic analysis demonstrated Y chromosome deletion.

After the patient was administered with bortezomib combined with cytarabine + aclarubicin + granulocyte colony-stimulating factor (CAG regimen), and evident curative effects were observed. The patient achieved and maintained complete remission for more than 6 months. Prior to the disease occurrence, the patient had received ultraviolet irradiation for 1 year and was detected with aberrant gene expression of RB-1, TP53, and CDKN2C (1p32). Nevertheless, the correlation of this phenomenon with the etiology of concurrent AML with MM remains unclear.

Conclusion

This study discussed the case of a patient diagnosed with AML concurrent with MM, who has no previous exposure to chemotherapy. This patient was successfully treated by bortezomib combined with CAG regimen. This study provides a basis for clinical treatment guidance for this specific group of patients and for confirmation of the disease etiology.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1743-6) contains supplementary material, which is available to authorized users.

Janus Kinase Inhibitors and Stem Cell Transplantation in Myelofibrosis

Myelofibrosis (MF) is characterized by splenomegaly, blood count abnormalities, particularly cytopenias, and a propensity for transformation to acute leukemia. The current treatment approach is to ameliorate symptoms due to these abnormalities. Treatment with Janus kinase 2 inhibitors reduces spleen size and improves symptoms in patients with MF, but most of the patients eventually have disease progression and stop responding. Allogeneic stem cell transplantation remains the only curative option. However, its efficacy must be balanced against the risk of treatment-related death and long-term sequelae of transplant like chronic graft versus host disease. The challenge is to integrate treatment with Janus kinase inhibitors with allogeneic stem cell transplantation.

Emerging drugs for the treatment of myelofibrosis

INTRODUCTION

Myelofibrosis (MF) is a myeloproliferative neoplasm associated with significant disease burden composed of splenomegaly, constitutional symptoms and a reduced life expectancy. The advent of targeted treatments has provided new means by which to improve MF associated splenomegaly, symptoms, health-related quality of life and even mortality.

AREAS COVERED

We discuss the spectrum of targeted treatments currently under investigation for MF. We furthermore compare their effects on improving anemia, reducing fibrosis and splenomegaly and enhancing symptom control.

EXPERT OPINION

MF is a complex disorder, partly attributable to its heterogeneity. Although the severity of patient symptoms correlates with risk category, high symptom burden may also be observed in low-risk patients. Serial use of PRO tools allows clinicians to objectively evaluate the MF symptom burden, compare efficacy of therapies and adjust medications to improve symptom control. Novel targeted agents have proven superior to historic treatment regimens for symptom management. Promising treatment categories include JAK2 inhibitors, histone deacetylase inhibitors, hypomethylating agents, heat shock protein-90 inhibitors, hedgehog inhibitors, PI3-AKT-mTOR inhibitors, antifibrosing agents and telomerase inhibitors. The majority of therapies remain under investigation, either alone or in combination with other treatments. It is anticipated that these agents will be increasingly integrated into standard treatment algorithms for MF symptom management.

Therapeutic benefit of decitabine, a hypomethylating agent, in patients with high-risk primary myelofibrosis and myeloproliferative neoplasm in accelerated or blastic/acute myeloid leukemia phase

Myeloproliferative neoplasm (MPN) transformed to acute myeloid leukemia (MPN-AML), MPN in accelerated phase (MPN-AP), and high-risk primary myelofibrosis (PMF) are associated with a poor response to therapy and very short survival. Several reports have suggested clinical activity of hypomethylating agents in these patients. We conducted a retrospective study of 21 patients with MPN-AML, 13 with MPN-AP and 11 with DIPSS-plus high-risk PMF treated with decitabine at our institution over the last 7 years and evaluated their clinical outcomes. Six patients (29%) with MPN-AML responded to decitabine (3 CR, 2 CRi, and 1 PR); median response duration was 7 months. The median overall survival (OS) was significantly higher in those who responded (10.5 vs 4 months). Among patients with MPN-AP, 8 patients (62%) benefited; the median response duration was 6.5 months. The median OS was 11.8 months in responders vs 4.7 months in non-responders. Among patients with DIPSS-plus high-risk PMF, 9 (82%) benefited; the median response duration was 9 months. The median OS was 32 months in responders vs 16.3 months in non-responders. Decitabine is a viable therapeutic option for patients with MPN-AML, MP-AP and high-risk PMF. Prospective clinical studies combining decitabine with other clinically active agents are needed to improve overall outcome.

Janus kinase-1 and Janus kinase-2 inhibitors for treating myelofibrosis

BACKGROUND

Myelofibrosis is a bone marrow disorder characterized by excessive production of reticulin and collagen fiber deposition caused by hematological and non-hematological disorders. The prognosis of myelofibrosis is poor and treatment is mainly palliative. Janus kinase inhibitors are a novel strategy to treat people with myelofibrosis.

OBJECTIVES

To determine the clinical benefits and harms of Janus kinase-1 and Janus kinase-2 inhibitors for treating myelofibrosis secondary to hematological or non-hematological conditions.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, the Cochrane Library 2014, Issue 11), Ovid MEDLINE (from 1946 to 13 November 2014), EMBASE (from 1980 to 12 January 2013), and LILACS (from 1982 to 20 November 2014). We searched WHO International Clinical Trials Registry Platform and The metaRegister of Controlled Trials. We also searched for conference proceedings of the American Society of Hematology (from 2009 to October 2013), European Hematology Association (from 2009 to October 2013), American Society of Clinical Oncology (from 2009 to October 2013), and European Society of Medical Oncology (from 2009 to October 2013). We included searches in FDA, European Medicines Agency, and Epistemonikos. We handsearched the references of all identified included trials, and relevant review articles. We did not apply any language restrictions. Two review authors independently screened search results.

SELECTION CRITERIA

We included randomized clinical trials comparing Janus kinase-1 and Janus kinase-2 inhibitors with placebo or other treatments. Both previously treated and treatment naive patients were included.

DATA COLLECTION AND ANALYSIS

We used the hazard ratio (HR) and 95% confidence interval (95% CI) for overall survival, progression-free survival and leukemia-free survival, risk ratio (RR) and 95% CI for reduction in spleen size and adverse events binary data, and standardized mean differences (SMD) and 95% CI for continuous data (health-related quality of life). Two review authors independently extracted data and assessed the risk of bias of included trials. Primary outcomes were overall survival, progression-free survival and adverse events.

MAIN RESULTS

We included two trials involving 528 participants, comparing ruxolitinib with placebo or best available therapy (BAT). As the two included trials had different comparators we did not pool the data. The confidence in the results estimates of these trials was low due to the bias in their design, and their limited sample sizes that resulted in imprecise results.There is low quality evidence for the effect of ruxolitinib on survival when compared with placebo at 51 weeks of follow-up (HR 0.51, 95% CI 0.27 to 0.98) and compared with BAT at 48 weeks of follow-up (HR 0.70, 95% CI 0.20 to 2.47). Similarly there was very low quality evidence for the effect of ruxolitinib on progression free survival compared with BAT (HR 0.81, 95% CI 0.47 to 1.39).There is low quality evidence for the effect of ruxolitinib in terms of quality of life. Compared with placebo, the drug achieved a greater proportion of patients with a significant reduction of symptom scores (RR 8.82, 95% CI 4.40 to 17.69), and treated patients with ruxolitinib obtained greater MFSAF scores at the end of follow-up (MD -87.90, 95% CI -139.58 to -36.22). An additional trial showed significant differences in EORTC QLQ-C30 scores when compared ruxolitinib with best available therapy (MD 7.60, 95% CI 0.35 to 14.85).The effect of ruxolitinib on reduction in the spleen size of participants compared with placebo or BAT was uncertain (versus placebo: RR 64.58, 95% CI 9.08 to 459.56, low quality evidence; versus BAT: RR 41.78, 95% CI 2.61 to 669.75, low quality evidence).There is low quality evidence for the effect of the drug compared with placebo on anemia (RR 2.35, 95% CI 1.62 to 3.41), neutropenia (RR 3.57, 95% CI 1.02 to 12.55) and thrombocytopenia (RR 9.74, 95% CI 2.32 to 40.96). Ruxolitinib did not result in differences versus BAT in the risk of anemia (RR 1.35, 95% CI 0.91 to 1.99, low quality evidence) or thrombocytopenia (RR 1.20; 95% CI 0.44 to 3.28, low quality evidence). The risk of non-hematologic grade 3 or 4 adverse events (including fatigue, arthralgia, nausea, diarrhea, extremity pain and pyrexia) was similar when ruxolitinib was compared with placebo or BAT. The rate of neutropenia comparing ruxolitinib with standard medical treatment was not reported by the trial.

AUTHORS' CONCLUSIONS

Currently, there is insufficient evidence to allow any conclusions regarding the efficacy and safety of ruxolitinib for treating myelofibrosis. The findings of this Cochrane review should be interpreted with caution as they are based on trials sponsored by industry, and include a small number of patients. Unless powered randomized clinical trials provide strong evidence of a treatment effect, and the trade-off between potential benefits and harms is established, clinicians should be cautious when administering ruxolitinib for treating patients with myelofibrosis.

Profile of pomalidomide and its potential in the treatment of myelofibrosis

Myelofibrosis, a Philadelphia-negative myeloproliferative neoplasm, is in a new treatment era after the discovery of the JAK2V617F mutation in 2005. JAK inhibitors boast improvements in disease-related symptoms, splenomegaly, and overall survival; however, treatment of myelofibrosis remains a challenge, given the lack of improvement in cytopenias with these agents. Second-generation immunomodulatory agents, such as pomalidomide, have shown efficacy in myelofibrosis-associated anemia within multiple clinical trials. Five major pomalido-mide clinical trials have been completed to date, and demonstrate tolerability and efficacy with low-dose pomalidomide (0.5 mg/day) in the treatment of myelofibrosis, and no clinical benefit of elevated dosing regimens (≥2.5 mg/day). Anemia responses ranged from 17% to 36% as per the International Working Group for Myelofibrosis Research and Treatment consensus guidelines, while improvements in splenomegaly were rare, and observed in <1% of most clinical trials. In comparison with earlier immunomodulatory agents, pomalidomide was associated with an improved toxicity profile, with substantially lower rates of myelosuppression and neuropathy. Given the low overall response rate to pomalidomide as a single agent, combination strategies are of particular interest for future studies. Pomalidomide is currently being tested in combination with ruxolitinib, and other novel combinations are likely on the horizon.

Myelofibrosis patients in Belgium: disease characteristics

OBJECTIVE

To date, only a small number of epidemiological studies on myelofibrosis have been performed. The current study aimed to characterize the myelofibrosis patient population in Belgium according to pre-defined disease parameters (diagnosis, risk categories, hemoglobin <10 g/dl, spleen size, constitutional symptoms, platelet count, myeloblast count), with a view to obtaining a deeper understanding of the proportion of patients that may benefit from the novel myelofibrosis therapeutic strategies.

METHODS

A survey was used to collect data on prevalence and disease parameters on all myelofibrosis patients seen at each of 18 participating hematologic centers in 2011. Aggregated data from all centers were used for analysis. Analyses were descriptive and quantitative.

RESULTS

A total of 250 patients with myelofibrosis were captured; of these, 136 (54%) were male and 153 (61%) were over 65 years old. One hundred sixty-five (66%) of myelofibrosis patients had primary myelofibrosis and 85 (34%) had secondary myelofibrosis. One hundred ninety-three myelofibrosis patients (77%) had a palpable spleen. About a third of patients (34%) suffered from constitutional symptoms. Two hundred twenty-two (89%) myelofibrosis patients had platelet count ≧50 000/μl and 201 (80%) had platelet count ≧100 000/μl. Of 250 patients, 85 (34%) had a myeloblast count ≧1%. Six (2%) patients had undergone a splenectomy. Thirteen (5·2%) patients had undergone radiotherapy for splenomegaly.

CONCLUSIONS

The results of this survey provide insight into the characteristics of the Belgian myelofibrosis population. They also suggest that a large proportion of these patients could stand to benefit from the therapies currently under development.

Durable Red Blood Cell Transfusion Independence in a Patient with an MDS/MPN Overlap Syndrome Following Discontinuation of Iron Chelation Therapy

Background. Hematologic improvement (HI) occurs in some patients with acquired anemias and transfusional iron overload receiving iron chelation therapy (ICT) but there is little information on transfusion status after stopping chelation. Case Report. A patient with low IPSS risk RARS-T evolved to myelofibrosis developed a regular red blood cell (RBC) transfusion requirement. There was no response to a six-month course of study medication or to erythropoietin for three months. At 27 months of transfusion dependence, she started deferasirox and within 6 weeks became RBC transfusion independent, with the hemoglobin normalizing by 10 weeks of chelation. After 12 months of chelation, deferasirox was stopped; she remains RBC transfusion independent with a normal hemoglobin 17 months later. We report the patient's course in detail and review the literature on HI with chelation. Discussion. There are reports of transfusion independence with ICT, but that transfusion independence may be sustained long term after stopping chelation deserves emphasis. This observation suggests that reduction of iron overload may have a lasting favorable effect on bone marrow failure in at least some patients with acquired anemias.