Assessment of peripheral blood lymphocyte subsets in idiopathic myelofibrosis

Non-canonical Hedgehog signaling mediates profibrotic hematopoiesis-stroma crosstalk in myeloproliferative neoplasms

The role of hematopoietic Hedgehog signaling in myeloproliferative neoplasms (MPNs) remains incompletely understood despite data suggesting that Hedgehog (Hh) pathway inhibitors have therapeutic activity in patients. We aim to systematically interrogate the role of canonical vs. non-canonical Hh signaling in MPNs. We show that Gli1 protein levels in patient peripheral blood mononuclear cells (PBMCs) mark fibrotic progression and that, in murine MPN models, absence of hematopoietic Gli1, but not Gli2 or Smo, significantly reduces MPN phenotype and fibrosis, indicating that GLI1 in the MPN clone can be activated in a non-canonical fashion. Additionally, we establish that hematopoietic Gli1 has a significant effect on stromal cells, mediated through a druggable MIF-CD74 axis. These data highlight the complex interplay between alterations in the MPN clone and activation of stromal cells and indicate that Gli1 represents a promising therapeutic target in MPNs, particularly that Hh signaling is dispensable for normal hematopoiesis.

Philadelphia-negative myeloproliferative neoplasms display alterations in monocyte subpopulations frequency and immunophenotype

Philadelphia-negative myeloproliferative neoplasms (MPN) are clonal hematological diseases associated with driver mutations in JAK2, CALR, and MPL genes. Moreover, several evidence suggests that chronic inflammation and alterations in stromal and immune cells may contribute to MPN’s pathophysiology. We evaluated the frequency and the immunophenotype of peripheral blood monocyte subpopulations in patients with polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (MF). Peripheral blood monocytes from PV (n = 16), ET (n = 16), and MF (n = 15) patients and healthy donors (n = 10) were isolated and submitted to immunophenotyping to determine the frequency of monocyte subpopulations and surface markers expression density. Plasma samples were used to measure the levels of soluble CD163, a biomarker of monocyte activity. PV, ET, and MF patients presented increased frequency of intermediate and non-classical monocytes and reduced frequency of classical monocytes compared to controls. Positivity for JAK2 mutation was significantly associated with the percentage of intermediate monocytes. PV, ET, and MF patients presented high-activated monocytes, evidenced by higher HLA-DR expression and increased soluble CD163 levels. The three MPN categories presented increased frequency of CD56⁺ aberrant monocytes, and PV and ET patients presented reduced frequency of CD80/86⁺ monocytes. Therefore, alterations in monocyte subpopulations frequency and surface markers expression pattern may contribute to oncoinflammation and may be associated with the pathophysiology of MPN.

Patients With Myeloproliferative Neoplasms Harbor High Frequencies of CD8 T Cell-Platelet Aggregates Associated With T Cell Suppression

Myeloproliferative neoplasms (MPN) are chronic cancers of the hematopoietic stem cells in the bone marrow, and patients often harbor elevated numbers of circulating platelets (PLT). We investigated the frequencies of circulating PLT-lymphocyte aggregates in MPN patients and the effect of PLT-binding on CD8 T cell function. The phenotype of these aggregates was evaluated in 50 MPN patients and 24 controls, using flow cytometry. In vitro studies compared the proliferation, cytokine release, and cytoxicity of PLT-bound and PLT-free CD8 T cells. Frequencies of PLT-CD8 T cell aggregates, were significantly elevated in MPN patients. Advanced disease stage and CALR mutation associated with the highest aggregate frequencies with a predominance of PLT-binding to antigen-experienced CD8 T cells. PLT-bound CD8 T cells showed reduction in proliferation and cytotoxic capacity. Our data suggest that CD8 T cell responses are jeopardized in MPN patients. JAK2 and CALR exon 9 mutations – the two predominant driver mutations in MPN – are targets for natural T cell responses in MPN patients. Moreover, MPN patients have more infections compared to background. Thus, PLT binding to antigen experienced CD8 T cells could play a role in the inadequacy of the immune system to control MPN disease progression and prevent recurrent infections.

Managing patients with myelofibrosis and thrombocytopenia

INTRODUCTION

: Given the progressive nature of myelofibrosis, the incidence of thrombocytopenia increases over time. Furthermore, approved drugs ruxolitinib and fedratinib, induce thrombocytopenia. Hence, treatment of myelofibrosis patients with low platelet counts is an unmet need.

AREAS COVERED

: This review summarizes the current and emerging treatment options available for patients with myelofibrosis and thrombocytopenia. In the first section of this review, we summarized the use of JAK inhibitors in patients with thrombocytopenia, and in the second part, we focused on use of therapies other than JAK Inhibitors such as steroids, immunomodulatory agents, androgens and other novel agents.

EXPERT OPINION

: Up to 25% of patients with myelofibrosis have platelet counts below 100,000 at presentation. Patients with thrombocytopenia are more likely to be anemic and PRBC transfusion-dependent, as well as have high-risk disease characteristics and a poor overall survival rate.. Among all JAK inhibitors studied in phase 3 clinical trials, pacritinib seems not to induce significant thrombocytopenia while maintaining a good spleen response. Severe thrombocytopenia is a major impediment to myelofibrosis therapy, and more research, particularly on novel therapeutic agents aimed at cytopenic patient populations, is needed.

Philadelphia-Negative Chronic Myeloproliferative Neoplasms during the COVID-19 Pandemic: Challenges and Future Scenarios

An outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) started in December 2019 in China and then become pandemic in February 2020. Several publications investigated the possible increased rate of COVID-19 infection in hematological malignancies. Based on the published data, strategies for the management of chronic Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) are provided. The risk of severe COVID-19 seems high in MPN, particularly in patients with essential thrombocythemia, but not negligible in myelofibrosis. MPN patients are at high risk of both thrombotic and hemorrhagic complications and this must be accounted in the case of COVID-19 deciding on a case-by-case basis. There are currently no data to suggest that hydroxyurea or interferon may influence the risk or severity of COVID-19 infection. Conversely, while the immunosuppressive activity of ruxolitinib might pose increased risk of infection, its abrupt discontinuation during COVID-19 syndrome is associated with worse outcome. All MPN patients should receive vaccine against COVID-19; reassuring data are available on efficacy of mRNA vaccines in MPNs.

Cancer Immune Therapy for Philadelphia Chromosome-Negative Chronic Myeloproliferative Neoplasms

Philadelphia chromosome-negative chronic myeloproliferative neoplasms (MPN) are neoplastic diseases of the hematopoietic stem cells in the bone marrow. MPN are characterized by chronic inflammation and immune dysregulation. Of interest, the potent immunostimulatory cytokine interferon-α has been used to treat MPN for decades. A deeper understanding of the anti-cancer immune response and of the different immune regulatory mechanisms in patients with MPN has paved the way for an increased perception of the potential of cancer immunotherapy in MPN. Therapeutic vaccination targeting the driver mutations in MPN is one recently described potential new treatment modality. Furthermore, T cells can directly react against regulatory immune cells because they recognize proteins like arginase and programmed death ligand 1 (PD-L1). Therapeutic vaccination with arginase or PD-L1 therefore offers a novel way to directly affect immune inhibitory pathways, potentially altering tolerance to tumor antigens like mutant CALR and mutant JAK2. Other therapeutic options that could be used in concert with therapeutic cancer vaccines are immune checkpoint-blocking antibodies and interferon-α. For more advanced MPN, adoptive cellular therapy is a potential option that needs more preclinical investigation. In this review, we summarize current knowledge about the immune system in MPN and discuss the many opportunities for anti-cancer immunotherapy in patients with MPN.

Impaired virus-specific T cell responses in patients with myeloproliferative neoplasms treated with ruxolitinib

Ruxolitinib is effective in myeloproliferative neoplasms (MPN) but can cause reactivation of silent infections. We aimed at evaluating viral load and T-cell responses to human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) in a cohort of 25 MPN patients treated with ruxolitinib. EBV-DNA and HCMV-DNA were quantified monthly using real-time polimerase chain reaction (PCR) on peripheral blood samples, and T-cell subsets were analyzed by flowcytometry. HCMV and EBV-directed T-cell responses were evaluated using the IFN-γ ELISPOT assay. Most patients had CD4+ and/or CD8+ T-cells below the normal range; these reductions were related to the duration of ruxolitinib treatment. In fact, reduced T-lymphocytes' subsets were found in 93% of patients treated for ≥5 years and in 45% of those treated for <5 years (P = .021). The former also had lower median numbers of CD4+ and CD8+ cells. Subclinical reactivation of EBV and HCMV occurred in 76% and 8% of patients. We observed a trend to an inverse relationship between EBV and CMV-specific CD4+ and CD8+ T-cell responses and viral load, and a trend to an inverse correlation with ruxolitinib dose. Therefore, our data suggest that the ruxolitinib treatment may interfere with immunosurveillance against EBV and HCMV.

The role of circulating monocytes and JAK inhibition in the infectious-driven inflammatory response of myelofibrosis

Myelofibrosis (MF) is characterized by chronic inflammation and hyper-activation of the JAK-STAT pathway. Infections are one of the main causes of morbidity/mortality. Therapy with Ruxolitinib (RUX), a JAK1/2 inhibitor, may further increase the infectious risk. Monocytes are critical players in inflammation/immunity through cytokine production and release of bioactive extracellular vesicles. However, the functional behavior of MF monocytes, particularly during RUX therapy, is still unclear. In this study, we found that monocytes from JAK2V617F-mutated MF patients show an altered expression of chemokine (CCR2, CXCR3, CCR5) and cytokine (TNF-α-R, IL10-R, IL1β-R, IL6-R) receptors. Furthermore, their ability to produce and secrete free and extracellular vesicles-linked cytokines (IL1β, TNF-α, IL6, IL10) under lipopolysaccharides (LPS) stimulation is severely impaired. Interestingly, monocytes from RUX-treated patients show normal level of chemokine, IL10, IL1β, and IL6 receptors together with a restored ability to produce intracellular and to secrete extracellular vesicles-linked cytokines after LPS stimulation. Conversely, RUX therapy does not normalize TNF-R1/2 receptors expression and the LPS-driven secretion of free pro/anti-inflammatory cytokines. Accordingly, upon LPS stimulation, in vitro RUX treatment of monocytes from MF patients increases their secretion of extracellular vesicles-linked cytokines but inhibits the secretion of free pro/anti-inflammatory cytokines. In conclusion, we demonstrated that in MF the infection-driven response of circulating monocytes is defective. Importantly, RUX promotes their infection-driven cytokine production suggesting that infections following RUX therapy may not be due to monocyte failure. These findings contribute to better interpreting the immune vulnerability of MF and to envisaging strategies to improve the infection-driven immune response.

A journey through infectious risk associated with ruxolitinib

Ruxolitinib has proved to be effective for the treatment of patients with myelofibrosis (either primary or secondary) and polycythaemia vera, and its approval led to a significant change in the current treatment algorithm. Despite its efficacy and beyond its well described haematological toxicity, a peculiar immunosuppressive effect emerged as our clinical experience grew, both within and outside of a clinical trial setting. Definite and negative interactions with multiple pathways of the immune system of patients have been reported so far, involving both adaptive and innate immune responses. These pathophysiological mechanisms may contribute to the increased risk of reactivation of silent infections (e.g., tuberculosis, hepatitis B virus and varicella zoster virus) that have been associated with the drug. Even though such infectious events may be fatal or may lead to significant impairment of organ function, compromising the eligibility of patients for an allotransplant procedure, there are no dedicated guidelines that may help us in assessing and managing the risk of developing serious infections. On this basis, our aim for the present work was to review the current knowledge on the pathophysiological mechanisms through which ruxolitinib may exert its immunosuppressive effect, and to illustrate our personal approach to the management of three peculiar clinical scenarios, for which a risk-based algorithm is suggested.

B-cell frequencies and immunoregulatory phenotypes in myeloproliferative neoplasms: Influence of ruxolitinib, interferon-α2, or combination treatment

OBJECTIVE

Given a proposed role for PD-L1⁺ and IL-10-producing B-cell subsets in promoting certain cancers, we sought to characterize the frequency and phenotype of B cells in patients with chronic myeloproliferative neoplasms (MPNs) and the influence of ruxolitinib and interferon-α2 therapy.

METHODS

We analyzed B-cell frequencies and phenotype in patients with MPNs (n = 107), before and during treatment with ruxolitinib (n = 29), interferon-α2 (n = 21), or the two drugs in combination (COMBI; n = 42) and healthy donors (HDs; n = 52) using flow cytometry.

RESULTS

Myelofibrosis patients had lower lymphocyte counts and proportions of B cells than patients with essential thrombocythemia or polycythemia vera and HDs. The B-cell count correlated inversely with JAK2-V617F allele burden and spleen size and increased after ruxolitinib or COMBI treatment. The proportions of PD-L1⁺ B cells and PD-1⁺ B cells were significantly higher in patients with myelofibrosis or polycythemia vera than in HDs and decreased during ruxolitinib and COMBI treatment. The proportions of TNF-α⁺ and IL-6⁺ B cells were elevated in myelofibrosis patients. The proportion of IL-6⁺ B cells decreased, and the proportion of IL-10⁺ B cells increased during ruxolitinib treatment.

CONCLUSION

B-cell frequency and phenotype were altered in MPN patients. Ruxolitinib therapy had marked effects on both frequency and phenotype.

Expression of CD markers in JAK2V617F positive myeloproliferative neoplasms: Prognostic significance

Myeloproliferative neoplasms (MPNs) are clonal stem cell disorders characterized by the presence of JAK2^V617F mutation. Thrombohemorrhagic as well as autoimmune or inflammatory phenomena are common clinical outcomes of these disorders. Recent studies have shown that abnormality in frequency and function of blood cells manifested by an alteration in CD markers' expression patterns play a key role in these complications. So, there may be a relationship between CD markers' expressions and prognosis of JAK2^V617F positive MPNs. Therefore, in this review, we have focused on these abnormalities from the perspective of changing expressions of CD markers and assessment of the relationship between these changes with prognosis of JAK2^V617F positive MPNs. It can be stated that the abnormal expression of a large number of CD markers can be used as a prognostic biomarker for clinical outcomes including thrombohememorrhagic events, as well as autoimmune and leukemic transformation in JAK2^V617F positive MPNs. Considering the possible role of CD markers' expressions in JAK2^V617F MPNs prognosis, further studies are needed to confirm the relationship between the expression of CD markers with prognosis to be able to find an appropriate therapeutic approach via targeting CD markers.

Epidemiology, outcome, and risk factors for infectious complications in myelofibrosis patients receiving ruxolitinib: A multicenter study on 446 patients

Infections represent one of the major concerns regarding the utilization of ruxolitinib (RUX) in patients with myelofibrosis. With the aim to investigate epidemiology, outcome and risk factors for infections in RUX-exposed patients, we collected clinical and laboratory data of 446 myelofibrosis patients treated with RUX between June 2011 and November 2016 in 23 European Hematology Centers. After a median RUX exposure of 23.5 months (range, 1-56), 123 patients (28%) experienced 161 infectious events (grades 3-4 32%, fatal 9%), for an incidence rate of 17 cases per 100 pts/y. The rate of infections tended to decrease over time: 14% of patients developed the first infection within 6 months, 5% between 6 and 12 months, 3.7% between 12 and 18 months, 3.4% between 18 and 24 months, and 7.9% thereafter (P < .0001). Respiratory tract infections were more frequently observed (81 events, 50%), and bacteria were the most frequent etiological agents (68.9%). However, also viral (14.9%) and fungal infections (2.5%) were observed. In multivariate analysis, previous infectious event (HR 2.54; 95% CI, 1.51-4.28; P = .0005) and high international prognostic score system category (IPSS) (HR 1.53; 95% CI, 1.07-2.20; P = .021) significantly correlated with higher infectious risk. On the contrary, spleen reduction ≥50% from baseline after 3 months of treatment (P = .02) was associated with better infection-free survival. Taken together, these findings reinforce the concept of disease severity as the most important risk factor for infections, and describe, for the first time, that a positive therapeutic effect in reducing splenomegaly may also reduce subsequent infectious complications.

Spontaneous T-cell responses against the immune check point programmed-death-ligand 1 (PD-L1) in patients with chronic myeloproliferative neoplasms correlate with disease stage and clinical response

The Chronic Myeloproliferative Neoplasms (MPN) are cancers characterized by hyperinflammation and immune deregulation. Concurrently, the expression of the immune check point programmed death ligand 1 (PD-L1) is induced by inflammation. In this study we report on the occurrence of spontaneous T cell responses against a PD-L1 derived epitope in patients with MPN. We show that 71% of patients display a significant immune response against PD-L1, and patients with advanced MPN have significantly fewer and weaker PD-L1 specific immune responses compared to patients with non-advanced MPN. The PD-L1 specific T cell responses are CD4⁺ T cell responses, and by gene expression analysis we show that expression of PD-L1 is enhanced in patients with MPN. This could imply that the tumor specific immune response in MPN could be enhanced by vaccination with PD-L1 derived epitopes by boosting the anti-regulatory immune response hereby allowing tumor specific T cell to exert anti-tumor immunity.

Assessing serum albumin concentration, lymphocyte count and prognostic nutritional index might improve prognostication in patients with myelofibrosis

BACKGROUND

Primary and secondary myelofibrosis (PMF and SMF) are malignant diseases of hematopoietic stem cell characterized by the neoplastic myeloproliferation and a strong inflammatory milieu. The prognostic nutritional index (PNI) integrates information on albumin and absolute lymphocyte count (ALC) and reflects the inflammatory, nutritional and immune status of a patient. The clinical and prognostic significance of albumin, ALC and PNI in patients with myelofibrosis has not been previously investigated.

METHODS

We retrospectively analyzed a cohort of 83 myelofibrosis patients treated in our institution from 2006 to 2017. Albumin, ALC and PNI were assessed in addition to other disease specific markers.

RESULTS

The PMF and SMF patients had significantly lower ALC and PNI but similar albumin compared to controls. Lower albumin was significantly associated with older age and parameters reflecting more aggressive disease biology (e.g. anemia, lower platelet levels, higher lactate dehydrogenase (LDH), circulatory blasts, transfusion dependency, blast phase disease), inflammation (higher C reactive protein (CRP), constitutional symptoms) and higher degree of bone marrow fibrosis. Lower ALC was significantly associated with lower white blood cells (WBC) and lower circulatory blasts. Low PNI was associated with lower albumin, lower ALC, anemia, lower WBCs, lower serum iron and lower transferrin saturation. There was no difference in albumin, ALC and PNI regarding the driver mutations. In multivariate analysis adjusted for age and gender, low albumin (hazard ratio [HR] = 4.61, P = 0.001), low ALC (HR = 3.54, P = 0.004) and Dynamic International Prognostic Scoring System (DIPSS) (HR = 2.45, P = 0.001) were able to predict inferior survival independently of each other. Accordingly, low PNI (HR = 4.32, P < 0.001) predicted poor survival independently of DIPSS (HR = 3.31, P < 0.001).

CONCLUSION

Assessing albumin, ALC and PNI might improve prognostication in patients with myelofibrosis and could assist in recognition of patients under increased risk of death.

Fatal ruxolitinib-related JC virus meningitis

We report a possible association between ruxolitinib and JC virus meningitis. A 72-year-old man with myelofibrosis started treatment with ruxolitinib. Fourteen days later, the patient presented to the emergency department with fever and nausea. HIV test was negative. Ruxolitinib was suspended. Symptoms progressed with neck stiffness, cognitive impairment, and motor aphasia. CSF was positive for JC virus. MRI showed nonspecific abnormal findings. Five days after the clinical debut, the patient died. The clinical picture, MRI imaging, and positive JC virus PCR in CSF strongly suggest ruxolitinib-related JC virus meningitis.

Fatal ruxolitinib-related JC virus meningitis

We report a possible association between ruxolitinib and JC virus meningitis. A 72-year-old man with myelofibrosis started treatment with ruxolitinib. Fourteen days later, the patient presented to the emergency department with fever and nausea. HIV test was negative. Ruxolitinib was suspended. Symptoms progressed with neck stiffness, cognitive impairment, and motor aphasia. CSF was positive for JC virus. MRI showed nonspecific abnormal findings. Five days after the clinical debut, the patient died. The clinical picture, MRI imaging, and positive JC virus PCR in CSF strongly suggest ruxolitinib-related JC virus meningitis.

Risk factors for infections in myelofibrosis: role of disease status and treatment. A multicenter study of 507 patients

Although infectious complications represent a relevant cause of morbidity and mortality in patients with myelofibrosis (MF), little is known about their incidence, outcome and risk factors. We retrospectively evaluated a cohort of 507 MF patients, diagnosed between 1980 and 2014 in five Italian hematology centers, to define the epidemiology of infections and describe the impact of ruxolitinib (RUX) treatment. Overall, 112 patients (22%) experienced 160 infectious events (grade 3-4, 45%) for an incidence rate of 3.9% per patient-year. Infections were mainly bacterial (78%) and involving the respiratory tract (52% of cases). Also, viral (11%) and fungal infections (2%) were recorded. Overall, infections were fatal in 9% of the cases. Among baseline features, high/intermediate-2 IPSS category (HR 1.8, 95%CI:1.2-2.7; P = 0.02) and spleen length ≥10 cm below left costal margin (HR 1.6, 95%CI:1.1-2.5; P = 0.04) were associated with higher infectious risk in multivariate analysis. Overall, the rate of infections was higher in the cohort of 128 RUX-treated patients (44% vs. 20%, P < 0.001). In conclusion, IPSS-category and splenomegaly, emerged as the main risk factors for infections in MF. RUX-treated patients experienced significantly more infection episodes; however, future prospective studies are needed to isolate the confounding contribution of other risk factors such as disease stage. Am. J. Hematol. 92:37-41, 2017. © 2016 Wiley Periodicals, Inc.

Chronic lymphocytic leukemia and myeloproliferative neoplasms concurrently diagnosed: clinical and biological characteristics

Chronic lymphocytic leukemia (CLL) and myeloproliferative neoplasms (MPN) may occur concomitantly. However, little is known about the pathobiological characteristics and interaction between the neoplastic clones in these rare cases of coinciding malignancies. We retrospectively examined the clinical and biological characteristics of 13 patients with concomitant CLL and MPN--eight primary myelofibrosis (PMF), three essential thrombocytosis (ET), and two polycythemia vera (PV)--who presented to our institution between 1998 and 2014, and tested all patients for MPN-specific aberrations, such as JAK2, MPL and CALR mutations. Along with epidemiological and molecular characterization of this rare condition, we found that JAK2 mutation can be detected 9 years prior to PMF diagnosis, suggesting that PMF clinical phenotype may require several years to develop and CLL/MPN clinical co-occurrence might be sustained by common molecular events. Some features of these patients suggest that pathobiologies of these diseases might be intertwined.

Does primary myelofibrosis involve a defective stem cell niche? From concept to evidence

Primary myelofibrosis (PMF) is the rarest and the most severe Philadelphia-negative chronic myeloproliferative syndrome. By associating a clonal proliferation and a mobilization of hematopoietic stem cells from bone marrow to spleen with profound alterations of the stroma, PMF is a remarkable model in which deregulation of the stem cell niche is of utmost importance for the disease development. This paper reviews key data suggesting that an imbalance between endosteal and vascular niches participates in the development of clonal stem cell proliferation. Mechanisms by which bone marrow niches are altered with ensuing mobilization and homing of neoplastic hematopoietic stem cells in new or reinitialized niches in the spleen and liver are examined. Differences between signals delivered by both endosteal and vascular niches in the bone marrow and spleen of patients as well as the responsiveness of PMF stem cells to their specific signals are discussed. A proposal for integrating a potential role for the JAK2 mutation in their altered sensitivity is made. A better understanding of the cross talk between stem cells and their niche should imply new therapeutic strategies targeting not only intrinsic defects in stem cell signaling but also regulatory hematopoietic niche-derived signals and, consequently, stem cell proliferation.

Durable responses to thalidomide-based drug therapy for myelofibrosis with myeloid metaplasia

OBJECTIVE

To present the results of a long-term analysis of 2 sequential phase 2 trials of thalidomide (alone or in combination) for palliation of myelofibrosis with myeloid metaplasia (MMM).

PATIENTS AND METHODS

We analyzed (March 1999 to August 2003) initial and long-term outcomes from 36 patients with symptomatic MMM who had enrolled in either our thalidomide single-agent trial (n=15) or our trial of low-dose thalidomide (50 mg/d) combined with prednisone (n=21).

RESULTS

Among the 36 study patients, 20 (56%) showed some improvement in their clinical course. Response rates for specific end points included improvements in anemia (15 of 36 [42%]), thrombocytopenia (10 of 13 [77%]), or splenomegaly (5 of 30 [17%]). The combination of low-dose thalidomide and prednisone, as opposed to single-agent thalidomide, was better tolerated and more efficacious. After a median follow-up of 25 months (range, 20-56 months), 10 of 36 patients (28%) showed an ongoing response, including 8 patients in whom protocol treatment has been discontinued for a median of 21 months (range, 16-31 months). Durable treatment responses were documented for only anemia and thrombocytopenia. Treatment response was not affected by the baseline status of bone marrow fibrosis, angiogenesis, osteosclerosis, cytogenetics, or circulating myeloid progenitor (CD34) cell count. Unusual drug effects, all reversible, included leukocytosis (8 patients) and/or thrombocytosis (6 patients).

CONCLUSIONS

Thalidomide (alone or combined with prednisone) is an effective first-line treatment of symptomatic anemia or thrombocytopenia in MMM. Thalidomide-based therapy has the potential to produce durable responses in MMM-associated cytopenias, even after discontinuation of the drug.

A phase 2 trial of combination low-dose thalidomide and prednisone for the treatment of myelofibrosis with myeloid metaplasia

Single-agent thalidomide (THAL) at "conventional" doses (> 100 mg/d) has been evaluated in myelofibrosis with myeloid metaplasia (MMM) based on its antiangiogenic properties and the prominent neoangiogenesis that occurs in MMM. THAL monotherapy at such doses produces approximately a 20% response rate in anemia but is poorly tolerated (an adverse dropout rate of > 50% in 3 months). To improve efficacy and tolerability, we prospectively treated 21 symptomatic patients (hemoglobin level < 10 g/dL or symptomatic splenomegaly) with MMM with low-dose THAL (50 mg/d) along with a 3-month oral prednisone (PRED) taper (beginning at 0.5 mg/kg/d). THAL-PRED was well tolerated in all enrolled patients, with 20 patients (95%) able to complete 3 months of treatment. An objective clinical response was demonstrated in 13 (62%) patients, all improvements in anemia. Among 10 patients who were dependent on erythrocyte transfusions, 7 (70%) improved and 4 (40%) became transfusion independent. Among 8 patients with thrombocytopenia (platelet count < 100 x 10(9)/L), 6 (75%) experienced a 50% or higher increase in their platelet count. In 4 of 21 patients (19%), spleen size decreased by more than 50%. Responses observed were mostly durable after discontinuation of the PRED. The dose of THAL in this study (50 mg/d) was better tolerated than the higher doses used in previous studies. Adverse events associated with corticosteroid therapy were mild and transient. Clinical responses did not correlate with improvements in either intramedullary fibrosis or angiogenesis. THAL-PRED is well tolerated and preliminarily appears to be a promising drug regimen for treating cytopenias in patients with MMM.

Idiopathic myelofibrosis associated with classic polyarteritis nodosa

A woman with scleroderma and classic polyarteritis nodosa (PAN) who developed idiopathic myelofibrosis (IM) is reported. The patient presented with a one-year history of weakness, polyarthritis, Raynaud phenomenon, dry cough, and epigastralgia. The diagnosis of scleroderma with visceral involvement was made and treatment with prednisone subsequently started, with good clinical response. Six years later, fever, weight loss, livedo reticularis, and dysesthesias developed. Electromyographic studies were consistent with sensory neuropathy and a sural nerve biopsy yielded the diagnosis of PAN. The patient received cyclophosphamide plus prednisone with a favorable response, but 11 years later she was admitted because of weakness, constitutional symptoms, and abdominal pain due to spleen infarcts. Marked anemia, with aniso-poikilocytosis, tear-drop cells, immature myeloid precursors in the peripheral blood, and an increased serum LDH, was observed and the diagnosis of IM established by bone marrow biopsy. This case represents a new association between IM and an autoimmune disease and supports the hypothesis of an immune basis of IM in some patients.

Impaired NK cell differentiation of blood-derived CD34+ progenitors from patients with myeloid metaplasia with myelofibrosis

Cultured blood CD34(+) progenitors from patients with myeloid metaplasia with myelofibrosis (MMM) failed to differentiate into natural killer (NK) cells with recombinant interleukin (IL)-15. No NK cells either could be induced in coculture with IL-15-expressing fibroblasts from MMM patients' spleens. The impaired NK differentiation could be circumvented by using normal blood CD34(+) cells in the coculture. In this case, cell-to-cell contact and IL-15 interaction were crucial for NK cell differentiation. Pretreatment of normal CD34(+) progenitors with anti-IL-15 monoclonal antibody markedly reduced NK cell production while MMM fibroblast pretreatment did not. Both normal and MMM progenitors constitutively expressed IL-15. Analysis of endogenous IL-15 signaling pathway revealed a constitutive gammac/Jak3 association and STAT3 activation in the two types of progenitors. Anti-IL-15 monoclonal antibody treatment caused a downregulation of IL-15 signaling in normal but not MMM blood cells. The impaired NK differentiation in MMM may thus arise from a deregulated control of an endogenous IL-15 involved in hematopoietic progenitors' lymphoid differentiation.

Idiopathic myelofibrosis associated with ulcerative colitis

A patient with ulcerative colitis (UC) who developed idiopathic myelofibrosis (IM) is reported. The initial diagnosis of UC was established by colonoscopy and large bowel biopsy, performed after a one-month history of abdominal pain and bloody diarrhea. The patient showed a favorable response to prednisone and mesalamine treatment and six months later he developed a new episode of UC, which was successfully controlled with treatment. However, two years later splenomegaly and anemia were observed, with aniso-poikilocytosis, tear-drop cells, immature myeloid precursors in the peripheral blood, and increased serum LDH, arising the suspicion of IM, a diagnosis that was confirmed by bone marrow biopsy. The present case represents a new association of IM with an autoimmune disease and gives support to the hypothesis of a possible immune basis of some IM cases.

Idiopathic myelofibrosis associated with primary biliary cirrhosis

A patient with primary biliary cirrhosis (PBC) who developed idiopathic myelofibrosis (IM) is reported. The initial diagnosis of PBC was established by liver biopsy, performed after a 2-month history of constitutional symptoms associated with abnormalities of the serum liver enzymes, with typical serum immunological markers being found. Although a favorable response of PBC to prednisone was observed, one and a half year later the patient developed anemia with anisocytosis and poikilocytosis, tear-drop cells, and leukoerythroblastic picture, and IM was diagnosed by bone marrow biopsy. A few months later, a rapid worsening of the patient's clinical condition was noted, with an increase in the constitutional symptoms and need for frequent packed RBC transfusions, and she finally died from an infectious complication. This case represents a new association of IM with an autoimmune disease, supporting the hypothesis of a possible immune basis of IM in some cases.