Soluble TNF receptor fusion protein (etanercept) for the treatment of myelodysplastic syndrome: a pilot study

Inhibition of overactivated p38 MAPK can restore hematopoiesis in myelodysplastic syndrome progenitors

The myelodysplastic syndromes (MDSs) are collections of heterogeneous hematologic diseases characterized by refractory cytopenias as a result of ineffective hematopoiesis. Development of effective treatments has been impeded by limited insights into any unifying pathogenic pathways. We provide evidence that the p38 MAP kinase is constitutively activated or phosphorylated in MDS bone marrows. Such activation is uniformly observed in varied morphologic subtypes of low-risk MDS and correlates with enhanced apoptosis observed in MDS hematopoietic progenitors. Most importantly, pharmacologic inhibition of p38alpha by a novel small molecule inhibitor, SCIO-469, decreases apoptosis in MDS CD34+ progenitors and leads to dose-dependant increases in erythroid and myeloid colony formation. Down-regulation of the dominant p38alpha isoform by siRNA also leads to enhancement of hematopoiesis in MDS bone marrow progenitors in vitro. These data implicate p38 MAPK in the pathobiology of ineffective hematopoiesis in lowrisk MDS and provide a strong rationale for clinical investigation of SCIO-469 in MDS.

Effect of cA2 Anti–Tumor Necrosis Factor-α Antibody Therapy on Hematopoiesis of Patients with Myelodysplastic Syndromes

PURPOSE

Tumor necrosis factor alpha (TNF-alpha) plays a prominent role in the pathophysiology of myelodysplastic syndromes (MDS). The aim of this study was to explore the biological and immunoregulatory effect of the treatment with the anti-tumor necrosis factor-alpha monoclonal antibody cA2 on bone marrow (BM) progenitor/precursor and stromal cells and lymphocyte subsets, as well as the clinical response in MDS patients.

EXPERIMENTAL DESIGN

Ten low-intermediate risk MDS patients received i.v. cA2 (3 mg/kg) at weeks 0, 2, 6, and 12. The number, survival, and clonogenic potential of BM progenitor/precursor cells, the hematopoiesis-supporting capacity of BM stromal cells, and the lymphocyte activation status were investigated in the patients at baseline and following treatment using flow cytometry, clonogenic assays, and long-term BM cultures (LTBMC). Clinical response was evaluated according to standardized criteria.

RESULTS

cA2 administration reduced the proportion of apoptotic and Fas+ cells in the CD34+ cell compartment (P = 0.0215 and P = 0.0344, respectively) and increased the clonogenic potential of BM mononuclear and CD34+ cells (P = 0.0399 and P = 0.0304, respectively) compared with baseline. The antibody reduced tumor necrosis factor-alpha levels in LTBMC supernatants (P = 0.0043) and significantly improved the hematopoiesis-supporting capacity of LTBMC adherent cells. The proportion of activated peripheral blood and BM T-lymphocytes decreased significantly after treatment, suggesting an immunomodulatory effect of cA2. Two patients displayed minor hematologic responses whereas the remaining patients displayed stable disease with no disease progression.

CONCLUSIONS

The encouraging biological insights from cA2 administration may be useful in conducting further clinical trials using cA2 for selected MDS patients, particularly those with evidence of immune-mediated inhibition of hematopoiesis.

The hematologic response to anti-apoptotic cytokine therapy: results of pentoxifylline, ciprofloxacin, and dexamethasone treatment for patients with myelodysplastic syndrome

TNF-alpha mediated apoptosis of the hematopoietic cells has been thought to contribute to the ineffective hematopoiesis observed in myelodysplastic syndrome (MDS). The combination of pentoxifylline (P) and ciprofloxacin (C) has been shown to reduce the serum levels of TNF-alpha, and an earlier trial of P and C with dexamethasone (D) provided good palliation for patients with MDS. The purpose of this study is to assess the hematologic response to PCD therapy for patients suffering with MDS. 21 of 25 patients who completed at least of 12 weeks of treatment were evaluable for the treatment efficacy. At baseline, the patient's median age was 60 yr (range: 18-75 yr). The diagnoses according to WHO classification included: RA (n=5), RCMD (n=10), RARS (n=1), RCMD/RS (n=1), RAEB (3), and CMML (n=1). 11 patients (52%) had at least single lineage response. 3 patients (11%) showed improvement of triple lineage cytopenia. There were no differences in the response rates between the FAB subtypes. The median time to response was 4 weeks (range: 2-12 weeks), and it is interesting that 9 of 11 patients who had a response remained without relapse for a median of 177 days (range: 78-634 days). These preliminary results indicate that anti-cytokine therapy with PCD is an effective and well tolerated palliative treatment for patients with MDS.

Infections associated with tumor necrosis factor-alpha antagonists

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine involved in a wide range of important physiologic processes. This cytokine has a pathologic role in some diseases, and TNF-alpha antagonists are effective in treating inflammatory conditions. Given the putative role of TNF-alpha in host defense against tuberculosis and other infections, the risk of infection with TNF-alpha antagonists is a concern. Therefore, we searched the literature for reports of tuberculosis and other infections associated with TNF-alpha-antagonist therapy. Although tuberculosis was rarely reported in randomized clinical comparisons of these antagonists, case reports and submissions to the MedWatch program of the United States Food and Drug Administration have been numerous. Most instances were associated with infliximab, but etanercept and adalimumab may also be associated with an increased risk of tuberculosis. Histoplasmosis, listeriosis, aspergillosis, coccidioidomycosis, and candidiasis have been associated with TNF-alpha antagonists, but the causative relationship is not clear. Potential recipients of these drugs should be rigorously screened with skin testing, detailed questioning about recent travel and potential tuberculosis exposure, assessment for symptoms such as cough and weight loss, and chest radiography to minimize their risk of acquiring or reactivating tuberculosis. As with other immunosuppressant drugs, TNF-alpha antagonists should not be given to patients with active infection.

Over-expression of tumor necrosis factor-alpha in bone marrow biopsies from patients with myelodysplastic syndromes: relationship to anemia and prognosis

OBJECTIVES

An excessive intramedullar progenitor cell apoptosis, to which elevated expression of tumor necrosis factor-alpha (TNF-alpha) might contribute, is considered the main cause of inefficient hematopoiesis in myelodysplastic syndromes (MDS). Enhanced bone marrow (BM) angiogenesis is regarded as an essential cofactor in the progression of MDS to acute myelogenous leukemia (AML) and microvessel formation may be induced by TNF-alpha as well. To investigate TNF-alpha signaling and neoangiogenesis as potential molecular pathways for therapeutic intervention in MDS with respect to the various MDS subtypes, we performed a morphological and clinico-pathological study on a large series of paraffin-embedded trephine BM biopsies.

METHODS

TNF-alpha expression and BM vessels were immunohistochemically analyzed on 89 paraffin-embedded BM biopsies from patients with MDS and secondary AML, including 12 control samples. Data were correlated with clinico-pathological and laboratory parameters and analyzed for their prognostic significance considering overall survival.

RESULTS

TNF-alpha was over-expressed in MDS patients, especially in those with refractory anemia and its expression correlated with BM cellularity and with magnitude of anemia as well as with microvessel density (MVD). TNF-alpha over-expression was associated with premature deaths. MVD was increased in MDS and secondary AML and correlated with marrow cellularity and expression of TNF-alpha, but was not of prognostic significance.

CONCLUSIONS

TNF-alpha expression and MVD are elevated in MDS and secondary AML. TNF-alpha expression in BM progenitor cells appears to negatively impact erythropoiesis and overall survival in MDS, and may serve as a potential therapeutic target in patients with hypercellular MDS with marked anemia.

Role of the p38 Mitogen-Activated Protein Kinase Pathway in Cytokine-Mediated Hematopoietic Suppression in Myelodysplastic Syndromes

The p38 mitogen-activated protein kinase (MAPK) pathway is activated by IFNs and other cytokines to mediate signals for important cellular functions, including transcriptional regulation and apoptosis. We examined the role of the p38 pathway in the generation of the effects of myelosuppressive cytokines on human hematopoiesis. Pharmacologic inhibition of p38 using BIX-01208 resulted in reversal of IFN-, tumor necrosis factor-alpha (TNF-alpha)-, and transforming growth factor-beta (TGF-beta)-mediated suppression of human erythroid (blast-forming unit-erythroid) and myeloid (granulocyte-macrophage colony-forming unit) colony formation, consistent with a key role for p38 in the generation of myelosuppressive signals by different cytokines. Similarly, the myelosuppressive effects of TNF-alpha and TGF-beta were reversed by small interfering RNAs targeting p38alpha expression, further establishing the requirement of this kinase in the induction of myelosuppressive responses. As TNF overproduction has been implicated in the pathophysiology of bone marrow failure states, we determined whether pharmacologic inhibition of p38 reverses the hematopoietic defects seen in bone marrows from patients with myelodysplastic syndromes (MDS) and the anemia of chronic disease. Addition of pharmacologic inhibitors of p38 on such bone marrows resulted in increased numbers of erythroid and myeloid progenitors. Similarly, inhibition of the activity of the downstream effectors of p38, MAPK activated protein kinase-2, and mitogen and stress activated kinase 1 partially restored the hematopoietic defect seen in these bone marrows. Taken altogether, our data implicate the p38 MAPK in the pathophysiology of myelodysplasias and suggest that p38 pharmacologic inhibitors may have therapeutic applications in the treatment of MDS.

Immunobiologic therapies for myelodysplastic syndrome

Recent progress in understanding the pathobiology of the myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) have led to the development of various immunologically oriented therapies for these diseases. The existence of elevated levels of tumor necrosis factor-alpha (TNF-alpha) in bone marrow during early stages of MDS, and the possibility that TNF- proportional, variant suppresses normal hematopoiesis led to studies of attempts to block the activity of TNF-alpha. An anti-TNF monoclonal antibody and an antibody comprised of the soluble extracellular ligand-binding portion of the TNF receptor have both been evaluated recently in several small pilot studies. The recognition that marrow suppression in MDS may, in part, be a T-cell mediated autoimmune process has stimulated various trials of antithymocyte globulin and other similar agents. Gemtuzumab ozogamicin, an antibody against CD33 conjugated to the cytotoxic agent calicheamicin, is approved for use in AML and is currently being investigated as a potential therapeutic agent in MDS. Clinical trials were conducted as either monotherapy or in combination with cytokines such as IL-11 and chemotherapeutic agents including idarubicin, fludarabine, and/or cytarabine. Other antibodies are being developed as immunoconjugates with radioisotopes as part of conditioning regimens prior to bone marrow transplantation for AML or MDS. These include (131)I-anti-CD45 antibody (BC8), (131)I anti-CD33 antibody (p67), (213)Bi-M195 antibody, and (188)Re-labeled anti-CD66 antibody. The clearest example of successful immunotherapy for MDS (and AML) is the use of the graft-versus-tumor effect associated with allogeneic hematopoietic cell transplantation. Recently, nonmyeloablative transplants have been explored with encouraging results. Vaccines using overexposed self-antigens such as WT1 and PR1 are other attempts to induce a T-cell mediated response against MDS.

Efficacy of lenalidomide in myelodysplastic syndromes

BACKGROUND

Ineffective erythropoiesis is the hallmark of myelodysplastic syndromes. Management of the anemia caused by ineffective erythropoiesis is difficult. In patients with myelodysplastic syndromes and symptomatic anemia, we evaluated the safety and hematologic activity of lenalidomide, a novel analogue of thalidomide.

METHODS

Forty-three patients with transfusion-dependent or symptomatic anemia received lenalidomide at doses of 25 or 10 mg per day or of 10 mg per day for 21 days of every 28-day cycle. All patients either had had no response to recombinant erythropoietin or had a high endogenous erythropoietin level with a low probability of benefit from such therapy. The response to treatment was assessed after 16 weeks.

RESULTS

Neutropenia and thrombocytopenia, the most common adverse events, with respective frequencies of 65 percent and 74 percent, necessitated the interruption of treatment or a dose reduction in 25 patients (58 percent). Other adverse events were mild and infrequent. Twenty-four patients had a response (56 percent): 20 had sustained independence from transfusion, 1 had an increase in the hemoglobin level of more than 2 g per deciliter, and 3 had more than a 50 percent reduction in the need for transfusions. The response rate was highest among patients with a clonal interstitial deletion involving chromosome 5q31.1 (83 percent, as compared with 57 percent among those with a normal karyotype and 12 percent among those with other karyotypic abnormalities; P=0.007) and patients with lower prognostic risk. Of 20 patients with karyotypic abnormalities, 11 had at least a 50 percent reduction in abnormal cells in metaphase, including 10 (50 percent) with a complete cytogenetic remission. After a median follow-up of 81 weeks, the median duration of transfusion independence had not been reached and the median hemoglobin level was 13.2 g per deciliter (range, 11.5 to 15.8).

CONCLUSIONS

Lenalidomide has hematologic activity in patients with low-risk myelodysplastic syndromes who have no response to erythropoietin or who are unlikely to benefit from conventional therapy.

Hematologic responses of patients with MDS to antithymocyte globulin plus etanercept correlate with improved flow scores of marrow cells

Myelodysplastic syndrome (MDS) comprises a spectrum of heterogeneous diseases. Most patients present with ineffective hematopoiesis. The pathophysiology involves immune-mediated effects, cytokine dysregulation, and apoptosis, among others. We treated 14 transfusion-requiring patients with MDS, 10 with refractory anemia (RA) and four with RA with excess blasts (RAEB) with a 4-day course of antithymocyte globulin (ATG) followed by intermittent etanercept for 4 months. Among 13 evaluable patients, five are red blood cell and platelet transfusion independent for intervals extending beyond 2 years, and two have normalized their peripheral blood parameters. One additional patient showed a transient rise of platelet and neutrophil counts, for an overall response rate of 46%. Responding patients showed striking improvements in marrow cell abnormalities as characterized by flow cytometry. These data show that a combination of ATG plus etanercept offers effective palliative therapy for unselected patients with MDS. Further trials incorporating these two agents are warranted.

Novel therapies for myelodysplastic syndromes

BACKGROUND

The assessment of patients with myelodysplastic syndromes (MDS) and the choice of therapies remain challenging. New therapies are now emerging after the identification of molecular targets that result in improvement of hematologic parameters and may hold promise for the prevention of disease progression.

METHODS

A review of the English literature was performed that included original articles and related reviews from MEDLINE (PubMed) and abstracts based on published meeting material.

RESULTS

MDS is a heterogeneous group of disorders. Although current classification and prognostic schemes have proven valid to define subgroups, they are insufficient to take into consideration the significant biologic diversity of MDS. New molecular targets are identified as the mosaic of pathophysiologic pathways in MDS is being unraveled. Novel and targeted therapeutic agents, such as the inhibition of farnesyl transferases and receptor tyrosine kinases, more potent thalidomide analogs, and arsenic trioxide, have shown encouraging results and may offer durable benefit to patients with MDS.

CONCLUSIONS

Although progress has been made in the understanding of clinical manifestations and some of the molecular pathways underlying ineffective hematopoiesis and leukemic transformation in MDS, intensive clinical and laboratory research continues to 1) identify further relevant pathophysiologic pathways, 2) better define MDS subgroups, and 3) develop new drugs based on a clearer understanding of disease biology.

Update on myelodysplastic syndromes: New approaches to classification and therapy

Myelodysplastic syndromes have long provided hematologists with difficult therapeutic challenges, and until recently treatment options beyond supportive care were limited. Recent advances in our understanding of hematopoiesis, immunology, and genetics have led to a better understanding of the natural history of these disorders and have facilitated development of more rational and targeted treatment approaches. A number of promising agents are in various phases of study, including arsenic trioxide, CC5013, the farnesyltransferase inhibitors, and DNA methyltransferase inhibitors. In addition, less intensive strategies for allogeneic stem cell transplantation now permit us to offer potentially curative therapy to a larger proportion of patients. Optimal management of an individual patient requires consideration of the disease and its expected course, available treatment options, the patient's age and condition, and an ongoing assessment of the goals of therapy.

Myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are characterized by hemopoietic insufficiency associated with cytopenias leading to serious morbidity plus the additional risk of leukemic transformation. Therapeutic dilemmas exist in MDS because of the disease's multifactorial pathogenetic features, heterogeneous stages, and the patients' generally elderly ages. Underlying the cytopenias and evolutionary potential in MDS are innate stem cell lesions, cellular/cytokine-mediated stromal defects, and immunologic derangements. This article reviews the developing understanding of biologic and molecular lesions in MDS and recently available biospecific drugs that are potentially capable of abrogating these abnormalities. Dr. Peter Greenberg's discussion centers on decision-making approaches for these therapeutic options, considering the patient's clinical factors and risk-based prognostic category. One mechanism underlying the marrow failure present in a portion of MDS patients is immunologic attack on the hemopoietic stem cells. Considerable overlap exists between aplastic anemia, paroxysmal nocturnal hemoglobinuria, and subsets of MDS. Common or intersecting pathophysiologic mechanisms appear to underlie hemopoietic cell destruction and genetic instability, which are characteristic of these diseases. Treatment results and new therapeutic strategies using immune modulation, as well as the role of the immune system in possible mechanisms responsible for genetic instability in MDS, will be the subject of discussion by Dr. Neal Young. A common morphological change found within MDS marrow cells, most sensitively demonstrated by electron microscopy, is the presence of ringed sideroblasts. Such assessment shows that this abnormal mitochondrial iron accumulation is not confined to the refractory anemia with ring sideroblast (RARS) subtype of MDS and may also contribute to numerous underlying MDS pathophysiological processes. Generation of abnormal sideroblast formation appears to be due to malfunction of the mitochondrial respiratory chain, attributable to mutations of mitochondrial DNA, to which aged individuals are most vulnerable. Such dysfunction leads to accumulation of toxic ferric iron in the mitochondrial matrix. Understanding the broad biologic consequences of these derangements is the focus of the discussion by Dr. Norbert Gattermann.

Oxidative stress and the myelodysplastic syndromes

The evolution of higher organisms from anaerobic to aerobic living has promoted an elaborate mechanism of defense against potentially toxic oxidants. Many environmental toxicants implicated in the pathogenesis of myelodysplastic syndromes (MDS), including benzene and ionizing radiation, exert toxicity via pro-oxidant mechanisms. The emerging data suggest a probable genetic susceptibility to environmental carcinogenesis through functional polymorphic variants in enzymes that metabolize toxicants and/or protect against oxidative stress. The most studied enzyme is NAD(P)H:quinone oxidoreductase (NQO1). CD34+ cells from individuals homozygous for the NQO1 C609T nonfunctional allelic variant are incapable of enzyme induction following exposure to benzene, thus potentially increasing the hematotoxicity of benzene metabolites. Serologic and molecular markers of oxidative stress are present in many patients with MDS and include an increased concentration of the lipid peroxidation product malondialdehyde and the presence of oxidized bases in CD34+ cells. Potential mechanisms of oxidative stress include mitochondrial dysfunction via iron overload and mitochondrial DNA mutation, systemic inflammation, and bone marrow stromal defects. The biological activity of the antioxidant aminothiol amifostine in vivo suggests that these pathways may be meaningful targets for future therapy in MDS patients.

New indications for treatment of chronic inflammation by TNF-alpha blockade

The impressive anti-inflammatory effects of the tumor necrosis factor (TNF)alpha blockers etanercept and infliximab have led to their use in multiple inflammatory diseases besides their original indication, rheumatoid arthritis (RA). The well-studied clinical effects of both agents in RA are the reduction of signs and symptoms of joint inflammation as well as the arrest of bone destruction. Infliximab has also been Food and Drug Administration-approved in the treatment of Crohn disease; etanercept is now FDA-approved for juvenile chronic arthritis and psoriatic arthritis. Favorable initial clinical trials have been reported in other rheumatic diseases, including ankylosing spondylitis and adult Still disease. In addition, TNF alpha blockade is being studied in the treatment of uveitis, myelodysplastic syndromes, and graft-versus-host disease. Studies in sepsis and septic shock have identified small subsets of patients that may benefit from TNF alpha blockade, but broader use in septic patients has not improved survival. The TNF alpha blockers have had relatively infrequent serious side effects, especially compared with the immunosuppressive and cytotoxic agents otherwise employed to treat these diseases. Further studies of optimal dosing, combination with other therapies, and long-term benefits and side effects will emerge from future trials.

Myelodysplastic syndrome

The last decade has witnessed a multistep evolution in the understanding of the natural history, clinical manifestations, and some of the molecular mechanisms that underlie the ineffective hematopoiesis and leukemic transformation in the myelodysplastic syndrome (MDS). The international prognostic scoring system, FAB, and WHO classifications have helped define specific subgroups with their characteristic cytogenetic, molecular and immunological abnormalities. Until recently the mainstay of the treatment has been entirely supportive with blood and platelet transfusions. What is increasingly manifest now is the considerable excitement generated by the emergence of novel therapeutic strategies based on painstaking research findings from the laboratories. In Section I, Dr. Alan List reviews the therapeutic strategies with the specific emphasis on the relevance of molecular mechanism of apoptosis and targeted therapies using small molecules. Of particular interest is the excitement surrounding the clinical benefit obtained from potent immunomodulatory derivative (IMiD) of thalidomide CC5013. The review provides an update of the role of small molecule inhibitors of VEGF receptor tyrosine kinase, arsenic trioxide, oral matrix metalloprotease inhibitors, farnesyl transferase inhibitors, and imatinib mesylate in the treatment of MDS subgroups. In Section II, Dr. Steven Gore describes the results of clinical trials of inhibitors of DNA methylation such as 5 azacytidine (5 AC) and 5-aza 2-deoxycytidine (Decitabine). The review also provides an update on the rationale and results obtained from the combination therapy using histone deacetylases (HDAC) and DNA methyltransferase inhibitors in the treatment of MDS. In Section III, Professor Ghulam Mufti and Dr. Aloysius Ho describe the role of bone marrow transplantation with particular emphasis on recent results from reduced-intensity conditioned transplants, exploiting the graft versus leukemia effect without significant early treatment-related mortality. The section provides an update on the results obtained from the manipulation of the host's immune system with immunosuppressive agents such as ALG and/or cyclosporine A.

Recent progress in the treatment of myelodysplastic syndrome in adult patients

Peripheral blood cytopenias and dysplastic hematopoietic progenitors characterize the myelodysplastic syndrome. Patients suffer from the consequences of chronic cytopenias or progression to acute myelogenous leukemia. Although allogeneic hematopoietic stem cell transplantation is a potentially curative option, the standard of care for most patients with myelodysplastic syndrome continues to be supportive care, with blood product transfusion and antibiotics for infectious complications. Many patients with myelodysplastic syndrome are not candidates for allogeneic hematopoietic stem cell transplantation because of advanced age, comorbid illnesses, and lack of a histocompatible donor. Increased rates of apoptosis in hematopoietic progenitors, altered production of inflammatory cytokines, neoangiogenesis, and autoreactive T lymphocytes have all been shown to contribute to the phenotype of myelodysplastic syndrome. These recent insights into the pathophysiology of myelodysplastic syndrome have been translated into therapeutic trials of noncytotoxic agents for this disorder. Although clinical responses have been seen with these novel agents, the critical biologic targets have not yet been clearly defined.