Positive effects on hematopoiesis in patients with myelodysplastic syndrome receiving deferasirox as oral iron chelation therapy: a brief review

Long-term eltrombopag for bone marrow failure depletes iron

Eltrombopag (EPAG) has been approved for the treatment of aplastic anemia and for immune thrombocytopenia, and a subset of patients require long-term therapy. Due to polyvalent cation chelation, prolonged therapy leads to previously underappreciated iron depletion. We conducted a retrospective review of patients treated at the NIH for aplastic anemia, myelodysplastic syndrome, and unilineage cytopenias, comparing those treated with EPAG to a historical cohort treated with immunosuppression without EPAG. We examined iron parameters, duration of therapy, response assessment, relapse rates, and common demographic parameters. We included 521 subjects treated with (n = 315) or without EPAG (n = 206) across 11 studies with multiyear follow-up (3.6 vs. 8.5 years, respectively). Duration of EPAG exposure correlated with ferritin reduction (p = 4 × 10^-14 ) regardless of response, maximum dose, or degree of initial iron overload. Clearance followed first-order kinetics with faster clearance (half-life 15.3 months) compared with historical responders (47.5 months, p = 8 × 10^-10 ). Risk of iron depletion was dependent upon baseline ferritin and duration of therapy. Baseline ferritin did not correlate with response of marrow failure to EPAG or to relapse risk, and timing of iron clearance did not correlate with disease response. In conclusion, EPAG efficiently chelates total body iron comparable to clinically available chelators. Prolonged use can deplete iron and ultimately lead to iron-deficiency anemia mimicking relapse, responsive to iron supplementation.

Deferasirox induces cyclin D1 degradation and apoptosis in mantle cell lymphoma in a reactive oxygen species- and GSK3β-dependent mechanism

Mantle cell lymphoma (MCL) is a difficult-to-treat B-cell malignancy characterized by cyclin D1 (CD1) overexpression. Targeting CD1 in MCL has been shown to be of therapeutic significance. However, treatment of MCL remains challenging since patients are still subject to early and frequent relapse of the disease. To ensure their high proliferation rate, tumour cells have increased iron needs, making them more susceptible to iron deprivation. Indeed, several iron chelators proved to be effective anti-cancer agents. In this study, we demonstrate that the clinically approved iron chelator deferasirox (DFX) exerts an anti-tumoural effect in MCL cell lines and patient cells. The exposure of MCL cells to clinically feasible concentrations of DFX resulted in growth inhibition, cell cycle arrest and induction of apoptosis. We show that DFX unfolds its cytotoxic effect by a rapid induction of reactive oxygen species (ROS) that leads to oxidative stress and severe DNA damage and by triggering CD1 proteolysis in a mechanism that requires its phosphorylation on T286 by glycogen synthase kinase-3β (GSK3β). Moreover, we demonstrate that DFX mediates CD1 proteolysis by repressing the phosphatidylinositol 3-kinase (PI3K)/AKT/GSK3β pathway via ROS generation. Our data suggest DFX as a potential therapeutic option for MCL and paves the way for more treatment options for these patients.

Deferasirox drives ROS-mediated differentiation and induces interferon-stimulated gene expression in human healthy haematopoietic stem/progenitor cells and in leukemia cells

Background

Administration of the iron chelator deferasirox (DFX) in transfusion-dependent patients occasionally results in haematopoiesis recovery by a mechanism remaining elusive. This study aimed to investigate at a molecular level a general mechanism underlying DFX beneficial effects on haematopoiesis, both in healthy and pathological conditions.

Methods

Human healthy haematopoietic stem/progenitor cells (HS/PCs) and three leukemia cell lines were treated with DFX. N-Acetyl cysteine (NAC) and fludarabine were added as antioxidant and STAT1 inhibitor, respectively. In vitro colony-forming assays were assessed both in healthy and in leukemia cells. Intracellular and mitochondrial reactive oxygen species (ROS) as well as mitochondrial content were assessed by cytofluorimetric and confocal microscopy analysis; mtDNA was assessed by qRT-PCR. Differentiation markers were monitored by cytofluorimetric analysis. Gene expression analysis (GEA) was performed on healthy HS/PCs, and differently expressed genes were validated in healthy and leukemia cells by qRT-PCR. STAT1 expression and phosphorylation were assessed by Western blotting. Data were compared by an unpaired Student t test or one-way ANOVA.

Results

DFX, at clinically relevant concentrations, increased the clonogenic capacity of healthy human CD34⁺ HS/PCs to form erythroid colonies. Extension of this analysis to human-derived leukemia cell lines Kasumi-1, K562 and HL60 confirmed DFX capacity to upregulate the expression of specific markers of haematopoietic commitment. Notably, the abovementioned DFX-induced effects are all prevented by the antioxidant NAC and accompanied with overproduction of mitochondria-generated reactive oxygen species (ROS) and increase of mitochondrial content and mtDNA copy number. GEA unveiled upregulation of genes linked to interferon (IFN) signalling and tracked back to hyper-phosphorylation of STAT1. Treatment of leukemic cell lines with NAC prevented the DFX-mediated phosphorylation of STAT1 as well as the expression of the IFN-stimulated genes. However, STAT1 inhibition by fludarabine was not sufficient to affect differentiation processes in leukemic cell lines.

Conclusions

These findings suggest a significant involvement of redox signalling as a major regulator of multiple DFX-orchestrated events promoting differentiation in healthy and tumour cells. The understanding of molecular mechanisms underlying the haematological response by DFX would enable to predict patient’s ability to respond to the drug, to extend treatment to other patients or to anticipate the treatment, regardless of the iron overload.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1293-y) contains supplementary material, which is available to authorized users.

Deferasirox reduces oxidative DNA damage in bone marrow cells from myelodysplastic patients and improves their differentiation capacity

Patients with low-risk myelodysplastic syndromes (MDS) usually develop iron overload. This leads to a high level of oxidative stress in the bone marrow (BM) and increases haematopoietic cell dysfunction. Our objective was to analyse whether chelation with deferasirox (DFX) alleviates the consequences of oxidative stress and improves BM cell functionality. We analysed 13 iron-overloaded MDS patients' samples before and 4-10 months after treatment with DFX. Using multiparametric flow cytometry analysis, we measured intracellular reactive oxygen species (ROS), DNA oxidation and double strand breaks. Haematopoietic differentiation capacity was analysed by colony-forming unit (CFU) assays. Compared to healthy donors, MDS showed a higher level of intracellular ROS and DNA oxidative damage in BM cells. DNA oxidative damage decreased following DFX treatment. Furthermore, the clonogenic assays carried out before treatment suggest an impaired haematopoietic differentiation. DFX seems to improve this capacity, as illustrated by a decreased cluster/CFU ratio, which reached values similar to controls. We conclude that BM cells from MDS are subject to higher oxidative stress conditions and show an impaired haematopoietic differentiation. These adverse features seem to be partially rectified after DFX treatment.

Deferasirox in the treatment of iron overload during myeloproliferative neoplasms in fibrotic phase: does ferritin decrement matter?

Few data are available on the treatment with DFX in patients with transfusion dependent Ph- Myeloproliferative Neoplasms in fibrotic phase. Here we report 48MPNpatients and iron overload treated with DFX. Starting DFX dose was 20 mg/Kg in 23 patients, 15 mg/Kg in 20 patientsand 10 mg/Kg in 5 patients. After a median treatment of 27.6 months, 5 patients achieved ferritin<500 ng/ml, 11 < 1000 ng/ml and 3 a reduction >50% of basal ferritin with a global response rate of 41%. As to hematological improvement, 9/47 patients (19.1%) showed a persistent rise of Hb>1.5 g/dl, with disappearance of transfusion requirement in 6 cases. The median OS from DFX initiation in patients with chelation response was 61.0 months compared to 15.8 months in patients without chelation efficacy. Treatment with DFX is feasible and effective in MPN with iron overload and a hematological improvement can occur in a sizeable rate of patients.

Tuning the Anti(myco)bacterial Activity of 3-Hydroxy-4-pyridinone Chelators through Fluorophores

Controlling the sources of Fe available to pathogens is one of the possible strategies that can be successfully used by novel antibacterial drugs. We focused our interest on the design of chelators to address Mycobacterium avium infections. Taking into account the molecular structure of mycobacterial siderophores and considering that new chelators must be able to compete for Fe(III), we selected ligands of the 3-hydroxy-4-pyridinone class to achieve our purpose. After choosing the type of chelating unit it was also our objective to design chelators that could be monitored inside the cell and for that reason we designed chelators that could be functionalized with fluorophores. We didn’t realize at the time that the incorporation a fluorophore, to allow spectroscopic detection, would be so relevant for the antimycobacterial effect or to determine the affinity of the chelators towards biological membranes. From a biophysical perspective, this is a fascinating illustration of the fact that functionalization of a molecule with a particular label may lead to a change in its membrane permeation properties and result in a dramatic change in biological activity. For that reason we believe it is interesting to give a critical account of our entire work in this area and justify the statement “to label means to change”. New perspectives regarding combined therapeutic approaches and the use of rhodamine B conjugates to target closely related problems such as bacterial resistance and biofilm production are also discussed.

Prospective evaluation of the effect of deferasirox on hematologic response in transfusion-dependent patients with low-risk MDS and iron overload

OBJECTIVES

To assess the reduction of transfusions rate in transfusion-dependent patients with low-risk myelodysplastic syndrome (MDS) with iron overload treated with deferasirox.

METHODS

Prospective observational study. Primary endpoint was reduction in transfusion requirements (RTR) at 3 months, (assessed on 8-week period). Secondary endpoints were hematologic improvement according to International Working Group (IWG) 2006 criteria at 3, 6, and 12 months.

RESULTS

Fifty-seven patients were evaluable. After 3 months of chelation, no effect was seen on transfusion requirement (5.9 packed red blood cells (PRBC) vs 5.8 before chelation). According to the Kaplan-Meier analysis, the probability of RTR at 3, 6, and 12 months was assessed as 3.5%, 9.1%, and 18.7%, respectively. Median duration of RTR was 182 days. However, during the 12-month follow-up after deferasirox initiation, 17 patients (31.5%) achieved minor erythroid response [HI-E] according to IWG criteria, 10 of whom having achieved Hb improvement at month 12.

CONCLUSION

After 3 months of treatment, deferasirox had no impact on transfusion requirement in regularly transfused patients with low-risk MDS. However, deferasirox could induce 31% of erythroid response during the 12-month follow-up period thus suggesting that iron chelation therapy with deferasirox may induce an effect on hematopoiesis in a subset of patients with MDS and iron overload.

Phlebotomy as a preventive measure for crocidolite-induced mesothelioma in male rats

Malignant mesothelioma (MM) is a rare but socially important neoplasm due to its association with asbestos exposure. Malignant mesothelioma is difficult to diagnose at an early stage, yet there are no particularly effective treatments available at the advanced stage, thus necessitating efficient strategies to prevent MM in individuals already exposed to asbestos. We previously showed that persistent oxidative damage caused by foreign body reaction and affinity of asbestos both to hemoglobin and histones is one of the major pathogeneses. Accordingly, as an effective strategy to prevent asbestos‐induced MM, we undertook the use of an iron chelator, deferasirox, which decreased the epithelial–mesenchymal transition in a crocidolite‐induced rat MM model. However, this agent may show adverse effects. Here, we studied the effects of iron removal by phlebotomy as a realistic measure on the same rat model. We injected a total of 5 mg crocidolite i.p. to F1 hybrid rats between the Fischer‐344 and Brown‐Norway strains at the age of 6 weeks. We repeated weekly or biweekly phlebotomy of 6‐8 mL/kg/time from 10 to 60 weeks of age. The animals were observed until 120 weeks. In male rats, phlebotomy significantly decreased the weight and nuclear grade of MM, and modestly reduced the associated ascites and the fraction of more malignant sarcomatoid subtype. Weekly phlebotomy prolonged long‐term survival. Our results indicate that appropriate phlebotomy may be a practical preventive measure to attenuate the initiation and promotion capacity of asbestos towards MM by reducing iron in individuals exposed to asbestos.

Current treatment algorithm for the management of lower-risk MDS

Lower risk myelodysplastic syndromes (MDS), defined as MDS with a Revised International Prognostic Scoring System score ≤3.5 points, will remain a challenging entity in 2018. Supportive care continues to be the linchpin of treatment, although the options to reduce transfusion needs are broadening. To achieve red blood cell transfusion independence in non-del(5q) patients, erythropoiesis-stimulating agents remain a mainstay of therapy as long as endogenous erythropoietin levels are <500 U/L (and preferably <200 U/L). Experimental strategies for patients ineligible for erythropoiesis-stimulating agents or relapsing after gaining transfusion independence include immunosuppressive agents, transforming growth factor β inhibitors, and lenalidomide. All these alternatives have shown reasonable response rates in selected patient populations with lower risk MDS. Patients with del(5q) disease can derive long-term benefit from lenalidomide, and some patients remain transfusion free for extended periods even after discontinuation of the drug. In rare cases in which thrombocytopenia is the main clinical problem leading to clinically significant bleeding events, thrombopoietin receptor analogues may alleviate bleeding, increase platelet counts, and rarely lead to trilineage responses. It seems prudent to use these drugs only in patients with confirmed bone marrow blast counts <5%. Allogeneic stem cell transplantation is reasonable for patients with high molecular risk of progression and those failing several lines of treatment with signs of progression toward higher-risk MDS.

Reactive oxygen species levels control NF-κB activation by low dose deferasirox in erythroid progenitors of low risk myelodysplastic syndromes

Anemia is a frequent cytopenia in myelodysplastic syndromes (MDS) and most patients require red blood cell transfusion resulting in iron overload (IO). Deferasirox (DFX) has become the standard treatment of IO in MDS and it displays positive effects on erythropoiesis. In low risk MDS samples, mechanisms improving erythropoiesis after DFX treatment remain unclear. Herein, we addressed this question by using liquid cultures with iron overload of erythroid precursors treated with low dose of DFX (3μM), which corresponds to DFX 5 mg/kg/day, an unusual dose used for iron chelation. We highlight a decreased apoptosis rate and an increased proportion of cycling cells, both leading to higher proliferation rates. The iron chelation properties of low dose DFX failed to activate the Iron Regulatory Proteins and to support iron depletion, but low dose DFX dampers intracellular reactive oxygen species. Furthermore low concentrations of DFX activate the NF-κB pathway in erythroid precursors triggering anti-apoptotic and anti-inflammatory signals. Establishing stable gene silencing of the Thioredoxin (TRX) 1 genes, a NF-κB modulator, showed that fine-tuning of reactive oxygen species (ROS) levels regulates NF-κB. These results justify a clinical trial proposing low dose DFX in MDS patients refractory to erythropoiesis stimulating agents.

Protective effects of deferasirox and N-acetyl-L-cysteine on iron overload-injured bone marrow

Using an iron overload mouse model, we explored the protective effect of deferasirox (DFX) and N-acetyl-L-cysteine (NAC) on injured bone marrow hematopoietic stem/progenitor cells (HSPC) induced by iron overload. Mice were intraperitoneally injected with 25 mg iron dextran every 3 days for 4 weeks to establish an iron overload (Fe) model. DFX or NAC were co-administered with iron dextran in two groups of mice (Fe+DFX and Fe+NAC), and the function of HSPCs was then examined. Iron overload markedly decreased the number of murine HSPCs in bone marrow. Subsequent colony-forming cell assays showed that iron overload also decreased the colony forming capacity of HSPCs, the effect of which could be reversed by DFX and NAC. The bone marrow hematopoiesis damage caused by iron overload could be alleviated by DFX and NAC.

Observational Monitoring of Patients with Aplastic Anemia and Low/Intermediate-1 Risk of Myelodysplastic Syndromes Complicated with Iron Overload

BACKGROUND

This study focuses on the iron overload (IOL) of patients with transfused aplastic anemia (AA) or a low/intermediate-1 risk of myelodysplastic syndrome (MDS).

METHODS

Ninety-two AA or MDS patients with IOL were prospectively recruited. Clinical data were collected every 6 months, and organ magnetic resonance imaging T2* values were collected annually. Patients with IOL were chelated.

RESULTS

Serum ferritin was correlated with liver T2* and pancreatic T2* in the AA and MDS groups. Transfusion amounts were correlated with serum ferritin values, liver T2*, and pancreatic T2* in the AA group. At the 6-month and 1-year evaluations, patients with sufficient chelation experienced significant decreases in serum ferritin, and those with decreased serum ferritin experienced an obvious increase in hemoglobin. At their 1-year-follow-up, patients with adequate chelation showed significant increases in hepatic T2*, cardiac T2*, and left ventricular ejection fraction (LVEF). Patients with decreased serum ferritin (including those without chelation) experienced an increase in hemoglobin, hepatic T2*, cardiac T2*, and LVEF.

CONCLUSION

The transfusion amount was more reliable at predicting IOL in patients with AA than in those with MDS. Adequate iron chelation can decrease serum ferritin levels and may improve hepatic T2*, cardiac T2*, and LVEF levels. A decrease in serum ferritin, even in the absence of chelation, may also benefit patients.

Management of iron overload in hemoglobinopathies: what is the appropriate target iron level?

Patients with thalassemia become iron overloaded from increased absorption of iron, ineffective erythropoiesis, and chronic transfusion. Before effective iron chelation became available, thalassemia major patients died of iron-related cardiac failure in the second decade of life. Initial treatment goals for chelation therapy were aimed at levels of ferritin and liver iron concentrations associated with prevention of adverse cardiac outcomes and avoidance of chelator toxicity. Cardiac deaths were greatly reduced and survival was much longer. Epidemiological data from the general population draw clear associations between increased transferrin saturation (and, by inference, labile iron) and early death, diabetes, and malignant transformation. The rate of cancers now seems to be significantly higher in thalassemia than in the general population. Reduction in iron can reverse many of these complications and reduce the risk of malignancy. As toxicity can result from prolonged exposure to even low levels of excess iron, and survival in thalassemia patients is now many decades, it would seem prudent to refocus attention on prevention of long-term complications of iron overload and to maintain labile iron and total body iron levels within a normal range, if expertise and resources are available to avoid complications of overtreatment.

MRI-based evaluation of multiorgan iron overload is a predictor of adverse outcomes in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation

The medical records of 44 pediatric patients who underwent allogeneic transplantation from 2011 to 2015 were retrospectively reviewed. Magnetic resonance imaging was used to measure iron concentrations in the liver, spleen, pancreas and bone. These patients were divided into two groups, 18 with non-elevated (< 100 μmol/g; Group 1) liver iron concentration before transplantation and 26 with elevated (> 100 μmol/g; Group 2) concentration . We compared transplant-related outcomes in the two groups. Iron overload was a negative prognostic risk factor for sinusoidal obstruction syndrome (OR = 17), osteoporosis (OR = 6.8), pancreatic insufficiency (OR = 17) and metabolic syndrome (OR = 15.1). No statistically significant differences in overall survival, disease-free survival, relapse incidence and incidence of acute or chronic graft-versus host disease were observed between the two groups. Mean times to engraftment of platelets (43.0 ± 35.3 days vs. 22.1 ± 9.5 days, p < 0.05) and neutrophils (23.1 ± 10.4 days vs. 17.8 ± 4.6 days, p < 0.05) appear significantly longer in Group 2 than in Group 1. Time to platelet engraftment showed statistically significant correlation with pre-transplant liver (r = 0.5775; p < 0.001) and bone iron concentration (r = 0.7305; p < 0.001). Post-transplant evaluation pointed out that iron concentration analyzed at the first follow-up peaked in all tissues. The iron accumulation was highest in bone, followed by the spleen, liver and pancreas. One year post transplant 9 of 18 (50%) patients in Group 1 and 6 of 22 (27%) in Group 2 presented with bone and/or spleen iron overload, but not with liver overload. Liver iron concentration is not always a reliable indicator of systemic siderosis or of the efficacy of chelation therapy.

Iron-chelating therapy with deferasirox in transfusion-dependent, higher risk myelodysplastic syndromes: a retrospective, multicentre study

Iron chelation is controversial in higher risk myelodysplastic syndromes (HR-MDS), outside the allogeneic transplant setting. We conducted a retrospective, multicentre study in 51 patients with transfusion-dependent, intermediate-to-very high risk MDS, according to the revised international prognostic scoring system, treated with the oral iron chelating agent deferasirox (DFX). Thirty-six patients (71%) received azacitidine concomitantly. DFX was given at a median dose of 1000 mg/day (range 375-2500 mg) for a median of 11 months (range 0·4-75). Eight patients (16%) showed grade 2-3 toxicities (renal or gastrointestinal), 4 of whom (8%) required drug interruption. Median ferritin levels decreased from 1709 μg/l at baseline to 1100 μg/l after 12 months of treatment (P = 0·02). Seventeen patients showed abnormal transaminase levels at baseline, which improved or normalized under DFX treatment in eight cases. One patient showed a remarkable haematological improvement. At a median follow up of 35·3 months, median overall survival was 37·5 months. The results of this first survey of DFX in HR-MDS are comparable, in terms of safety and efficacy, with those observed in lower-risk MDS. Though larger, prospective studies are required to demonstrate real clinical benefits, our data suggest that DFX is feasible and might be considered in a selected cohort of HR-MDS patients.

[Effects of pre-immunosupressive therapy iron overload on hematologic response of severe aplastic anemia]

OBJECTIVE

To explore the effects of serum ferritin (SF) and iron overload (IO) pre-immunosupressive treatment (IST) on hematologic response of severe aplastic anemia (SAA/VSAA) patients treated with IST.

METHODS

257 SAA/VSAA patients who underwent first-line IST from Feb, 2003 to Dec, 2011 in Anemia Therapeutic Centre, Institute of Hematology and Blood Diseases Hospital were retrospectively analyzed, the status of SF before IST and the IO-affected factors were studied. The effects of IO on hematologic response of SAA/VSAA patients were evaluated as well.

RESULTS

The median level of SF of 257 patients was 387 (6-2 004) μg/L. 36 patients (14%) had IO, including 20 SAA and 16 VSAA patients. According to univariate logistical regression analyses, IO was influenced by age>14 years (P=0.010) and blood transfusion (P<0.001). The multivariate logistic regression analysis showed that blood transfusion [P=0.001, OR=0.218 (95% CI 0.092-0.520)] was the only independent prognostic factor. SAA (but not for VSAA) patients with IO had much lower hematologic response rate in 6 month after IST (P=0.037). Absolute reticulocyte count and IO correlated with response at 6 month by univariate logistical regression analysis (P=0.014, 0.037). The multivariate logistic regression analysis showed that IO [P=0.021, OR=4.092 (95% CI 1.235-13.563)], ARC ≥20×10(9)/L [P=0.040, OR=2.743 (95% CI 1.049-7.175)] were independent prognostic factors.

CONCLUSION

84.8% patients had high serum ferritin before IST, and 14.0% reached IO. Adult and more blood transfusion caused IO more likely. IO correlated with response at 6 month, and was independent prognostic factor.

Chelation efficacy and erythroid response during deferasirox treatment in patients with myeloproliferative neoplasms in fibrotic phase

At present, very few data are available on deferasirox (DFX) in the treatment of patients with Philadelphia-negative myeloproliferative neoplasms in fibrotic phase (FP-MPN) and transfusion dependence. To address this issue, a retrospective analysis of 28 patients (22 male and 6 female) with FP-MPN and iron overload secondary to transfusion dependence was performed, based on patients enrolled in the database of our regional cooperative group who received treatment with DFX. DFX was started after a median interval from diagnosis of 12.8 months (IR 7.1-43.1) with median ferritin values of 1415 ng/mL (IR 1168-1768). Extra-hematological toxicity was reported in 16 of 28 patients (57.1%), but only two patients discontinued treatment due to toxicity. Among 26 patients evaluable for response (≥6 months of treatment), after a median treatment period of 15.4 months (IR 8.1-22.3), 11 patients (42.3%) achieved a stable and consistent reduction in ferritin levels <1000 ng/mL. As for hematological improvement, 6 of 26 patients (23%) showed a persistent (>3 months) rise of Hb levels >1.5 g/dL, with disappearance of transfusion dependence in four cases. Treatment with DFX is feasible and effective in FP-MPN with iron overload. Moreover, in this setting, an erythroid response can occur in a significant proportion of patients.

Updated recommendations on the management of gastrointestinal disturbances during iron chelation therapy with Deferasirox in transfusion dependent patients with myelodysplastic syndrome - Emphasis on optimized dosing schedules and new formulations

Myelodysplastic syndromes (MDS) are oligoclonal hematopoietic disorders characterized by peripheral cytopenias with anemias being the most prevalent feature. The majority of patients will depend on regular transfusions of packed red blood cells (PRBC) during the course of the disease. Particularly patients with MDS and low risk for transformation into acute myeloid leukemia and low risk of early death will receive PRBC transfusions on a regular basis, which puts them at high risk for transfusional iron overload. Transfusion dependence has been associated with negative impact on organ function and reduced life expectancy. Recently, several retrospective but also some prospective studies have indicated, that transfusion dependent patients with MDS might benefit from consequent iron chelation with regard to morbidity and mortality. However, low treatment adherence due to adverse events mainly gastrointestinal in nature is an important obstacle in achieving sufficient iron chelation in MDS patients. Here, we will summarize and discuss the existing data on Deferasirox in low risk MDS published so far and provide recommendations for optimal management of gastrointestinal adverse events during iron chelation aiming at improving treatment compliance and, hence, sufficiently removing excess iron from the patients.

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.

Effects of iron overload on the bone marrow microenvironment in mice

OBJECTIVE

Using a mouse model, Iron Overload (IO) induced bone marrow microenvironment injury was investigated, focusing on the involvement of reactive oxygen species (ROS).

METHODS

Mice were intraperitoneally injected with iron dextran (12.5, 25, or 50 mg) every three days for two, four, and six week durations. Deferasirox(DFX)125 mg/ml and N-acetyl-L-cysteine (NAC) 40 mM were co-administered. Then, bone marrow derived mesenchymal stem cells (BM-MSCs) were isolated and assessed for proliferation and differentiation ability, as well as related gene changes. Immunohistochemical analysis assessed the expression of haematopoietic chemokines. Supporting functions of BM-MSCs were studied by co-culture system.

RESULTS

In IO condition (25 mg/ml for 4 weeks), BM-MSCs exhibited proliferation deficiencies and unbalanced osteogenic/adipogenic differentiation. The IO BM-MSCs showed a longer double time (2.07±0.14 days) than control (1.03±0.07 days) (P<0.05). The immunohistochemical analysis demonstrated that chemokine stromal cell-derived factor-1, stem cell factor -1, and vascular endothelial growth factor-1 expression were decreased. The co-cultured system demonstrated that bone marrow mononuclear cells (BMMNCs) co-cultured with IO BM-MSCs had decreased colony forming unit (CFU) count (p<0.01), which indicates IO could lead to decreased hematopoietic supporting functions of BM-MSCs. This effect was associated with elevated phosphatidylinositol 3 kinase (PI3K) and reduced of Forkhead box protein O3 (FOXO3) mRNA expression, which could induce the generation of ROS. Results also demonstrated that NAC or DFX treatment could partially attenuate cell injury and inhibit signaling pathway striggered by IO.

CONCLUSION

These results demonstrated that IO can impair the bone marrow microenvironment, including the quantity and quality of BM-MSCs.

Iron toxicity and its possible association with treatment of Cancer: lessons from hemoglobinopathies and rare, transfusion-dependent anemias

Exposure to elevated levels of iron causes tissue damage and organ failure, and increases the risk of cancer. The toxicity of iron is mediated through generation of oxidants. There is also solid evidence indicating that oxidant stress plays a significant role in a variety of human disease states, including malignant transformation. Iron toxicity is the main focus when managing thalassemia. However, the short- and long-term toxicities of iron have not been extensively considered in children and adults treated for malignancy, and only recently have begun to draw oncologists' attention. The treatment of malignancy can markedly increase exposure of patients to elevated toxic iron species without the need for excess iron input from transfusion. This under-recognized exposure likely enhances organ toxicity and may contribute to long-term development of secondary malignancy and organ failure. This review discusses the current understanding of iron metabolism, the mechanisms of production of toxic free iron species in humans, and the relation of the clinical marker, transferrin saturation (TS), to the presence of toxic free iron. We will present epidemiological data showing that high TS is associated with poor outcomes and development of cancer, and that lowering free iron may improve outcomes. Finally, we will discuss the possible relation between some late complications seen in survivors of cancer and those due to iron toxicity.

Phase IV open-label study of the efficacy and safety of deferasirox after allogeneic stem cell transplantation

This is the first prospective study of deferasirox in adult allogeneic hematopoietic stem cell transplant recipients with transfusional iron overload in hematologic malignancies. Patients at least six months post transplant were treated with deferasirox at a starting dose of 10 mg/kg/day for 52 weeks or until serum ferritin was less than 400 ng/mL on two consecutive occasions. Thirty patients were enrolled and 22 completed the study. A significant reduction from baseline in median serum ferritin and in liver iron concentration at 52 weeks was observed in the overall population: from 1440 to 755.5 ng/mL (P=0.002) and from 14.5 to 4.6 mg Fe/g dw (P=0.0007), respectively. Reduction in serum ferritin in patients who did not discontinue deferasirox therapy was significantly greater than that found in those who prematurely discontinued the treatment (from 1541 to 581 ng/mL vs. from 1416 to 1486 ng/mL; P=0.008). Drug-related adverse events, reported in 17 patients (56.7%), were mostly mild to moderate in severity. There were no drug-related serious adverse events. Twelve patients (40.0%) showed an increase of over 33% in serum creatinine compared to baseline and greater than the upper limit of normal on two consecutive visits. Two patients (6.7%) with active graft-versus-host disease showed an increase in alanine aminotransferase exceeding 10 times upper limit of normal; both resolved. In this prospective study, deferasirox provided a significant reduction in serum ferritin and liver iron concentration over one year of treatment in allogeneic hematopoietic stem cell transplant recipients with iron overload. In addition, the majority of adverse events related to deferasirox were mild or moderate in severity. (clinicaltrials.gov identifier:01335035).

Physiology and pathophysiology of iron in hemoglobin-associated diseases

Iron overload and iron toxicity, whether because of increased absorption or iron loading from repeated transfusions, can be major causes of morbidity and mortality in a number of chronic anemias. Significant advances have been made in our understanding of iron homeostasis over the past decade. At the same time, advances in magnetic resonance imaging have allowed clinicians to monitor and quantify iron concentrations noninvasively in specific organs. Furthermore, effective iron chelators are now available, including preparations that can be taken orally. This has resulted in substantial improvement in mortality and morbidity for patients with severe chronic iron overload. This paper reviews the key points of iron homeostasis and attempts to place clinical observations in patients with transfusional iron overload in context with the current understanding of iron homeostasis in humans.

Use of deferasirox in transfusion-dependent myelodysplastic syndromes with iron overload

SUMMARY 

In myelodysplastic syndromes (MDS), transfusion-dependent anemia has been established as an independent risk factor for decreased survival. Although evidence from prospective studies is still lacking, several guidelines recommend iron-chelating therapy in MDS patients with a longer life expectancy. With the recent introduction of deferasirox, an oral active iron-chelating drug, which has shown dose-dependent efficacy and acceptable tolerability, this therapeutic option has become feasible even in the elderly. Several retrospective and prospective studies showed that in MDS patients deferasirox is effective in reducing iron burden and in maintaining the circulating toxic iron fraction within the normal range. Moreover, in a substantial fraction of patients treated with deferasirox a significant improvement of peripheral cytopenias may occur.

Toward resolving the unsettled role of iron chelation therapy in myelodysplastic syndromes

Transfusion dependent low risk myelodysplastic syndromes (MDS) patients, eventually develop iron overload. Iron toxicity, via oxidative stress, can damage cellular components and impact organ function. In thalassemia major patients, iron chelation therapy lowered iron levels with recovery of cardiac and liver functions and significant improvement in survival. Several noncontrolled studies show inferior survival in MDS patients with iron overload, including an increase in transplant-related mortality and infection risk while iron chelation appears to improve survival in both lower risk MDS patients and in stem cell transplant settings. Collated data are presented on the pathophysiological impact of iron overload; measuring techniques and chelating agents' therapy positive impact on hematological status and overall survival are discussed. Although suggested by retrospective analyses, the lack of clear prospective data of the beneficial effects of iron chelation on morbidity and survival, the role of iron chelation therapy in MDS patients remains controversial.

Iron overload as a major targetable pathogenesis of asbestos-induced mesothelial carcinogenesis

Few people expected that asbestos, a fibrous mineral, would be carcinogenic to humans. In fact, asbestos is a definite carcinogen in humans, causing a rare but aggressive cancer called malignant mesothelioma (MM). Mesothelial cells line the three somatic cavities and thus do not face the outer surface, but reduce the friction among numerous moving organs. MM has several characteristics: extremely long incubation period of 30-40 years after asbestos exposure, difficulty in clinical diagnosis at an early stage, and poor prognosis even under the current multimodal therapies. In Japan, 'Kubota shock' attracted considerable social attention in 2005 for asbestos-induced mesothelioma and, thereafter, the government enacted a law to provide the people suffering from MM a financial allowance. Several lines of recent evidence suggest that the major pathology associated with asbestos-induced MM is local iron overload, associated with asbestos exposure. Preclinical studies to prevent MM after asbestos exposure with iron reduction are in progress. In addition, novel target genes in mesothelial carcinogenesis have been discovered with recently recognized mesothelioma-prone families. Development of an effective preventive strategy is eagerly anticipated because of the long incubation period for MM.

Mayor erythropoietic response after deferasirox treatment in a transfusion-dependent anemic patient with primary myelofibrosis

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm frequently complicated by transfusion dependent anemia. Both anemia and transfusion-dependence are associated with a poor outcome, at least in part because of toxic effects of iron overload (IOL). Iron-chelating therapy (ICT) is increasingly used in order to prevent IOL in this setting. Here, we describe the case of a 73-year-old man affected by PMF and severe transfusion-dependent anemia who experienced a dramatic erythroid response after being treated with deferasirox to prevent IOL.

Transfusion-dependent low-risk myelodysplastic patients receiving deferasirox: Long-term follow-up

Myelodysplastic syndromes (MDSs) are characterized by ineffective hematopoiesis that results in peripheral cytopenias. Anemia is the most common symptom of MDS and the majority of patients become transfusion-dependent with the risk of iron overload, which may lead to cardiac, hepatic and endocrine complications. Deferasirox is an orally available iron chelator administered once-daily in transfusion-dependent patients with various chronic anemias. Its efficacy has been established in controlled clinical trials. In the present study, we describe our experience with 55 consecutive MDS patients [International Prognostic Scoring System risk score of low (n=32) or intermediate-1 (n=23)] treated with deferasirox in a routine clinical setting following Consensus Guidelines on Iron Chelation Therapy. According to WHO classifications, patients had refractory anemia (n=30), refractory anemia with ringed sideroblasts (n=16), refractory cytopenia with multilineage dysplasia (n=8) or refractory cytopenia with multilineage dysplasia and ringed sideroblasts (n=1). The median monthly transfusion requirement at baseline was 3 units. Patients received a starting dosage of 10 mg/kg/day, subsequently titrated according to serum ferritin (SF) levels which were measured monthly. Safety assessment included monitoring of liver and renal parameters and recording adverse events (AE) during treatment. At the baseline, the mean ± SD SF level was 2,362±172 ng/ml and after 24 months, the mean ± SD decrease in SF was 1,679±209 ng/ml. Sixteen patients had sustained hematological improvement meeting International Working Group 2006 criteria. One patient became transfusion-independent. No severe AE were reported. In conclusion, deferasirox therapy was effective and safe in reducing transfusional iron overload and it reduces transfusion requirement in a subset of patients.

Iron chelation therapy in myelodysplastic syndromes: where do we stand?

Anemia leading to transfusion dependency (TD) and iron overload (IO) is commonly observed in patients with myelodysplastic syndromes (MDS). In MDS, TD and IO have been retrospectively associated with inferior survival and worse clinical outcomes, including cardiac, hepatic and endocrine dysfunction, and, in some analyses, with leukemic progression and infectious complications. Although suggested by retrospective analyses, clear prospective documentation of the beneficial effects of iron chelation therapy (ICT) on organ function and survival in MDS patients with TD and IO is currently lacking. Consequently, the role of ICT in MDS patients with TD and IO remains a very controversial aspect in the management of MDS. In this review, the authors summarize the current knowledge regarding IO in MDS and the role of ICT.

Free iron catalyzes oxidative damage to hematopoietic cells/mesenchymal stem cells in vitro and suppresses hematopoiesis in iron overload patients

OBJECTIVES

Transfusional iron overload is of major concern in hematological disease. Iron-overload-related dyserythropoiesis and reactive oxygen species (ROS)-related damage to hematopoietic stem cell (HSC) function are major setbacks in treatment for such disorders. We therefore aim to investigate the effect of iron overload on hematopoiesis in the patients and explore the role of ROS in iron-induced oxidative damage in hematopoietic cells and microenvironment in vitro.

PATIENTS AND METHODS

The hematopoietic colony-forming capacity and ROS level of bone marrow cells were tested before and after iron chelation therapy. In vitro, we first established an iron overload model of bone marrow mononuclear cells (BMMNC) and umbilical cord-derived mesenchymal stem cells (UC-MSC). ROS level, cell cycle, and apoptosis were measured by FACS. Function of cells was individually studied by Colony-forming cell (CFC) assay and co-culture system. Finally, ROS-related signaling pathway was also detected by Western blot.

RESULTS

After administering deferoxamine (DFO), reduced blood transfusion, increased neutrophil, increased platelet, and improved pancytopenia were observed in 76.9%, 46.2%, 26.9%, and 15.4% of the patients, respectively. Furthermore, the colony-forming capacity of BMMNC from iron overload patient was deficient, and ROS level was higher, which were partially recovered following iron chelation therapy. In vitro, exposure of BMMNC to ferric ammonium citrate (FAC) for 24 h decreased the ratio of CD34(+) cell from 0.91 ± 0.12% to 0.39 ± 0.07%. Excessive iron could also induce apoptosis, arrest cell cycle, and decrease function of BMMNC and UC-MSC, which was accompanied by increased ROS level and stimulated p38MAPK, p53 signaling pathway. More importantly, N-acetyl-L-cysteine (NAC) or DFO could partially attenuate cell injury and inhibit the signaling pathway induced by excessive iron.

CONCLUSIONS

Our study shows that iron overload injures the hematopoiesis by damaging hematopoietic cell and hematopoietic microenvironment, which is mediated by ROS-related signaling proteins.

Iron chelation in the treatment of cancer: a new role for deferasirox?

Iron plays a crucial role in a number of metabolic pathways including oxygen transport, DNA synthesis, and ATP generation. Although insufficient systemic iron can result in physical impairment, excess iron has also been implicated in a number of diseases including ischemic heart disease, diabetes, and cancer. Iron chelators are agents which bind iron and facilitate its excretion. Experimental iron chelators have demonstrated potent anti-neoplastic properties in a number of cancers in vitro. These agents have yet to be translated into clinical practice, however, largely due to the significant side effects encountered in pre-clinical models. A number of licensed chelators, however, are currently in clinical use for the treatment of iron overload associated with certain non-neoplastic diseases. Deferasirox is one such agent and the drug has shown significant anti-tumor effects in a number of in vitro and in vivo studies. Deferasirox is orally administered and has demonstrated a good side effect profile in clinical practice to date. It represents an attractive agent to take forward into clinical trials of iron chelators as anti-cancer agents.

Safety and efficacy of deferasirox in the management of transfusion-dependent patients with myelodysplastic syndrome and aplastic anaemia: a perspective review

Deferasirox is an orally administered, once-daily iron chelator with a generally good safety and efficacy profile. Reported adverse events in the older myelodysplastic population are somewhat different to the more intensively investigated and younger thalassaemic population. Renal impairment is the most concerning adverse event, but this is reversible if identified and the drug is withdrawn early. Gastrointestinal effects, particularly diarrhoea, can be troublesome for older patients, but can be minimized with tailored therapy. Negative iron balance can be achieved in most patients with a median dose of 20 mg/kg/day, and doses up to 40 mg/kg are possible in patients with severe iron overload, who are at risk of cardiac decompensation.

Hematologic responses in patients with aplastic anemia treated with deferasirox: a post hoc analysis from the EPIC study

Reports are emerging of hematologic responses associated with iron chelation therapy; however, studies are limited in aplastic anemia patients. Deferasirox reduced iron overload in aplastic anemia patients enrolled in the EPIC (Evaluation of Patients' Iron Chelation with Exjade(®)) study (n=116). A post hoc analysis of hematologic responses was conducted on 72 patients with evaluable hematologic parameters (according to UK guideline criteria), 24 of whom received deferasirox without concomitant immunosuppressive treatment. Partial hematologic responses were observed in 11 of 24 (45.8%) patients; all became transfusion-independent. One patient had an additional platelet response and one patient had an additional platelet and hemoglobin response. Mean serum ferritin levels at end of study were significantly reduced in partial hematologic responders (n=11; -3948 ± 4998 ng/mL; baseline 6693 ± 7014 ng/mL; percentage change from baseline -45.7%; P=0.0029). In non-responders, the reduction in serum ferritin was less pronounced (n=13; -2021 ± 3242 ng/mL; baseline 4365 ± 3063 ng/mL; % change from baseline -27.6%; P=0.0171). Alongside reduction in iron overload, deferasirox may, therefore, improve hematologic parameters in a subset of aplastic anemia patients. Further investigation is required to elucidate the mechanisms involved.

Differential effects of the type of iron chelator on the absolute number of hematopoietic peripheral progenitors in patients with β-thalassemia major

Several studies have established an association between iron chelation therapy with deferasirox and hematopoietic improvement in patients with myelodysplastic syndromes. There are no data from patients with β-thalassemia major. In a cross-sectional study, we evaluated the absolute number of several hematopoietic peripheral progenitors (colony-forming unit-granulocyte/macrophage, erythroid burst-forming units, colony-forming unit-granulocyte/erythrocyte/macrophage/megakaryocyte, and long-term culture-initiating cells) in 30 patients with β-thalassemia major (median age 29.5 years, 40% males) and 12 age-matched controls. For the β-thalassemia major patients, data on splenectomy status, the type of iron chelator used, and serum ferritin levels reflecting changes in iron status on the chelator were also retrieved. All patients had to be using the same iron chelator for at least 6 months with >80% compliance. The absolute number of all hematopoietic peripheral progenitors was higher in β-thalassemia major patients than in controls, and varied between splenectomized and non-splenectomized patients (lower number of erythroid burst-forming units and higher numbers of colony-forming unit-granulocyte/macrophage, colony-forming unit-granulocyte/erythrocyte/macrophage/megakaryocyte, and long-term culture-initiating cells). The number of erythroid burst-forming units was significantly higher in patients taking deferasirox (n=10) than in those taking either deferoxamine (n=10) or deferiprone (n=10) (P<0.05). After adjusting for age, sex, splenectomy status, and serum ferritin changes, the association between a higher absolute number of erythroid burst-forming units in deferasirox-treated patients than in patients taking deferoxamine or deferiprone remained statistically significant (P=0.011). In conclusion, in β-thalassemia major patients, compared with other iron chelators, deferasirox therapy is associated with higher levels of circulating erythroid burst-forming units. This variation is independent of iron status changes and is more likely to be due to the type of chelator.

Improvement in hematopoiesis after iron chelation therapy with deferasirox in patients with aplastic anemia

Iron overload due to regular transfusions of packed red cells can cause multiple organ damage. Iron chelation therapy (ICT) is important in patients with aplastic anemia (AA) who require blood transfusions as supportive management. With the introduction of the oral iron chelator deferasirox, ICT has become more widely available and feasible. We studied 4 adult AA patients who had transfusion-induced iron overload and showed hematological improvement after ICT with oral deferasirox. Following deferasirox treatment, hemoglobin increased and serum ferritin levels decreased, and the patients subsequently became transfusion independent. Our experience raises the possibility of the potential benefit of ICT on hematopoiesis. Further long-term studies in larger patient cohorts are needed to clarify the effect of the restoration of hematopoiesis after iron chelation therapy.