Kinetics and efficacy of deferoxamine in iron-overloaded hemodialysis patients

Ferroportin depletes iron needed for cell cycle progression in head and neck squamous cell carcinoma

Introduction

Ferroportin (FPN), the only identified eukaryotic iron efflux channel, plays an important role in iron homeostasis and is downregulated in many cancers. To determine if iron related pathways are important for Head and Neck Squamous Cell Carcinoma (HNSCC) progression and proliferation, we utilize a model of FPN over-expression to simulate iron depletion and probe associated molecular pathways.

Methods

The state of iron related proteins and ferroptosis sensitivity was assessed in a panel of metastatic HNSCC cell lines. Stable, inducible expression of FPN was confirmed in the metastatic HNSCC lines HN12 and JHU-022 as well as the non-transformed normal oral keratinocyte (NOK) cell line and the effect of FPN mediated iron depletion was assessed in these cell lines.

Results

HNSCC cells are sensitive to iron chelation and ferroptosis, but the non-transformed NOK cell line is not. We found that FPN expression inhibits HNSCC cell proliferation and colony formation but NOK cells are unaffected. Inhibition of cell proliferation is rescued by the addition of hepcidin. Decreases in proliferation are due to the disruption of iron homeostasis via loss of labile iron caused by elevated FPN levels. This in turn protects HNSCC cells from ferroptotic cell death. Expression of FPN induces DNA damage, activates p21, and reduces levels of cyclin proteins thereby inhibiting cell cycle progression of HNSCC cells, arresting cells in the S-phase. Induction of FPN severely inhibits Edu incorporation and increased β-galactosidase activity, indicating cells have entered senescence. Finally, in an oral orthotopic mouse xenograft model, FPN induction yields a significant decrease in tumor growth.

Conclusions

Our results indicate that iron plays a role in HNSCC cell proliferation and growth and is important for cell cycle progression. Iron based interventional strategies such as ferroptosis or iron chelation may have potential therapeutic benefits in advanced HNSCC.

Red blood cell transfusion risks in patients with end-stage renal disease

Prior to the introduction of recombinant human erythropoietin (EPO), red blood cell (RBC) transfusions were frequently required when iron and anabolic steroids failed to improve the clinical symptoms of anemia associated with hemoglobin (Hb) levels that were commonly less than 7 g/dl. After the approval of EPO in the United States in 1989, the Hb levels of patients on hemodialysis dramatically improved and the need for RBC transfusions decreased significantly. The need for RBC transfusion remains for patients who require an immediate increase in their RBC mass due to symptomatic anemia and is likely to increase due to changes in the management of anemia in dialysis patients resulting from clinical trials data, regulatory changes, and new reimbursement policies for EPO. The safety of the blood supply has greatly improved over the last few decades, and the risk of transfusion-transmitted diseases has now been dramatically reduced. Noninfectious complications of transfusion currently cause the majority of morbidity and mortality associated with transfusion in the United States. Transfusion also brings a risk of alloimmunization, a particular concern for dialysis patients waiting for kidney transplantation. Knowledge of the risks of RBC transfusions will help clinicians better assess the risks and benefits of transfusing patients with ESRD. This article reviews the modern day infectious and noninfectious risks of allogeneic RBC transfusions.

Iron chelator deferasirox rescued mice from Fas-induced fulminant hepatitis

AIM

  Fulminant hepatitis is a disease characterized by development of hepatic failure due to severe liver cell injury. Orthotopic liver transplantation is the therapy proven to improve patient survival; however, less burdensome and safer strategies are required. In a previous study, we showed that iron was intimately involved in hepatocyte apoptosis by demonstrating that spontaneous development of fulminant hepatitis in Long-Evans cinnamon rats was prevented by feeding an iron-deficient diet. Recently, a new iron chelator, deferasirox, has become widely available for the treatment of transfusional hemosiderosis. Deferasirox demonstrated good efficacy and improved compliance due to convenient, once-daily p.o. administration. Our aim was to investigate the efficacy of deferasirox as a therapeutic drug against fulminant hepatitis.

METHODS

  Human primary hepatocytes undergoing Fas-stimulated apoptosis were challenged with deferoxamine (DFO) in vitro. In further in vivo experiments, we tested DFO in a mice model of fulminant hepatitis induced by Fas-stimulation.

RESULTS

  The apoptosis-inducing activity of anti-Fas antibody on human primary hepatocytes was inhibited by the chelation of iron with DFO. DFO suppressed the Fas-induced production of reactive oxygen species (ROS) and the activation of caspase-3, both of which were also suppressed by antioxidant, N-acetyl-L-cystein. In the in vivo experiments, deferasirox effectively reduced hepatic iron concentrations and rescued mice from Fas-induced fulminant hepatitis.

CONCLUSION

  These findings indicated that the iron chelation exerted a hepatoprotective effect by scavenging ROS upstream of caspase-3 and that iron chelation with deferasirox is a potential treatment for patients with fulminant hepatitis.

Safety issues with intravenous iron products in the management of anemia in chronic kidney disease

Anemia is a very common clinical problem in patients with chronic kidney disease (CKD) and is associated with increased morbidity and mortality in these patients. Erythropoietin is a hormone synthesized that is deficient in the majority of patients with advanced kidney disease, thereby predisposing these patients to anemia. The other cause of anemia is deficiency of iron. Iron deficiency anemia is common in people with CKD and its importance in supporting erythropoiesis is unquestioned, especially in those patients treated with erythropoietin. Intravenous iron is frequently used to treat anemia in CKD patients and is very efficacious in increasing hemoglobin but at the same time there are some safety issues associated with it. The objective of this review is to assess the frequency of adverse drug events associated with four different iron formulations: two iron dextran products known as high and low molecular weight iron dextran, iron sucrose, and sodium ferric gluconate complex. Several electronic databases were searched. In general, with the exception of high molecular weight iron dextran, serious or life-threatening adverse events appeared rare. Iron sucrose has the least reported adverse events and high molecular weight iron dextran has the highest number of reported adverse events. Low molecular weight iron dextran and ferric gluconate fall in between these two for number of adverse drug events.

Considerations for optimal iron use for anemia due to chronic kidney disease

BACKGROUND

Availability of recombinant human erythropoietin (rHuEPO) has improved the treatment of anemia due to chronic kidney disease (CKD). Iron deficiency is the most common cause of resistance to rHuEPO therapy, contributing to ineffective erythropoiesis and hematocrit/hemoglobin values below the recommended target range (33%-36%/11-12 g/dL). I.v. iron supplementation is necessary to meet increased iron demands from stimulation of erythropoiesis and chronic blood loss; however, questions remain as to the optimal supplementation strategy to maintain appropriate yet safe iron status. Treatment guidelines for anemia management have been developed through the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-K/DOQI).

OBJECTIVE

This review presents the basis of need for the NKF-K/DOQI guidelines and includes detailed information concerning iron physiology, metabolism, iron preparations, and evaluation of iron status.

METHODS

This review was based on a MEDLINE search and complemented by references from the NKF-K/DOQI guidelines (whose review extended beyond MEDLINE). References focusing on normal iron physiology and metabolism, alterations in iron physiology in patients with CKD, laboratory evaluation methods, and strategies for iron supplementation were obtained from MEDLINE and reviewed for content.

RESULTS

Controversy over appropriate use of iron supplementation has led to disparity in accepted practice procedures. Oral iron (ferrous salts and polysaccharide iron complex) and i.v. iron preparations (iron dextran, sodium ferric gluconate, and iron sucrose) are available. Problems with oral iron supplementation include limited absorption and patient noncompliance. Although most available data on i.v. iron use in the United States are specific to iron dextran preparations, published information based on clinical use of sodium ferric gluconate and iron sucrose products has been promising. The use of chronic i.v. iron administration to sustain iron stores has been more widely accepted to prevent development of absolute and functional iron deficiency.

CONCLUSIONS

Although iron therapy is commonly warranted in patients with CKD, questions remain as to the most favorable supplementation strategy to optimize therapy through improvements in hematocrits, efficient use of rHuEPO, and maintenance of appropriate and safe iron levels. Clinicians will need to devise strategies based on the compilation of information from clinical experience and the available literature. Clinical practice guidelines devised by the NKF-K/DOQI have provided a useful tool for the medical community using both these resources.

Acute encephalopathy due to aluminum toxicity successfully treated by combined intravenous deferoxamine and hemodialysis

Acute aluminum intoxication is uncommon in clinical practice but can be fatal. This limited experience is reflected in the paucity of data assessing a viable approach to the treatment of these patients. In this report, the authors describe the clinical course and successful, pharmacokinetic-based deferoxamine-hemodialysis treatment regimen of a patient with severe aluminum encephalopathy following alum bladder irrigation. The combined use of deferoxamine and appropriately timed hemodialysis appears to be a very reasonable means of treating patients with severe acute aluminum intoxication.

Low dose desferrioxamine can improve erythropoiesis in iron-overload hemodialysis patients without side effects

OBJECTIVE

Multiple blood transfusions were often required to treat anemia in uremia patients before the era of recombinant human erythropoietin (r-HuEPO). Iron overload thus frequently occurred in chronic hemodialysis patients. Desferrioxamine (DFO) is an effective chelating agent, which can remove excessive iron and can enhance erythropoiesis. Large dose DFO treatment is a therapy associated with the development of severe complications. In this study, a low dose DFO regime was used to treat iron overloaded hemodialysis patients. The efficacy and side effects of this regiment were evaluated.

MATERIALS AND METHODS

Eight iron overloaded chronic hemodialysis patients were enrolled in this study. All patients received DFO 500 mg intravenously twice-a-week for eight months. Serum aluminum, transferrin saturation (TFS) and r-HuEPO requirement were recorded before and after DFO treatment. Serum ferritin and hematocrit (Hct) were measured before, during, and after the DFO withdrawal period. All patients were evaluated and followed closely during treatment.

RESULTS

Changes in aluminum, TFS and r-HuEPO dosage were unremarkable (p > 0.05). Hct increased significantly after eight months of DFO treatment (from 25.3% to 27.0%, p < 0.05). Ferritin level was reduced by 43.2% at the end of treatment and an evident decline of ferritin was achieved after four months of treatment (2102 ng/mL to 1166 ng/mL, p < 0.05). All patients tolerated the treatment well and no complications were found.

CONCLUSION

Low dose DFO can chelate iron effectively in chronic hemodialysis patients. This treatment can enhance erythropoiesis without adverse effects.

An indistinct balance: the safety and efficacy of parenteral iron therapy

Recombinant epoetin therapy and correction of the chronic anemia of renal failure have greatly reduced the number of red cell transfusions and hence the propensity to iron overload. The majority of HD patients require intravenous iron therapy to achieve the hematocrit levels that correspond to improved outcome measures. Although the short-term benefits of intravenous iron have been clearly defined, the long-term risks of intravenous iron are less well-defined. Iron overload before the availability of epoetin constituted a serious problem; our review of the literature does not decisively conclude that these patients had more serious bacterial infections or increased mortality when compared with their non-iron overloaded counterparts, unless chronic transfusion-related hepatic disease was superimposed. Specifically, no data unequivocally confirm that iron overload from parenteral iron contributes to all-cause patient morbidity or mortality. Furthermore, therapy that maintains intravenous iron optimal iron stores and replaces iron losses associated with the dialytic procedure does not engender iron overload in the carefully monitored patient. Optimized anemia therapy in ESRD requires individualized and specific application of epoetin and iron for each patient, and significant cost savings can result from such a strategy. Prospective studies are clearly necessary to define those parameters that reflect adequacy of iron storage in renal failure patients. We should develop alternative means of iron delivery and develop monitors that accurately discriminate between patients who will respond to additional iron therapy and those who will not. Whether ferritin should be supplanted by another parameter and whether iron itself poses an increased risk to those patients it has so beneficially served are issues that must be resolved. Until these answers are known, the importance of carefully crafted iron therapy cannot be overstated.

Iron overload in renal failure patients: changes since the introduction of erythropoietin therapy

Iron overload was a common complication in patients with chronic renal failure treated with dialysis prior to the availability of recombinant human erythropoietin (rHuEPO) therapy. Iron overload was the result of hypoproliferative erythroid marrow function coupled with the need for frequent red blood cell transfusions to manage symptomatic anemia. The repetitive use of intravenous iron with or without the use of red blood cell transfusions also contributed to iron loading and was associated with iron deposition in liver parenchymal and reticuloendothelial cells; however, there were no abnormal liver function tests or evidence of cirrhosis unless viral hepatitis resulted from the transfusions. With rHuEPO therapy, the excess iron stores were shifted back into circulating red blood cells as the anemia was partially corrected, and red blood cells were lost from circulation by the hemodialysis procedure. After several years of rHuEPO therapy, most hemodialysis patients required iron supplements to replace the continuing blood losses related to hemodialysis. The potential complications of iron overload (parenchymal iron deposition, permanent organ damage, increased risk of bacterial infections, and increased free radical generation) are reviewed in the context of this setting.

Urinary and biliary excretion of aluminoxamine and ferrioxamine in dogs with various renal function

We assessed the pharmacokinetics of aluminoxamine and ferrioxamine in dogs with sustained intermittent bile duct ligation and either normal renal function or stable chronic renal failure. A first group of male beagle dogs were given aluminoxamine and ferrioxamine, while a second group received desferrioxamine after loading them with iron and aluminum. Only minute amounts of ferrioxamine and aluminoxamine were found in the bile after administration of these compounds. The distribution volume of aluminoxamine and ferrioxamine appeared to be confined to the extracellular space and their renal excretion correlated with renal function. Administration of desferrioxamine to iron and aluminum-loaded dogs resulted in an increased biliary ferrioxamine but negligible aluminoxamine excretion. Renal clearance of the in vivo formed ferrioxamine and aluminoxamine in this group strongly correlated with renal function. Our observations indicate that biliary excretion of intravenously administered ferrioxamine and aluminoxamine is negligible even in renal failure. The data presented in this study provide indirect evidence that desferrioxamine administration to iron- and aluminum-loaded dogs results in the intra-hepatic formation of ferrioxamine which is partly excreted in the bile. Biliary excretion of aluminoxamine after desferrioxamine administration remained negligible.

Assessment of exposure to parenteral and oral aluminum with and without citrate using a desferrioxamine test in rats

The primary purpose of this study was to determine the relative usefulness of various measures to monitor body aluminum burden in weanling rats fed various amounts of aluminum (0.39 mumol Al/g diet for 29 days, approximately 40 mumol Al/g diet with or without citrate for 29 days and approximately 100 mumol Al/g diet with citrate for 12 or 29 days) or injected intraperitoneally with graded doses of aluminum (0.01, 4.6, 11.8, 23.5 or 94 mumol Al). Twenty-four hours prior to sacrifice, all rats were injected intraperitoneally with either desferrioxamine (75 mg DFO) or buffer. All seven indices of aluminum exposure monitored (i.e. tibia, liver, kidney and serum aluminum concentrations; changes in serum aluminum concentrations in response to DFO; urinary aluminum excretion with and without DFO treatment) were highly (P < 0.001) correlated to parenteral aluminum exposure. Five of these measures (i.e. tibia, liver and serum aluminum concentrations and urinary aluminum excretion with and without DFO treatment) were also highly (P < 0.001) correlated to oral aluminum loads. Changes induced by DFO were very small. Moreover, the 'DFO stimulated' serum and urine aluminum concentrations were not more correlated to the body load of aluminum, as indicated by tibia aluminum concentrations, than baseline values. Comparisons of aluminum exposure in tibias and sera of rats exposed to parenteral and oral aluminum indicated that only 0.01-0.04% of dietary aluminum was absorbed. Ingestion of citrate had small but significant effects on aluminum retention.

The use of nuclear magnetic resonance imaging in monitoring total body iron in hemodialysis patients with hemosiderosis treated with erythropoietin and phlebotomy

Two hemodialysis patients with hemosiderosis were treated with combined erythropoietin and repeated phlebotomy. Serial nuclear magnetic resonance (NMR) imaging and serum ferritin levels were used to monitor the efficacy of treatment. This treatment modality has definite advantages over chronic deferoxamine therapy. NMR image-derived parameters offer an objective, accurate, and noninvasive indication of tissue iron stores.

Recombinant human erythropoietin and phlebotomy in the treatment of iron overload in chronic hemodialysis patients

Five long-term hemodialysis patients with clinical iron overload were treated with 300 U/kg of recombinant human erythropoietin (rHuEPO) intravenously (IV) after each hemodialysis. The patients were phlebotomized after each hemodialysis at any time the predialysis hematocrit was 35% or greater. Over a period of 1 year, the average phlebotomy rate varied from 0.5 to 1.1 U/wk with a mean phlebotomy rate of 45.8 +/- 5.6 U/yr (range, 27 to 57 U). The mean serum ferritin decreased from 8,412 +/- 1,599 micrograms/L (ng/mL) to 3,007 +/- 1,129 micrograms/L (ng/mL), and the mean iron removal over this period was 9.5 g. Liver iron deposition, as measured by density on computed tomographic (CT) scan, improved, while skin color lightened significantly. Patients tolerated phlebotomy with no major symptoms or complications and exhibited no change in the hemogram or serum chemistries. In patients with severe iron overload, changes in serum ferritin with erythropoietin treatment alone may not reflect true change in iron burden. Use of high-dose erythropoietin and phlebotomy is an effective and safe (at least for 1 year) method of reducing iron overload in long-term hemodialysis patients.