Safety and efficacy of iron chelation therapy with deferiprone in patients with transfusion-dependent thalassemia

Real-world evidence: Long-term safety of deferiprone in a large cohort of patients with sickle cell disease enrolled in a registry for up to 10 years

Patients with sickle cell disease (SCD) and other anemias who receive blood transfusions are at risk of organ damage due to transfusional iron overload. Deferiprone is an iron chelator with a well-established safety and efficacy profile that is indicated for the treatment of transfusional iron overload. Here, we report safety data from the large-scale, retrospective Ferriprox® Total Care Registry, which involved all patients with SCD taking deferiprone following the 2011 approval of deferiprone in the United States through August 2020. A total of 634 patients who had initiated deferiprone treatment were included. The mean (SD) duration of deferiprone exposure in the registry was 1.6 (1.6) years (range 0 to 9.7 years). In the overall patient population (N = 634), 64.7% (n = 410) of patients reported a total of 1885 adverse events (AEs). In subgroup analyses, 54.6% (n = 71) of pediatric patients and 67.3% (n = 339) of adult patients reported AEs. The most common AEs reported in patients receiving deferiprone were sickle cell crisis (22.7%), nausea (12.1%), vomiting (8.7%), abdominal discomfort (5.4%), and fatigue (5.4%). Neutropenia was reported in four (0.6%) patients and severe neutropenia/agranulocytosis (defined as absolute neutrophil count <0.5 × 109/L) was reported in two (0.3%) patients. Of patients with evaluable data, all cases of neutropenia and severe neutropenia/agranulocytosis resolved with deferiprone discontinuation. Results from the nearly 10 years of real-world data collected in the Ferriprox® Total Care Registry demonstrate that deferiprone is safe and well tolerated in patients with SCD or other anemias who have transfusional iron overload.

Broadening horizons: ferroptosis as a new target for traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide, with ~50 million people experiencing TBI each year. Ferroptosis, a form of regulated cell death triggered by iron ion-catalyzed and reactive oxygen species-induced lipid peroxidation, has been identified as a potential contributor to traumatic central nervous system conditions, suggesting its involvement in the pathogenesis of TBI. Alterations in iron metabolism play a crucial role in secondary injury following TBI. This study aimed to explore the role of ferroptosis in TBI, focusing on iron metabolism disorders, lipid metabolism disorders and the regulatory axis of system Xc-/glutathione/glutathione peroxidase 4 in TBI. Additionally, we examined the involvement of ferroptosis in the chronic TBI stage. Based on these findings, we discuss potential therapeutic interventions targeting ferroptosis after TBI. In conclusion, this review provides novel insights into the pathology of TBI and proposes potential therapeutic targets.

Accelerated atherosclerosis in beta-thalassemia

Children with beta-thalassemia (BT) present with an increase in carotid intima-medial thickness, an early sign suggestive of premature atherosclerosis. However, it is unknown if there is a direct relationship between BT and atherosclerotic disease. To evaluate this, wild-type (WT, littermates) and BT (Hbbth3/+) mice, both male and female, were placed on a 3-mo high-fat diet with low-density lipoprotein receptor suppression via overexpression of proprotein convertase subtilisin/kexin type 9 (PCSK9) gain-of-function mutation (D377Y). Mechanistically, we hypothesize that heme-mediated oxidative stress creates a proatherogenic environment in BT because BT is a hemolytic anemia that has increased free heme and exhausted hemopexin, heme's endogenous scavenger, in the vasculature. We evaluated the effect of hemopexin (HPX) therapy, mediated via an adeno-associated virus, to the progression of atherosclerosis in BT and a phenylhydrazine-induced model of intravascular hemolysis. In addition, we evaluated the effect of deferiprone (DFP)-mediated iron chelation in the progression of atherosclerosis in BT mice. Aortic en face and aortic root lesion area analysis revealed elevated plaque accumulation in both male and female BT mice compared with WT mice. Hemopexin therapy was able to decrease plaque accumulation in both BT mice and mice on our phenylhydrazine (PHZ)-induced model of hemolysis. DFP decreased atherosclerosis in BT mice but did not provide an additive benefit to HPX therapy. Our data demonstrate for the first time that the underlying pathophysiology of BT leads to accelerated atherosclerosis and shows that heme contributes to atherosclerotic plaque development in BT.NEW & NOTEWORTHY This work definitively shows for the first time that beta-thalassemia leads to accelerated atherosclerosis. We demonstrated that intravascular hemolysis is a prominent feature in beta-thalassemia and the resulting increases in free heme are mechanistically relevant. Adeno-associated virus (AAV)-hemopexin therapy led to decreased free heme and atherosclerotic plaque area in both beta-thalassemia and phenylhydrazine-treated mice. Deferiprone-mediated iron chelation led to deceased plaque accumulation in beta-thalassemia mice but provided no additive benefit to hemopexin therapy.

Kinetic aspects of iron(III)-chelation therapy with deferasirox (DFX) revealed by the solvolytic dissociation rate of the Fe(III)-DFX complex estimated with capillary electrophoretic reactor

Capillary electrophoresis was used to estimate the solvolytic dissociation rate (k_d) of metal complexes of deferasirox (DFX, H₃L), a drug used to treat iron overload. Inert Co^IIIL₂^3- did not dissociate. The estimated k_d value for Fe^IIIL₂^3- was (2.7 ± 0.3) × 10^-4 s^-1 (298 K, pH 7.4). The k_d values of other complexes (Al^IIIL₂^3-, Ni^IIL₂^4-, and Mn^IIL^-) were in the range 10^-3-10^-4 s^-1. In contrast, Zn^IIL^- and Cu^IIL^- were too labile to allow k_d estimation. The fact that the half-life of Fe^IIIL₂^3- (43.3 min) is shorter than the blood half-life of DFX (8-16 h) implies that the blood concentration of DFX should be high enough to prevent dissociation of Fe^IIIL₂^3-. The possibility of a safer iron-chelation therapy that avoids excretion of other essential metal ions such as Zn^II is discussed, highlighting the importance of selectivity in terms of kinetic stability.

Quality by design approach for green HPLC method development for simultaneous analysis of two thalassemia drugs in biological fluid with pharmacokinetic study

This work implements a combined experimental approach of analytical quality-by-design (AQbD) and green analytical chemistry (GAC) to develop an HPLC method for simultaneous determination of the two thalassemia drugs, deferasirox (DFX) and deferiprone (DFP), in biological fluid for the first time. This integration was designed to maximize efficiency and minimize environmental impacts, as well as energy and solvent consumption. To accomplish this goal, an analytical quality-by-design approach was performed, beginning with quality risk assessment and scouting analysis, followed by Placket-Burman design screening for five chromatographic parameters. Critical method parameters were thoroughly recognized and then optimized by using a two levels-three factors custom experimental design to evaluate the optimum conditions that achieved the highest resolution with acceptable peak symmetry within the shortest run time. The desirability function was used to define the optimal chromatographic conditions, and the optimal separation was achieved using an XBridge® HPLC RP-C18 (4.6 × 250 mm, 5 μm) column with ethanol : acidic water at pH 3.0 adjusted by phosphoric acid in the ratio of (70 : 30, v/v) as the mobile phase at a flow rate of 1 mL min^-1 with UV detection at 225 nm at a temperature of 25 °C. Linearity was obtained over the concentration range of 0.30-20.00 μg mL^-1 and 0.20-20.00 μg mL^-1 for DFX and DFP, respectively, using 20.00 μg mL^-1 ibuprofen (IBF) as an internal standard. The established method's greenness profile was evaluated and measured using various assessment tools, and the developed method was green. For the validation of the developed method, FDA recommendations were followed, and all the results obtained met the acceptance criteria. The suggested method was successfully used to study the pharmacokinetic parameters of DFX and DFP in rat plasma. Due to the substantial increase in bioavailability of the two iron chelating drugs, the results from this study strongly recommend their co-administration.

Deferiprone vs deferoxamine for transfusional iron overload in SCD and other anemias: a randomized, open-label noninferiority study

Many people with sickle cell disease (SCD) or other anemias require chronic blood transfusions, which often causes iron overload that requires chelation therapy. The iron chelator deferiprone is frequently used in individuals with thalassemia syndromes, but data in patients with SCD are limited. This open-label study assessed the efficacy and safety of deferiprone in patients with SCD or other anemias receiving chronic transfusion therapy. A total of 228 patients (mean age: 16.9 [range, 3-59] years; 46.9% female) were randomized to receive either oral deferiprone (n = 152) or subcutaneous deferoxamine (n = 76). The primary endpoint was change from baseline at 12 months in liver iron concentration (LIC), assessed by R2* magnetic resonance imaging (MRI). The least squares mean (standard error) change in LIC was -4.04 (0.48) mg/g dry weight for deferiprone vs -4.45 (0.57) mg/g dry weight for deferoxamine, with noninferiority of deferiprone to deferoxamine demonstrated by analysis of covariance (least squares mean difference 0.40 [0.56]; 96.01% confidence interval, -0.76 to 1.57). Noninferiority of deferiprone was also shown for both cardiac T2* MRI and serum ferritin. Rates of overall adverse events (AEs), treatment-related AEs, serious AEs, and AEs leading to withdrawal did not differ significantly between the groups. AEs related to deferiprone treatment included abdominal pain (17.1% of patients), vomiting (14.5%), pyrexia (9.2%), increased alanine transferase (9.2%) and aspartate transferase levels (9.2%), neutropenia (2.6%), and agranulocytosis (0.7%). The efficacy and safety profiles of deferiprone were acceptable and consistent with those seen in patients with transfusion-dependent thalassemia. This trial study was registered at www://clinicaltrials.gov as #NCT02041299.

Effects of B1 + Heterogeneity on Spin Echo-Based Liver Iron Estimates

BACKGROUND

Liver iron concentration (LIC) measured by MRI has become the clinical reference standard for managing iron overload in chronically transfused patients. Transverse relaxivity (R₂ or R₂ ^* ) measurements are converted to LIC units using empirically derived calibration curves.

HYPOTHESIS

That flip angle (FA) error due to B₁ ⁺ spatial heterogeneity causes significant LIC quantitation error. B₁ ⁺ scale (b₁ , [FA_actual /FA_specified ]) variation is a major problem at 3 T which could reduce the accuracy of transverse relaxivity measurements.

STUDY TYPE

Prospective.

POPULATION

Forty-seven subjects with chronic transfusional iron overload undergoing clinically indicated LIC assessment.

FIELD STRENGTH/SEQUENCE

5 T/3 T dual-repetition time B₁ ⁺ mapping sequence ASSESSMENT: We quantified the average/standard deviation b₁ in the right and left lobes of the liver from B₁ ⁺ maps acquired at 1.5 T and 3 T. The impact of b₁ variation on spin echo LIC estimates was determined using a Monte Carlo model.

STATISTICAL TESTS

Mean, median, and standard deviation in whole liver and right and left lobes; two-sided t-test between whole-liver b₁ means.

RESULTS

Average b₁ within the liver was 99.3% ± 12.3% at 1.5 T versus 69.6% ± 14.6% at 3 T and was independent of iron burden (P < 0.05). Monte Carlo simulations demonstrated that b₁ systematically increased R₂ estimates at lower LIC (<~25 mg/g at 1.5 T, <~15 mg/g at 3 T) but flattened or even inverted the R₂ -LIC relationship at higher LIC (≥~25 mg/g to 1.5 T, ≥~15 mg/g to 3 T); changes in the R₂ -LIC relationship were symmetric with respect to over and under excitation and were similar at 1.5 T and 3 T (for the same R₂ value). The R₂ ^* -LIC relationship was independent of b₁ .

CONCLUSION

Spin echo R₂ measurement of LIC at 3 T is error-prone without correction for b₁ errors. The impact of b₁ error on current 1.5 T spin echo-based techniques for LIC quantification is large enough to introduce measurable intersubject variability but the in vivo effect size needs a dedicated validation study.

LEVEL OF EVIDENCE

1.

TECHNICAL EFFICACY STAGE

2.

Therapeutic potential of iron chelators on osteoporosis and their cellular mechanisms

Iron is an essential trace element in the metabolism of almost all living organisms. Iron overload can disrupt bone homeostasis by significant inhibition of osteogenic differentiation and stimulation of osteoclastogenesis, consequently leading to osteoporosis. Iron accumulation is also involved in the osteoporosis induced by multiple factors, such as estrogen deficiency, ionizing radiation, and mechanical unloading. Iron chelators are first developed for treating iron overloaded disorders. However, growing evidence suggests that iron chelators can be potentially used for the treatment of bone loss. In this review, we focus on the therapeutic effects of iron chelators on bone loss. Iron chelators have therapeutic effects not only on iron overload induced osteoporosis, but also on osteoporosis induced by estrogen deficiency, ionizing radiation, and mechanical unloading, and in Alzheimer's disease-associated osteoporotic deficits. Iron chelators differently affect the cellular behaviors of bone cells. For osteoblast lineage cells (bone mesenchymal stem cells and osteoblasts), iron chelation stimulates osteogenic differentiation. Conversely, iron chelation significantly inhibits osteoclast differentiation. These different responses may be associated with the different needs of iron during differentiation. Fibroblast growth factor 23, angiogenesis, and antioxidant capability are also involved in the osteoprotective effects of iron chelators.

Neutropenia and Life-threatening Agranulocytosis Among Children With β-Thalassemia Treated With Oral Iron Chelators in a Community With Background of Ethnic Neutropenia

INTRODUCTION

Neutropenia and agranulocytosis are rare side effects of deferiprone (DFP) in patients treated for iron overload. Unfortunately, no study directly addressed special risks in countries with a background of ethnic neutropenia, such as Oman.

AIM

The aim of this study was to report the incidence of neutropenia in Omani children with β-thalassemia treated with different iron chelators.

METHODS/DESIGN

This was a retrospective study that included 179 Omani pediatric patients. For patients who developed neutropenia, demographic data, iron-chelating agent, clinical presentation, management, and outcome were recorded. Detailed clinical, laboratory±radiologic information was added for patients with agranulocytosis.

RESULTS

Neutropenia was encountered in 43.6% of patients: severe neutropenia in 10 patients, moderate in 29, and mild in 69 patients. Severe and moderate neutropenia had similar incidence among DFP-exposed and DFP-naive patients (P=0.515 and 0.421, respectively), while mild neutropenia was common among DFP-naive patients (P=0.0001). A higher incidence of DFP-related agranulocytosis (4.1%) was noted compared with previous reports, but none had a fatal outcome.

CONCLUSIONS

In a community with ethnic neutropenia, mild to moderate neutropenia is common. Higher incidence of severe neutropenia and agranulocytosis mandates careful monitoring and rational modification of iron-chelating agents to avoid life-threatening complications.

Vitamin and mineral supplementation for β-thalassemia during COVID-19 pandemic

AIM

Low levels of immune-related micronutrients have been identified in β-thalassemia samples. Moreover, the excess amount of iron, contributing to oxidative stress in the pathogenesis of the disease, alters the immune system in β-thalassemia, which is important during the COVID-19 pandemic.

MATERIALS & METHODS

Searches of PUBMED and EMBASE were conducted to identify the level and supplementation of micronutrients in β-thalassemia, published from 2001-May 2020.

RESULTS

The review found six observational and five interventional studies supporting the importance of supplementing vitamins and minerals among patients with β-thalassemia.

CONCLUSION

Supplementation of immune-related vitamins and minerals might bring benefits to the immune system, especially in reducing oxidative stress in β-thalassemia.

Two novel polymorphic forms of iron-chelating agent deferiprone

Thalassemia is a genetic blood disorder requiring life-long blood transfusions. This process often results in iron overload and can be treated by an iron-chelating agent, like deferiprone (3-hydroxy-1,2-dimethylpyridin-4-one), C₇H₉NO₂, in an oral formulation. The first crystal structure of deferiprone, (Ia), was reported in 1988 [Nelson et al. (1988). Can. J. Chem. 66, 123-131]. In the present study, two novel polymorphic forms, (Ib) and (Ic), of deferiprone were identified concomitantly with polymorph (Ia) during the crystallization experiments. Polymorph (Ia) was redetermined at low temperature for comparison of the structural features and lattice energy values with polymorphs (Ib) and (Ic). Polymorph (Ia) crystallized in the orthorhombic space group Pbca, whereas both polymorphs (Ib) and (Ic) crystallized in the monoclinic space group P2₁/c. The asymmetric units of (Ia) and (Ib) contain one deferiprone molecule, while polymorph (Ic) has three crystallographically independent molecules (A, B and C). All three polymorphs have similar hydrogen-bonding features, such as an R₂²(10) dimer formed by O-H...O hydrogen bonds, an R₄³(20) tetramer formed by C-H...O hydrogen bonds and π-π interactions, but the polymorphs differ in their molecular arrangements in the solid state and are classified as packing polymorphs. O-H...O and C-H...O hydrogen bonds lead to the formation of two-dimensional hydrogen-bonded parallel sheets which are interlinked by π-π stacking interactions. In the three-dimensional crystal packing, the deferiprone molecules were aggregated as corrugated sheets in polymorphs (Ia) and (Ic), whereas in polymorph (Ib), they were aggregated as a square-grid network. The characteristic crystalline peaks of polymorphs (Ia), (Ib) and (Ic) were established through powder X-ray diffraction analysis. The Rietveld analysis was also performed to estimate the contribution of the polymorphs to the bulk material.

The effects of iron overload on mitochondrial function, mitochondrial dynamics, and ferroptosis in cardiomyocytes

Excessive iron accumulation in the heart can lead to iron overload cardiomyopathy (IOC), the leading cause of death in hemochromatosis patients. Current understanding regarding the mechanism by which iron overload causes a deterioration in cardiac performance, mitochondrial dysfunction, and impaired mitochondrial dynamics remains limited. Ferroptosis, a newly identified form of regulated cell death, has recently been revealed influencing the pathophysiological process of IOC. Nevertheless, the direct effect of cardiac iron overload on ferroptotic cell death is incompletely characterized. This review article comprehensively summarizes and discusses the effects of iron overload on cardiac mitochondrial function, cardiac mitochondrial dynamics, ferroptosis of cardiomyocytes, and left ventricular function in in vitro and in vivo reports. This review also provides relevant consistent and controversial information which can facilitate further mechanistic investigation into iron-induced cardiac dysfunction in the clinical setting in the near future.

Antiplatelet activity of deferiprone through cyclooxygenase-1 inhibition

Thalassemia patients are susceptible to both iron overload and thromboembolism. Deferiprone is an iron chelator that shows an antiplatelet activity and thus may alleviate platelet hyperactivation in thalassemia. Therefore, this study aimed to characterize the inhibitory effects and mechanisms of deferiprone on normal human platelets. The results illustrated that deferiprone inhibited platelet aggregation at the iron chelating concentrations (0.08-0.25 mmol/l). Deferiprone inhibited human platelet aggregation stimulated by arachidonic acid and ADP more potently than epinephrine and collagen, with the IC₅₀ of 0.24 mmol/l and 0.25 mmol/l vs. 3.36 mmol/l and 3.73 mmol/l, respectively. Interestingly, deferiprone significantly inhibited COX-1 activity, with the IC₅₀ of 0.33 mmol/l, and slightly increased cAMP level at the high concentration of 4 mmol/l. Moreover, the results from molecular docking showed that deferiprone interacted closely with key residues in the peroxidase active site of COX-1. These results suggested that deferiprone possessed antiplatelet activity mainly through the inhibition of COX-1 activity.

3-Chloro-N'-(2-hydroxybenzylidene) benzohydrazide: An LSD1-Selective Inhibitor and Iron-Chelating Agent for Anticancer Therapy

Despite the discovery and development of novel therapies, cancer is still a leading cause of death worldwide. In order to grow, tumor cells require large quantities of nutrients involved in metabolic processes, and an increase in iron levels is known to contribute to cancer proliferation. Iron plays an important role in the active site of a number of proteins involved in energy metabolism, DNA synthesis and repair, such as ribonucleotide reductase, which induce G0/S phase arrest and exert a marked antineoplastic effect, particularly in leukemia and neuroblastoma. Iron-depletion strategies using iron chelators have been shown to result in cell cycle arrest and apoptosis. Deferoxamine (DFO) was the first FDA-approved drug for the treatment of iron overload pathologies, and has also been recognized as having anticancer properties. The high cost, low permeability and short plasma half-life of DFO led to the development of other iron-chelating drugs. Pyridoxal isonicotinoyl hydrazone (PIH) and its analogs chelate cellular iron by tridentate binding, and inhibit DNA synthesis more robustly than DFO, demonstrating an effective antiproliferative activity. Here, we investigated the biological effects of a PIH derivative, 3-chloro-N′-(2-hydroxybenzylidene)benzohydrazide (CHBH), known to be a lysine-specific histone demethylase 1A inhibitor. We showed that CHBH is able to induce cell proliferation arrest in several human cancer cell lines, including lung, colon, pancreas and breast cancer, at micromolar levels. Our findings indicate that CHBH exerts a dual anticancer action by strongly impairing iron metabolism and modulating chromatin structure and function.

Efficacy of Deferasirox as an Oral Iron Chelator in Paediatric Thalassaemia Patients

INTRODUCTION

Thalassaemia Major patients require frequent blood transfusion leading to iron overload. Excessive iron gets deposited in vital organs and leads to dysfunction of the heart, liver, anterior pituitary, pancreas, and joints. Our body has limited mechanism to excrete iron, so patients with iron overload and its complications need safe and effective iron chelation therapy.

AIM

To assess the efficacy of Deferasirox (DFX) as an iron chelator, with specific reference to reduction in serum ferritin level.

MATERIALS AND METHODS

This is a prospective; observational study done in 45 multitransfused Thalassaemia Major Children receiving DFX therapy at registered Thalassaemia society Raipur Chhattisgarh. DFX was given in an initial dose of 20 mg/kg/day and according to response increased to a maximum of 40 mg/kg/day. Serum ferritin level was estimated at time of registration and at every three monthly intervals (four times during study period). The primary end point of the study was change in serum ferritin level after 12 months of DFX therapy.

RESULTS

The mean serum ferritin before DFX therapy of all cases was 3727.02 ng/mL. After 12 months of mean dose of 38 mg/kg/day of DFX, the mean decline in serum ferritin was 1207.11 ng/mL (drop by 32.38%, p-value <0.001).

CONCLUSION

DFX monotherapy has a good safety profile and effectively chelates total body iron in Thalassaemia major patients.

Analogues of desferrioxamine B designed to attenuate iron-mediated neurodegeneration: synthesis, characterisation and activity in the MPTP-mouse model of Parkinson's disease

One dual-function (2) and one first-generation (9) conjugate of the Fe(iii) chelator desferrioxamine B (DFOB,1) showed significant rescue of neurons in the MPTP mouse model of Parkinson's disease.

Chemical features of in use and in progress chelators for iron overload

An excessive amount of iron may become extremely toxic both for its ability to generate reactive oxygen species, and for the lack of regulatory mechanisms for iron excretion in humans. Chelation therapy has been introduced in clinical practice in the 1970's to defend thalassemia patients from the effects of iron overload and it has dramatically changed both life expectancy and quality of life. The disadvantages of the drugs in clinical use make the research for new, more suitable iron chelating agents, urgent. This review defines the requirements of an iron chelator, then points out the principal chemical features of the iron chelators in use. Finally, a survey on the last ten years of the literature relative to iron chelators is done, and the most interesting ligands are presented, with particular emphasis to those that reached clinical trials.

Frequency of neutropenia among Turkish and Syrian pediatric thalassemia patients under deferiprone monotherapy

Weekly monitoring of absolute neutrophil count (ANC) under deferiprone therapy in thalassemia patients is recommended to avoid agranulocytosis adverse event. Actually, this recommendation may not be applicable in clinical setting. Our study aimed to establish incidence of neutropenia under deferiprone (DFP) monotherapy when it was monitored bimonthly due to socioeconomic conditions effecting local and refugee thalassemic patients including Syrian origin (SYR; n = 26) and Turkish origin (TR; n = 26) groups. Patients on DFP were followed up for 12 months. Fifteen neutropenic episodes were seen in 5 patients. All 5 patients (4 from SYR group and 1 from TR group) had splenomegaly and hypersplenism, and neutropenia ceased in 4 patients after splenectomy despite continuation of deferiprone. In the TR group, the frequency of patients who have neutropenia (absolute neutrophil count [ANC] <1500/mm(3)) was 3.8% (n = 1) in the 1st month, no patients in TR group had neutropenia until 10th month when again there was 1 patient with mild neutropenia. In SYR group, the frequency of patients who have neutropenia was 3.8% (n = 1), 7.7% (n = 2), and 11.5% (n = 3) in the 1st, 2nd, and 3rd months, respectively, and was found to be 3.8% (n = 1) between 6 and 12 months. Whether or not DFP therapy should be interrupted in case of mild neutropenia and the frequency of monitoring ANC in real-life conditions should be documented with further studies. Other causes of neutropenia in DFP-treated patients should also be kept in mind.

Zinc(II) and copper(II) complexes with hydroxypyrone iron chelators

High stability of the complexes formed at physiological pH is one of the basic requisites that a good iron chelator must possess. At the same time the chelating agent must be selective toward iron, i.e., the stability of iron complexes must be significantly higher than that of the complexes formed with essential metal ions, in order that these last ones do not perturb iron chelation. In the frame of our research on iron chelators we have designed and synthesized a series of tetradentate derivatives of kojic acid, and examined their binding properties toward Fe(3+) and Al(3+). In this paper, for a characterization of the behavior of the proposed iron chelating agents in biological fluids, their complex formation equilibria with copper(II) and zinc(II) ions have been fully characterized together with a speciation study, showing the degree at which the iron chelators interfere with the homeostatic equilibria of these two essential metal ions.

A Speciation Study on the Perturbing Effects of Iron Chelators on the Homeostasis of Essential Metal Ions

A number of reports have appeared in literature calling attention to the depletion of essential metal ions during chelation therapy on β-thalassaemia patients. We present a speciation study to determine how the iron chelators used in therapy interfere with the homeostatic equilibria of essential metal ions. This work includes a thorough analysis of the pharmacokinetic properties of the chelating agents currently in clinical use, of the amounts of iron, copper and zinc available in plasma for chelation, and of all the implied complex formation constants. The results of the study show that a significant amount of essential metal ions is complexed whenever the chelating agent concentration exceeds the amount necessary to coordinate all disposable iron--a frequently occurring situation during chelation therapy. On the contrary, copper and zinc do not interfere with iron chelation, except for a possible influence of copper on iron speciation during deferiprone treatment.

Role of vitamin C as an adjuvant therapy to different iron chelators in young β-thalassemia major patients: efficacy and safety in relation to tissue iron overload

BACKGROUND

Vitamin C, as antioxidant, increases the efficacy of deferoxamine (DFO).

AIM

To investigate the effects of vitamin C as an adjuvant therapy to the three used iron chelators in moderately iron-overloaded young vitamin C-deficient patients with β-thalassemia major (β-TM) in relation to tissue iron overload.

METHODS

This randomized prospective trial that included 180 β-TM vitamin C-deficient patients were equally divided into three groups (n = 60) and received DFO, deferiprone (DFP), and deferasirox (DFX). Patients in each group were further randomized either to receive vitamin C supplementation (100 mg daily) or not (n = 30). All patients received vitamin C (group A) or no vitamin C (group B) were followed up for 1 yr with assessment of transfusion index, hemoglobin, iron profile, liver iron concentration (LIC) and cardiac magnetic resonance imaging (MRI) T2*.

RESULTS

Baseline vitamin C was negatively correlated with transfusion index, serum ferritin (SF), and LIC. After vitamin C therapy, transfusion index, serum iron, SF, transferrin saturation (Tsat), and LIC were significantly decreased in group A patients, while hemoglobin and cardiac MRI T2* were elevated compared with baseline levels or those in group B without vitamin C. The same improvement was found among DFO-treated patients post-vitamin C compared with baseline data. DFO-treated patients had the highest hemoglobin with the lowest iron, SF, and Tsat compared with DFP or DFX subgroups.

CONCLUSIONS

Vitamin C as an adjuvant therapy possibly potentiates the efficacy of DFO more than DFP and DFX in reducing iron burden in the moderately iron-overloaded vitamin C-deficient patients with β-TM, with no adverse events.

The ongoing pursuit of neuroprotective therapies in Parkinson disease

Many agents developed for neuroprotective treatment of Parkinson disease (PD) have shown great promise in the laboratory, but none have translated to positive results in patients with PD. Potential neuroprotective drugs, such as ubiquinone, creatine and PYM50028, have failed to show any clinical benefits in recent high-profile clinical trials. This 'failure to translate' is likely to be related primarily to our incomplete understanding of the pathogenic mechanisms underlying PD, and excessive reliance on data from toxin-based animal models to judge which agents should be selected for clinical trials. Restricted resources inevitably mean that difficult compromises must be made in terms of trial design, and reliable estimation of efficacy is further hampered by the absence of validated biomarkers of disease progression. Drug development in PD dementia has been mostly unsuccessful; however, emerging biochemical, genetic and pathological evidence suggests a link between tau and amyloid-β deposition and cognitive decline in PD, potentially opening up new possibilities for therapeutic intervention. This Review discusses the most important 'druggable' disease mechanisms in PD, as well as the most-promising drugs that are being evaluated for their potential efficiency in treatment of motor and cognitive impairments in PD.

Association of antitumor antibiotic Mithramycin with Mn2+ and the potential cellular targets of Mithramycin after association with Mn2+

Mithramycin (MTR), an aureolic acid group of antitumor antibiotic is used for the treatment of several types of tumors. We have reported here the association of MTR with an essential micronutrient, manganese (Mn(2+)). Spectroscopic methods have been used to characterize and understand the kinetics and mechanism of complex formation between them. MTR forms a single type of complex with Mn(2+) in the mole ratio of 2:1 [MTR: Mn(2+)] via a two step kinetic process. Circular dichroism (CD) spectroscopic study indicates that the complex [(MTR)2 Mn(2+)] has a right-handed twist conformation similar in structure with the complexes reported for Mg(2+) and Zn(2+). This conformation allows binding via minor groove of DNA with (G, C) base preference during the interaction with double-stranded B-DNA. Using absorbance, fluorescence, and CD spectroscopy we have shown that [(MTR)2 Mn(2+)] complex binds to double-stranded DNA with an apparent dissociation constant of 32 μM and binding site size of 0.2 (drug/nucleotide). It binds to chicken liver chromatin with apparent dissociation constant value 298 μM. Presence of histone proteins in chromatin inhibits the accessibility of the complex for chromosomal DNA. We have also shown that MTR binds to Mn(2+) containing metalloenzyme manganese superoxide dismutase from Escherichia coli.

Iron chelation and multiple sclerosis

Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6-8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood-brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.

Combined therapy of iron chelator and antioxidant completely restores brain dysfunction induced by iron toxicity

Background

Excessive iron accumulation leads to iron toxicity in the brain; however the underlying mechanism is unclear. We investigated the effects of iron overload induced by high iron-diet consumption on brain mitochondrial function, brain synaptic plasticity and learning and memory. Iron chelator (deferiprone) and antioxidant (n-acetyl cysteine) effects on iron-overload brains were also studied.

Methodology

Male Wistar rats were fed either normal diet or high iron-diet consumption for 12 weeks, after which rats in each diet group were treated with vehicle or deferiprone (50 mg/kg) or n-acetyl cysteine (100 mg/kg) or both for another 4 weeks. High iron-diet consumption caused brain iron accumulation, brain mitochondrial dysfunction, impaired brain synaptic plasticity and cognition, blood-brain-barrier breakdown, and brain apoptosis. Although both iron chelator and antioxidant attenuated these deleterious effects, combined therapy provided more robust results.

Conclusion

In conclusion, this is the first study demonstrating that combined iron chelator and anti-oxidant therapy completely restored brain function impaired by iron overload.

Acquired aplastic anemia in children

This article provides a practice-based and concise review of the etiology, diagnosis, and management of acquired aplastic anemia in children. Bone marrow transplantation, immunosuppressive therapy, and supportive care are discussed in detail. The aim is to provide the clinician with a better understanding of the disease and to offer guidelines for the management of children with this uncommon yet serious disorder.