Iron chelation: an update

Adherence to Iron Chelation Therapy Among Children with Beta Thalassemia Major: A Multicenter Cross-Sectional Study

BACKGROUND

Adherence to iron chelation therapy (ICT) remains an issue among thalassemia patients. This study aimed to determine the prevalence of non-adherence to ICT among children with beta thalassemia major in Malaysia and the factors associated with it.

METHODS

This was a cross-sectional study conducted between November 2019 and November 2021 at seven tertiary hospitals in Malaysia. Participants registered with Malaysian Thalassemia Registry were recruited by convenience sampling. Adherence was measured via pill count and self-reported adherence. Knowledge about thalassemia and ICT was measured using a questionnaire from Modul Thalassemia by Ministry of Health of Malaysia. A decision tree was used to identify predictors of non-adherence.

RESULTS

A total of 135 patients were recruited. The prevalence of non-adherence to ICT in those who took subcutaneous ± oral medications was 47.5% (95% CI: 31.5%, 63.9%) and the prevalence of non-adherence to ICT in those who took oral medications only was 21.1% (95% CI: 13.4%, 30.6%). The median knowledge score was 67.5% (IQR 15%). A decision tree has identified two factors associated with non-adherence. They were ICT's route of administration and knowledge score. Out of 100 patients who were on oral medications only, 79 were expected to adhere. Out of 100 patients who were on subcutaneous ± oral medications and scored less than 56.25% in knowledge questionnaire, 86 were expected to non-adhere. Based on the logistic regression, the odds of non-adherence in patients who took oral medications only was 71% lower than the odds of non-adherence in patients who took subcutaneous ± oral medications (OR = 0.29; 95% CI = 0.13, 0.65; p = .002).

CONCLUSION

The prevalence of non-adherence to ICT among children with beta thalassemia major in Malaysia was 20/95 (21.1%) in those who took oral medications only and the prevalence of non-adherence was 19/40 (47.5%) in those who took subcutaneous ± oral medications. The factors associated with non-adherence were ICT's route of administration and knowledge score.

Genetic Engineering of Talaromyces marneffei to Enhance Siderophore Production and Preliminary Testing for Medical Application Potential

Siderophores are compounds with low molecular weight with a high affinity and specificity for ferric iron, which is produced by bacteria and fungi. Fungal siderophores have been characterized and their feasibility for clinical applications has been investigated. Fungi may be limited in slow growth and low siderophore production; however, they have advantages of high diversity and affinity. Hence, the purpose of this study was to generate a genetically modified strain in Talaromyces marneffei that enhanced siderophore production and to identify the characteristics of siderophore to guide its medical application. SreA is a transcription factor that negatively controls iron acquisition mechanisms. Therefore, we deleted the sreA gene to enhance the siderophore production and found that the null mutant of sreA (ΔsreA) produced a high amount of extracellular siderophores. The produced siderophore was characterized using HPLC-MS, HPLC-DAD, FTIR, and 1H- and 13C-NMR techniques and identified as a coprogen B. The compound showed a powerful iron-binding activity and could reduce labile iron pool levels in iron-loaded hepatocellular carcinoma (Huh7) cells. In addition, the coprogen B showed no toxicity to the Huh7 cells, demonstrating its potential to serve as an ideal iron chelator. Moreover, it inhibits the growth of Candida albicans and Escherichia coli in a dose-dependent manner. Thus, we have generated the siderophore-enhancing strain of T. marneffei, and the coprogen B isolated from this strain could be useful in the development of a new iron-chelating agent or other medical applications.

Melatonin: Potential avenue for treating iron overload disorders

Iron overload as a highly risk factor, can be found in almost all human chronic and common diseases. Iron chelators are often used to treat iron overload; however, patient adherence to these chelators is poor due to obvious side effects and other disadvantages. Numerous studies have shown that melatonin has a high iron chelation ability and direct free radical scavenging activity, and can inhibit the lipid peroxidation process caused by iron overload. Therefore, melatonin may become potential complementary therapy for iron overload-related disorders due to its iron chelating and antioxidant activities. Here, the research progress of iron overload is reviewed and the therapeutic potential of melatonin in the treatment of iron overload is analyzed. In addition, studies related to the protective effects of melatonin on oxidative damage induced by iron overload are discussed. This review provides a foundation for preventing and treating iron homeostasis disorders with melatonin.

New Deferric Amine Compounds Efficiently Chelate Excess Iron to Treat Iron Overload Disorders and to Prevent Ferroptosis

Excess iron accumulation occurs in organs of patients with certain genetic disorders or after repeated transfusions. No physiological mechanism is available to excrete excess iron and iron overload to promote lipid peroxidation to induce ferroptosis, thus iron chelation becomes critical for preventing ion toxicity in these patients. To date, several iron chelators have been approved for iron chelation therapy, such as deferiprone and deferoxamine, but the current iron chelators suffer from significant limitations. In this context, new agents are continuously sought. Here, a library of new deferric amine compounds (DFAs) with adjustable skeleton and flexibility is synthesized by adopting the beneficial properties of conventional chelators. After careful evaluations, compound DFA1 is found to have greater efficacy in binding iron through two molecular oxygens in the phenolic hydroxyl group and the nitrogen atom in the amine with a 2:1 stoichiometry. This compound remarkably ameliorates iron overload in diverse murine models through both oral and intravenous administration, including hemochromatosis, high iron diet-induced, and iron dextran-stimulated iron accumulation. Strikingly, this compound is found to suppress iron-induced ferroptosis by modulating the intracellular signaling that drives lipid peroxidation. This study opens a new approach for the development of iron chelators to treat iron overload.

Comparative Efficacy and Safety Between Deferiprone and Deferasirox with Special Reference to Serum Ferritin Level and Cardiac Function in Bengali β-Thalassemia Major Children

Deferiprone (DFP) and deferasirox (DFX) are the most well-known, efficacious and safe chelators to reduce the serum ferritin (SF) level in multi transfused thalassemic children, although there are few reports available for assessing the efficacy between DFP and DFX. We compared the efficacy of DFP vs. DFX as iron chelating drugs in β-thalassemia major (β-TM) patients. Pediatric patients diagnosed to carry β-TM, aged between 2 and 10 years, were recruited. A suitable data collection form and questionnaire were used. Paired and unpaired t-tests were used to compare the safety and efficacy of the chelating drugs DFP and DFX. The mean SF level at the 12th month was found to be 3016.73 ± 670.04 ng/mL (p = 0.002) in the DFX-treated group, which was quite significant in contrast to DFP response, where the value was 3204.06 ± 690.15 ng/mL (p = 0.14). There is no statistically significant (p = 0.15) difference on relative changes of the left ventricular ejection fraction (LVEF), between these two groups. The adverse effects were transient and none of them required stoppage of therapy. Deferasirox is more effective when compared to DFP in reducing chelating drug-related complications and iron overload specially in multiple transfusion dependent β-TM patients.

Thalassemias: From gene to therapy

Thalassemias (α, β, γ, δ, δβ, and εγδβ) are the most common genetic disorders worldwide and constitute a heterogeneous group of hereditary diseases characterized by the deficient synthesis of one or more hemoglobin (Hb) chain(s). This leads to the accumulation of unstable non-thalassemic Hb chains, which precipitate and cause intramedullary destruction of erythroid precursors and premature lysis of red blood cells (RBC) in the peripheral blood. Non-thalassemic Hbs display high oxygen affinity and no cooperativity. Thalassemias result from many different genetic and molecular defects leading to either severe or clinically silent hematologic phenotypes. Thalassemias α and β are particularly diffused in the regions spanning from the Mediterranean basin through the Middle East, Indian subcontinent, Burma, Southeast Asia, Melanesia, and the Pacific Islands, whereas δβ-thalassemia is prevalent in some Mediterranean regions including Italy, Greece, and Turkey. Although in the world thalassemia and malaria areas overlap apparently, the RBC protection against malaria parasites is openly debated. Here, we provide an overview of the historical, geographic, genetic, structural, and molecular pathophysiological aspects of thalassemias. Moreover, attention has been paid to molecular and epigenetic pathways regulating globin gene expression and globin switching. Challenges of conventional standard treatments, including RBC transfusions and iron chelation therapy, splenectomy and hematopoietic stem cell transplantation from normal donors are reported. Finally, the progress made by rapidly evolving fields of gene therapy and gene editing strategies, already in pre-clinical and clinical evaluation, and future challenges as novel curative treatments for thalassemia are discussed.

Calcium chelator BAPTA‑AM protects against iron overload‑induced chondrocyte mitochondrial dysfunction and cartilage degeneration

Osteoarthritis (OA) is a common joint disease that is characterized by cartilage degradation. Iron deposition in the joints is common during the pathogenic progression of OA and recent studies have indicated that iron overload is an important contributor to OA progression. Calcium chelators have been reported to inhibit iron influx via modulating transferrin receptor protein 1 internalization, and they have been identified as a potential approach to the treatment of iron overload‑induced diseases. The aim of the present study was to investigate the effect of calcium chelators on the progression of iron overload‑induced OA. Primary chondrocytes were treated with various concentrations of ferric ammonium citrate (FAC) to mimic iron overload in vitro, followed by co‑treatment with the calcium chelator BAPTA acetoxymethyl ester (BAPTA‑AM). Subsequently, intracellular iron levels, cell viability, reactive oxygen species (ROS) levels, mitochondrial function and morphological changes, as well as MMP levels, were detected using commercial kits. It was demonstrated that FAC treatment significantly promoted chondrocyte apoptosis and the expression of MMPs, and these effects were reversed by co‑treatment with BAPTA‑AM. Moreover, BAPTA‑AM suppressed iron influx into chondrocytes and inhibited iron overload‑induced ROS production and mitochondrial dysfunction. These results indicated that calcium chelators may be of value in the treatment of iron metabolism‑related diseases and iron overload‑induced OA progression.

A diffusion cell adapted to nuclear imaging instruments for the measurement of molecular release and pharmacokinetics across membranes

Diffusion cells are routinely used in pharmacology to measure the permeation of pharmaceutical compounds and contaminants across membranes (biological or synthetic). They can also be used to study drug release from excipients. The device is made of a donor (DC) and an acceptor (AC) compartment, separated by a membrane. Usually, permeation of molecules across membranes is measured by sampling from the AC at different time points. However, this process disturbs the equilibrium of the cell. Furthermore, analytical techniques used in association with diffusion cells sometimes lack either accuracy, sensitivity, or both. This work reports on the development of nuclear imaging - compatible diffusion cells. The cell is made of a polymer transparent to high-energy photons typically detected in positron emission tomography (PET). It was tested in a finite-dose set-up experiment with a pre-clinical PET system. Porous cellulose membranes (3.5, 25 and 300 kDa), a common excipient in pharmacology, as well as for dialysis membranes, were used as test membranes. The radioisotope ⁸⁹Zr chelated with deferoxamine B (DFO; 0.65 kDa), was used as an imaging probe (7-10 MBq; 0.2-0.3 nMol ⁸⁹Zr-DFO). In medicine, DFO is also commonly used for iron removal treatments and pharmacological formulations often require the association of this molecule with cellulose. Permeation profiles were obtained by measuring the radioactivity in the DC and AC for up to 2 weeks. The kinetic profiles were used to extract lag time, influx, and diffusion coefficients of DFO across porous cellulose membranes. A sensitivity threshold of 0.005 MBq, or 3.4 fmol of ⁸⁹Zr-DFO, was revealed. The lag time to permeation (τ) measured in the AC compartment, was found to be 1.33, 0.5, and 0.19 h with 3.5, 25, and 300 kDa membranes, respectively. Diffusion coefficients of 3.65 × 10^-6, 8.33 × 10^-6, and 4.74 × 10^-5 cm² h^-1 where revealed, with maximal pseudo steady-state influx values (J_pss) of 6.55 × 10^-6, 1.76 × 10^-5, and 1.29 × 10^-5 nmol cm^-2 h^-1. This study confirms the potential of the technology for monitoring molecular diffusion and release processes at low concentrations, high sensitivities, in real time and in a visual manner.

Drug utilization study and cost analysis of adult β-thalassemia major patient therapy at Dr. Soetomo General Hospital Surabaya

OBJECTIVES

The main therapy of β-thalassemia major are blood transfusion and iron chelation drugs. However, those therapies also have some adverse effects and problems such as iron overload, transfusion reactions, nutritional deficiencies, and patient compliance problems. Those arising problems also have an impact on therapy cost. Hence, this study was designed to analyze drug utilization study and cost of therapy in β-thalassemia major adult patients at Dr. Soetomo General Hospital Surabaya.

METHODS

This research was conducted in descriptive observational-retrospective design using secondary data obtained from patient's medical records and billing registrations from January 1-December 31, 2019.

RESULTS

There were 18 patients out of 233 patients that were analyzed. Deferasirox was the most administered drug with doses between 500 mg/day-1,500 mg/day while deferiprone was ranged between 1,500 and 4,500 mg/day. Patients also received transfusion reaction drugs with dexamethasone injection 5 mg/ml which was administered the most. The most administered supplement was folic acid 1 mg. Patients had an increase in serum ferritin due to low compliance. Deferasirox had the most adherence number of patients with decrease of serum ferritin. The two highest costs of direct medical components were top-up medicines and consumable medical supplies. Overall, the hospital gained profit from national health insurance claims.

CONCLUSIONS

The most administered chelating agent was deferasirox. Deferasirox also had the most adherence number of patients with decreased number of serum ferritin. However, deferasirox also yielded the highest cost. Yet, overall, the hospital gained profit from national health insurance claims.

Deferoxamine B: A Natural, Excellent and Versatile Metal Chelator

Deferoxamine B is an outstanding molecule which has been widely studied in the past decade for its ability to bind iron and many other metal ions. The versatility of this metal chelator makes it suitable for a number of medicinal and analytical applications, from the well-known iron chelation therapy to the most recent use in sensor devices. The three bidentate hydroxamic functional groups of deferoxamine B are the centerpiece of its metal binding ability, which allows the formation of stable complexes with many transition, lanthanoid and actinoid metal ions. In addition to the ferric ion, in fact, more than 20 different metal complexes of deferoxamine b have been characterized in terms of their chemical speciation in solution. In addition, the availability of a terminal amino group, most often not involved in complexation, opens the way to deferoxamine B modification and functionalization. This review aims to collect and summarize the available data concerning the complex-formation equilibria in solutions of deferoxamine B with different metal ions. A general overview of the progress of its applications over the past decade is also discussed, including the treatment of iron overload-associated diseases, its clinical use against cancer and neurodegenerative disorders and its role as a diagnostic tool.

Iron chelation rescues hemolytic anemia and skin photosensitivity in congenital erythropoietic porphyria

Congenital erythropoietic porphyria (CEP) is an inborn error of heme synthesis resulting from uroporphyrinogen III synthase (UROS) deficiency and the accumulation of nonphysiological porphyrin isomer I metabolites. Clinical features are heterogeneous among patients with CEP but usually combine skin photosensitivity and chronic hemolytic anemia, the severity of which is related to porphyrin overload. Therapeutic options include symptomatic strategies only and are unsatisfactory. One promising approach to treating CEP is to reduce the erythroid production of porphyrins through substrate reduction therapy by inhibiting 5-aminolevulinate synthase 2 (ALAS2), the first and rate-limiting enzyme in the heme biosynthetic pathway. We efficiently reduced porphyrin accumulation after RNA interference-mediated downregulation of ALAS2 in human erythroid cellular models of CEP disease. Taking advantage of the physiological iron-dependent posttranscriptional regulation of ALAS2, we evaluated whether iron chelation with deferiprone could decrease ALAS2 expression and subsequent porphyrin production in vitro and in vivo in a CEP murine model. Treatment with deferiprone of UROS-deficient erythroid cell lines and peripheral blood CD34+-derived erythroid cultures from a patient with CEP inhibited iron-dependent protein ALAS2 and iron-responsive element-binding protein 2 expression and reduced porphyrin production. Furthermore, porphyrin accumulation progressively decreased in red blood cells and urine, and skin photosensitivity in CEP mice treated with deferiprone (1 or 3 mg/mL in drinking water) for 26 weeks was reversed. Hemolysis and iron overload improved upon iron chelation with full correction of anemia in CEP mice treated at the highest dose of deferiprone. Our findings highlight, in both mouse and human models, the therapeutic potential of iron restriction to modulate the phenotype in CEP.

Conjugates of desferrioxamine and aromatic amines improve markers of iron-dependent neurotoxicity

Alzheimer's Disease (AD) is a complex neurodegenerative disorder associated in some instances with dyshomeostasis of redox-active metal ions, such as copper and iron. In this work, we investigated whether the conjugation of various aromatic amines would improve the pharmacological efficacy of the iron chelator desferrioxamine (DFO). Conjugates of DFO with aniline (DFOANI), benzosulfanylamide (DFOBAN), 2-naphthalenamine (DFONAF) and 6-quinolinamine (DFOQUN) were obtained and their properties examined. DFOQUN had good chelating activity, promoted a significant increase in the inhibition of β-amyloid peptide aggregation when compared to DFO, and also inhibited acetylcholinesterase (AChE) activity both in vitro and in vivo (Caenorhabditis elegans). These data indicate that the covalent conjugation of a strong iron chelator to an AChE inhibitor offers a powerful approach for the amelioration of iron-induced neurotoxicity symptoms.

Inherited iron overload disorders

Hereditary iron overload includes several disorders characterized by iron accumulation in tissues, organs, or even single cells or subcellular compartments. They are determined by mutations in genes directly involved in hepcidin regulation, cellular iron uptake, management and export, iron transport and storage. Systemic forms are characterized by increased serum ferritin with or without high transferrin saturation, and with or without functional iron deficient anemia. Hemochromatosis includes five different genetic forms all characterized by high transferrin saturation and serum ferritin, but with different penetrance and expression. Mutations in HFE, HFE2, HAMP and TFR2 lead to inadequate or severely reduced hepcidin synthesis that, in turn, induces increased intestinal iron absorption and macrophage iron release leading to tissue iron overload. The severity of hepcidin down-regulation defines the severity of iron overload and clinical complications. Hemochromatosis type 4 is caused by dominant gain-of-function mutations of ferroportin preventing hepcidin-ferroportin binding and leading to hepcidin resistance. Ferroportin disease is due to loss-of-function mutation of SLC40A1 that impairs the iron export efficiency of ferroportin, causes iron retention in reticuloendothelial cell and hyperferritinemia with normal transferrin saturation. Aceruloplasminemia is caused by defective iron release from storage and lead to mild microcytic anemia, low serum iron, and iron retention in several organs including the brain, causing severe neurological manifestations. Atransferrinemia and DMT1 deficiency are characterized by iron deficient erythropoiesis, severe microcytic anemia with high transferrin saturation and parenchymal iron overload due to secondary hepcidin suppression. Diagnosis of the different forms of hereditary iron overload disorders involves a sequential strategy that combines clinical, imaging, biochemical, and genetic data. Management of iron overload relies on two main therapies: blood removal and iron chelators. Specific therapeutic options are indicated in patients with atransferrinemia, DMT1 deficiency and aceruloplasminemia.

Treatment of iron overload syndrome: a general review

SUMMARY INTRODUCTION Iron overload is a broad syndrome with a large spectrum of causative etiologies that lead to iron deposition. When iron exceeds defenses, it causes oxidative damage and tissular disfunction. Treatment may prevent organ dysfunction, leading to greater life expectancy. METHODS Literature from the last five years was reviewed through the use of the PubMed database in search of treatment strategies. DISCUSSION Different pharmacological and non-pharmacological strategies are available for the treatment of iron overload and must be used according to etiology and patient compliance. Therapeutic phlebotomy is the basis for the treatment of hereditary hemochromatosis. Transfusional overload patients and those who cannot tolerate phlebotomy need iron chelators. CONCLUSION Advances in the understanding of iron overload have lead to great advances in therapies and new pharmacological targets. Research has lead to better compliance with the use of oral chelators and less toxic drugs.

Non-canonical translation initiation of the spliced mRNA encoding the human T-cell leukemia virus type 1 basic leucine zipper protein

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL). The HTLV-1 basic leucine zipper protein (HBZ) is expressed in all cases of ATL and is directly associated with virus pathogenicity. The two isoforms of the HBZ protein are synthesized from antisense messenger RNAs (mRNAs) that are either spliced (sHBZ) or unspliced (usHBZ) versions of the HBZ transcript. The sHBZ and usHBZ mRNAs have entirely different 5′untranslated regions (5′UTR) and are differentially expressed in cells, with the sHBZ protein being more abundant. Here, we show that differential expression of the HBZ isoforms is regulated at the translational level. Translation initiation of the usHBZ mRNA relies on a cap-dependent mechanism, while the sHBZ mRNA uses internal initiation. Based on the structural data for the sHBZ 5′UTR generated by SHAPE in combination with 5′ and 3′ deletion mutants, the minimal region harboring IRES activity was mapped to the 5′end of the sHBZ mRNA. In addition, the sHBZ IRES recruited the 40S ribosomal subunit upstream of the initiation codon, and IRES activity was found to be dependent on the ribosomal protein eS25 and eIF5A.

Design of Safe Nanotherapeutics for the Excretion of Excess Systemic Toxic Iron

Chronic transfusion of red blood cells (RBCs) to patients with β-thalassemia, sickle cell disease, and other acquired anemic disorders generates significant amounts of bioactive iron deposits in the body. The inactivation and excretion of redox active iron(III) from the blood pool and organs are critical to prevent organ damage, and are the focus of iron chelation therapy (ICT) using low molecular weight Fe(III) specific chelators. However, the current ICT is suboptimal because of the short circulation time of chelators, toxicity, severe side effects, difficult regime of administration, and patient noncompliance. To address this issue, we have designed long circulating and biodegradable nanoconjugates with enhanced circulation time and well-defined biodegradability to improve iron excretion and avoid nonspecific organ accumulation. A series of iron chelating nanoconjugates were generated with deferoxamine (DFO) as the iron(III) specific chelator using polymer scaffolds containing structurally different acidic pH sensitive ketal groups. The type of degradation linkages used in the polymer scaffold significantly influenced the vascular residence time, biodistribution, and mode of excretion of chelators in mice. Remarkably, the conjugate, BGD-60 (140 kDa; R h, 10.6 nm; cyclic ketal), exhibited the long circulation half-life (t 1/2β, 64 h), a 768-fold increase compared to DFO, and showed minimal polymer accumulation in major organs. The nanoconjugates were found to be nontoxic and excreted iron significantly better than DFO in iron overloaded mice. BGD-60 showed greater iron mobilization from plasma (p = 0.0390), spleen (p < 0.0001), and pancreas (p < 0.0001) whereas BDD-200 (340 kDa; R h, 13.7 nm; linear ketal) mobilized iron significantly better from the spleen, liver, and pancreas (p < 0.0001, p < 0.0001, and p < 0.0001, respectively) compared to DFO at equivalent doses. The nanoconjugate's favorable long blood circulation time, biodegradability, and iron excretion profiles highlight their potential for future clinical translation.

A 1-year randomized trial of deferasirox alone versus deferasirox and deferoxamine combination for the treatment of iron overload in thalassemia major

AIM

Iron chelators are extensively used to reduce iron overload. Our purpose was to compare effects of deferasirox versus deferasirox and deferoxamine in patients with thalassemia major.

METHODS

This randomized and double blind trial was performed on 62 patients. Patients were assigned 1:1 to oral 30 mg/kg deferasirox daily or oral 30 mg/kg deferasirox daily plus SC 50 mg/kg deferoxamine for 5 days a week. Treatment continued for 12 months in both groups.

RESULTS

Fifty-five patients completed the 1 year of treatment. Mean age was 24.5 years with an excess of females. Combined therapy caused a significant increase in myocardial T2* from 23.1 ± 7.5 ms at baseline to 27.1 ± 7.0 ms at 12 months (P < 0.05). This difference was statistically significant between 2 groups at 12 months (P = 0.01). Combined therapy and monotherapy had no significant effect on liver T2*. At 12 months, serum ferritin levels were reduced in two groups; however, the difference was significant (737 ± 459 μg/ml vs 1085 ± 919 μg/ml, P < 0.01).

CONCLUSION

Our study indicates that combined treatment with deferasirox and deferoxmaine is more effective than deferasirox for reduction of iron over load in patients with thalassemia major.

Scaffold Based Search on the Desferithiocin Archetype

Iron overload disorder and diseases where iron mismanagement plays a crucial role require orally available iron chelators with favourable pharmacokinetic and toxicity profile. Desferrithiocin (DFT), a tridentate and orally available iron chelator has a favourable pharmacokinetic profile but its use has been clinically restricted due to its nephrotoxic potential. The chemical architecture of the DFT has been naturally well optimized for better iron chelation and iron clearance from human biological system. Equally they are also responsible for its toxicity. Hence, subsequent research has been devoted to develop a non-nephrotoxic analogue of DFT without losing its iron clearance ability. The review has been designed to classify the compounds reported till date and to discuss the structure activity relationship with reference to modifications attempted at different positions over pyridine and thiazoline ring of DFT. Compounds are clustered under two major classes: (i) Pyridine analogues and (ii) phenyl analogue and further each class has been further subdivided based on the presence or absence and the number of hydroxy functional groups present over pyridine or phenyl ring of the DFT analogues. Finally a summary and few insights into the development of newer analogues are provided.

Cell Permeable Imidazole-Desferrioxamine Conjugates: Synthesis and In Vitro Evaluation

Desferrioxamine (DFO), a clinically approved iron chelator used for iron overload, is unable to chelate labile plasma iron (LPI) because of its limited cell permeability. Herein, alkyl chain modified imidazolium cations with varied hydrophobicities have been conjugated with DFO. The iron binding abilities and the antioxidant properties of the conjugates were found to be similar to DFO. The degree of cellular internalization was much higher in the octyl-imidazolium-DFO conjugate (IV) compared with DFO, and IV was able to chelate LPI in vitro. This opens up a new avenue in using N-alkyl imidazolium salts as a delivery vector for hydrophilic cell-impermeable drugs.

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.

Polymeric Nanoparticles Enhance the Ability of Deferoxamine To Deplete Hepatic and Systemic Iron

Chelators are commonly used to remove excess iron in iron-loading disorders. Deferoxamine (DFO) is an effective and safe iron chelator but an onerous parenteral administration regimen limits its routine use. To develop more effective methods for delivering iron chelators, we examined whether amphiphilic copolymer nanoparticles (NPs) could deliver DFO more efficiently. Physical characterization showed a uniform and stable preparation of DFO nanoparticles (DFO-NPs) with an average diameter of 105.3 nm. In macrophage (RAW264.7) and hepatoma (HepG2) cell lines, DFO-NPs proved more effective at depleting iron than free DFO. In wild-type mice previously loaded with iron dextran, as well as Hbb ^{th3 /+} and Hfe ^-/- mice, which are predisposed to iron loading, DFO-NPs (40 mg/kg DFO; alternate days; 4 weeks) reduced hepatic iron levels by 71, 46, and 37%, respectively, whereas the equivalent values for free DFO were 53, 7, and 15%. Staining for tissue iron and urinary iron excretion confirmed these findings. Pharmacokinetic analysis showed that NP-encapsulated DFO had a much longer elimination half-life than free DFO (48.63 ± 28.80 vs 1.46 ± 0.59 h), and that DFO-NPs could be readily taken up by tissues and in particular by hepatic Kupffer cells. In vitro, DFO-NPs were less toxic to several cell lines than free DFO, and in vivo they did not elicit any specific inflammatory responses or histological changes. Our results suggest that using a nanoformulation of DFO is a valuable strategy for improving its efficiency as an iron chelator and that this could broaden its clinical use for the treatment of human iron overload disorders.

Growth Inhibition of a Novel Iron Chelator, DpdtC, against Hepatoma Carcinoma Cell Lines Partly Attributed to Ferritinophagy-Mediated Lysosomal ROS Generation

Some iron chelators display significant anticancer activity that may involve ferritin degradation either in proteasomes or in lysosomes, and the latter might involve ferritinophagy with a period. However, the correlation of ferritinophagy with anticancer activity of iron chelator was not fully determined. Revealing the underlying link therefore is required. Di-2-pyridylketone dithiocarbamate (DpdtC), a novel iron chelator, could mobilize iron from ferritin and displayed excellent antitumor against hepatoma carcinoma cell lines (IC_50s = 0.4 ± 0.2 for HepG2 and 3.5 ± 0.3 μM for Bel-7402, resp.); we speculated that the antiproliferative action of DpdtC might involve ferritinophagy. To this end, the alterations of ferritin, microtubule-associated protein light chain 3 (LC3-II), and nuclear receptor coactivator 4 (NCOA4) were investigated after exposure of DpdtC to the cells. The results revealed that DpdtC could cause increases of autophagic vacuoles and LC3-II. The data from cellular immunofluorescence and Western blotting showed a reciprocal relation between abundances of ferritin and LC3-II, but the trends of NCOA4 and LC3-II in abundance were in a similar manner, indicating that a ferritinophagy occurred. Further studies revealed that the ferritinophagy evoked an iron-driven intralysosomal oxidative reaction, resulting in LMP change and lipid peroxidation. Thus, a ferritinophagy-mediated lysosomal ROS generation playing a role in the antiproliferative action of DpdtC could be proposed, which will enrich our knowledge of iron chelator in cancer therapy.

Collagen Prolyl 4-Hydroxylase as a Therapeutic Target

Collagen is the dominant protein of the extracellular matrix. Its distinguishing feature is a three-stranded helix of great tensile strength. (2 S,4 R)-4-Hydroxyproline residues are essential for the stability of this triple helix. These residues arise from the post-translational modification of (2 S)-proline residues by collagen prolyl 4-hydroxylases (CP4Hs), which are members of the Fe(II)- and α-ketoglutarate (AKG)-dependent dioxygenase family. Here, we provide a framework for the inhibition of CP4Hs as the basis for treating fibrotic diseases and cancer metastasis. We begin with a summary of the structure and enzymatic reaction mechanism of CP4Hs. Then, we review the metal ions, metal chelators, mimetics of AKG and collagen strands, and natural products that are known to inhibit CP4Hs. Our focus is on inhibitors with potential utility in the clinic. We conclude with a prospectus for more effective inhibitors.

Preparation of 5-Functionalised Pyridine Derivatives using a Br/Mg Exchange Reaction: Application to the Synthesis of an Iron-Chelator Prodrug

A novel preparation of 5-functionalised pyridine derivatives is reported from 5-bromo-4-tosyloxypyridines via a Br/Mg exchange procedure with i-PrMgCl·LiCl, followed by addition of an electrophile. The reaction was carried out under mild conditions and gave good to high yields. The resulting 5-functionalised pyridine derivatives enrich the library of pyridinone-type iron-chelator prodrugs.

Clarifying busulfan metabolism and drug interactions to support new therapeutic drug monitoring strategies: a comprehensive review

INTRODUCTION

Busulfan (Bu) is an alkylating agent with a limited therapeutic margin and exhibits inter-patient variability in pharmacokinetics (PK). Despite decades of use, mechanisms of Bu PK-based drug-drug interactions (DDIs), as well as the negative downstream effects of these DDIs, have not been fully characterized. Areas covered: This article provides an overview of Bu PK, with a primary focus on how known and potentially unknown drug metabolism pathways influence Bu-associated DDIs. In addition, pharmacogenomics of Bu chemotherapy and Bu-related DDIs observed in the stem cell transplant clinic (SCT) are summarized. Finally the increasing importance of Bu therapeutic drug monitoring is highlighted. Expert opinion: Mechanistic studies of Bu metabolism have shown that in addition to GST isoenzymes, other oxidative enzymes (CYP, FMO) and ABC/MDR drug transporters likely contribute to the overall clearance of Bu. Despite many insights, results from clinical studies, especially in polypharmacy settings and between pediatric and adult patients, remain conflicting. Further basic science and clinical investigative efforts are required to fully understand the key factors determining Bu PK characteristics and its effects on complications after SCT. Improved TDM strategies are promising components to further investigate, for instance DDI mechanisms and patient outcomes, in the highly complex SCT treatment setting.

Neurocognitive dysfunction in children with β thalassemia major: psychometric, neurophysiologic and radiologic evaluation

OBJECTIVE

To evaluate the impact of iron chelating drugs and serum ferritin on the neurocognitive functions of patients with β thalassemia major (β-TM), using psychometric, neurophysiologic and radiologic tests.

METHODS

Eighty children with β-TM were enrolled into the study and were compared to 40 healthy controls. All participants were evaluated by measuring serum ferritin, neurocognitive assessment by Benton Visual Retention Test, Wechsler Intelligence Scale for Children, Wisconsin Card Sort Test, P300 and magnetic resonance spectroscopy (MRS).

RESULTS

WISC in our study showed that 40% of cases were borderline mental function as regards total IQ. Neurophysiologic tests were significantly impaired in patients compared to control group, with significant impairment in those receiving desferrioxamine (DFO). P300 amplitude was significantly lower in cases compared to controls (2.24 and 4.66 uv, respectively), recording the shortest amplitude in patients receiving DFO. Altered metabolic markers in the brain were detected by MRS in the form of reduced N-acetylaspartate to creatine ratio in 78.3% of our cases. There were significant correlations between psychometric tests and both neurophysiologic (P300) and radiologic (MRS) tests.

CONCLUSION

β-TM is associated with neurocognitive impairment that can be assessed by psychometric, neurophysiologic and radiologic tests. The role of hemosiderosis and iron chelation therapy on cognitive functioning still need more research.

ABBREVIATIONS

β-TM: beta thalassemia major; DFO: Dysferal; DFP: Deferiprone; DFX: Deferasirox; WISC: Wechsler Intelligence Scale for Children; VIQ: verbal IQ; PIQ: performance IQ; TIQ: total IQ; BVRT: Benton Visual Retention Test; WCST: Wisconsin Card Sort Test; MRS: Magnetic resonant spectroscopy; NAA/Cr ratio: N-acetylaspartate to creatine ratio.

Advances in iron chelation therapy: transitioning to a new oral formulation

Iron overload is a concern for patients who require repeated red-blood-cell transfusions due to conditions such as sickle cell disease, thalassemia, or myelodysplastic syndromes. The recommended treatment for removing excess iron in these patients is iron chelation therapy. Currently available iron chelators include deferoxamine, which is administered by injection, and deferasirox and deferiprone, both of which are administered orally. Adherence to iron chelator therapy is an important consideration and may be affected by side effects. A new formulation of deferasirox, a film-coated tablet (FCT), has the potential to improve adherence by offering greater flexibility in administration compared with the original formulation of deferasirox, a dispersible tablet (DT) for oral suspension. This review provides an overview of the currently available iron chelator formulations, with a focus on a comparison between deferasirox DT for oral suspension and deferasirox FCT. The new formulation may be associated with fewer side effects and has increased bioavailability. In addition, alternative strategies for iron chelation, such as combining two different iron chelators, will be discussed.

Optimizing the diagnosis and the treatment of iron overload diseases

A number of human disorders are related to chronic iron overload, either of genetic or acquired origin. The multi-organ damage produced by iron excess leads, in adults and in children, to severe clinical consequences, affecting both quality of life and life expectancy. The diagnosis is increasingly based on a non-invasive strategy, resorting to clinical, biological and imaging data. The treatment rests on either venesection or chelation therapy, depending on the etiology. Major advances in the fields of molecular biology, pharmacology, and biotechnology pave the road for key improvements in the diagnostic and therapeutic management of the patients.

Discovering Novel and Diverse Iron-Chelators in Silico

Specific iron chelation is a validated strategy in anticancer drug discovery. However, only a few chemical classes (4-5 categories) have been reported to date. We discovered in silico five new structurally diverse iron-chelators by screening through models based on previously known chelators. To encompass a larger chemical space and propose newer scaffolds, we used our iterative stochastic elimination (ISE) algorithm for model building and subsequent virtual screening (VS). The ISE models were developed by training a data set of 130 reported iron-chelators. The developed models are statistically significant with area under the receiver operating curve greater than 0.9. The models were used to screen the Enamine chemical database of ∼1.8 million molecules. The top ranked 650 molecules were reduced to 50 diverse structures, and a few others were eliminated due to the presence of reactive groups. Finally, 34 molecules were purchased and tested in vitro. Five compounds were identified with significant iron-chelation activity in Cal-G assay. Intracellular iron-chelation study revealed one compound as equivalent in potency to the iron chelating "gold standards" deferoxamine and deferiprone. The amount of discovered positives (5 out of 34) is expected by the realistic enrichment factor of the model.

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.

Targeting deoxyhypusine hydroxylase activity impairs cap-independent translation initiation driven by the 5'untranslated region of the HIV-1, HTLV-1, and MMTV mRNAs

Replication of the human immunodeficiency virus type 1 (HIV-1) is dependent on eIF5A hypusination. Hypusine is formed post-translationally on the eIF5A precursor by two consecutive enzymatic steps; a reversible reaction involving the enzyme deoxyhypusine synthase (DHS) and an irreversible step involving the enzyme deoxyhypusine hydroxylase (DOHH). In this study we explored the effect of inhibiting DOHH activity and therefore eIF5A hypusination, on HIV-1 gene expression. Results show that the expression of proteins from an HIV-1 molecular clone is reduced when DOHH activity is inhibited by Deferiprone (DFP) or Ciclopirox (CPX). Next we evaluated the requirement of DOHH activity for internal ribosome entry site (IRES)-mediated translation initiation driven by the 5'untranslated region (5'UTR) of the full length HIV-1 mRNA. Results show that HIV-1 IRES activity relies on DOHH protein concentration and enzymatic activity. Similar results were obtained for IRES-dependent translation initiation mediated by 5'UTR of the human T-cell lymphotropic virus type 1 (HTLV-1) and the mouse mammary tumor virus (MMTV) mRNAs. Interestingly, activity of the poliovirus IRES, was less sensitive to the targeting of DOHH suggesting that not all viral IRESs are equally dependent on the cellular concentration or the activity of DOHH. In summary we present evidence indicating that the cellular concentration of DOHH and its enzymatic activity play a role in HIV-1, HTLV-1 and MMTV IRES-mediated translation initiation.

Deferasirox pharmacokinetic and toxicity correlation in β-thalassaemia major treatment

OBJECTIVES

Deferasirox adverse effects include the following: gastrointestinal disturbance, mild elevations in serum creatinine levels and intermittent proteinuria; these events are dose-dependent and reversible with drug discontinuation, but this solution can lead to an inadequate iron chelation. For these reasons, interindividual variability of drug plasma concentration could help the clinical management of deferasirox dosage. We sought to describe deferasirox plasma exposure in a cohort of 60 adult patients.

METHODS

A fully validated chromatographic method was used to quantify deferasirox concentration in plasma collected from β-thalassaemia adult patients. Samples obtained before and after 2, 4, 6 and 24 h drug administration were evaluated. Associations between variables were tested using the Pearson test.

KEY FINDINGS

Concerning pharmacokinetic parameters, a higher interindividual variability was shown. A positive correlation was found between deferasirox area under the concentration curve over 24 h and serum creatinine (r = 0.314; P = 0.018) and between area and drug dose (r = 0.311; P = 0.016). Moreover, a negative correlation resulted among area under the concentration curve over 24 h and serum ferritin (r = -0.291; P = 0.026) and among drug half-life and its dose (r = -0.319; P = 0.013).

CONCLUSIONS

Treatment decision based on the individual characteristics could strongly contribute to minimize toxicity and increase efficacy of deferasirox therapy.

Iron homeostasis: transport, metabolism, and regulation

PURPOSE OF REVIEW

Iron is essential for normal cellular function and many diseases result from disturbances in iron homeostasis. This review describes some of the recent key advances in iron transport and its regulation, how this relates to iron-related disorders, and emerging therapies for these diseases.

RECENT FINDINGS

The iron-regulatory hormone hepcidin and its target, the iron exporter ferroportin (FPN), play central roles in iron homeostasis. Recent studies have expanded our understanding of how hepcidin is regulated in response to stimulated erythropoiesis and have added some new players to the complex network of factors that influences hepcidin expression. Novel structural insights into how FPN transports iron have been an important addition to the field, as has the recognition that some zinc transporters such as ZIP14 can transport iron. Investigations into cardiac iron homeostasis have revealed a key role for FPN, and transferrin receptor 1, which is essential for cellular iron uptake, has been shown to be critical for normal immune function.

SUMMARY

The increased understanding of mechanisms of iron homeostasis that has resulted from recent research has greatly improved our ability to diagnose and manage iron-related disorders, and has offered new therapies for this important class of human diseases.

Calcium channel blockers ameliorate iron overload-associated hepatic fibrosis by altering iron transport and stellate cell apoptosis

Liver fibrosis is the principal cause of morbidity and mortality in patients with iron overload. Calcium channel blockers (CCBs) can antagonize divalent cation entry into renal and myocardial cells and inhibit fibrogenic gene expression. We investigated the potential of CCBs to resolve iron overload-associated hepatic fibrosis. Kunming mice were assigned to nine groups (n=8 per group): control, iron overload, deferoxamine, high and low dose verapamil, high and low dose nimodipine, and high and low dose diltiazem. Iron deposition and hepatic fibrosis were measured in mouse livers. Expression levels of molecules associated with transmembrane iron transport were determined by molecular biology approaches. In vitro HSC-T6 cells were randomized into nine groups (the same groups as the mice). Changes in proliferation, apoptosis, and metalloproteinase expression in cells were detected to assess the anti-fibrotic effects of CCBs during iron overload conditions. We found that CCBs reduced hepatic iron content, intracellular iron deposition, the number of hepatic fibrotic areas, collagen expression levels, and hydroxyproline content. CCBs rescued abnormal expression of α1C protein in L-type voltage-dependent calcium channel (LVDCC) and down-regulated divalent metal transporter-1 (DMT-1) expression in mouse livers. In iron-overloaded HSC-T6 cells, CCBs reduced iron deposition, inhibited proliferation, induced apoptosis, and elevated expression of matrix metalloproteinase-13 (MMP-13) and tissue inhibitor of metalloproteinase-1 (TIMP-1). CCBs are potential therapeutic agents that can be used to address hepatic fibrosis during iron overload. They resolve hepatic fibrosis probably correlated with regulating transmembrane iron transport and inhibiting HSC growth.

Role of pharmacogenetics on deferasirox AUC and efficacy

AIM

We evaluated deferasirox pharmacokinetic according to SNPs in genes involved in its metabolism and elimination. Moreover, we defined a plasma area under the curve cut-off value predicting therapy response.

PATIENTS & METHODS

Allelic discrimination was performed by real-time PCR. Drug plasma concentrations were measured by a high performance liquid chromatography system coupled with an ultraviolet method.

RESULTS

Pharmacokinetic parameters were significantly influenced by UGT1A1 rs887829C>T, UGT1A3 rs1983023C>T and rs3806596A>G SNPs. Area under the curve cut-off values of 360 μg/ml/h for efficacy were here defined and 250 μg/ml/h for nonresponse was reported. UGT1A3 rs3806596GG and ABCG2 rs13120400CC genotypes were factors able to predict efficacy, whereas UGT1A3 rs3806596GG was a nonresponse predictor.

CONCLUSION

These data show how screening patient's genetic profile may help clinicians to optimize iron chelation therapy with deferasirox.

Thalassemia 2016: Modern medicine battles an ancient disease

Thalassemia was first clinically described nearly a century ago and treatment of this widespread genetic disease has greatly advanced during this period. DNA-based diagnosis elucidated the molecular basis of the disease and clarified the variable clinical picture. It also paved the way for modern methods of carrier identification and prevention via DNA-based prenatal diagnosis. Every aspect of supportive care, including safer blood supply, more regular transfusions, specific monitoring of iron overload, parenteral and oral chelation, and other therapies, has prolonged life and improved the quality of life of these patients. Significant advances have also been made in allogenic bone marrow transplantation, the only curative therapy. Recently, there has been a rejuvenated interest in studying thalassemia at the basic science level, leading to the discovery of previously unknown mechanisms leading to anemia and enabling the development of novel therapies. These will potentially improve the treatment of, and possibly cure the disease. Pathways involving activin receptors, heat shock proteins, JAK2 inhibitors and macrophage targeted therapy, among others, are being studied or are currently in clinical trials for treating thalassemia. Novel types of genetic therapies are in use or under investigation. In addition to the challenges of treating each individual patient, the longer survival of thalassemia patients has raised considerations regarding worldwide control of thalassemia, since prevention is not universally implemented. This review will trace a number of the original medical milestones of thalassemia diagnosis and treatment, as well as some of the most recent developments which may lead to innovative therapeutic modalities.

Recent advances in cancer treatment by iron chelators

The development of new therapeutic alternatives for cancers is a major public health priority. Among the more promising approaches, the iron depletion strategy based on metal chelation in the tumoral environment has been particularly studied in recent decades. After a short description of the importance of iron for cancer cell proliferation, we will review the different iron chelators developed as potential chemotherapeutics. Finally, the recent efforts to vectorize the chelating agents specifically in the microtumoral environment will be discussed in detail.

Quantification of severe liver iron overload using MRI offset echoes

Magnetic resonance imaging (MRI) has become the clinical standard to estimate liver iron overload. The most commonly used method is to measure the transversal relaxation time, T2*, from a multi gradient recalled echo sequence (MGRE). While this technique is reliable in low to moderate liver iron concentrations (LIC), it will be inaccurate when it is severe. We report a case with severe liver hemochromatosis and show the benefit of using an easily implemented MRI offset echo sequence to more accurately estimate LIC. After adjusting treatment, both Ferritin and LIC decreased. Using standard MGRE this reduction could not have been detected.

Speciation in Metal Toxicity and Metal-Based Therapeutics

Metallic elements, ions and compounds produce varying degrees of toxicity in organisms with which they come into contact. Metal speciation is critical to understanding these adverse effects; the adjectives "heavy" and "toxic" are not helpful in describing the biological properties of individual elements, but detailed chemical structures are. As a broad generalization, the metallic form of an element is inert, and the ionic salts are the species that show more significant bioavailability. Yet the salts and other chelates of a metal ion can give rise to quite different toxicities, as exemplified by a range of carcinogenic potential for various nickel species. Another important distinction comes when a metallic element is organified, increasing its lipophilicity and hence its ability to penetrate the blood brain barrier, as is seen, for example, with organic mercury and tin species. Some metallic elements, such as gold and platinum, are themselves useful therapeutic agents in some forms, while other species of the same element can be toxic, thus focusing attention on species interconversions in evaluating metal-based drugs. The therapeutic use of metal-chelating agents introduces new species of the target metal in vivo, and this can affect not only its desired detoxification, but also introduce a potential for further mechanisms of toxicity. Examples of therapeutic iron chelator species are discussed in this context, as well as the more recent aspects of development of chelation therapy for uranium exposure.

Influence of single-nucleotide polymorphisms on deferasirox C trough levels and effectiveness

Deferasirox (DFX) is the only once-daily oral chelator for iron overload and its pharmacokinetic has been related with response to therapy. Our aim was to evaluate DFX plasma concentrations according to single-nucleotide polymorphisms in genes involved in its metabolism (UGT1A1, UGT1A3, CYP1A1, CYP1A2 and CYP2D6) and elimination (MRP2 and BCRP1). Further aim was to define a plasma concentration cutoff value predicting an adequate response to therapy. Plasma concentrations were determined at the end of dosing interval (C trough) using an high-performance liquid chromatography-ultraviolet method. Allelic discrimination was performed by real-time PCR. C trough levels were influenced by UGT1A1C>T rs887829, CYP1A1C>A rs2606345, CYP1A2A>C rs762551, CYP1A2C>T rs2470890 and MRP2G>A rs2273697 polymorphisms. A DFX plasma efficacy cutoff value of 20,000 ng ml(-1) was identified; CYP1A1C>A rs2606345 AA and CYP1A2C>T rs2470890 TT genotypes may predict this value, suggesting a negative predictive role in therapy efficacy. Our data suggest the feasibility of a pharmacogenetic-based DFX dose personalization.

Noncontrast myocardial T1 mapping using cardiovascular magnetic resonance for iron overload

PURPOSE

To explore the use and reproducibility of magnetic resonance-derived myocardial T1 mapping in patients with iron overload.

MATERIALS AND METHODS

The research received ethics committee approval and all patients provided written informed consent. This was a prospective study of 88 patients and 67 healthy volunteers. Thirty-five patients underwent repeat scanning for reproducibility. T1 mapping used the shortened modified Look-Locker inversion recovery sequence (ShMOLLI) with a second, confirmatory MOLLI sequence in the reproducibility group. T2 * was performed using a commercially available sequence. The analysis of the T2 * interstudy reproducibility data was performed by two different research groups using two different methods.

RESULTS

Myocardial T1 was lower in patients than healthy volunteers (836 ± 138 msec vs. 968 ± 32 msec, P < 0.0001). Myocardial T1 correlated with T2 * (R = 0.79, P < 0.0001). No patient with low T2 * had normal T1 , but 32% (n = 28) of cases characterized by a normal T2 * had low myocardial T1 . Interstudy reproducibility of either T1 sequence was significantly better than T2 *, with the results suggesting that the use of T1 in clinical trials could decrease potential sample sizes by 7-fold.

CONCLUSION

Myocardial T1 mapping is an alternative method for cardiac iron quantification. T1 mapping shows the potential for improved detection of mild iron loading. The superior reproducibility of T1 has potential implications for clinical trial design and therapeutic monitoring.