Pharmacotherapy of iron overload in thalassaemic patients

A Comparison of ChatGPT and Multidisciplinary Team Meeting Treatment Recommendations in 10 Consecutive Cervical Cancer Patients

Background The preparation of multidisciplinary team (MDT) meetings can be time-consuming. In addition to the clinical data being available digitally in subsystems, the preparation of more complex cases requires literature research. Several expert systems have been developed to support this process. However, the interaction with these systems has to be trained. Current development enables linguistic interaction with such artificial intelligence (AI) systems. To the best of our knowledge, these have not been tested as premedical screening tools for MDT. Methods This is a retrospective consecutive case series of 10 cervical cancer cases comparing the medical recommendations of the MDT and artificial intelligence (AI) on a low level (i.e., surgery, systemic treatment, and radiotherapy). Results The clinical cases ranged from primary diagnosis via suspected recurrence to palliative settings. The AI repeatedly stated that medical professionals need to be consulted before treatment decisions. The AI answers ranged from no agreement to overachievement by mentioning treatment options for preexisting risk factors (such as obesity). In standard cases, the AI answer matched well with the expert recommendations. In some cases, the AI answers were contrary to our treatment recommendation. Conclusion The interaction with current language AIs is temptingly easy, and the replies are very understandable. Despite the AI warning regarding medical recommendations in the majority of our cases, there was a good match with the MDT recommendations. However, in some cases, the medical evidence behind the answers was missing or in the worst case fictional. In our case series, the AI did not meet the requirements to support a clinical MDT meeting by prescreening the therapeutic options. However, it did exceed the expectations regarding the risk factors of the patients.

Steric Blockade of Oxy-Myoglobin Oxidation by Thiosemicarbazones: Structure-Activity Relationships of the Novel PPP4pT Series

The di-2-pyridylketone thiosemicarbazones demonstrated marked anticancer efficacy, prompting progression of DpC to clinical trials. However, DpC induced deleterious oxy-myoglobin oxidation, stifling development. To address this, novel substituted phenyl thiosemicarbazone (PPP4pT) analogues and their Fe(III), Cu(II), and Zn(II) complexes were prepared. The PPP4pT analogues demonstrated potent antiproliferative activity (IC50: 0.009-0.066 μM), with the 1:1 Cu:L complexes showing the greatest efficacy. Substitutions leading to decreased redox potential of the PPP4pT:Cu(II) complexes were associated with higher antiproliferative activity, while increasing potential correlated with increased redox activity. Surprisingly, there was no correlation between redox activity and antiproliferative efficacy. The PPP4pT:Fe(III) complexes attenuated oxy-myoglobin oxidation significantly more than the clinically trialed thiosemicarbazones, Triapine, COTI-2, and DpC, or earlier thiosemicarbazone series. Incorporation of phenyl- and styryl-substituents led to steric blockade, preventing approach of the PPP4pT:Fe(III) complexes to the heme plane and its oxidation. The 1:1 Cu(II):PPP4pT complexes were inert to transmetalation and did not induce oxy-myoglobin oxidation.

Iron Accumulation and Lipid Peroxidation in the Aging Retina: Implication of Ferroptosis in Age-Related Macular Degeneration

Iron is an essential component in many biological processes in the human body. It is critical for the visual phototransduction cascade in the retina. However, excess iron can be toxic. Iron accumulation and reduced efficiency of intracellular antioxidative defense systems predispose the aging retina to oxidative stress-induced cell death. Age-related macular degeneration (AMD) is characterized by retinal iron accumulation and lipid peroxidation. The mechanisms underlying AMD include oxidative stress-mediated death of retinal pigment epithelium (RPE) cells and subsequent death of retinal photoreceptors. Understanding the mechanism of the disruption of iron and redox homeostasis in the aging retina and AMD is crucial to decipher these mechanisms of cell death and AMD pathogenesis. The mechanisms of retinal cell death in AMD are an area of active investigation; previous studies have proposed several types of cell death as major mechanisms. Ferroptosis, a newly discovered programmed cell death pathway, has been associated with the pathogenesis of several neurodegenerative diseases. Ferroptosis is initiated by lipid peroxidation and is characterized by iron-dependent accumulation. In this review, we provide an overview of the mechanisms of iron accumulation and lipid peroxidation in the aging retina and AMD, with an emphasis on ferroptosis.

The Fungal Iron Chelator Desferricoprogen Inhibits Atherosclerotic Plaque Formation

Hemoglobin, heme and iron are implicated in the progression of atherosclerosis. Therefore, we investigated whether the hydrophobic fungal iron chelator siderophore, desferricoprogen (DFC) inhibits atherosclerosis. DFC reduced atherosclerotic plaque formation in ApoE^-/- mice on an atherogenic diet. It lowered the plasma level of oxidized LDL (oxLDL) and inhibited lipid peroxidation in aortic roots. The elevated collagen/elastin content and enhanced expression of adhesion molecule VCAM-1 were decreased. DFC diminished oxidation of Low-density Lipoprotein (LDL) and plaque lipids catalyzed by heme or hemoglobin. Formation of foam cells, uptake of oxLDL by macrophages, upregulation of CD36 and increased expression of TNF-α were reduced by DFC in macrophages. TNF-triggered endothelial cell activation (vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecules (ICAMs), E-selectin) and increased adhesion of monocytes to endothelium were attenuated. The increased endothelial permeability and intracellular gap formation provoked by TNF-α was also prevented by DFC. DFC acted as a cytoprotectant in endothelial cells and macrophages challenged with a lethal dose of oxLDL and lowered the expression of stress-responsive heme oxygenase-1 as sublethal dose was employed. Saturation of desferrisiderophore with iron led to the loss of the beneficial effects. We demonstrated that DFC accumulated within the atheromas of the aorta in ApoE^-/- mice. DFC represents a novel therapeutic approach to control the progression of atherosclerosis.

Multivesicular Liposome (Depofoam) in Human Diseases

Drug development is a key point in the research of new therapeutic treatments for increasing maximum drug loading and prolonged drug effect. Encapsulation of drugs into multivesicular liposomes (DepoFoam) is a nanotechnology that allow delivery of the active constituent at a sufficient concentration during the entire treatment period. This guarantees the reduction of drug administration frequency, a very important factor in a prolonged treatment. Currently, diverse DepoFoam drugs are approved for clinical use against neurological diseases and for post-surgical pain management while other are under development for reducing surgical bleeding and for post-surgical analgesia. Also, on pre-clinical trials on cancer DepoFoam can improve bioavailability and stability of the drug molecules minimizing side effects by site-specific targeted delivery. In the current work, available literature on structure, preparation and pharmacokinetics of DepoFoam are reviewed. Moreover, we investigated approved DepoFoam formulations and preclinical studies with this nanotechnology.

Thiosemicarbazones suppress expression of the c-Met oncogene by mechanisms involving lysosomal degradation and intracellular shedding

Considering the role of proto-oncogene c-Met (c-Met) in oncogenesis, we examined the effects of the metastasis suppressor, N-myc downstream-regulated gene-1 (NDRG1), and two NDRG1-inducing thiosemicarbazone-based agents, Dp44mT and DpC, on c-Met expression in DU145 and Huh7 cells. NDRG1 silencing without Dp44mT and DpC up-regulated c-Met expression, demonstrating that NDRG1 modulates c-Met levels. Dp44mT and DpC up-regulated NDRG1 by an iron-dependent mechanism and decreased c-Met levels, c-Met phosphorylation, and phosphorylation of its downstream effector, GRB2-associated binding protein 1 (GAB1). However, incubation with Dp44mT and DpC after NDRG1 silencing or silencing of the receptor tyrosine kinase inhibitor, mitogen-inducible gene 6 (MIG6), decreased c-Met and its phosphorylation, suggesting NDRG1- and MIG6-independent mechanism(s). Lysosomal inhibitors rescued the Dp44mT- and DpC-mediated c-Met down-regulation in DU145 cells. Confocal microscopy revealed that lysosomotropic agents and the thiosemicarbazones significantly increased co-localization between c-Met and lysosomal-associated membrane protein 2 (LAMP2). Moreover, generation of c-Met C-terminal fragment (CTF) and its intracellular domain (ICD) suggested metalloprotease-mediated cleavage. In fact, Dp44mT increased c-Met CTF while decreasing the ICD. Dp44mT and a γ-secretase inhibitor increased cellular c-Met CTF levels, suggesting that Dp44mT induces c-Met CTF levels by increasing metalloprotease activity. The broad metalloprotease inhibitors, EDTA and batimastat, partially prevented Dp44mT-mediated down-regulation of c-Met. In contrast, the ADAM inhibitor, TIMP metallopeptidase inhibitor 3 (TIMP-3), had no such effect, suggesting c-Met cleavage by another metalloprotease. Notably, Dp44mT did not induce extracellular c-Met shedding that could decrease c-Met levels. In summary, the thiosemicarbazones Dp44mT and DpC effectively inhibit oncogenic c-Met through lysosomal degradation and metalloprotease-mediated cleavage.

Ironing out the role of the cyclin-dependent kinase inhibitor, p21 in cancer: Novel iron chelating agents to target p21 expression and activity

Iron (Fe) has become an important target for the development of anti-cancer therapeutics with a number of Fe chelators entering human clinical trials for advanced and resistant cancer. An important aspect of the activity of these compounds is their multiple molecular targets, including those that play roles in arresting the cell cycle, such as the cyclin-dependent kinase inhibitor, p21. At present, the exact mechanism by which Fe chelators regulate p21 expression remains unclear. However, recent studies indicate the ability of chelators to up-regulate p21 at the mRNA level was dependent on the chelator and cell-type investigated. Analysis of the p21 promoter identified that the Sp1-3-binding site played a significant role in the activation of p21 transcription by Fe chelators. Furthermore, there was increased Sp1/ER-α and Sp1/c-Jun complex formation in melanoma cells, suggesting these complexes were involved in p21 promoter activation. Elucidating the mechanisms involved in the regulation of p21 expression in response to Fe chelator treatment in neoplastic cells will further clarify how these agents achieve their anti-tumor activity. It will also enhance our understanding of the complex roles p21 may play in neoplastic cells and lead to the development of more effective and specific anti-cancer therapies.

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.

Iron chelation: an adjuvant therapy to target metabolism, growth and survival of murine PTEN-deficient T lymphoma and human T lymphoblastic leukemia/lymphoma

Iron is an essential nutrient, acting as a catalyst for metabolic reactions that are fundamental to cell survival and proliferation. Iron complexed to transferrin is delivered to the metabolism after endocytosis via the CD71 surface receptor. We found that transformed cells from a murine PTEN-deficient T-cell lymphoma model and from T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/T-LL) cell lines overexpress CD71. As a consequence, the cells developed an addiction toward iron whose chelation by deferoxamine (DFO) dramatically affected their survival to induce apoptosis. Interestingly, DFO displayed synergistic activity with three ALL-specific drugs: dexamethasone, doxorubicin, and L-asparaginase. DFO appeared to act through a reactive oxygen species-dependent DNA damage response and potentiated the action of an inhibitor of the PARP pathway of DNA repair. Our results demonstrate that targeting iron metabolism could be an interesting adjuvant therapy for acute lymphoblastic leukemia.

Comparative study of the protective effect between deferoxamine and deferiprone on chronic iron overload induced cardiotoxicity in rats

Patients with iron overload frequently suffer from hemochromatosis of major organs, such as the heart and liver. Heart affection is the most common cause of death in patients with iron overload. Although the beneficial effects of deferoxamine (DFO) on iron-associated mortality are well documented, the role of deferiprone in the management of transfusional iron overload is controversial. The aim of this study was to compare the protective effect of iron chelators (DFO and deferiprone) individually and in combination with the anti-oxidant (vitamin C) in the prevention of myocardial damage. Sixty albino rats were divided into six groups: two control groups (noniron-loaded and iron-loaded) and four iron-loaded groups classified as follows: DFO group, DFO combined with vitamin C group, deferiprone group and deferiprone combined with vitamin C group. Heart tissue and blood samples were taken for histopathological examination of the heart, determination of total iron-binding capacity, 8-OH-deoxyguanosine (8-OH-dG), myocardial lipid peroxidation and glutathione (GSH) content. Less histopathological cardiac changes and a significant decrease in all biochemical parameters, except myocardial GSH, were observed in the deferiprone group. The addition of vitamin C improves the biochemical and histopathological changes in comparison to those rats administered DFO or deferiprone individually.

Targeting cancer by binding iron: Dissecting cellular signaling pathways

Newer and more potent therapies are urgently needed to effectively treat advanced cancers that have developed resistance and metastasized. One such strategy is to target cancer cell iron metabolism, which is altered compared to normal cells and may facilitate their rapid proliferation. This is supported by studies reporting the anti-neoplastic activities of the clinically available iron chelators, desferrioxamine and deferasirox. More recently, ligands of the di-2-pyridylketone thiosemicarbazone (DpT) class have demonstrated potent and selective anti-proliferative activity across multiple cancer-types in vivo, fueling studies aimed at dissecting their molecular mechanisms of action. In the past five years alone, significant advances have been made in understanding how chelators not only modulate cellular iron metabolism, but also multiple signaling pathways implicated in tumor progression and metastasis. Herein, we discuss recent research on the targeting of iron in cancer cells, with a focus on the novel and potent DpT ligands. Several key studies have revealed that iron chelation can target the AKT, ERK, JNK, p38, STAT3, TGF-β, Wnt and autophagic pathways to subsequently inhibit cellular proliferation, the epithelial-mesenchymal transition (EMT) and metastasis. These developments emphasize that these novel therapies could be utilized clinically to effectively target cancer.

Redox cycling metals: Pedaling their roles in metabolism and their use in the development of novel therapeutics

Essential metals, such as iron and copper, play a critical role in a plethora of cellular processes including cell growth and proliferation. However, concomitantly, excess of these metal ions in the body can have deleterious effects due to their ability to generate cytotoxic reactive oxygen species (ROS). Thus, the human body has evolved a very well-orchestrated metabolic system that keeps tight control on the levels of these metal ions. Considering their very high proliferation rate, cancer cells require a high abundance of these metals compared to their normal counterparts. Interestingly, new anti-cancer agents that take advantage of the sensitivity of cancer cells to metal sequestration and their susceptibility to ROS have been developed. These ligands can avidly bind metal ions to form redox active metal complexes, which lead to generation of cytotoxic ROS. Furthermore, these agents also act as potent metastasis suppressors due to their ability to up-regulate the metastasis suppressor gene, N-myc downstream regulated gene 1. This review discusses the importance of iron and copper in the metabolism and progression of cancer, how they can be exploited to target tumors and the clinical translation of novel anti-cancer chemotherapeutics.

TLc-A, the leading nanochelating-based nanochelator, reduces iron overload in vitro and in vivo

Iron chelation therapy is an effective approach to the treatment of iron overload conditions, in which iron builds up to toxic levels in the body and may cause organ damage. Treatments using deferoxamine, deferasirox and deferiprone have been introduced and despite their disadvantages, they remain the first-line therapeutics in iron chelation therapy. Our study aimed to compare the effectiveness of the iron chelation agent TLc-A, a nano chelator synthetized based on the novel nanochelating technology, with deferoxamine. We found that TLc-A reduced iron overload in Caco2 cell line more efficiently than deferoxamine. In rats with iron overload, very low concentrations of TLc-A lowered serum iron level after only three injections of the nanochelator, while deferoxamine was unable to reduce iron level after the same number of injections. Compared with deferoxamine, TLc-A significantly increased urinary iron excretion and reduced hepatic iron content. The toxicity study showed that the intraperitoneal median lethal dose for TLc-A was at least two times higher than that for deferoxamine. In conclusion, our in vitro and in vivo studies indicate that the novel nano chelator compound, TLc-A, offers superior performance in iron reduction than the commercially available and widely used deferoxamine.

Quantitative assessment of iron in heart and liver phantoms using dual-energy computed tomography

The aim of the present study was to determine the correlation between dual-energy computed tomography (DECT) Hounsfield units (HU) and iron concentration, as well as the correlation between HU and magnetic resonance imaging (MRI)-derived R2^* values, in phantoms of the heart and liver tissue. Phantoms were constructed containing pig heart or liver tissue and varying concentrations of iron (0.1, 5, 10, 15, 20 and 25 mg/ml). The phantoms were then examined by DECT and MRI. Linear regression analysis was used to determine the correlations between HU and iron concentration and HU and R2^* values. The HU value of DECT increased with increasing iron concentrations in the liver and heart phantoms in a linear manner. The slope of the HU value change against iron concentration revealed that ΔH_80–140 provided a better discernment of iron concentration as compared with ΔH_100–140. The derived R² values were all >0.9 for the associations of DECT and MRI measurements with iron concentrations. Therefore, DECT may be used for the determination of iron concentration in the liver and heart tissue, with the results correlating with those obtained with MRI.

Blockade of mitochondrial calcium uniporter prevents cardiac mitochondrial dysfunction caused by iron overload

AIM

Iron overload in the heart can lead to iron-overload cardiomyopathy and cardiac arrhythmia. In the past decades, growing evidence has suggested that cardiac mitochondrial dysfunction is associated with the development of cardiac dysfunction and lethal arrhythmias. Despite these facts, the effect of iron overload on cardiac mitochondrial function is still unclear. In this study, we determined the effects of iron overload on the cardiac mitochondrial function and the routes of cardiac mitochondrial iron uptake. We tested the hypothesis that iron overload can lead to cardiac mitochondrial dysfunction and that mitochondrial calcium uniporter (MCU) plays a major role for cardiac mitochondrial iron uptake under iron-overload condition. Cardiac mitochondrial function was assessed via the determination of mitochondrial swelling, mitochondrial reactive oxygen species (ROS) production and mitochondrial membrane potential changes.

METHODS

Isolated cardiac mitochondria from male Wistar rats were used in this study. To determine the routes for cardiac mitochondrial iron uptake, isolated mitochondria were exposed to MCU blocker (Ru360), mitochondrial permeability transition pore (mPTP) blocker (cyclosporin A) and an iron chelator (deferoxamine).

RESULTS

We found that (i) iron overload caused cardiac mitochondrial dysfunction, indicated by increased ROS production, mitochondrial membrane depolarization and mitochondrial swelling; and (ii) only MCU blocker completely protected cardiac mitochondrial dysfunction caused by iron overload.

CONCLUSIONS

These findings strongly suggest that MCU could be the major route for iron uptake into cardiac mitochondria. The inhibition of MCU could be the novel pharmacological intervention for preventing iron-overload cardiomyopathy.

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.

Novel chelators for cancer treatment: where are we now?

SIGNIFICANCE

Under normal circumstances, cellular iron levels are tightly regulated due to the potential toxic effects of this metal ion. There is evidence that tumors possess altered iron homeostasis, which is mediated by the perturbed expression of iron-related proteins, for example, transferrin receptor 1, ferritin and ferroportin 1. The de-regulation of iron homeostasis in cancer cells reveals a particular vulnerability to iron-depletion using iron chelators. In this review, we examine the absorption of iron from the gut; its transport, metabolism, and homeostasis in mammals; and the molecular pathways involved. Additionally, evidence for alterations in iron processing in cancer are described along with the perturbations in other biologically important transition metal ions, for example, copper(II) and zinc(II). These changes can be therapeutically manipulated by the use of novel chelators that have recently been shown to be highly effective in terms of inhibiting tumor growth.

RECENT ADVANCES

Such chelators include those of the thiosemicarbazone class that were originally thought to target only ribonucleotide reductase, but are now known to have multiple effects, including the generation of cytotoxic radicals.

CRITICAL ISSUES

Several chelators have shown marked anti-tumor activity in vivo against a variety of solid tumors. An important aspect is the toxicology and the efficacy of these agents in clinical trials.

FUTURE DIRECTIONS

As part of the process of the clinical assessment of the new chelators, an extensive toxicological assessment in multiple animal models is essential for designing appropriate dosing protocols in humans.

The management of iron chelation therapy: preliminary data from a national registry of thalassaemic patients

Thalassaemia and other haemoglobinopathies constitute an important health problem in Mediterranean countries, placing a tremendous emotional, psychological, and economic burden on their National Health systems. The development of new chelators in the most recent years had a major impact on the treatment of thalassaemia and on the quality of life of thalassaemic patients. A new initiative was promoted by the Italian Ministry of Health, establishing a Registry for thalassaemic patients to serve as a tool for the development of cost-effective diagnostic and therapeutic approaches and for the definition of guidelines supporting the most appropriate management of the iron-chelating therapy and a correct use of the available iron-chelating agents. This study represents the analysis of the preliminary data collected for the evaluation of current status of the iron chelation practice in the Italian thalassaemic population and describes how therapeutic interventions can widely differ in the different patients' age groups.

An extended-release formulation of desferrioxamine for subcutaneous administration

Desferrioxamine mesylate (DFO) remains the first line iron chelating agent. Since it has a short half-life and poor absorption through the gastrointestinal tract, DFO must be administered parenterally, usually by daily subcutaneous infusion administered over 8-12 h. The objective of this paper was the development of multivesicular liposome (depofoam) for the extended-release of DFO and study of iron excretion efficiency compared to the free form of DFO. Depofoam particles were characterized by their morphology, particle size, capture volume, and in vitro release. Also, in vivo activity of this formulation in iron overload rats was studied. The in vitro studies in 0.9% sodium chloride at 37 degrees C showed that the multivesicular liposomes released DFO slowly over several days without a rapid initial release, and 57% of DFO was released in 9 days. Administration of a single dose of 100 mg/kg of an optimized Depo-DFO formulation in an iron overload rats, as a single bolus subcutaneous injection, led to significant elevation of urinary iron excretion at the first day that were maintained at levels of more than 110 microg/kg for 3 days. Administration of the unencapsulated DFO at the same dose resulted in elevation of urinary iron excretion in the first day (approximately 73% amount of iron excretion by Depo-DFO) followed by a quick decline to base line levels in the second day. The total urinary iron excreted by Depo-DFO is 3-times greater than that elicited by DFO. In conclusion, Depo-DFO appears to have potential usefulness as an extended-release formulation of DFO.

Splenectomy for haematological disorders: a single center study in 150 patients from Oman

BACKGROUND

Haematological disorders, in particular sickle cell disease (SCD) and thalassaemia, are relatively common in Oman. We report our experience of splenectomy for haematological disorders and review the literature on splenectomy role in their management.

OBJECTIVES

To review our experience in the management of 150 patients with haematological disorders undergoing splenectomy with emphasis on indications and outcome. To compare our experience with those reported from outside this region.

METHODS

The records of 150 patients who underwent splenectomy over a thirteen year period were reviewed retrospectively, analyzing the age and sex of the patients, indication for splenectomy, operative procedures, complications, peri-operative management and outcome.

RESULTS

Of the 150 patients, 96 (64%) had SCD and 34 (22.6%) had beta-thalassaemia; the rest comprised patients with refractory idiopathic thrombocytopenic purpura (ITP) n=12, hereditary spherocytosis (HS) n=6, and auto-immune haemolytic anaemia (AHA) n=2. In SCD patients, the main indications for splenectomy were recurrent splenic sequestration (60.4%) and hypersplenism (36.4%), whereas in thalassaemic patients it was increased requirement of packed red blood cells (PRBC) transfusion (mean 310 ml, range 242-372 of PRBC/kg/year). All patients received prophylactic antibiotics and vaccination against pneumococcal infection and when the vaccine was available for Haemophilus influenzae. PRBC and platelet concentrates as well as intravenous fluids were infused preoperatively as per protocol. Concomitant procedures at laparotomy included liver biopsy (14.6%) and cholecystectomy (8.6%). The postoperative morbidity was low (8.6%) and there was no mortality. All patients were maintained on long term penicillin and proguanil, and the mean follow-up was 4.6 years. In SCD patients splenectomy eliminated the risks of life threatening acute splenic sequestration and improved significantly the blood counts of the hypersplenic cases, while in thalassaemic patients it reduced significantly the mean transfusion requirement by 100ml PRBC/kg/year (p<0.0001). Of the patients with refractory ITP, two thirds had a good response to splenectomy (p<0.0001). All HS and AHA patients benefited from splenectomy.

CONCLUSION

The predominant indications for splenectomy were recurrent acute splenic sequestration and hypersplenism in SCD patients, and increased transfusion demand in the thalassaemics. Overall, splenectomy proved beneficial in eliminating the risk of splenic sequestration in SCD patients, in improving the blood counts in SCD with hypersplenism and in reducing transfusion requirement in thalassaemic patients, while in ITP group two thirds of the patients benefited.

Quantum chemical analysis of the deferiprone-iron binding reaction

To prevent side effects of excessive accumulation of iron in the body, chelation therapy is recommended in transfusion-dependent patients. The reaction between deferiprone and iron to form a complex red substance can be described as 3 molecules of the chelator, deferiprone, reacting with a molecule of iron. However, the actual mechanism of the deferiprone-iron binding reaction is not well understood. A quantum chemical analysis of the deferiprone-iron binding reaction was performed, focusing on the reaction between 1 molecule of deferiprone and I molecule of iron. The two main alternative pathways for the deferiprone-iron binding reaction were shown to be C-C cleavage and C-O cleavage. The required energy for complex formation in C-C cleavage was less than for C-O cleavage. The total energy requirement for C-C cleavage was negative, implying that this reaction can occur without any external energy source. The resulting complex fits the reported tertiary structure model for the deferiprone-iron complex.

Iron chelators deferoxamine and diethylenetriamine pentaacetic acid induce apoptosis in ovarian carcinoma

OBJECTIVES

Ovarian cancer remains a leading cause of death in women and development of new therapies is essential. Deprivation of iron (Fe), an essential micro-nutrient, by chelation is known to inhibit proliferation of several human cancers but its potential in ovarian cancer treatment remains unknown. We have evaluated the anti-proliferative activities of iron chelators, deferoxamine (DFO), and diethylenetriamine pentaacetic acid (DTPA), in human and rat ovarian cancer cells.

METHODS

The effect of DFO and DTPA on CaOV-3 (human) and NUTU-19 (rat) ovarian cancer cells was determined by cell proliferation and apoptosis assays (Hoechst staining, DNA fragmentation, and caspase activation), cell cycle analysis, and Fe supplementation studies.

RESULTS

DFO and DTPA were cytotoxic to ovarian cancer cells in a dose- and time-dependent manner. DFO inhibited proliferation of NUTU-19 and CaOV-3 cells (IC(50) at 45 and 280 microM, respectively), while DTPA inhibited proliferation of only NUTU-19 cells (IC(50) at 50 microM), at 48 h. DNA synthesis was inhibited in CaOV-3 cells by DFO (>90% at 200 microM) and in NUTU-19 by both DFO and DTPA (>90% at 50 microM). Fe supplementation effectively reversed the cytotoxic effects of DFO and DTPA. Cell cycle analysis showed a G0/G1- and S-phase block with increased apoptosis. DNA fragmentation analysis confirmed apoptosis. Increase in caspase-3, -8, and -9 activities ( approximately 2.4-fold) was associated with apoptosis.

CONCLUSIONS

Our studies show that Fe chelators suppress ovarian cancer growth by inhibiting proliferation and inducing apoptosis. Therefore, Fe chelators can be potentially developed as novel therapeutic agents to treat ovarian cancer.

Study of intermittent intravenous deferrioxamine high-dose therapy in heavily iron-loaded children with beta-thalassemia major poorly compliant to subcutaneous injections

The authors tested the efficacy and safety of intermittent high doses of iv deferrioxamine (DFX) on a twice-weekly basis through an externalized venous catheter on 14 thalassemic children who were heavily iron-loaded and poorly or noncomplaint to subcutaneous DFX. The main reasons for their noncompliance were resistance of the child because of severe local reactions or more than one family member affected, with very high burden on the mother to look after all the affected children. There were 9 males and 5 females and their age range was 7-13 years (mean 10.93 +/- 1.9 years). All patients were given a 48-h continuous iv infusion of DFX 200-240 mg/kg/day (approximately 10 mg/kg/h) every 2 weeks, combined with subcutaneous 10-h infusion of DFX 3 days/week. One month after the start of the intermittent high-dose DFX program, the 24 h urinary iron excretion was 29.1-1.50 mg/kg/24 h (mean 69.7 +/- 32.5 mg/kg/24 h). These values dropped significantly to 29-53 mg/kg/24 h (mean 39.8 +/- 7.9 mg/kg/24 h) 1 year after the study (p <.004) and remained almost the same over the second year (mean 39.07 +/- 6.58 mg/kg/24 h). Serum ferritin levels markedly elevated before the start of high-dose chelation fell steadily during iv high-dose DFX therapy. Mean values were 6215.5 +/- 578.3, 3971.5 +/- 321.6, 2507.2 +/- 131.2, and 1866.5 +/- 110 ng/mL at 0, 6, 12, and 24 months, respectively. No serious side effects were reported. Intermittent high-dose DFX therapy combined with 3 days of subcutaneous DFX is safe and effective in reducing iron stores and improving the compliance of these heavily iron-loaded thalassemic children.