Treatment of beta-thalassemia

Gonadal function of young patients with beta-thalassemia following bone marrow transplantation

Bone marrow transplantation (BMT) can induce short- and long-term impairment of gonadal function. Patients with beta-thalassemia represent a special group, as their primary diagnosis and its treatment modalities are responsible for gonadal dysfunction. To address the effect of BMT on puberty and gonadal function, we investigated 25 patients (12 males) with thalassemia who received allogenic BMT during childhood or adolescence and at the post-transplant evaluation were at an age that the pubertal process should have started. Pubertal stage by Tanner of breast and pubic hair, as well as testicular volume were assessed pre-BMT once and post-BMT at least twice. Menstrual history was recorded. FSH, LH, testosterone and estradiol levels were also determined. The impact of BMT appears to be different in the two sexes. Males seem to have higher tolerance, as all males who were pubertal at the time of BMT had normal testosterone, and all but one normal gonadotropin levels. From those who were prepubertal at BMT, 62% proceeded to normal pubertal development. Post-menarcheal females seem to be an extremely sensitive group to the deleterious effect of the transplantation process, as 100% of the post-menarcheal females exhibited amenorrhea and elevated gonadotropin levels. These findings are important for pre- and post-BMT counseling.

Ham-Wasserman Lecture

Over the past fifty years, many advances in our understanding of the general principles controlling gene expression during hematopoiesis have come from studying the synthesis of hemoglobin. Discovering how the α and β globin genes are normally regulated and documenting the effects of inherited mutations which cause thalassemia have played a major role in establishing our current understanding of how genes are switched on or off in hematopoietic cells. Previously, nearly all mutations causing thalassemia have been found in or around the globin loci, but rare inherited and acquired trans-acting mutations are being found with increasing frequency. Such mutations have demonstrated new mechanisms underlying human genetic disease. Furthermore, they are revealing new pathways in the regulation of globin gene expression which, in turn, may eventually open up new avenues for improving the management of patients with common types of thalassemia.

Pharmacologic and cytokine treatment of commonly encountered anemias

Anemia has multiple etiologies: it may be caused by nutritional deficiencies or congenital abnormalities, or it may be associated with a number of conditions, such as chronic kidney disease, cancer, or human immunodeficiency virus (HIV) infection. Anemia is associated with an increase in morbidity and mortality in patients with endstage renal disease, cancer, or HIV infection. Each case of anemia is different, with different causes, clinical consequences, and treatment strategies. Identifying the most appropriate treatment requires an understanding of the etiology of the anemia and investigation of the nature of the causative medical condition. In some cases, such as anemia associated with chronic kidney disease, treatment is well defined and consists of administration of erythropoiesis-stimulating agents, accompanied by iron supplementation where appropriate. In other instances, such as megaloblastic anemia, which may be caused by vitamin or folate deficiency, vitamin supplementation alone may be a clinically appropriate treatment. This article gives an overview of the etiologies and current therapies of the most commonly encountered types of anemia, highlighting both the diverse nature of the condition, and the equally diverse pharmacologic and supportive treatment approaches.

Estimates of the effect on hepatic iron of oral deferiprone compared with subcutaneous desferrioxamine for treatment of iron overload in thalassemia major: a systematic review

BACKGROUND: Beta thalassemia major requires regular blood transfusions and iron chelation to alleviate the harmful accumulation of iron. Evidence on the efficacy and safety of the available agents, desferrioxamine and deferiprone, is derived from small, non-comparative, heterogeneous observational studies. This evidence was reviewed to quantitatively compare the ability of these chelators to reduce hepatic iron. METHODS: The literature was searched using Medline and all reports addressing the effect of either chelator on hepatic iron were considered. Data were abstracted independently by two investigators. Analyses were performed using reported individual patient data. Hepatic iron concentrations at study end and changes over time were compared using ANCOVA, controlling for initial iron load. Differences in the proportions of patients improving were tested using chi2. RESULTS: Eight of 11 reports identified provided patient-level data relating to 30 desferrioxamine- and 68 deferiprone-treated patients. Desferrioxamine was more likely than optimal dose deferiprone to decrease hepatic iron over the average follow-up of 45 months (odds ratio, 19.0, 95% CI, 2.4 to 151.4). The degree of improvement was also larger with desferrioxamine. CONCLUSIONS: This analysis suggests that desferrioxamine is more effective than deferiprone in lowering hepatic iron. This comparative analysis - despite its limitations - should prove beneficial to physicians faced with the challenge of selecting the optimal treatment for their patients.

Combine-ARMS: a rapid and cost-effective protocol for molecular characterization of beta-thalassemia in Malaysia

Beta-thalassemia major patients have chronic anemia and are dependent on blood transfusions to sustain life. Molecular characterization and prenatal diagnosis of beta3-thalassemia is essential in Malaysia because about 4.5% of the population are heterozygous carriers for beta-thalassemia. The high percentage of compound heterozygosity (47.62%) found in beta-thalassemia major patients in the Thalassaemia Registry, University of Malaya Medical Centre (UMMC), Malaysia, also supports a need for rapid, economical, and sensitive protocols for the detection of beta-thalassemia mutations. Molecular characterization of beta-thalassemia mutations in Malaysia is currently carried out using ARMS, which detects a single beta-thalassemia mutation per PCR reaction. We developed and evaluated Combine amplification refractory mutation system (C-ARMS) techniques for efficient molecular detection of two to three beta-thalassemia mutations in a single PCR reaction. Three C-ARMS protocols were evaluated and established for molecular characterization of common beta-thalassemia mutations in the Malay and Chinese ethnic groups in Malaysia. Two C-ARMS protocols (cd 41-42/IVSII #654 and -29/cd 71-72) detected the beta-thalassemia mutations in 74.98% of the Chinese patients studied. The CARMS for cd 41-42/IVSII #654 detected beta-thalassemia mutations in 72% of the Chinese families. C-ARMS for cd 41-42/IVSI #5/cd 17 allowed detection of beta-thalassemia mutations in 36.53% of beta-thalassemia in the Malay patients. C-ARMS for cd 41-42/IVSI #5/cd 17 detected beta-thalassemia in 45.54% of the Chinese patients. We conclude that C-ARMS with the ability to detect two to three mutations in a single reaction provides more rapid and cost-effective protocols for beta-thalassemia prenatal diagnosis and molecular analysis programs in Malaysia.

Bone marrow transplantation for beta-thalassemia: the University of California San Francisco experience

We report the results of allogeneic HLA-matched family donor stem cell transplantation in 17 North American children with beta-thalassemia major or hemoglobin E/beta-thalassemia who received transplants at the University of California San Francisco. Pretransplantation conditioning was with busulfan, cyclophosphamide, and antithymocyte globulin and graft-versus-host prophylaxis used cyclosporine, usually with added methotrexate. Twelve children are alive, well, and free of the clinical manifestations of thalassemia. Four experienced graft rejection and autologous recovery, and one died from complications shortly after transplantation. Overall survival was 94% and event-free survival 71%, results similar to those obtained by other transplantation centers. Improved conditioning regimes and enlargement of the donor pool will be needed to improve the outcome of transplantation and to make this treatment available to more children with thalassemia.

Iron overload and iron-chelating therapy in hemoglobin E-beta thalassemia

Whereas hemoglobin (Hb) E-beta thalassemia is recognized as probably the most common serious hemoglobinopathy worldwide, its natural history remains poorly defined. The interaction of hemoglobin E and beta-thalassemia result in a wide spectrum of clinical disorders, some indistinguishable from thalassemia major and some milder and not transfusion-dependent. Partially as a result of this wide range of phenotypes, clear guidelines for approaches to transfusion and to iron-chelating therapy for patients with Hb E-beta thalassemia have not been developed. By contrast, data that have accumulated during the past 10 years in patients with beta-thalassemia permit a quantitative approach to the management of iron overload and provide guidelines for the control of body iron burden in individual patients treated with iron-chelating therapy. These guidelines may be applicable to patients with Hb E-beta thalassemia. Preliminary evidence from our studies of iron loading in affected patients with Hb E-beta thalassemia in Sri Lanka suggest that this disorder may be associated with variable, but accelerated, gastrointestinal iron absorption, and that the iron loading associated with chronic transfusions in patients with Hb E-beta thalassemia is similar to that observed in patients with beta-thalassemia. These data, in the only cohort of patients with Hb E-beta thalassemia to have undergone quantitative assessment of body iron burden, suggest that the principles that guide assessment of iron loading and initiation of chelating therapy in patients with beta-thalassemia may be generally applicable to those with Hb E-beta thalassemia. Further quantitative studies in both nontransfused and transfused patients will be necessary to permit firm conclusions.

Red cells I: inherited anaemias

Examination of the genetic mechanisms underlying the thalassaemias has led to a clearer understanding of the control of eukaryotic genes in general. Inherited disorders of haemoglobin synthesis are an important cause worldwide of morbidity and mortality, and place a large burden on patients, families, and ultimately communities. The haemoglobin disorders can be controlled, by counselling and prenatal diagnosis. Treatment is usually symptomatic, though bone-marrow transplantation for beta-thalassaemia may be successful in suitable patients.

First human studies with a high-molecular-weight iron chelator

The release of free, reactive iron from cellular iron stores has been implicated as an important contributor to tissue damage in a variety of clinical situations, including ischemia and reperfusion injury, hemorrhagic shock, and burn injury. Deferoxamine mesylate (DFO), the only iron chelator currently approved for clinical use, is used for the treatment of iron overload, including acute iron poisoning and treatment of chronic iron overload in transfusion-dependent anemias such as beta-thalassemia. However, it is not suitable for acute care situations because of its toxicity, primarily hypotension when given at high intravenous doses, and its short plasma half-life. We have produced a high-molecular-weight iron chelator by chemically coupling DFO to hydroxyethyl starch. This novel chelator (HES-DFO) was administered to healthy male subjects by intravenous infusion over a 4-hour period. The drug was well tolerated, and signs of DFO acute toxicity were not observed. Maximum plasma chelator levels of approximately 3 mmol/L were achieved with HES-DFO, which is more than an order of magnitude higher than has been reported with injections of DFO. Drug residence time in plasma was markedly prolonged, with an initial half-life of 22 to 33 hours. Urinary iron excretion was 7.1 +/- 2.2 mg in 48 hours in the highest dose group, as compared with 0.06 +/- 0.15 mg in control subjects who received normal saline infusions. Intravenous infusion of HES-DFO is well tolerated, produces substantial and prolonged plasma chelator levels, and markedly stimulates urinary iron excretion.

Thalassaemia: clinical management

Advances in the management of thalassaemia major have greatly improved the prognosis for patients with this disease. In countries able to afford programmes of regular transfusion and iron-chelating therapy, survival to the fourth decade is now common, and most complications associated with the primary disease are now infrequently observed. This situation stands in contrast to that in emerging countries, where the widespread implementation of these expensive treatment regimens is still awaited. This review will focus on recent advances in the treatment of thalassaemia and briefly review the progress in experimental approaches to treatment of this disorder.