Bone marrow transplant for the haemoglobinopathies: past, present and future

Hydroxyurea in Sickle Cell Disease: Our Experience in Western India

Sickle cell disease (SCD) is common in tribal belt of Gujarat, but not addressed effectively as it should be with effective use of Hydroxyurea, supportive care and counseling. In our single centre study of 70 patients of SCD who were only on Folic acid and Blood transfusion support, were analyzed and followed up for 1 year in terms of their clinical symptoms, Blood transfusion requirement, laboratory parameters before and after Hydroxyurea therapy. We found statistically significant improvement in clinical symptoms and positive changes in laboratory parameters studied. This validates the well established role of Hydroxyurea in SCD as seen in the various international trials. Hence it is imperative that the well documented benefits of Hydroxyurea in various International studies should be translated into clinical practice. SCD should be treated like a chronic disorder needing preventive therapy in form of Hydroxyurea and counseling with regular follow up.

Insight onto the pathophysiology and clinical complications of thalassemia intermedia

Our understanding of the molecular and pathophysiological mechanisms underlying the disease process in patients with thalassemia intermedia (TI) has substantially increased over the past decade. TI encompasses a wide clinical spectrum of beta-thalassemia phenotypes. Some TI patients are asymptomatic until adult life, whereas others are symptomatic from as young as 2 years. A number of clinical complications commonly associated with TI are rarely seen in thalassemia major, including extramedullary hematopoiesis, leg ulcers, gallstones, thrombosis, and pulmonary hypertension. There are a number of options currently available for managing patients with TI, including transfusion therapy, iron chelation therapy, modulation of fetal hemoglobin production, and hematopoietic stem cell transplantation. However, at present, there are no clear guidelines for an orchestrated optimal treatment plan.

Thalassaemia intermedia: an update

Our understanding of the molecular and pathophysiological mechanisms underlying the disease process in patients with thalassaemia intermedia (TI) has substantially increased over the past decade. TI encompasses a wide clinical spectrum of beta-thalassaemia phenotypes. Some TI patients are asymptomatic until adult life, whereas others are symptomatic from as young as 2 years of age. A number of clinical complications commonly associated with TI are rarely seen in thalassaemia major, including extramedullary hematopoiesis, leg ulcers, gallstones, thrombosis and pulmonary hypertension. There are a number of options currently available for managing patients with TI, including transfusion therapy, iron chelation therapy, modulation of foetal haemoglobin production and haematopoietic stem cell transplantation. However, at present, there are no clear guidelines for an orchestrated optimal treatment plan.

Thalassemia intermedia: Revisited

Thalassemia intermedia encompasses a wide clinical spectrum of beta-thalassemia phenotypes. Some thalassemia intermedia patients are asymptomatic until adult life, whereas others are symptomatic from as young as 2 years of age. A number of clinical complications commonly associated with thalassemia intermedia are rarely seen in thalassemia major, including extramedullary hematopoiesis, leg ulcers, gallstones and thrombophilia. Prevention of these complications, possibly with blood transfusion therapy, is ideal since they may be difficult to manage. Currently, many patients with thalassemia intermedia receive only occasional or no transfusions, since they are able to maintain hemoglobin levels between 7-9 g/dl; the risk of iron overload, necessitating adequate chelation therapy, is also a contributing factor. At present, there are no clear guidelines for initiating and maintaining transfusions in thalassemia intermedia for the prevention or treatment of complications. Here, we review the major clinical complications in thalassemia intermedia and suggest some therapeutic strategies based on retrospective clinical observations.

Utility of obtaining blood cultures in febrile neutropenic patients undergoing bone marrow transplantation

Infection remains an important cause of morbidity and mortality after bone marrow or stem cell transplantation. To evaluate the role of obtaining blood cultures for intermittent or persistent fever in neutropenic patients on antibiotic therapy, we performed a retrospective chart review of 196 consecutive patients admitted to the Bone Marrow Transplant Unit at the University of North Carolina Hospitals from 1995 to 1998. From the cohort of 196 patients, 154 patients developed neutropenic fever. The initial blood culture was positive in 16 of 145 patients during the first fever episode giving a prevalence of 11%. From the total of 109 patients that had blood cultures drawn after day 1 of fever, five patients had blood cultures positive for a pathogen, a prevalence of 4.6%. In only one patient, did blood cultures drawn after day 1 identify an organism not present on day 1 (prevalence 0.9%). After reviewing the results in the first 105 patients, we changed our timing of collection of blood cultures. Forty-nine patients were treated in this manner and we found that the mean number of blood cultures decreased from 9.2 to 4.7 per patient without a change in the frequency of infectious complications or length of hospitalization.

High-level transfer and long-term expression of the human beta-globin gene in a mouse transplant model

Insertion of a normally functioning human beta-globin gene into the hematopoietic stem cells (HSC) of patients with beta-thalassemia may be an effective approach to the therapy of this disorder. Safe, efficient gene transfer and long-term, high-level expression of the transferred human beta-globin gene in animal models are prerequisites for HSC somatic gene therapy. We have recently shown for the first time that, using a modified beta-globin retroviral vector in a mouse transplant model, long-term, high-level expression of a transferred human beta-globin gene is possible. The human beta-globin gene continues to be detected up to eight months post-transplantation of beta-globin-transduced hematopoietic cells into lethally irradiated mice. The transferred human beta-globin gene is detected in three of five mice surviving long-term (> 4 months) transplanted with bone marrow cells transduced with high-titer virus. The unrearranged 5.1 kb human beta-globin gene-containing provirus is seen by Southern blotting in two of these mice. More importantly, long-term expression of the transferred gene is seen in two mice at levels of 5% and 20% that of endogenous murine beta-globin. We document stem cell transduction by showing continued high-level expression of the human beta-globin gene in secondarily transplanted recipient mice. These results provide evidence of HSC transduction with a human beta-globin gene in animals and demonstrate that retroviral-mediated unrearranged human beta-globin gene transfer leads to a high level of human beta-globin gene expression in the long term for the first time. A gene therapy strategy may be a feasible therapeutic approach to the beta-thalassemias if consistent human beta-globin gene transfer and expression into HSC can be achieved.

Late effects of bone marrow transplantation for thalassemia

Long term effects of BMT in thalassemia were monitored in 33 patients transplanted between 1987 and 1995 and compared with 155 patients matched for age and treated during the same period with conventional therapy (CT). The incidence of fulminant sepsis and growth impairment was significantly higher in transplanted patients, whereas the occurrence of hypothyroidism, hypogonadism, and cardiopathy was higher in CT patients. For diabetes, liver disease, and severe infections, the differences were not statistically significant. After BMT we performed monthly erythrocytaferesis for iron removal in 23 (70%) patients, obtaining a complete normalization of iron stores in 91% of cases; among untreated patients, 60% had evidence of iron up to 8.3 years after BMT. Protection against poliovirus, tetanus, diphtheria, and hepatitis B has been lost in 74%, 47%, 78%, and 44%, respectively. After BMT a careful follow-up is needed to monitor and treat late transplant-related and thalassemia-related complications.

Thalassemia major 1995: older patients, new therapies

There have been many advances in supportive treatment used for beta-thalassemia major. Survival has increased substantially, and an increasing number of patients reach adolescence and adulthood. These older patients present new clinical challenges. Complications of transfusion, most commonly hepatitis C, are still a cause of mortality and morbidity. The achievement of optimal growth and development, including fertility, is an important goal of conservative management. Long-term survival has also been achieved with bone marrow transplantation. Assessment of growth, development and iron balance in the years after transplantation reveals residual problems requiring treatment despite cure of thalassemia. New therapies of beta-thalassemia are still being developed, both supportive and curative in nature. Supportive care improvements include oral chelation and methods to increase HbF production. Advances in curative modalities include use of new sources of stem cells, such as cord blood and fetal liver. In the future, gene therapy may allow for cure of the older patient without the mortality and morbidity of allogenic transplantation. Treatment of thalassemia major requires consideration of the available therapeutic options for each patient, and the risk/benefit ratio of a supportive versus curative approach.