Allogeneic stem cell transplantation for Evans syndrome

Evans syndrome: clinical perspectives, biological insights and treatment modalities

Evans syndrome (ES) is a rare and chronic autoimmune disease characterized by autoimmune hemolytic anemia and immune thrombocytopenic purpura with a positive direct anti-human globulin test. It is classified as primary and secondary, with the frequency in patients with autoimmune hemolytic anemia being 37%–73%. It predominates in children, mainly due to primary immunodeficiencies or autoimmune lymphoproliferative syndrome. ES during pregnancy is associated with high fetal morbidity, including severe hemolysis and intracranial bleeding with neurological sequelae and death. The clinical presentation can include fatigue, pallor, jaundice and mucosal bleeding, with remissions and exacerbations during the person’s lifetime, and acute manifestations as catastrophic bleeding and massive hemolysis. Recent molecular theories explaining the physiopathology of ES include deficiencies of CTLA-4, LRBA, TPP2 and a decreased CD4/CD8 ratio. As in other autoimmune cytopenias, there is no established evidence-based treatment and steroids are the first-line therapy, with intravenous immunoglobulin administered as a life-saving resource in cases of severe immune thrombocytopenic purpura manifestations. Second-line treatment for refractory ES includes rituximab, mofetil mycophenolate, cyclosporine, vincristine, azathioprine, sirolimus and thrombopoietin receptor agonists. In cases unresponsive to immunosuppressive agents, hematopoietic stem cell transplantation has been successful, although it is necessary to consider its potential serious adverse effects. In conclusion, ES is a disease with a heterogeneous course that remains challenging to patients and physicians, with prospective clinical trials needed to explore potential targeted therapy to achieve an improved long-term response or even a cure.

Diagnosis and management of chronic and refractory immune cytopenias in children, adolescents, and young adults

Children, adolescents, and young adults with chronic refractory autoimmune cytopenias represent a rare but challenging group of patients, who are managed frequently by pediatric hematologists. Novel diagnostic tests and genomic discoveries are refining historical diagnoses of Evans syndrome and common variable immunodeficiency, while also elucidating the cellular and molecular basis for these disorders. Genetic characterization of chronic and refractory autoimmune cytopenias has led to targeted therapies with improved clinical outcomes and fewer off-target toxicities. In this review, we focus on the appropriate diagnostic workup, expanded genetic testing, and novel treatment opportunities that are available for these challenging patients.

Natural History, Pathogenesis, and Treatment of Evans Syndrome in Children

Primary Evans syndrome (ES) is defined by the concurrent or sequential occurrence of immune thrombocytopenia and autoimmune hemolytic anemia in the absence of an underlying etiology. The syndrome is characterized by a chronic, relapsing, and potentially fatal course requiring long-term immunosuppressive therapy. Treatment of ES is hardly evidence-based. Corticosteroids are the mainstay of therapy. Rituximab has emerged as the most widely used second-line treatment, as it can safely achieve high response rates and postpone splenectomy. An increasing number of new genetic defects involving critical pathways of immune regulation identify specific disorders, which explain cases of ES previously reported as "idiopathic".

Evans Syndrome Secondary to Common Variable Immune Deficiency

Evans syndrome is an underdiagnosed condition consisting of simultaneous or sequential combination of autoimmune hemolytic anemia and immune-mediated thrombocytopenia. We report a case of severe Evans syndrome presenting as altered mental status, a rare presenting sign of the disease. This case highlights the difficulty in diagnosing Evans syndrome and provides a review of the literature and management strategies for treating the disorder.

Primary Evan Syndrome With Disseminated Intravascular Coagulation Suggests Progressive Immune Dysregulation and Early Immunosuppressive Intervention is Key to Improving Outcomes

Evan syndrome (ES) is a rare hematological disorder that involves 2 or more immune cytopenias. It usually includes autoimmune hemolytic anemia and autoimmune thrombocytopenia. Although occasionally associated with immune neutropenia, its association with disseminated intravascular coagulation (DIC) is rare. And, early diagnosis with appropriate intervention is important because mortality from ES is known to be greater than that of isolated immune hemolytic anemia and probably worse in the presence of DIC. Considering that the presence of DIC can make the diagnosis of ES challenging, a strong clinical suspicion is important as early initiation of therapy is critical to reducing the morbidity and mortality associated with this syndrome. We report a case of ES complicated by DIC.

Treatment-refractory multi-lineage autoimmune cytopenia after unrelated cord blood transplantation: remission after combined bortezomib and vincristine treatment

Autoimmune cytopenias (AC) after allogeneic hematopoietic stem cell transplantation (HSCT) are associated with a dismal prognosis. We describe a 1-year-old female with multi-lineage AC occurring on day +43 after HSCT. Multi-agent treatment with high-dose prednisolone, intravenous immunoglobulins, cyclosporine A, mycophenolate mofetil, sirolimus, and rituximab was unsuccessful. Combined treatment with bortezomib and vincristine in addition to ongoing immunosuppressive therapy was started on day +414 with transfusion-independence after day +444. Immunosuppressants were tapered until day +638. On day +1,121 the patient remained in remission. Bortezomib with vincristine may be a promising treatment modality for refractory AC after HSCT that requires further study.

Transplantation for autoimmune diseases in north and South America: a report of the Center for International Blood and Marrow Transplant Research

Hematopoietic cell transplantation (HCT) is an emerging therapy for patients with severe autoimmune diseases (AID). We report data on 368 patients with AID who underwent HCT in 64 North and South American transplantation centers reported to the Center for International Blood and Marrow Transplant Research between 1996 and 2009. Most of the HCTs involved autologous grafts (n = 339); allogeneic HCT (n = 29) was done mostly in children. The most common indications for HCT were multiple sclerosis, systemic sclerosis, and systemic lupus erythematosus. The median age at transplantation was 38 years for autologous HCT and 25 years for allogeneic HCT. The corresponding times from diagnosis to HCT were 35 months and 24 months. Three-year overall survival after autologous HCT was 86% (95% confidence interval [CI], 81%-91%). Median follow-up of survivors was 31 months (range, 1-144 months). The most common causes of death were AID progression, infections, and organ failure. On multivariate analysis, the risk of death was higher in patients at centers that performed fewer than 5 autologous HCTs (relative risk, 3.5; 95% CI, 1.1-11.1; P = .03) and those that performed 5 to 15 autologous HCTs for AID during the study period (relative risk, 4.2; 95% CI, 1.5-11.7; P = .006) compared with patients at centers that performed more than 15 autologous HCTs for AID during the study period. AID is an emerging indication for HCT in the region. Collaboration of hematologists and other disease specialists with an outcomes database is important to promote optimal patient selection, analysis of the impact of prognostic variables and long-term outcomes, and development of clinical trials.

Stem cell transplantation for patients with Evans syndrome

Evans syndrome (ES) is a chronic hematological disorder characterized by autoimmune hemolytic anemia and immune-mediated thrombocytopenia that often requires profound and long-term immunosuppression. Only a few small case series or single case studies of autologous and allogeneic hematopoietic stem cell transplantation (HSCT) in patients with ES have been reported in the literature, with long-term remissions being observed after both autologous and allogeneic HSCT. Patients with ES suffering from refractory disease, multiple relapses and serious disease-related complications should be offered allogeneic HSCT, which is the only treatment with curative potential. Autologous HSCT might be preferable in patients with serious pre-existing comorbidities lacking an HLA-identical donor. Owing to the rarity of this disease and the small number of patients receiving HSCT for ES, prospective controlled studies on this approach are not available. A prospective registration of patients transplanted for ES would allow the development of optimal transplant strategies.

Increased lymphocyte Fas expression and high incidence of common variable immunodeficiency disorder in childhood Evans' syndrome

Evans' syndrome (ES) is characterized by autoimmune hemolytic anemia and thrombocytopenia and has been associated with immune deficiency and lymphoproliferation in some cases. Abnormalities of Fas-mediated apoptosis have been reported in various immune dysregulation disorders associated with autoimmunity and lymphoproliferation. We measured lymphocyte Fas expression and Fas-mediated T lymphocyte apoptosis in 7 children with ES, 7 with acute idiopathic thrombocytopenic purpura (ITP) and 9 with non-immune-mediated disorders. Patients with ES had higher Fas expression on peripheral blood T and B lymphocytes (P<0.001 and P=0.046, respectively) and increased Fas-mediated elimination of activated T lymphocytes compared with the control groups. While two ES patients had panhypogammaglobulinemia at testing, three more developed it later, reaching a frequency of 83%. Some children with ES have increased lymphocyte Fas expression and Fas-mediated T lymphocyte apoptosis and these may be early signs of common variable immunodeficiency disorder in ES.

Management of a young patient with combined autoimmunity: Evans syndrome: a case report

Management of patients with autoimmune disease can present a challenge for clinicians. Combinations of autoimmune disorders carry a worse prognosis and are often difficult to diagnose. Evans syndrome is a rare hematologic disorder characterized by the concurrent presentation of autoimmune hemolytic anemia and immune thrombocytopenic purpura. This paper reports the first case of the dental management of a young patient with Evans, discusses the current literature surrounding the differential diagnosis and treatment of Evans syndrome, and suggests a guide for the oral medicine, pediatric dentist, or hospital dental clinician when treating these patients.

Catastrophic relapse of Evans syndrome five years after allogeneic BMT notwithstanding full donor chimerism. Terminal hemolytic-uremic syndrome

A patient with severe Evans syndrome received an allo-BMT from his HLA-identical sister on November, 2000. Full marrow and blood donor chimerism were achieved only after 5 donor lymphocyte infusions (DLI), and coincided with complete clinical remission and disappearence of auto-antibodies. Five years later, hemolytic anemia recurred with rapid increase of serum bilirubin to over 50 mg%: he responded to combined therapy, but died on day +17 from admission of an acute hemolytic uremic syndrome (HUS). All circulating blood cells, including erythrocytes, were 100% donor. Ex vivo cultured and expanded T and B cells from the peripheral blood were also 100% donor. The supernatants from B cell cultures, containing either IgM or IgG, did not react with a panel of erythrocytes. Thus in this typical autoimmune disease with a predominant B cell pathogenesis the donor immune system resulted "innocent of autoimmunity". The persistence of long-lived recipient autoreactive plasma-cell lines in survival niches, still producing autoantibodies, may be hypothesized for this and similar cases. The postulated graft-versus-autoimmunity (GVA) effect was apparently not sufficient to eradicate autoimmunity in this patient.

Successful unrelated cord blood transplantation in a 7-year-old boy with Evans syndrome refractory to immunosuppression and double autologous stem cell transplantation

Evans syndrome is an autoimmunopathy characterized by thrombocytopenia and autoimmune hemolytic anemia with poor response to immunosuppression. A 2-yr-old boy with Evans syndrome showed only short-lasting responses to immunosuppressive treatment including double autologous peripheral stem cell transplantation (SCT). Intracranial bleeding required emergency splenectomy and external ventricular drainage. Unrelated umbilical cord blood was given following conditioning with busulfan, thiotepa, etoposide and antithymocyte globulin. One year after SCT the patient shows stable blood counts without immunosuppression. This is the first child reported with Evans syndrome successfully treated by means of unrelated cord blood transplantation.

Management of Evans syndrome

Evans syndrome is an uncommon condition defined by the combination (either simultaneously or sequentially) of immune thrombocytopenia (ITP) and autoimmune haemolytic anaemia (AIHA) with a positive direct antiglobulin test (DAT) in the absence of known underlying aetiology. This condition generally runs a chronic course and is characterised by frequent exacerbations and remissions. First-line therapy is usually corticosteroids and/or intravenous immunoglobulin, to which most patients respond; however, relapse is frequent. Options for second-line therapy include immunosuppressive drugs, especially ciclosporin or mycophenolate mofetil; vincristine; danazol or a combination of these agents. More recently a small number of patients have been treated with rituximab, which induces remission in the majority although such responses are often sustained for <12 months and the long-term effects in children are unclear. Splenectomy may also be considered although long-term remissions are less frequent than in uncomplicated ITP. For very severe and refractory cases stem cell transplantation (SCT) offers the only chance of long-term cure. The limited data available suggest that allogeneic SCT may be superior to autologous SCT but both carry risks of severe morbidity and of transplant-related mortality. Cure following reduced-intensity conditioning has now been reported and should be considered for younger patients in the context of controlled clinical trials.

Syndrome d'Evans : étude rétrospective de la société d'hématologie et d'immunologie pédiatrique (36 cas)

Evans' Syndrome (ES) is defined as the combination of immune thrombocytopenia (ITP) and autoimmune haemolytic anemia (AIHA), in the absence of any known underlying etiology. Pathophysiology, epidemiology and outcome remain unclear.

POPULATION

Thirty-six children (20 male, 16 female), who were diagnosed in the SHIP french centres (Société d'hématologie et d'immunologie pédiatrique) between 1990 and 2002 with ES, were included in this retrospective study.

RESULTS

Median age at diagnosis was 4 years. In 21 children, ES occurred in the setting of consanguinity, family history of autoimmune/inflammatory disease, associated autoimmune disorder or immunoregulatory abnormalities (serum imunoglobulins, peripheral blood lymphocytes subsets, low level of the C3-C4 complement components, nuclear antibodies). Several successive treatments were used in this serie (median: 3, range: 0-10) including corticosteroid therapy (35/36), intravenous immunoglobulins (32/36), immunosuppressive agents (14/36), splenectomy (9/36) and anti CD 20 monoclonal antibodies (6/36). Patients with a low level of serum immunoglobulins were more often non-responders to corticosteroidtherapy/intravenous immunoglobulins and required more frequently further therapy (P=0.03). Three patients died (intracranial bleeding, N=2, Guillain-Barre syndrome; N=1).

CONCLUSION

ES was a severe, life-threatening disease, requiring aggressive immunosuppressive therapy in as many as half the patients. Our forthcoming study aims to (i) describe homogeneously-studied and prospectively-analysed cohort of childhood ES, (ii) separate ES from specific immune deficiency (especially fas gene mutations), generalised autoimmune/inflammatory disorders and genetic diseases, (iii) identify well-defined ES subsets, (iv) establish prognostic factors and optimal treatment within these subsets.

Treatment of severe autoimmune disease by stem-cell transplantation

Transplantation of haematopoietic stem cells--cells capable of self renewing and reconstituting all types of blood cell--can treat numerous lethal diseases, including leukaemias and lymphomas. It may now be applicable for the treatment of severe autoimmune diseases, such as therapy-resistant rheumatoid arthritis and multiple sclerosis. Studies in animal models show that the transfer of haematopoietic stem cells can reverse autoimmunity, and several mechanistic pathways may explain this phenomenon. The outcome of ongoing clinical trials, as well as of studies in patients and animal models, will help to determine the role that stem-cell transplantation can play in the treatment of autoimmune diseases.

Haemopoietic stem cell transplantation in autoimmune diseases: a European perspective

The potential of haemopoietic stem cell transplantation (HSCT) for the treatment of autoimmune and inflammatory diseases was originally supported by almost three decades of animal experiments and by the serendipitous remissions of autoimmune disease observed in patients undergoing transplantation for haematological disorders. Improved safety of both autologous and allogeneic HSCT over the last decade has been followed by increasing acceptance of HSCT as an experimental treatment for severe autoimmune diseases that are resistant to conventional treatment. International databases have collated over 700 procedures performed specifically for a variety of autoimmune diseases. Phase III clinical trials are in progress for some diseases. This review provides a comprehensive update on the efficacy and toxicity of HSCT in severe autoimmune disease. Future directions in the context of other evolving therapies are discussed.

Nonmyeloablative allogeneic bone marrow transplantation for treatment of childhood overlap syndrome and small vessel vasculitis

A 13-year-old Caucasian female with a systemic connective tissue disease (overlap syndrome with pulmonary vasculitis) underwent nonmyeloablative allogeneic BMT after failure of prolonged combination immunosuppressives to induce remission. The procedure also included cotransplantation of donor bone chips as a source of stromal cells. The unique protocol allowed good engraftment of hematopoietic (>95%) and bone core stromal cells (>60%). The patient was clinically improved, stable, and off all immunosuppressive medications 36 months post-transplant. To our knowledge, this is the first pediatric nonmyeloablative BMT with cotransplantation of stromal cells solely for treatment of an autoimmune disease.

Rituximab for refractory Evans syndrome and other immune-mediated hematologic diseases

The authors describe a 21-year-old man with long-lasting Evans syndrome refractory to corticosteroids and immunosuppressive agents; the patient responded to four weekly infusions of rituximab. The patient relapsed with thrombocytopenia 7 months post-therapy and was successfully re-treated with two weekly doses of the same monoclonal antibody. He remains in remission for 7-plus months after the second treatment. Therapy was well tolerated, and no infectious complications occurred, despite avoiding administration of prophylactic gammaglobulin. Rituximab appears safe and modestly effective in a variety of immune-mediated hematologic diseases, including autoimmune hemolytic anemia, chronic immune thrombocytopenia, Evans syndrome, pure red cell aplasia, mixed type II cryoglobulinemia, cold agglutinin disease, and Waldenstrom's macroglobulinemia. However, as most of the published literature consists of case reports and small case series, international collaboration is essential in order to better define the efficacy and safety of this agent in children and adults with hematologic diseases.

Haematopoetic stem cell transplantation for refractory autoimmune cytopenia

This study describes the outcome of patients receiving haematopoietic stem cell transplantation (HSCT) to treat severe refractory autoimmune cytopenia. The registry of the European Group of Blood and Marrow Transplantation holds data on 36 patients receiving 38 transplants, the first transplant was autologous for 27 and allogeneic for nine patients. Patients had autoimmune haemolytic anaemia (autologous: 5; allogeneic: 2), Evans's syndrome (autologous: 2; allogeneic: 5); immune thrombocytopenia (autologous: 12), pure red cell aplasia (autologous: 4; allogeneic: 1), pure white cell aplasia (autologous: 1; allogeneic 1), or thrombotic thrombocytopenic purpura (autologous: 3). Patients had longstanding disease having failed multiple prior treatments. Among 26 evaluable patients mobilized for autologous HSCT, three died of treatment-related causes, one died of disease progression, seven were non-responders, six patients had transient responses and nine had continuous partial or complete remission. Of the seven evaluable patients receiving allogeneic HSCT, one died of treatment-related complications, one with transient response died of progressive disease and five had a continuous response. Autologous and allogeneic HSCT may induce a response in a subset of patients with autoimmune cytopenia of long duration albeit at the price of considerable toxicity.

Targeted bone marrow radioablation with 153Samarium-lexidronam promotes allogeneic hematopoietic chimerism and donor-specific immunologic hyporesponsiveness

BACKGROUND

Transplantation tolerance, defined as acceptance of a graft by an otherwise fully immunocompetent host, has been an elusive goal. Although robust tolerance has been achieved by the induction of stable hematopoietic chimerism after bone marrow transplantation, lethal or sublethal radiation conditioning used to induce long-term chimerism precludes its clinical use. We studied whether targeted delivery of radiation to bone marrow could allow for bone marrow cell (BMC) engraftment, chimerism, and donor-specific tolerance in the absence of the side effects associated with external irradiation.

METHODS

We administered a radioactive bone-seeking compound (Samarium-Lexidronam, Quadramet, Berlex Laboratories, Wayne, NJ) together with transient T-cell costimulatory blockade to recipient mice. Allogeneic BMCs were given 7 or 14 days after preconditioning. Costimulatory blockade was obtained by the use of an anti-CD154 antibody for 4 weeks. Chimerism was assessed by flow cytometry. Mice then received donor-specific and third-party skin grafts. Graft survival was analyzed with mechanisms of donor-specific hyporesponsiveness.

RESULTS

High levels of stable chimerism across an allogeneic barrier were achieved in mice by a single administration of Samarium-Lexidronam, transient T-cell costimulatory blockade, and BMC transplantation. A large percentage of chimeric animals retained donor-derived skin grafts for more than 120 days without requiring additional immunosuppression, suggesting that harsh cytotoxic preconditioning is not necessary to achieve stable chimerism and donor specific hyporesponsiveness. Analysis of the T-cell repertoire in chimeras indicates T-cell deletional mechanisms.

CONCLUSIONS

These data broaden the potential use of BMC transplantation for tolerance induction and argue for its potential in treating autoimmune diseases.

Rituximab for immune cytopenia in adults: idiopathic thrombocytopenic purpura, autoimmune hemolytic anemia, and Evans syndrome

OBJECTIVE

To evaluate the efficacy of rituximab for the treatment of adult patients with immune cytopenia, including idiopathic thrombocytopenic purpura (ITP), autoimmune hemolytic anemia, and Evans syndrome.

PATIENTS AND METHODS

We retrospectively reviewed the medical charts of all patients treated with rituximab for immune cytopenia at the Mayo Clinic in Rochester, Minn, through January 1, 2003. Fourteen patients (median age at first diagnosis, 51 years; range, 21-79 years) were identified who received 1 or more treatment courses of rituximab for treatment of refractory ITP (12 patients), autoimmune hemolytic anemia (AIHA) (5 patients), or both ITP and AIHA (classified as Evans syndrome) (4 patients). Data regarding age, diagnosis, date of diagnosis, previous treatments, comorbid conditions, blood cell counts before taking rituximab, number of rituximab treatments, and response to treatment were extracted and analyzed.

RESULTS

Of 12 patients treated for ITP, 6 were receiving corticosteroid-based treatment either alone or combined with other immunosuppressive therapy at the time they received rituximab. Complete remission occurred in 5 (42%) of 12 patients with ITP and in 2 (40%) of 5 patients with AIHA. Response to rituximab in patients with Evans syndrome was seen in either ITP or AIHA, but not both. Complete response was often durable in ITP. Responses were seen in both splenectomized and nonsplenectomized patients.

CONCLUSIONS

Our findings, considered with the results of other studies, suggest that rituximab deserves early consideration as salvage therapy for immune cytopenias that are refractory to both corticosteroid treatment and splenectomy. This series represents the largest series of adult patients with AIHA and Evans syndrome.

The promise of hematopoietic stem cell transplantation for autoimmune diseases

Hematopoietic stem cell transplantation (HSCT) is being increasingly utilized for the treatment of a whole spectrum of severe autoimmune diseases refractory to conventional therapy. Although allogeneic HSCT has been followed by durable complete remission in a restricted number of patients with coincidental disease, the autologous procedure is generally preferred because of its lesser toxicity. Most autoimmune diseases are the consequence of a multistep process, mainly originating from the interplay of genetic, environmental, and hormonal factors. It has been postulated that if immunosuppressive regimens can eliminate or effectively reduce the level of autoreactive T and B cells, then regeneration of de novo immunity even in the autologous setting may bypass the initial breakdown of self-tolerance and ensure prolonged disease remission. As mentioned in a recent review of this field, protocol design including conditioning regimen, patient selection, stem cell source and final outcome are likely to be disease-specific. The following is a summary of the 2002 International Bone Marrow Transplantation Registry/American Society of Blood and Bone Marrow Transplantation (IBMTR/ASBMT) satellite symposium in Orlando, Florida on 24 February 2002 on 'Expanding the Promise of Hematopoietic Stem Cell Transplantation in Autoimmune Diseases'.

Refractory Evans' syndrome treated with allogeneic SCT followed by DLI. Demonstration of a graft-versus-autoimmunity effect

Evans' syndrome, a combination of autoimmune haemolytic anaemia and autoimmune (idiopathic) thrombocytopenic purpura, is generally harder to treat and more refractory than the single entities. In a male patient with refractory disease, predominantly thrombocytopenic, an allogeneic reduced intensity BMT from his human leukocyte antigen (HLA)-identical sister was followed by a dramatic platelet peak while he was still experiencing initial engraftment (presumably of autologous origin), but subsequently by progressive relapse associated with mixed chimerism. Five gradually incremental DLI achieved complete donor chimerism, which was associated not only with grade II graft-versus-host disease (GVHD), but also with complete clinical and biological remission for 2 years post-transplant. Long-term FU is necessary before claiming that allogeneic stem cell transplantation (SCT) is capable of curing an autoimmune blood disease. However, there is evidence for a graft-versus-autoimmunity effect in this case.

High-dose cyclophosphamide with autologous lymphocyte-depleted peripheral blood stem cell (PBSC) support for treatment of refractory chronic autoimmune thrombocytopenia

Patients with refractory chronic autoimmune thrombocytopenia (AITP) have a significant risk of morbidity and mortality related to hemorrhage. High-dose (HD) cytotoxic therapy may produce remissions but entails risks related to myelosuppression. Hematopoietic stem cell support with lymphocyte-depleted grafts may accelerate hematologic recovery and concomitantly reduce repopulation by autoreactive immunocytes. Fourteen patients with chronic AITP, in whom multiple prior therapies including corticosteroids, splenectomy, intravenous immunoglobulin, and various cytotoxic or immunomodulatory regimens had failed, were treated with HD cyclophosphamide (50 mg/kg/d) and autologous granulocyte colony-stimulating factor (G-CSF)-mobilized leukocytes depleted of lymphocytes by immunomagnetic CD34(+) selection. There were no significant adverse events related to G-CSF, intravenous device insertion, or leukapheresis. Treatment-related complications included transient hemorrhagic cystitis (1 patient), vaginal bleeding (2 patients), gastrointestinal bleeding (1 patient), epistaxis (1 patient), and antibiotic-responsive febrile neutropenia (all patients). The mean time to absolute neutrophil count (ANC) more than 500/mm(3) was 9 +/- 0.6 days. Eight patients experienced antibiotic-responsive gram-positive bacteremia. A median of 2 platelet transfusions was required for stem cell mobilization, intravenous catheter insertion, and apheresis and a median of 9 platelet transfusions was required during hematopoietic recovery. Six patients obtained durable complete responses (platelet counts > 100 000/mm(3) without other therapy) with maximum follow-up of 42 months. Two additional patients obtained durable partial responses (platelet counts significantly increased over baseline with reduced medication requirements and cessation of bleeding complications). This therapeutic approach is feasible for patients with severe chronic AITP, a substantial proportion of whom may obtain durable remissions. Larger controlled trials are recommended.

Clinical developments in reduced intensity haematopoietic stem cell transplantation

Reduced intensity conditioning regimens prior to allogeneic haematopoietic stem cell transplantation (HSCT) were first described in the 1970s, and have developed rapidly over the past few years to become an important consideration as immunological therapy for patients with haematological and selected solid organ malignancies. This is especially the case for patients considered ineligible for conventional allogeneic HSCT due to age or medical contraindications. With the development of minimally toxic conditioning regimens, additional potential applications include the provision of normal haematopoietic repopulating cells to patients who have an inherited gene defect such as an haemoglobinopathy or an inborn error of metabolism. Intensive investigation in stem cell research promises to provide dramatic new insights into human biology, paving the way for new therapeutic approaches to malignant and inherited disorders.

Induction of tolerance in autoimmune diseases by hematopoietic stem cell transplantation: getting closer to a cure?

Hematopoietic stem cells (HSCs) are the earliest cells of the immune system, giving rise to B and T lymphocytes, monocytes, tissue macrophages, and dendritic cells. In animal models, adoptive transfer of HSCs, depending on circumstances, may cause, prevent, or cure autoimmune diseases. Clinical trials have reported early remission of otherwise refractory autoimmune disorders after either autologous or allogeneic hematopoietic stem cell transplantation (HSCT). By percentage of transplantations performed, autoimmune diseases are the most rapidly expanding indication for stem cell transplantation. Although numerous editorials or commentaries have been previously published, no prior review has focused on the immunology of transplantation tolerance or development of phase 3 autoimmune HSCT trials. Results from current trials suggest that mobilization of HSCs, conditioning regimen, eligibility and exclusion criteria, toxicity, outcome, source of stem cells, and posttransplantation follow-up need to be disease specific. HSCT-induced remission of an autoimmune disease allows for a prospective analysis of events involved in immune tolerance not available in cross-sectional studies.