Treatment of aplastic anemia with antilymphocyte globulin and methylprednisolone with or without cyclosporine. The German Aplastic Anemia Study Group

Horse versus rabbit antithymocyte globulin in acquired aplastic anemia

BACKGROUND

In severe acquired aplastic anemia, hematopoietic failure is the result of immune-mediated destruction of bone marrow stem and progenitor cells. Immunosuppressive therapy with antithymocyte globulin (ATG) plus cyclosporine is an effective alternative to stem-cell transplantation and improves blood counts and survival. Although horse ATG is the standard therapy, rabbit ATG is more potent in depleting peripheral-blood lymphocytes and is preferred in other clinical circumstances.

METHODS

From December 2005 through July 2010, we performed a randomized trial comparing these two ATG formulations in conventional regimens. Patients were treated at a single facility. The primary outcome was hematologic response at 6 months, as determined by blood counts. The study was designed to enroll 60 patients each for the rabbit-ATG and horse-ATG groups and was powered to detect a difference of 25 percentage points in the response rate.

RESULTS

A large, unexpected difference was observed in the rate of hematologic response at 6 months in favor of horse ATG (68%; 95% confidence interval [CI], 56 to 80) as compared with rabbit ATG (37%; 95% CI, 24 to 49; P<0.001). Overall survival at 3 years also differed, with a survival rate of 96% (95% CI, 90 to 100) in the horse-ATG group as compared with 76% (95% CI, 61 to 95) in the rabbit-ATG group (P=0.04) when data were censored at the time of stem-cell transplantation, and 94% (95% CI, 88 to 100) as compared with 70% (95% CI, 56 to 86; P=0.008) in the respective groups when stem-cell-transplantation events were not censored.

CONCLUSIONS

In a randomized study, rabbit ATG was inferior to horse ATG as a first treatment for severe aplastic anemia, as indicated by hematologic response and survival. (Funded by the Intramural Research Program of the National Institutes of Health; ClinicalTrials.gov number, NCT00260689.).

Aplastic anemia: immunosuppressive therapy in 2010

Acquired aplastic anemia (AA) is the typical bone marrow failure syndrome characterized by an empty bone marrow; an immune-mediated pathophysiology has been demonstrated by experimental works as well as by clinical observations. Immunusuppressive therapy (IST) is a key treatment strategy for aplastic anemia; since 20 years the standard IST for AA patients has been anti-thymocyte globuline (ATG) plus cyclosporine A (CyA), which results in response rates ranging between 50% and 70%, and even higher overall survival. However, primary and secondary failures after IST remain frequent, and to date all attempts aiming to overcome this problem have been unfruitful. Here we review the state of the art of IST for AA in 2010, focusing on possible strategies to improve current treatments. We also discuss very recent data which question the equality of different ATG preparations, leading to a possible reconsideration of the current standards of care for AA patients.

Decreased infection-related mortality and improved survival in severe aplastic anemia in the past two decades

BACKGROUND

Persistent neutropenia associated with severe aplastic anemia (SAA) is an important risk factor for development of life-threatening infections. Earlier studies underscored the high mortality associated with invasive fungal infections (IFIs) in SAA. However, little is known about the current patterns of infections and the impact of advances in anti-infective therapy on survival in SAA.

METHODS

We reviewed the records of 174 patients with SAA admitted to the Hematology Branch at NHLBI from 1989 to 2008 who were unresponsive to initial immunosuppressive therapy (IST) at 6 months. Three patient groups determined by IST protocol and time interval were compared: group 1 (43 patients; December 1989-October 1996), group 2 (51 patients; November 1996-October 2002), and group 3 (80 patients; November 2002-April 2008). Outcome variables included infections, patterns of resistance, survival, and infection-related mortality.

RESULTS

During the past 2 decades, infection-related mortality decreased from 37% in group 1 to 11% in group 3 (P < .001), and the frequency of IFIs decreased from 49% in group 1 to 8% in group 3 (P < .001). Overall 5-year survival for all patients (n = 420) increased from 64% in group 1 to 79% in group 3 (P < .001). Among non-responders (n = 174), it increased from 23% in group 1 to 57% in group 3 (P < .001). In multivariate analysis, younger age, absolute neutrophil count > 200 cells/μL before IST, absence of IFIs, and use of voriconazole were independently predictive of survival.

CONCLUSION

During the past 2 decades, there has been a significant decrease in IFIs, infection-related mortality, and overall mortality in patients with SAA unresponsive to initial IST.

Efficacy of rabbit anti-thymocyte globulin in severe aplastic anemia

BACKGROUND

A combination of horse anti-thymocyte globulin and cyclosporine produces responses in 60-70% of patients with severe aplastic anemia. We performed a phase II study of rabbit anti-thymocyte globulin and cyclosporine as first-line therapy for severe aplastic anemia.

DESIGN AND METHODS

Twenty patients with severe aplastic anemia treated with rabbit anti-thymocyte globulin were compared to 67 historical control cases with matched clinical characteristics treated with horse anti-thymocyte globulin.

RESULTS

Response rates at 3, 6 and 12 months were similar for patients treated with rabbit anti-thymocyte globulin or horse anti-thymocyte globulin: 40% versus 55% (P=0.43), 45% versus 58% (P=0.44) and 50% versus 58% (P=0.61), respectively. No differences in early mortality rates or overall survival were observed. We then performed multivariable analyses of response at 6 months and overall survival and identified the presence of a paroxysmal nocturnal hemoglobinuria clone (P=0.01) and a pretreatment absolute reticulocyte count greater than 30×10(9)/L (P=0.007) as independent predictors of response and younger age (P=0.003), higher pretreatment absolute neutrophil (P=0.02) and absolute lymphocyte counts (P=0.03) as independent predictors of overall survival. None of the immunogenetic polymorphisms studied was predictive of response to immunosupressive therapy.

CONCLUSIONS

Despite reports suggesting differences in biological activity of different anti-thymocyte globulin preparations, rabbit and horse anti-thymocyte globulin appear to have a similar efficacy for up-front treatment of severe aplastic anemia. Clinicaltrial.gov: NCT01231841).

Immunosuppressive therapies in the management of immune-mediated marrow failures in adults: where we stand and where we are going

Immunosuppression is a key treatment strategy for aplastic anaemia (AA) and the related immune-mediated bone marrow failure syndromes (BMFS). For the last 20 years the standard immunosuppressive regimen for AA patients has been anti-thymocyte globulin (ATG) plus ciclosporin A (CyA), which results in response rates ranging between 50% and 70%, and even higher overall survival. However, primary and secondary failures after immunosuppressive therapy remain frequent, and to date all attempts aiming to overcome this problem have been unfruitful. This article reviews the state of the art of current immunosuppressive therapies for AA, focusing on open questions linked to standard immunosuppressive treatment, and on experimental immunosuppressive strategies which could lead to future improvement of current treatments. Specific immunosuppressive strategies employed for other BMFS, such as lineage-restricted marrow failures, myelodysplastic syndromes and large granular lymphocyte leukaemia-associated cytopenias, are also briefly discussed.

Optimization of therapy for severe aplastic anemia based on clinical, biologic, and treatment response parameters: conclusions of an international working group on severe aplastic anemia convened by the Blood and Marrow Transplant Clinical Trials Network, March 2010

Although recent advances in therapy offer the promise for improving survival in patients with severe aplastic anemia (SAA), the small size of the patient population, lack of a mechanism in North America for longitudinal follow-up of patients, and inadequate cooperation among hematologists, scientists, and transplant physicians remain obstacles to conducting large studies that would advance the field. To address this issue, the Blood and Marrow Transplant Clinical Trials Network (BMT CTN) convened a group of international experts in March 2010 to define the most important questions in the basic science, immunosuppressive therapy (IST), and bone marrow transplantation (BMT) of SAA and propose initiatives to facilitate clinical and biologic research. Key conclusions of the working group were: (1) new patients should obtain accurate, expert diagnosis and early identification of biologic risk; (2) a population-based SAA outcomes registry should be established in North America to collect data on patients longitudinally from diagnosis through and after treatment; (3) a repository of biologic samples linked to the clinical data in the outcomes registry should be developed; (4) innovative approaches to unrelated donor BMT that decrease graft-versus-host disease are needed; and (5) alternative donor transplantation approaches for patients lacking HLA-matched unrelated donors must be improved. A partnership of BMT, IST, and basic science researchers will develop initiatives and partner with advocacy and funding organizations to address these challenges. Collaboration with similar study groups in Europe and Asia will be pursued.

Th17 immune responses contribute to the pathophysiology of aplastic anemia

T helper type 17 (Th17) cells have been characterized based on production of interleukin-17 (IL-17) and association with autoimmune diseases. We studied the role of Th17 cells in aplastic anemia (AA) by isolating Th17 cells from patients blood (n = 41) and bone marrow (BM) mononuclear cells (n = 7). The frequency and total number of CD3(+)CD4(+)IL-17-producing T cells were increased in AA patients at presentation compared with healthy controls (P = .0007 and .02, respectively) and correlated with disease activity. There was an inverse relationship between the numbers of Th17 cells and CD4(+)CD25(high)FoxP3(+) regulatory T cells (Tregs) in the blood of AA patients. Concomitant with the classical Th1 response, we detected the presence of CD4(+) and CD8(+) IL-17-producing T cells in a mouse model of lymph node infusion-induced BM failure. Although anti-IL-17 treatment did not abrogate BM failure, early treatment with the anti-IL-17 antibody reduced the severity of BM failure with significantly higher platelet (P < .01) and total BM cell (P < .05) counts at day 10. Recipients that received anti-IL-17 treatment had significantly fewer Th1 cells (P < .01) and more Treg cells (P < .05) at day 10 after lymph node infusion. Th17 immune responses contribute to AA pathophysiology, especially at the early stage during disease progression.

Outcome of allogeneic hematopoietic cell transplantation from HLA-identical siblings for severe aplastic anemia in patients over 40 years of age

Patients with severe aplastic anemia (SAA) over 40 years of age are often not offered treatment with hematopoietic cell transplantation (HCT) because of concerns about treatment-related morbidity or mortality. To evaluate this risk, we analyzed outcomes after allogeneic HCT from HLA-identical sibling donors for all older patients with SAA at our center since 1988. The 23 consecutive patients ranged in age from 40 to 68 years. The conditioning regimen was cyclophosphamide (200 mg/kg) and horse antithymocyte globulin. Methotrexate and cyclosporine were given for postgrafting immunosuppression. The cumulative incidences of grades II, III, and IV acute graft-versus-host-disease were 30%, 4%, and 0%, respectively; that for chronic GVHD was 26%. With a median follow-up of 9.1 years, overall survival was 65%. Documented infections within 1 month before HCT were significantly associated with risk of early treatment-related mortality (P < .001). The median time to discontinuation of posttransplant immunosuppression was 6.2 (range: 5.9-92.0) months. Three patients developed superficial basal cell carcinoma between 5.5 and 15 years after HCT. Our data favor a practice of extending HLA-identical sibling HCT for treatment of SAA in patients older than 40 years of age who are without significant medical comorbidities.

Low concentration of serum haptoglobin has impact on understanding complex pathophysiology in patients with acquired bone marrow failure syndromes

To clarify whether measurement of serum haptoglobin (Hp) has impact on understanding pathophysiology in bone marrow failure (BMF) syndromes, we investigated concentrations of serum Hp by nephelometric procedure in 156 Japanese patients with BMF, including 54 aplastic anemia (AA), 50 paroxysmal nocturnal hemoglobinuria (PNH), and 52 myelodysplastic syndromes (MDS) patients. The frequencies with low concentrations of serum Hp (<42 mg/dL) in PNH patients (98.0%) were significantly higher than those in AA (27.8%; P < 0.0001) and MDS (38.5%; P < 0.0001) patients. In AA patients, white blood cell (WBC), absolute neutrophil, and platelet counts were significantly decreased in the group (n = 15) with low concentrations of serum Hp than in that (n = 39) with normal concentrations of it, and WBC counts were positively correlated with concentrations of serum Hp, suggesting that WBC counts may affect the concentrations. In MDS patients, hemoglobin concentrations and serum iron were significantly decreased and increased, respectively, in the group (n = 20) with low concentrations of serum Hp than in that (n = 32) with normal concentrations of it, and the values of serum iron were inversely correlated with concentrations of serum Hp, suggesting that ineffective erythropoiesis may affect the concentrations. Several AA and MDS patients with low concentrations of serum Hp had Coombs-negative autoimmune hemolytic anemia determined by immunoradiometric assay. In conclusion, several factors in conjunction with pathophysiology contribute to decrease of serum Hp in BMF.

Comparison of matched-sibling donor BMT and unrelated donor BMT in children and adolescent with acquired severe aplastic anemia

From January 1991 to March 2007, 61 children and adolescent with acquired severe aplastic anemia received BMT in our institutions. We retrospectively compared the outcome of 30 cases of matched-sibling donor BMT (MSD-BMT) and 31 cases of unrelated donor BMT (URD-BMT). We observed one graft failure among MSD-BMT recipients and three graft failures among URD-BMT recipients, respectively. No patients in the MSD-BMT group developed grades II-IV acute GVHD compared with 11 of 30 patients (37%) in the URD-BMT group (P<0.001). One of 30 MSD-BMT recipients (3%) developed chronic GVHD compared with 8 of 30 URD-BMT recipients (27%) (P=0.013). The incidence of EBV and CMV reactivation was 11 of 20 URD-BMT recipients and 23 of 30, respectively. One patient in the URD-BMT group died of a motor accident 5.5 years after BMT. Ten-year OS was 100% in MSD-BMT recipients and 93.8% (95% CI, 81.9-100%) in URD-BMT recipients, respectively (P=0.252). Ten-year failure-free survival was 96.7% (95% CI, 90.2-100%) in the MSD-BMT group and 84.7% (95% CI, 70.2-99.2%) in the URD-BMT group, respectively (P=0.161).

High-dose cyclophosphamide for severe aplastic anemia: long-term follow-up

Severe aplastic anemia (SAA) is a life-threatening bone marrow failure disorder that can be treated with bone marrow transplantation, immunosuppressive therapy, and high-dose cyclophosphamide. Here, we report long-term follow-up on 67 SAA patients (44 treatment-naive and 23 refractory) treated with high-dose cyclophosphamide. At 10 years, the overall actuarial survival was 88%, the response rate was 71% with the majority being complete, and the actuarial event-free survival was 58% in 44 treatment-naive SAA patients. Patients with refractory SAA fared less well after high-dose cyclophosphamide therapy; at 10 years, overall actuarial survival, response, and actuarial event-free survival rates were 62%, 48%, and 27%, respectively. High-dose cyclophosphamide is highly effective therapy for severe aplastic anemia. Large randomized controlled trials will be necessary to establish how results of high-dose cyclophosphamide compare with either bone marrow transplantation or standard immunosuppressive regimens, such as antithymocyte globulin and cyclosporine.

Natural history of transfusion-independent non-severe aplastic anemia in children

Although the known clinical courses of non-severe aplastic anemia (NSAA) in children comprise spontaneous resolution, persistent NSAA, or progression to severe aplastic anemia (SAA), only a few published reports have indicated the outcome of transfusion-independent NSAA. We retrospectively evaluated the incidence and time of progression from transfusion-independent to transfusion-dependent NSAA or SAA. We reviewed the records of 70 children with acquired AA who were referred to our hospital between 1986 and 2006, and among them we found 22 patients who had transfusion-independent NSAA at diagnosis and were treated with supportive care alone until progression to transfusion-dependent AA. 22 patients were followed up for a median of 86 months (range, 11-198 months). The Kaplan-Meier estimates for progression-free survival were 62 +/- 12 and 22 +/- 13% at 60 and 120 months after diagnosis, respectively. None of the patients treated with supportive care alone improved hematologically. In conclusion, because the incidence of disease progression was high in patients with NSAA, a prospective randomized trial of early intervention with IST or observation alone until disease progression to SAA, followed by IST when the patients become transfusion-dependent is warranted.

Treatment of severe aplastic anemia with a combination of horse antithymocyte globulin and cyclosporine, with or without sirolimus: a prospective randomized study

BACKGROUND

We hypothesized that the addition of sirolimus to standard horse antithymocyte globulin (h-ATG) and cyclosporine (CsA) would improve response rates in severe aplastic anemia, due to its complementary and synergistic properties to cyclosporine A.

DESIGN AND METHODS

To test this hypothesis, we conducted a prospective randomized study comparing hATG/CsA/sirolimus to standard h-ATG/CsA. A total of 77 patients were treated from June 2003 to November 2005; 35 received h-ATG/CsA/sirolimus and 42 h-ATG/CsA. The two groups were well matched demographically and in blood counts prior to therapy. The primary end-point was hematologic response rate at 3 months, defined as no longer meeting the criteria for severe aplastic anemia. The study was powered to show a superior hematologic response rate of h-ATG/CsA/sirolimus compared to standard h-ATG/CsA.

RESULTS

The overall response rate at 3 months was 37% for h-ATG/CsA/sirolimus and 50% for h-ATG/CsA and at 6 months 51% for h-ATG/CsA/sirolimus and 62% for h-ATG/CsA. After a planned interim analysis of 30 evaluable patients in each arm, accrual to the h-ATG/CsA/sirolimus arm was closed, as the conditional power for rejecting the null hypothesis was less than 1%. The rate of relapse, clonal evolution, and survival (secondary outcomes) did not differ significantly between patients treated with the two different regimens.

CONCLUSIONS

Despite a theoretical rationale for its use, sirolimus did not improve the response rate in patients with severe aplastic anemia when compared to standard h-ATG/CsA.

The clinical feature of invasive fungal infection in pediatric patients with hematologic and malignant diseases: a 10-year analysis at a single institution at Japan

Invasive fungal infections (IFI) are an important complication in hematologic malignancies and stem-cell transplantation (SCT). However, there are limited data characterizing IFI in children. The clinical feature of IFI after chemotherapy and SCT were analyzed in 334 pediatric patients treated at Hokkaido University Hospital from 1997 to 2006. The cumulative incidence of IFI was 6.9%; this comprised cases of proven, probable and possible IFI at rates of 1.2%, 3.0%, and 2.7%, respectively. The infected lesions were lung in 14 patients, liver in 5 patients, brain in 3 patients, fungemia in 2 patients, kidney in 1 patient, and endophthalmitis in 1 patient. The mortality of IFI was 48.2%, excluding patients who died due to relapse and interstitial pneumonitis; in particular, 71.4% patients with a lung lesion (10/14) died due to IFI. Fifty-nine pediatric patients died in our institution over the 10-year period of the study and IFI was the direct cause of death in 18.6% (11/59) of the patients. Risk factors for IFI with chemotherapy and SCT were also analyzed. Univariate analysis showed that age at diagnosis older than 10 years, relapse of original disease, long-term administration of broad-spectrum antibiotics, and acute myelogenous leukemia (AML) were the risk factors for IFI. All patients with IFI received long-term antibiotic therapy. AML was most strongly associated using a multivariate analysis. The prognosis of IFI has been expected poor; therefore, prevention of this condition, especially for older patients with AML, would be important.

Predicting response to immunosuppressive therapy and survival in severe aplastic anaemia

Horse anti-thymocyte globulin (h-ATG) and ciclosporin are the initial therapy for most patients with severe aplastic anaemia (SAA), but there is no practical and reliable method to predict response to this treatment. To determine whether pretreatment blood counts discriminate patients with SAA who have a higher likelihood of haematological response at 6 months to immunosuppressive therapy (IST), we conducted a single institution retrospective analysis on 316 SAA patients treated with h-ATG-based IST from 1989 to 2005. In multivariate analysis, younger age, higher baseline absolute reticulocyte count (ARC), and absolute lymphocyte count (ALC) were highly predictive of response at 6 months. Patients with baseline ARC > or = 25 x 10(9)/l and ALC > or = 1 x 10(9)/l had a much greater probability of response at 6 months following IST compared to those with lower ARC and ALC (83% vs. 41%, respectively; P < 0.001). This higher likelihood of response translated to greater rate of 5-year survival in patients in the high ARC/ALC group (92%) compared to those with a low ARC/ALC (53%). In the era of IST, the baseline ARC and ALC together serve as a simple predictor of response following IST, which should guide in risk stratification among patients with SAA.

The national marrow donor program 20 years of unrelated donor hematopoietic cell transplantation

In the 20 years since the National Marrow Donor Program (NMDP) facilitated the first unrelated donor transplant, the organization has grown to include almost 7 million donors, and has facilitated over 30,000 transplants on 6 continents. This remarkable accomplishment has been facilitated by the efforts of over 600 employees, and an extensive international network including 171 transplant centers, 73 donor centers, 24 cord blood banks, 97 bone marrow collection centers, 91 apheresis centers, 26 HLA typing laboratories, and 26 Cooperative Registries. In this article, we review the history of the NMDP, and cite the major trends in patient demographics, graft sources, and conditioning regimens over the last 20 years.

[Evaluation of a prospective therapeutic protocol in adult patients with nonsevere aplastic anemia in South Tunisia]

INTRODUCTION

Immunosuppressive drugs are usually used in the treatment of acquired aplastic anemia (AAA). The aim of this study was to evaluate the efficiency of a prospective therapeutic protocol using cyclosporine and androgens in the treatment of adult patients with nonsevere AAA.

METHODS

Twenty-nine patients diagnosed and treated at the University Hospital of Sfax (Tunisia), during a 10-year period (1991-2000) were included. In addition to symptomatic treatment (transfusion, antibiotics), all the patients received a specific treatment including two drugs: cyclosporine 5mg/kg per day and androgens 0,5mg/kg per day.

RESULTS

The response rate at three, six and 12 months were 48, 75, and 87%, respectively. Survival rate was 52% at one year, and 37% at five and 10 years. The main toxicities were hepatic, renal, and hypertension, observed in 53, 16 and 15%, respectively. These toxicities were reversible in 65, 87 and 100% of the cases, respectively.

CONCLUSION

The response and survival rates in our series are quite satisfactory when compared to those obtained with other immunosuppressive drugs (cyclosporine and antilymphocyte serum) in the literature. The addition of androgens in our patients seemed to potentiate the immunosuppression induced by ciclosporin, but secondary toxic effects were more common.

Aplastic anemia

PURPOSE OF REVIEW

Most acquired aplastic anemia is the result of immune-mediated destruction of hematopoietic stem cells causing pancytopenia and an empty bone marrow, which can be successfully treated with either immunosuppressive therapy or hematopoietic stem-cell transplantation.

RECENT FINDINGS

In aplastic anemia, oligoclonally expanded cytotoxic T cells induce apoptosis of hematopoietic progenitors. T-bet, a transcription factor that binds to the interferon-gamma promoter region, is upregulated in aplastic anemia T cells. Regulatory T cells are significantly reduced in patients' peripheral blood and in an aplastic anemia murine model, infusion of regulatory T cells ameliorates disease progression. In a minority of cases, loss-of-function mutations in telomerase complex genes may underlie disease development. Long-term survival, once strongly linked to response to immunosuppressive therapy, can now be achieved even among nonresponders due to significant advances in supportive care and better salvage treatments.

SUMMARY

Evidence has accumulated in the recent years further corroborating an immune-mediated process underlying aplastic anemia pathogenesis. Hematopoietic stem-cell transplantation from a matched sibling donor is preferred for children and young adults with severe aplastic anemia, and immunosuppressive therapy is employed when hematopoietic stem-cell transplantation is not feasible due to age, lack of a histocompatible sibling, co-morbidities, or by patient choice.

Protein therapeutics: a summary and pharmacological classification

Once a rarely used subset of medical treatments, protein therapeutics have increased dramatically in number and frequency of use since the introduction of the first recombinant protein therapeutic--human insulin--25 years ago. Protein therapeutics already have a significant role in almost every field of medicine, but this role is still only in its infancy. This article overviews some of the key characteristics of protein therapeutics, summarizes the more than 130 protein therapeutics used currently and suggests a new classification of these proteins according to their pharmacological action.

Antithymocyte globulin and cyclosporin in children with acquired aplastic anemia

OBJECTIVE

To assess the responses to ATG and cyclosporin combination in patients of aplastic anemia.

METHODS

Twenty three (17M: 6F) patients of aplastic anemia (11 very severe aplastic anemia (VSAA) and 12 severe aplastic anemia (SAA), were administered antithymocyte globulin and cyclosporin.

RESULTS

The median age of patents was 8 years (range 6-12 years). Three patients died within 2 months of therapy. Twenty children (11 SAA and 9 VSAA) were finally analysed. Six months after the start of treatment, 8/20 (40%) patients responded-2 complete (CR) and 6 partial responses (PR). At the end of 1 year; 2 patients maintained CR and seven patients continued PR (overall responders 45%). The response was better in SAA (54.5%) with 2 CR and 4 PR; than in VSAA (33%) with 3 PR . Eleven (55%) children were alive without response. One patient developed AML 13 months later.

CONCLUSION

We conclude that antithymocyte globulin and cyclosporin combination is an effective treatment for aplastic anemia patients who are ineligible for bone marrow transplantation.

Outcome of children with aplastic anemia treated with immunosuppressive therapy

BACKGROUND

Immunosuppressive therapy (IST) is the alternative treatment in children with aplastic anemia (AA) who do not have an HLA-matched sibling. The aim of this study is to evaluate the outcome of children with AA treated with IST.

METHODS

We retrospectively reviewed the hospital records of children with AA from 1984 to 2004, treated at our institution with antithymocyte globulin (ATG), cyclosporine (CS), and short course of prednisone.

RESULT

Forty-two patients were treated with IST (24 boys, 18 girls); of whom 26% received G-CSF. The median age at diagnosis was 8.5 years. Sixty-nine, 19, and 12% were diagnosed with severe, very severe, and moderate AA, respectively. Twenty-one percent had hepatitis-associated AA. Median follow-up time was 53.3 months. Sixty-two percent had complete response; 19% had partial response. Two patients relapsed and received a second course of ATG; both had a partial response. The actuarial 5 years survival rate was 67.5%. Two patients developed myelodysplastic syndrome (MDS); both received long-term G-CSF and had partial response after two courses of IST. Fifteen percent of survivors had significant hypertension which persisted after CS was discontinued.

CONCLUSIONS

This study shows promising response in children with AA treated with IST; however, the outcome was inferior to our institutional results with hematopoietic stem cell transplantation from a sibling donor. Hypertension and MDS are late complications. Longer follow-up, larger cohorts, and prospective studies are warranted to evaluate late complications and risk factors.

Evolution in the management of acute liver failure-associated aplastic anaemia in children: a single centre experience

BACKGROUND/AIMS

Bone marrow failure (BMF) is a potentially life-threatening complication of acute liver failure (ALF).

METHODS

To investigate prevalence and evolving management of BMF associated with ALF, we reviewed all cases seen in our centre over 17 years. BMF was classified as: (a) bone marrow hypoplasia, (b) severe aplastic anaemia (SAA) and (c) very severe aplastic anaemia (VSAA), using standard criteria. We compared outcomes in children receiving: (1) medical treatment only with or without immunomodulation (anti-lymphocyte globulin, calcineurin inhibitors, G-CSF); (2) medical treatment with or without immunomodulation plus liver transplantation (LT); (3) haematopoietic stem cell transplantation (HSCT).

RESULTS

Of 213 patients with ALF, 20 [(9.4%); 14 (70%) boys] developed BMF after a median of 1 month (range, 0.5 to 7). Seven had VSAA, 7 SAA and 6 bone marrow hypoplasia. Five children were treated medically, including 3 by immunomodulation; 10 (50%) received LT, with immunomodulation in 6; 5 (25%) received HSCT, in one after LT. Four (20%) children died, only one as consequence of AA. There was no difference in recovery, complication rates or outcome among the three groups.

CONCLUSIONS

Aggressive management of ALF-associated AA, including immunomodulation, HSCT and LT, is successful in most cases. HSCT has the advantage of removing the risk of late clonal disorders.

Prospective multicenter trial comparing repeated immunosuppressive therapy with stem-cell transplantation from an alternative donor as second-line treatment for children with severe and very severe aplastic anemia

We conducted a prospective multicenter study to compare the efficacy of repeated immunosuppressive therapy (IST) with stem-cell transplantation (SCT) from an alternative donor in children with acquired aplastic anemia (AA) who failed to respond to an initial course of IST. Patients with severe (n = 86) and very severe disease (n = 119) received initial IST consisting of antithymocyte globulin (ATG) and cyclosporine. Sixty patients failed to respond to IST after 6 months from the initial IST and were eligible for second-line treatment. Among them, 21 patients lacking suitable donors received a second course of IST. Three patients developed an anaphylactoid reaction to ATG and could not complete the second IST. A trilineage response was seen in only 2 of 18 (11%) evaluable patients after 6 months. Thirty-one patients received SCT from an alternative donor. At 5 years from the initiation of second-line therapy, the estimated failure-free survival (FFS), defined as survival with response, was 83.9% (+/- 16.1%, SD) in the SCT group compared with 9.5% (+/- 9.0%) in the IST group (P = .001). These results suggest that SCT from an alternative donor offers a better chance of FFS than a second IST in patients not responding to an initial IST.

Favorable outcome with allogeneic hematopoietic stem cell transplantation in pediatric acquired aplastic anemia patients

The data of allogeneic HSCT in nine children with acquired AA between June 1998 and July 2006 were analyzed retrospectively. The median duration of time to neutrophil and platelet engraftment was 18 and 25 days, respectively. None of the patients had primary graft failure. Two (22.2%) patients developed acute GVHD and of these, one (11.1%) was Grade 1, and the other (11.1%) was Grade 3. Although the study group was composed of higher risk patients, including six of nine resistant to previous immunosuppressive treatment, eight had multiple not irradiated or filtered transfusion histories and one of the cases was only 5/6 HLA-compatible with his donor, the five-yr overall and EFS was 100%, and all recipients are alive without any graft failure. This may be attributed to the dose adjusted use of ATG according to individual transfusion history and gradual tapering of CsA and cessation at least nine months after allogeneic HSCT.

Treatment of acquired severe aplastic anemia with antilymphocyte globulin, cyclosporin A, methyprednisolone, and granulocyte colony-stimulating factor

Fifty-six adult patients with newly diagnosed acquired severe aplastic anemia (SAA) received horse antilymphocyte globulin (ALG), cyclosporin A (CyA), methylprednisolone (Mpred), granulocyte colony-stimulating factor (G-CSF) as first-line therapy. The median age was 34 (range, 17-72) and median neutrophil count 0.280 x 10(9)/L. Trilineage hematologic recovery (at a median interval of 105 days from treatment) was seen in 46 patients (37 complete, 9 partial) after one (n = 38) or two (n = 8) courses of ALG. Cytogenetic abnormalities were observed in three unresponders, clonal hematologic disease in three complete responders, and relapse of marrow aplasia in four complete responders. Median follow up for surviving patients was 1,668 days (range, 237-4,012). The actuarial survival at 5 years was 82%, falling to 77.1% at 7 years and was stationary at 7 and 8 years. Survival was not influenced by the neutrophil count (72% vs. 87%, for neutrophils less than vs. greater than 0.2 x 10(9)/L; P = 0.54). Immunosuppressive treatment of SAA with the 4-drug combination appears to be effective. The significant prognostic effect of an enduring increase of the white blood cell (WBC) count during G-CSF treatment may suggest complete and partial response to therapy. In nonresponders, the WBC count either did not change or elevated values gradually returned to nearly their initial levels while the patients were still under G-CSF treatment. In patients not responsive to treatment but living under CyA and G-CSF, the possibility of developing cytogenetic abnormalities does not seem to be low, despite the absence of findings attributable to manifest myelodysplastic syndrome.

Immunotherapy for severe aplastic anemia following orthotopic liver transplantation in children

Severe aplastic anemia is a well-recognized complication of fulminant non-A, non-B, and non-C hepatitis requiring orthotopic liver transplantation. The first line of therapy for cure in the treatment of aplastic anemia is a histocompatible bone marrow transplant. Immunosuppressive therapy is also effective if a histocompatible donor is not available. We describe two children who developed severe aplastic anemia following orthotopic liver transplant who achieved bone marrow recovery with a single course of anti-thymocyte globulin, solumedrol, and adjustments to their immunosuppressive therapy for prevention of liver allograft rejection.

Acquired pure megakaryocytic aplasia: report of a single case treated with mycophenolate mofetil

Acquired pure megakaryocytic aplasia (APMA) is a rare disorder in the field of hematological diseases. We report the case of a patient with APMA treated with mycophenolate mofetil and review the literature associated with this. Until today, very few cases of APMA have been reported and the disease etiology still seems to be unclear. There have been no reported cases of treatment of APMA treated with mycophenolate mofetil.

Cyclosporine therapy for acquired aplastic anemia: predictive factors for the response and long-term prognosis

Although cyclosporine (CsA) is a key drug in the treatment of acquired aplastic anemia (AA), the role of single-agent therapy with CsA remains unclear. To determine the efficacy of CsA in the treatment of AA, we treated 38 AA patients with CsA alone and followed up the patients for 6 months to 16 years. Twenty patients (53%) achieved either a partial or complete remission within 1 year of starting CsA therapy. Thirteen (81%) of 16 patients who showed an increase in the reticulocyte count of >20 x 10(9)/L within 2 months achieved remission, whereas the response rate was only 32% in patients who failed to show such an increase in the reticulocyte count. The actuarial overall survival and failure-free survival rates at 5 years were 91% and 37%, respectively. These data indicate that CsA alone can achieve a sustained remission in approximately 40% of AA patients, with a low probability of inducing secondary clonal diseases. Given its low toxicity and because the effectiveness of CsA can be judged within 2 months of therapy, CsA may be the first drug of choice at outpatient clinics for AA patients not requiring transfusions.

Allogeneic stem cell transplantation for aplastic anemia

Aplastic anemia encompasses a heterogeneous group of diseases with distinct pathophysiologies and a common clinical endpoint of marrow failure. Patients with severe aplastic anemia can be treated with immunosuppressive therapy (IST) or hematopoietic stem cell transplantation (HSCT). Over the last 30 years, advances in both treatment modalities have significantly improved the prognosis for this disease; yet this evolution complicates the central therapeutic question in aplastic anemia: which patients should receive IST and which ones should receive HSCT as front-line therapy? In this review, we describe the major improvements that have occurred in transplantation for aplastic anemia in the last 3 decades. We then outline a framework for deciding which patients should be considered for upfront transplantation.

Treatment of severe aplastic anemia with antithymocyte globulin and cyclosporin A with or without G-CSF in adults: a multicenter randomized study in Japan

We report the results of a randomized study to elucidate whether addition of granulocyte colony-stimulating factor (G-CSF) to immunosuppressive therapy is valuable for the treatment of severe aplastic anemia (SAA) in adults. A total of 101 previously untreated patients (median age, 54 years; range, 19 to 75 years) were randomized to receive antithymocyte globulin (ATG) and cyclosporin A (CyA) (G-CSF- group) or ATG, CyA, and G-CSF (G-CSF+ group). In the G-CSF+ group, the hematologic response rate at 6 months was higher (77% vs 57%; P = .03) than in the G-CSF- group. No differences were observed between the groups in terms of the incidence of infections and febrile episodes. There were no differences between the G-CSF- group and the G-CSF+ group in terms of survival (88% vs 94% at 4 years), and the development of myelodysplastic syndrome (MDS)/acute leukemia (AL) (1 patient vs 2 patients). However, the relapse rate was lower in the G-CSF+ group compared with the G-CSF- group (42% vs 15% at 4 years; P = .01). Further follow-up is required to elucidate the role of G-CSF in immunosuppressive therapy for adult SAA.

HLA association is different in children and adults with severe acquired aplastic anemia

BACKGROUND

Severe aplastic anemia (SAA) is defined as pancytopenia caused by bone marrow failure. The pathogenesis of SAA is thought to involve autoimmune processes. Increased susceptibility to autoimmunity has been shown to be associated with several different HLA alleles. In SAA, few large studies based on data mainly from adults describe a positive HLA correlation with HLA-DR2 (DRB1*15) and HLA-B14.

PROCEDURE

This study explored the HLA constitution of 181 children with SAA who were enrolled in the prospective multi-center study SAA94 between January 1994 and January 2002. The control group consisted of 303 healthy individuals of comparable demographic background. Allelic frequencies between patients and controls are compared using Fisher's exact test.

RESULTS

In our pediatric cohort, we describe a positive association with HLA-B14 (P = 0.0039), but no association of HLA-DR2 with SAA.

CONCLUSION

HLA associations appear to be different in children and adults with SAA. This might point towards a difference in pathophysiology between at least part of the children and adults.

Treatment of severe aplastic anaemia with combined immunosuppression: anti-thymocyte globulin, ciclosporin and mycophenolate mofetil

Severe aplastic anaemia (SAA) can be successfully treated with immunosuppressive therapies or haematopoietic stem cell transplantation (HSCT). Response rates with horse anti-thymocyte globulin (h-ATG) plus ciclosporin (CsA) are about 60-70%, and robust responders have an excellent long-term survival. We introduced a third immunosuppressive agent to standard h-ATG/CsA, mycophenolate mofetil (MMF), in an attempt to improve the response rate and survival, and to decrease the relapse rate and clonal evolution to myelodysplasia. A total of 104 consecutive patients with SAA were treated with h-ATG/CsA/MMF between May 1999 and June 2003 at the National Institutes of Health Clinical Center. The overall response rate at 6 months was 62%, with 24 (37% of responders) patients relapsing at a median of 389 d from ATG. Nine patients showed evidence of clonal evolution following ATG. After a median follow up of 42 months, the median survival among responders was not reached and among non-responders was 58 months. Over half of the relapses occurred during MMF administration. Despite a strong theoretical rationale for its use, MMF did not result in the improvement of response or relapse rates when compared with historical standard h-ATG/CsA.

Identification of novel regulators in T-cell differentiation of aplastic anemia patients

BACKGROUND

Aplastic anemia (AA) is a bone marrow failure syndrome mostly characterized by an immune-mediated destruction of marrow hematopoietic progenitor/stem cells. The resulting hypocellularity limits a detailed analysis of the cellular immune response. To overcome this technical problem we performed a microarray analysis of CD3+ T-cells derived from bone marrow aspirates and peripheral blood samples of newly diagnosed AA patients and healthy volunteers. Two AA patients were additionally analyzed after achieving a partial remission following immunosuppression. The regulation of selected candidate genes was confirmed by real-time RT-PCR.

RESULTS

Among more than 22,200 transcripts, 583 genes were differentially expressed in the bone marrow of AA patients compared to healthy controls. Dysregulated genes are involved in T-cell mediated cytotoxicity, immune response of Th1 differentiated T-cells, and major regulators of immune function. In hematological remission the expression levels of several candidate genes tend to normalize, such as immune regulators and genes involved in proinflammatory immune response.

CONCLUSION

Our study suggests a pivotal role of Th1/Tc1 differentiated T-cells in immune-mediated marrow destruction of AA patients. Most importantly, immune regulatory genes could be identified, which are likely involved in the recovery of hematopoiesis and may help to design new therapeutic strategies in bone marrow failure syndromes.

High frequency of several PIG-A mutations in patients with aplastic anemia and myelodysplastic syndrome

To clarify some characteristics of phosphatidylinositol glycan-class A gene (PIG-A) mutations in aplastic anemia (AA) and myelodysplastic syndrome (MDS) patients compared with those in paroxysmal nocturnal hemoglobinuria (PNH) patients, we investigated PIG-A mutations in CD59- granulocytes and CD48- monocytes from seven AA, eight MDS, and 11 PNH Japanese patients. The most frequent base or type abnormalities of the PIG-A gene in AA and MDS patients were base substitutions or missense mutations, respectively, and deletions or frameshift mutations, respectively, in PNH patients. Several PIG-A mutations, most of which were statistically minor, were found in glycosylphosphatidylinositol-negative cells from all AA and MDS patients but not from all PNH patients. However, the common PIG-A mutations during the clinical course between CD59- granulocytes and/or CD48- monocytes from each AA or MDS patient, except for Case 5, were not found. PIG-A mutations were different between the granulocytes and monocytes from five AA and five MDS patients. Our results indicate that there were some characteristics of PIG-A mutations in AA and MDS patients compared with PNH patients and that several minor PNH clones in these patients occurred at random during the clinical course. This partly explains the transformation of AA or MDS to PNH at intervals.

Immunosuppressive therapy for acquired severe aplastic anemia (SAA): a prospective comparison of four different regimens

OBJECTIVE

This study was designed to investigate four different immunosuppressive therapy (IST) regimens as treatment of acquired severe aplastic anemia (SAA).

PATIENTS AND METHODS

142 consecutive SAA patients were randomized to receive one of the following IST regimens: equine anti-human thymocyte immunoglobulin (E-ATG) alone (IST regimen I); E-ATG and cyclosporine A (CSA) (IST regimen II); E-ATG, CSA plus recombinant human granulocyte-macrophage colony-stimulating factor (rhuGM-CSF) and rhu erythropoietin (rhuEPO) (IST regimen III); or rabbit ATG (ATG-F), CSA, rhuGM-CSF, and rhuEPO (IST regimen IV). No repeated courses of E-ATG or ATG-F were given for nonresponders. All patients also received stanozolol or testosteron propionate.

RESULTS

The overall response rate to IST regimen I was 58%. The response to IST regimen II (79%) was significantly higher (p = 0.04), more rapid and complete than after IST regimen I. The response rate to IST regimen IV (53%) was significantly lower than that of IST regimen III (73%, p = 0.039). The additional use of growth factors did not reduce early deaths and did not accelerate hematopoietic recovery after IST. Of the 142 patients enrolled in this trial, 92 (65%) are alive at a median follow-up time of 102 months (range, 54-166 months). The 5-year actuarial survival for IST regimens I, II, III, and IV was 58%, 81%, 80%, and 66%, respectively.

CONCLUSION

The combination of E-ATG and CSA remains the best combination for the treatment of SAA patients, producing a survival advantage at 5 years. The addition of growth factors did not improve these results. Rabbit ATG-F appeared less effective than E-ATG.

Minor population of CD55-CD59- blood cells predicts response to immunosuppressive therapy and prognosis in patients with aplastic anemia

We investigated the clinical significance of a minor population of paroxysmal nocturnal hemoglobinuria (PNH)-type blood cells in patients with acquired aplastic anemia (AA). We quantified CD55-CD59- granulocytes and red blood cells (RBCs) in peripheral blood from 122 patients with recently diagnosed AA and correlated numbers of PNH-type cells and responses to immunosuppressive therapy (IST). Flow cytometry detected 0.005% to 23.1% of GPI-AP- cells in 68% of patients with AA. Sixty-eight of 83 (91%) patients with an increased proportion of PNH-type cells (PNH+) responded to antithymocyte globulin (ATG) + cyclosporin (CsA) therapy, whereas 18 of 39 (48%) without such an increase (PNH-) responded. Failure-free survival rates were significantly higher (64%) among patients with PNH+ than patients with PNH- (12%) at 5 years, although overall survival rates were comparable between the groups. Numbers of PNH-type and normal-type cells increased in parallel among most patients with PNH+ who responded to IST, suggesting that these cells are equally sensitive to immune attack. These results indicate that a minor population of PNH-type cells represents a reliable marker of a positive IST response and a favorable prognosis among patients with AA. Furthermore, immune attack against hematopoietic stem cells that allows PNH clonal expansion might occur only at the onset of AA.

Evaluation of angiogenesis and vascular endothelial growth factor expression in the bone marrow of patients with aplastic anemia

It is generally appreciated that bone marrow function and growth of myelopoietic cells depends on an intact microvasculature. A pivotal regulator of angiogenesis is vascular endothelial growth factor (VEGF). Here, we describe analysis of VEGF expression and microvessel density in the bone marrow of patients with aplastic anemia by immunohistochemistry. Bone marrow was examined at diagnosis and at the time of hematological remission after immunosuppressive therapy using anti-thymocyte globulin, cyclosporin A, and glucocorticoids or allogeneic stem cell transplantation. At diagnosis, both VEGF expression and microvessel density were found to be significantly lower in aplastic anemia compared to normal bone marrow (aplastic anemia, 1.1 +/- 0.7 events per field, versus controls, 5.9 +/- 3.0 events per field; P < 0.05). In response to successful therapy, VEGF and microvessel density in the bone marrow increased substantially. Serum VEGF levels were also found to be significantly lower at diagnosis in aplastic anemia compared to healthy controls (aplastic anemia, 51 +/- 35 pg/ml versus controls, 444 +/- 220 pg/ml; P < 0.05). VEGF in the serum increased substantially after successful immunosuppressive therapy or stem cell transplantation (P < 0.05). Taken together, these data show that aplastic anemia is associated with reduced angiogenesis and reduced VEGF expression.

Diagnosis and treatment of children with aplastic anemia

BACKGROUND

Long-term survival rates among children diagnosed with severe aplastic anemia (SAA) are excellent due to the success of human leukocyte antigen (HLA)-identical related hematopoietic stem cell transplantation (HSCT), concurrent advances in immunosuppressive treatment (IST), and improved supportive care. The challenge in making treatment recommendations for children with SAA, therefore, is to balance the apparent chronicity and morbidity following IST, with the potential up-front toxicity and complications of HSCT.

METHODS

This review provides an update on the diagnosis and a risk-based treatment algorithm for children with acquired SAA. Recent experience using alternative donor HSCT and efforts to extend HSCT eligibility through advances in donor matching, de-escalation of conditioning regimens, and potential marrow graft engineering are highlighted. We discuss IST response rates, risks of relapse, and complications including clonal evolution.

CONCLUSIONS

While good treatment options exist for a majority of children diagnosed with SAA, novel non-transplantation treatments for unresponsive and relapsed patients without suitable transplant donors are needed. Further improvements in outcome will ultimately require a more complete understanding of the pathophysiology of aplastic anemia (AA).