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

Real-world outcomes with immunosuppressive therapy for aplastic anemia in patients treated at the University of Michigan

Aplastic anemia (AA) is a rare bone marrow failure disorder that is treated with either allogeneic stem cell transplant or immunosuppressive therapy (IST) consisting of antithymocyte globulin (ATG), cyclosporine (CSA), and eltrombopag. While outcomes are favorable in younger patients, older patients (>60) have significantly worse long-term survival. The dose of ATG is often reduced in older patients and those with multiple comorbidities given concerns for tolerability. The efficacy and safety of dose-attenuated IST in this population is largely undescribed. We performed a retrospective review of patients with AA treated with IST. Our analysis was confounded by changes in practice patterns and the introduction of eltrombopag. We identified 53 patients >60 years old, of which, 20 received dose-attenuated IST, with no statistically significant difference in overall survival between full and attenuated dose cohorts. Overall response rates in both cohorts were similar at 6 months at 71% and 68%. There were more documented infectious complications in the full dose cohort (13 vs. 3). This supports the consideration of dose-attenuated IST in older patients with concerns about tolerance of IST. Lastly, our data confirmed favorable outcomes of younger patients receiving IST, especially in combination with eltrombopag.

Antihuman T lymphocyte porcine immunoglobulin combined with cyclosporine as first-line immunosuppressive therapy for severe aplastic anemia in China: a large single-center, 10-year retrospective study

Background

Antihuman T lymphocyte porcine immunoglobulin (p-ATG) has been the most common ATG preparation in immunosuppressive therapy (IST) in Chinese patients with severe aplastic anemia (SAA) since 2009.

Objectives

This study aimed to evaluate the early hematologic response and long-term outcomes of a large cohort of patients with SAA who received p-ATG plus cyclosporine (CsA) as first-line therapy from 2010 to 2019.

Design

This is a single-center retrospective study of medical records.

Methods

We analyzed the data of 1023 consecutive patients with acquired aplastic anemia (AA) who underwent p-ATG combined with CsA as a first-line IST treatment from 2010 to 2019 at our department.

Results

The median age of the patients was 24 (4-75) years, and the median follow-up time was 57.2 months (3 days-137.5 months). There was an early mortality rate of 2.8% with a median death time of 0.9 months (3 days-2.9 months). The overall response rates were 40.6% and 56.1% at 3 and 6 months, respectively. The 5-year cumulative incidences of relapse and clonal evolution were 9.0% [95% confidence interval (CI) = 4.2-16.0%] and 4.5% (95% CI = 1.4-10.6%), respectively. The 5-year overall survival (OS) and event-free survival rates were 83.7% (95% CI = 81.1-86.0%) and 50.4% (95% CI = 47.1-53.5%), respectively.

Conclusion

p-ATG combined with CsA for the treatment of AA is effective and safe, and p-ATG can be used as an alternative ATG preparation for the standard IST regimen in areas in which h-ATG is not available.

Long-term effects of hematopoietic growth factors in aplastic anemia patients treated with immunosuppression: Meta-analysis of randomized controlled trials

BACKGROUND AND PURPOSE

Immunosuppressive therapy is the frontline treatment for aplastic anemia patients ineligible for transplantation. The long-term effects of hematopoietic growth factors (HGF) added to standard immunosuppressive therapy are still unclear. We performed a systematic review and meta-analysis to clarify this issue.

METHODS

A comprehensive search of databases was conducted including 5 international electronic databases (Cochrane, PubMed, Embase, Web of Science, and LILACS) and 4 Chinese electronic databases (Chinese Bio-medicine Database, Chinese National Knowledge Infrastructure, WanFang Data, and China Science and Technology Journal Database databases) from database inception until February, 2022. We included randomized controlled trials that assigned patients with acquired aplastic anemia treated with immunosuppressive therapy (IST), which compared between the addition of HGF and placebo or no treatment. The co-primary outcome were the overall survival (OS) and late clonal malignant evolution at the end of follow-up.

RESULTS

Nine randomized controlled trials including 719 participants were identified. The addition of growth factors to immunosuppression yielded no difference in OS (relative risks [RR], 1.08, 95% confidence interval [CI] 0.99-1.18). HGF was not associated with higher occurrence of secondary myelodysplastic syndromes/acute myeloid leukemia (RR, 1.09, 95% CI 0.43-2.78) or paroxysmal nocturnal hemoglobulinemia (RR, 1.38, 95% CI 0.68-2.81) at the end of follow-up. No difference were found in overall response (RR, 1.16, 95% CI 0.98-1.37), infections occurrence (RR, 0.82; 95% CI, 0.51-1.31) or relapse (RR, 0.65; 95% CI, 0.37-1.13).

CONCLUSIONS

HGF as an adjunct to IST has no impact on long-term OS, late clonal malignant evolution, response rate, relapse or infections occurrence. HGF could be added to standard IST for high-risk patients with delayed neutrophil recovery without concern for long-term consequences but could not be recommended as routine clinical practice.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42021275188.

First-line haploidentical stem cell transplantation in children and adolescents with severe aplastic anemia using mobilized peripheral blood as source of CD34+: Single-institutional experience in a transplant center from northeast Mexico

INTRODUCTION

The only curative treatment for severe aplastic anemia in children is an allogeneic stem cell transplant; however, few patients have a matched related or unrelated donor. Haploidentical stem cell transplantation (haplo-SCT) using bone marrow (BM) and peripheral blood stem cells (PBSC) has been recently described as effective and safe. In this study, we retrospectively report the outcome of twelve pediatric patients who underwent haplo-SCT using only PBSC.

METHODS

The conditioning regimen consisted on rabbit anti-thymocyte globulin (r-ATG) 2.5 mg/kg/d on days -7, -6,-5, and -4, and cyclophosphamide (Cy) 50 mg/kg/d on days -3 and -2. We used Cy 50 mg/kg/d on days +3 and +4, tacrolimus and mycophenolic acid as graft versus host disease (GVHD) prophylaxis.

RESULTS

The median follow-up was 1,099 days (45-1258 days). The overall survival rate up-to-date is 83.3%. In 10 of the 12 patients, a sustained graft was achieved. None of the patients had acute or chronic GVHD.

CONCLUSIONS

Haplo-SCT could be established as a first-line treatment when there is no matched related or unrelated donor. According to this short sample and previous reports, PBSC are a feasible option effectively used as the sole source of stem cells. Additionally, post-transplant cyclophosphamide remains a good strategy for GVHD prevention.

A comparative study of porcine antihuman lymphocyte globulin versus antithymocyte globulin-fresenius in an allogeneic hematopoietic cell transplantation conditioning regimen for severe aplastic anemia

OBJECTIVES

To compare the outcomes of antihuman T lymphocyte globulin (ATG-F) and porcine antihuman lymphocyte globulin (p-ALG) as part of a conditioning regimen in hematopoietic stem cell transplantation (HSCT) for severe aplastic anemia (SAA).

METHODS

we performed a retrospective analysis, evaluating the outcome of patients with SAA who received ATG-F based conditioning (n = 26) with those receiving p-ALG conditioning (n = 34).

RESULTS

The median time to neutrophil engraftment was 11 days (range, 8 - 38) and 11 days (range, 9 - 24) in the p-ALG and ATG-F groups (P = 0.857); the median platelet engraftment time was 15 (range, 9 - 330) days and 13 (range, 10 - 56) days (P = 0.155). There were no significant differences in grades II - IV acute graft-versus-host disease (aGVHD), grades III - IV aGVHD, chronic GVHD (cGVHD), and the moderate-severe cGVHD between the ATG-F and p-ALG groups (P>0.05).

DISCUSSION

Patients in the ATG-F group functioned significantly better on role-physical (P = 0.006), general health (P = 0.029), and physical component summary (P = 0.009). The estimated overall survival and failure free survival rates at 5 years were 88.5% ± 6.3% vs. 82.4% ± 6.5% (P = 0.515), 84.6% ± 7.1% vs. 79.4% ± 6.9%, respectively (P = 0.579). The infection rates were 61.53% and 47.05%, respectively (P = 0.265).

CONCLUSION

As part of the conditioning regimen, p-ALG achieved a similar efficacy as ATG-F without increasing the incidence of transplantation complications in SAA patients.

Special issues related to the diagnosis and management of acquired aplastic anemia in countries with restricted resources, a report on behalf of the Eastern Mediterranean blood and marrow transplantation (EMBMT) group and severe aplastic anemia working party of the European Society for blood and marrow transplantation (SAAWP of EBMT)

Aplastic anemia is a relatively rare but potentially fatal disorder, with a reported higher incidence in developing countries in comparison to the West. There are significant variations in epidemiological as well as etiological factors of bone marrow failure syndromes in the developing countries in comparison to the developed world. Furthermore, the management of bone marrow failure syndromes in resource constraint settings has significant challenges including delayed diagnosis and referral, limited accessibility to healthcare facilities, treatment modalities as well as limitations related to patients who require allogeneic stem cell transplantation. Here we will provide a review of the available evidence related to specific issues of aplastic anemia in the developing countries and we summarize suggested recommendations from the Eastern Mediterranean blood and bone marrow transplantation (EMBMT) group and the severe aplastic anemia working party of the European Society of blood and marrow transplantation (SAAWP of EBMT) related to the diagnosis and therapeutic options in countries with restricted resources.

Acquired severe aplastic anaemia: how medical therapy evolved in the 20th and 21st centuries

The progress in aplastic anaemia (AA) management is one of success. Once an obscure entity resulting in death in most affected can now be successfully treated with either haematopoietic stem cell transplantation (HSCT) or immunosuppressive therapy (IST). The mechanisms that underly the diminution of haematopoietic stem cells (HSCs) are now better elucidated, and include genetics and immunological alterations. Advances in supportive care with better antimicrobials, safer blood products and iron chelation have greatly impacted AA outcomes. Working somewhat 'mysteriously', anti-thymocyte globulin (ATG) forms the base for both HSCT and IST protocols. Efforts to augment immunosuppression potency have not, unfortunately, led to better outcomes. Stimulating HSCs, an often-sought approach, has not been effective historically. The thrombopoietin receptor agonists (Tpo-RA) have been effective in stimulating early HSCs in AA despite the high endogenous Tpo levels. Dosing, timing and best combinations with Tpo-RAs are being defined to improve HSCs expansion in AA with minimal added toxicity. The more comprehensive access and advances in HSCT and IST protocols are likely to benefit AA patients worldwide. The focus of this review will be on the medical treatment advances in AA.

Allogeneic hematopoietic stem cell transplantation in aplastic anemia: current indications and transplant strategies

Treatment options for newly diagnosed aplastic anemia (AA) patient includes upfront allogeneic hematopoietic stem cell transplant (HSCT) or immunosuppressive therapy (IST). With recent advances in supportive care, conditioning regimens and post-transplant immunosuppression the overall survival for HSCT approaches 70-90%. Transplant eligibility needs to be assessed considering age, comorbidities, donor availability and probability of response to immunosuppressive therapy (IST). Upfront HSCT should be offered to children and young adults with matched related donor (MRD). Upfront HSCT may also be offered to children and young adults with rapidly available matched unrelated donor (MUD) who require urgent HSCT. Bone marrow (BM) graft source and cyclosporine (CsA) plus methotrexate (MTX) as graft versus host disease (GVHD) prophylaxis are preferable when using anti-thymocyte globulin (ATG) based conditioning regimens. Alemtuzumab is an acceptable alternative to ATG and is used with CsA alone and with either BM or peripheral blood stem cells (PBSC). Cyclophosphamide (CY) plus ATG conditioning is preferable for patients receiving MRD transplant, while Fludarabine (Flu) based conditioning is reserved for older adults, those with risk factors of graft failure and those receiving MUD HSCT. For haploidentical transplant, use of low dose radiotherapy and post-transplant cyclophosphamide has resulted in a marked reduction in graft failure and GVHD.

Initial dosage optimization of ciclosporin in pediatric Chinese patients who underwent bone marrow transplants based on population pharmacokinetics

Bone marrow transplants (BMT) are an established therapeutic strategy for patients with severe aplastic anemia, acute lymphoblastic leukemia, acute myeloid leukemia or chronic myeloid leukemia. However, the successful application of BMT is limited by graft-vs.-host disease (GVHD). Ciclosporin has been widely used for treating GVHD in pediatric patients who underwent BMT. The present study aimed to optimize the dosage of ciclosporin for safety and effectiveness based on population pharmacokinetics. A non-linear mixed-effects model was used to analyze the clinical data of pediatric patients who underwent BMT between September 2016 and September 2019 at the Children's Hospital of Fudan University. Monte Carlo simulations were used to identify the optimal dose of ciclosporin. The final population pharmacokinetic model indicated that body weight and days post-transplant influenced the clearance of ciclosporin in pediatric patients who underwent BMT. The present study indicated that the optimal initial dose of ciclosporin for pediatric patients weighing 5-30 kg who underwent BMT was 6 mg/kg/day split into 2 doses.

Long-term outcome of a randomized controlled study in patients with newly diagnosed severe aplastic anemia treated with antithymocyte globulin and cyclosporine, with or without granulocyte colony-stimulating factor: a Severe Aplastic Anemia Working Party Trial from the European Group of Blood and Marrow Transplantation

This follow-up study of a randomized, prospective trial included 192 patients with newly diagnosed severe aplastic anemia receiving antithymoglobulin and cyclosporine, with or without granulocyte colony-stimulating factor (G-CSF). We aimed to evaluate the long-term effect of G-CSF on overall survival, event-free survival, probability of secondary myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML), clinical paroxysmal nocturnal hemoglobinuria, relapse, avascular osteonecrosis and chronic kidney disease. The median follow-up was 11.7 years (95% CI, 10.9-12.5). The overall survival rate at 15 years was 57±12% in the group given G-CSF and 63±12% in the group not given G-CSF (P=0.92); the corresponding event-free survival rates were 24±10% and 23±10%, respectively (P=0.36). In total, 9 patients developed MDS or AML, 10 only a clonal cytogenetic abnormality, 7 a solid cancer, 18 clinical paroxysmal nocturnal hemoglobinuria, 8 osteonecrosis, and 12 chronic kidney disease, without any difference between patients treated with or without G-CSF. The cumulative incidence of MDS, AML or isolated cytogenetic abnormality at 15 years was 8.5±3% for the G-CSF group and 8.2±3% for the non-G-CSF group (P=0.90). The cumulative incidence of any late event including myelodysplastic syndrome or acute myeloid leukemia, isolated cytogenetic abnormalities, solid cancer, clinical paroxysmal nocturnal hemoglobinuria, aseptic osteonecrosis, chronic kidney disease and relapse was 50±12% for the G-CSF group and 49±12% for the non-G-CSF group (P=0.65). Our results demonstrate that it is unlikely that G-CSF has an impact on the outcome of severe aplastic anemia; nevertheless, very late events are common and eventually affect the prognosis of these patients, irrespectively of their age at the time of immunosuppressive therapy (NCT01163942).

Activity of eltrombopag in severe aplastic anemia

Since the approval of horse antithymocyte globulin (ATG) decades ago, there was a long hiatus in therapies with activity in severe aplastic anemia (SAA). This scenario changed in 2014 when eltrombopag, a thrombopoietin receptor agonist, was approved for SAA after an insufficient response to initial immunosuppressive therapy (IST). The basis for this approval was the observation of single-agent activity of eltrombopag in this patient population, where 40% to 50% recovered blood counts at times involving >1 lineage. The achievement of transfusion independence confirmed the clinical benefit of this approach. Increase in marrow cellularity and CD34+ cells suggested a recovery to a more functioning bone marrow. Further in its development, eltrombopag was associated with standard horse ATG plus cyclosporine in first line, producing increases in overall (at about 90%) and complete response rates (at about 40%) and leading to transfusion independence and excellent survival. Interestingly, best results were observed when all drugs were started simultaneously. The cumulative incidence of clonal cytogenetic abnormalities to date has compared favorably with the vast experience with IST alone in SAA. Longer follow-up will help in define these long-term risks. In this review, the development of eltrombopag in SAA will be discussed.

Therapeutic Outcomes of Haploidentical Allogeneic Hematopoietic Stem Cell Transplantation in Patients With Severe Aplastic Anemia: A Multicenter Study

BACKGROUND

Haploidentical donor (HID) allogeneic hematopoietic stem cell transplantation (HSCT) is an alternative curative treatment for patients with severe aplastic anemia (SAA) who do not have suitable matched related donors (MRD). The aim of this study was to compare the therapeutic outcomes of HID-HSCT with those of MRD-HSCT for SAA.

METHODS

A total of 235 SAA patients who underwent HID-HSCT (116) or MRD-HSCT (119) at 11 transplantation centers from January 2007 to January 2016 were included. Complications and survival outcomes were evaluated and compared between the 2 groups.

RESULTS

The HID group had a lower incidence of secondary graft failure but higher incidences of acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD). However, the incidence of severe aGVHD (grades III-IV), poor graft function, and infections was comparable between groups. Patients in the HID group had a significantly lower survival and overall survival rates than those in the MRD group. The estimated 3-year survival rates for the MRD and HID groups were 82.82% and 75.00%, respectively. Ferritin levels, graft failure, poor graft function, severe aGVHD, and infections were the significant risk factors for survival.

CONCLUSIONS

The overall survival rate is acceptable for patients who underwent HID-HSCT, making it a feasible treatment choice for SAA patients.

Activity of eltrombopag in severe aplastic anemia

Since the approval of horse antithymocyte globulin (ATG) decades ago, there was a long hiatus in therapies with activity in severe aplastic anemia (SAA). This scenario changed in 2014 when eltrombopag, a thrombopoietin receptor agonist, was approved for SAA after an insufficient response to initial immunosuppressive therapy (IST). The basis for this approval was the observation of single-agent activity of eltrombopag in this patient population, where 40% to 50% recovered blood counts at times involving >1 lineage. The achievement of transfusion independence confirmed the clinical benefit of this approach. Increase in marrow cellularity and CD34+ cells suggested a recovery to a more functioning bone marrow. Further in its development, eltrombopag was associated with standard horse ATG plus cyclosporine in first line, producing increases in overall (at about 90%) and complete response rates (at about 40%) and leading to transfusion independence and excellent survival. Interestingly, best results were observed when all drugs were started simultaneously. The cumulative incidence of clonal cytogenetic abnormalities to date has compared favorably with the vast experience with IST alone in SAA. Longer follow-up will help in define these long-term risks. In this review, the development of eltrombopag in SAA will be discussed.

Addition of eltrombopag to immunosuppressive therapy in patients with newly diagnosed aplastic anemia

BACKGROUND

The immune-mediated destruction of hematopoietic stem cells is implicated in the pathophysiology of aplastic anemia (AA). Immunosuppressive therapy (IST) using antithymocyte globulin and cyclosporine is successful in this setting. Eltrombopag is active in patients with refractory AA, presumably by increasing the bone marrow progenitors.

METHODS

This phase 2 trial initially was designed to evaluate standard IST in newly diagnosed patients with severe AA and later was amended to add eltrombopag to simultaneously address immune destruction and stem cell depletion. The primary outcome was the overall response rate (ORR) at 3 months and 6 months.

RESULTS

A total of 38 patients were enrolled: 17 (45%) received IST alone and 21 (55%) received additional eltrombopag. The ORR was 74%. Patients receiving IST plus eltrombopag had a similar ORR (76% vs 71%; P = .72), complete remission rate (38% vs 29%; P = .73), and median time to response (84 days vs 57 days; P = .30) compared with those receiving IST alone. The 2-year overall survival rate in the IST group was 91% compared with 82% for those patients treated with IST plus eltrombopag (P = .82). No cumulative toxicities were noted after the addition of eltrombopag.

CONCLUSIONS

The addition of eltrombopag to standard IST was well tolerated and resulted in similar responses.

Rabbit antithymocyte globulin dose does not affect response or survival as first-line therapy for acquired aplastic anemia: a multicenter retrospective study

In a prospective randomized study, treatment for aplastic anemia (AA) with rabbit antithymocyte globulin (r-ATG) and cyclosporine showed inferior hematological response and survival in comparison to horse antithymocyte globulin (h-ATG) and cyclosporine. However, h-ATG was discontinued in most Asian, South American, and European countries, where r-ATG became the only ATG formulation available. We retrospectively evaluated consecutive patients with acquired AA who received either rabbit (n = 170) or horse (n = 85) ATG and cyclosporine for first-line treatment from 1992 to 2014 in seven referral centers in Brazil and Argentina. Overall response at 3 months was 17% (95%CI, 11-23%) for r-ATG and 44% (95%CI, 33-55%) for h-ATG (p < 0.001). At 6 months, it was 31% (95%CI, 34-39%) for r-ATG and 59% (95%CI, 48-69%) for h-ATG (p < 0.001). Overall survival at 5 years was 57% (95%CI, 47-65%) for r-ATG and 80% (95%CI, 69-87%) for h-ATG (log-rank = 0.001). Relapse was significantly higher in patients receiving h-ATG (28%; 95%CI, 17-43%) as compared to r-ATG (9.4%; 95%CI, 4-21%; log-rank, p = 0.01). The type of ATG was the only factor associated with both response and survival. The r-ATG dose varied from 1 to 5 mg/kg/day, but it did not correlate with outcomes. In summary, this is the largest multicenter study comparing the two ATG formulations in AA. Our results indicate that the dose of r-ATG does not influence hematologic response or survival in first-line therapy for acquired AA. Considering the toxicity and costs of r-ATG, our findings challenge its aggregate benefit to cyclosporine therapy and further strengthen that h-ATG should remain standard therapy in AA.

Idiopathic severe aplastic anemia with a delayed response to immunosuppressive therapy: a case report

Bone marrow transplantation is the definitive treatment of severe aplastic anemia; however, with the absence of this option, combined immunosuppressive therapy with antithymocyte globulin (ATG) and cyclosporine A is used as a first‐line therapy. This case report highlights the possible delay in response to ATG protocol in treating aplastic anemia.

Clinical outcomes in adult patients with aplastic anemia: A single institution experience

Newer treatment modalities are being investigated to improve upon historical outcomes with standard immunosuppressive therapy (IST) in aplastic anemia (AA). We analyzed outcomes of adult patients with AA treated with various combinatorial anti-thymoglobulin-based IST regimens in frontline and relapsed/refractory (R/R) settings. Pretreatment and on-treatment clinical characteristics were analyzed for relationships to response and outcome. Among 126 patients reviewed, 95 were treatment-naïve (TN) and 63, R/R (including 32 from the TN cohort); median ages were 49 and 50 years, respectively. Overall survival (OS) was superior in IST responders (P < .001). Partial response to IST was associated with shorter relapse-free survival (RFS), as compared with complete response (P = .03). By multivariate analysis, baseline platelet and lymphocyte count predicted for IST response at 3 and 6 months, respectively. While additional growth factor interventions led to faster count recovery, there were no statistically significant differences in RFS or OS across the various frontline IST regimens (i.e., with/without G-CSF or eltrombopag). While marrow cellularity did not correlate with peripheral-blood counts at 3 months, cytomorphological assessment revealed dyspoietic changes in all nonresponders with hypercellular-marrow indices. Covert dysplasia, identified through early bone marrow assessment, has implications on future therapy choices after IST failure. Salvage IST response depended upon prior response to ATG: prior responders (46%) vs. primary refractory (0%) (P < .01). In the R/R setting, there was no survival difference between IST and allogeneic stem cell transplant groups, with a trend toward superior OS in the former. Transplant benefits in the R/R setting may be underrealized due to transplant-related mortality.

Nontransplant therapy for bone marrow failure

Nontransplant therapeutic options for acquired and constitutional aplastic anemia have significantly expanded during the last 5 years. In the future, transplant may be required less frequently. That trilineage hematologic responses could be achieved with the single agent eltrombopag in refractory aplastic anemia promotes new interest in growth factors after years of failed trials using other growth factor agents. Preliminary results adding eltrombopag to immunosuppressive therapy are promising, but long-term follow-up data evaluating clonal evolution rates are required before promoting its standard use in treatment-naive disease. Danazol, which is traditionally less preferred for treating cytopenias, is capable of preventing telomere attrition associated with hematologic responses in constitutional bone marrow failure resulting from telomere disease.

Treatment of aplastic anaemia with lower-dose anti-thymocyte globulin produces similar response rates and survival as per standard dose anti-thymocyte globulin schedules

BACKGROUND

Aplastic anaemia (AA) is a rare acquired bone marrow failure syndrome resulting from the immune-mediated destruction of haemopoietic stem cells. For adults in whom first-line haemopoietic progenitor cell transplantation is not feasible, combination anti-thymocyte globulin (ATGAM) plus cyclosporine A is standard therapy; however, there are minimal data available regarding the optimal ATGAM dosage in terms of efficacy and survival.

AIMS

Our institutions have historically used different dosing protocols of ATGAM in the treatment of AA. We aimed to review the outcome of AA patients treated with these protocols and compare them to the published literature.

METHODS

We conducted a retrospective study of 31 adults who received first-line ATGAM for AA and compared response rates and survival between cohorts who received standard (40 mg/kg/day D1-4) versus lower-dose (15 mg/kg/day D1-5) ATGAM schedules.

RESULTS

There were similar rates of response (64 vs 71%, P = 1.0), relapse (33 vs 33%, P = 1.0), transformation (14 vs 24%, P = 0.66) or infection (43 vs 47%, P = 1.0), respectively, between standard and lower-dose cohorts. At a median follow up of 24 months, there was no statistical difference between standard and lower-dose cohorts in either event-free (42.2 vs 64.7%, P = 0.91) or overall survival (73.1 vs 88.2%, P = 0.75).

CONCLUSION

Our experience suggests that lower-dose ATGAM at 15 mg/kg/day D1-5 as treatment of AA produces similar responses and outcomes as per standard-dose ATGAM schedules. Prospective trials comparing ATGAM dose schedules in AA are warranted.

[Aplastic anemia: Current state of diagnosis and treatment]

Aplastic anemia (AAI) is a rare life-threatening disorder which is characterized by bi- or tricytopenia and hypoplastic or aplastic bone marrow. AA can present as an acquired or congenital disorder. In recent years it was noted that a subgroup of patients with seemingly acquired AA with onset in adulthood carry mutations which cause or at least predispose to bone marrow failure, e.g. mutations in the genes of the telomerase complex. Options for first-line treatment are allogeneic stem cell transplantation or immunosuppression. The decision depends on severity of the disease, age and comorbidity of the patient and availability of a matched stem cell donor. Probability of survival after HLA-identical sibling transplantation exceeds 90% in young patients with bone marrow as the stem cell source and conditioning with an ATG-containing regimen. Results of matched unrelated donor transplantation have improved substantially over the last 10 years. Matched unrelated donor transplantation is increasingly considered as the first-line treatment for very young patients who are candidates for transplantation, but lack an HLA-identical sibling donor. The gold standard for immunosuppression is the combination of antithymocyte globulin (ATG) and cyclosporine A (CsA). ATG, a polyvalent antibody preparation, is obtained from animals after immunization with human thymocytes. Response rate and overall survival after horse ATG treatment are significantly higher compared to rabbit ATG. Recent trials reported a surprisingly high rate of bi- and trilinear response to treatment with the thrombopoietin receptor agonist eltrombopag in patients refractory to immunosuppression. Ongoing trials now address the potential role of eltrombopag as an adjunct to immunosuppression in first-line treatment.

Immunosuppressive therapy for transplant-ineligible aplastic anemia patients

Aplastic anemia is a rare life-threatening bone marrow failure that is characterized by bicytopenia or pancytopenia in the peripheral blood and a hypoplastic or aplastic bone marrow. The patients are at risk of infection and hemorrhage due to neutropenia and thrombocytopenia and suffer from symptoms of anemia. The main treatment approaches are allogeneic stem cell transplantation and immunosuppression. Here, we review current standard immunosuppression and the attempts that have been made in the past two decades to improve results: review of recent developments also reveals that sometimes not only the advent of new drugs, good ideas and well-designed clinical trials decide the progress in the field but also marketing considerations of pharmaceutical companies. Aplastic anemia experts unfortunately had to face the situation that efficient drugs were withdrawn simply for marketing considerations. We will discuss the current options and challenges in first-line treatment and management of relapsing and refractory patients with an emphasis on adult patients. Some promising new approaches are currently under investigation in prospective, randomized trials.

Porcine antilymphocyte globulin (p-ALG) plus cyclosporine A (CsA) treatment in acquired severe aplastic anemia: a retrospective multicenter analysis

Severe aplastic anemia (SAA) is a life-threatening bone marrow failure syndrome characterized by pancytopenia and hypocellular bone marrow. Antithymocyte globulin (ATG) is the drug of choice for immunosuppressive therapy (IST) in patients with SAA ineligible for allogeneic stem cell transplantation. This study aimed to evaluate the efficacy and safety profile of porcine antilymphocyte globulin (p-ALG) plus CsA in the treatment of acquired SAA. Clinical information of 69 SAA patients treated with p-ALG plus CsA was collected and retrospectively analyzed for early mortality, response rate, survival rate, side effects, and other complications. The median age at diagnosis was 27 years (range 14 to 52). The overall response rate was 76.8 % with a 90-day median response time (range 30 ~ 360 days). Overall response rates at 3, 6, 12, 18, and 24 months were 63.8, 73.9, 76.8, 75.4, and 75.4 %, respectively. The median follow-up time for surviving patients was 24 months (range 4 ~ 44 months) and the 2-year overall survival (OS) rate was 88.4 %. The disease-free survival (DFS) rate at 2 years was 85.5 %. Older age (≥45 years), very (v)SAA subgroup, and lower baseline absolute lymphocyte count (<1 × 10(9)/L) were independent unfavorable predictors of overall survival (p < 0.05). Less than one third of patients had serum sickness or allergic reaction during ALG therapy, but symptoms could easily be relieved by steroid treatment; 27.54 % had mild hepatic impairment. Taken together, p-ALG showed similar efficacy and safety profiles to rabbit or horse ATG in IST of acquired SAA. It can be a suitable alternative preparation for rabbit ATG with the great advantage of lower medical expenses.

Early intensified intravenous cyclosporine therapy predicts favorable response to immunosuppressive therapy with rabbit antithymocyte globulin in patients with severe aplastic anemia

Because of relapse after horse ATG (hATG) therapy, rabbit ATG (rATG) would be a realistic alternative as second line immunosuppressive therapy (IST) in severe aplastic anemia (SAA) patients. We investigated whether intensified intravenous (IV) CsA therapy with rATG would increase the response of IST in SAA patients. Sixty-one of the 123 patients received IV CsA therapy with rATG during initial 2 weeks then changed to oral form (IV CsA group), while other 62 patients just received oral CsA therapy with rATG (oral CsA group). Hematologic response rates at 3 and 6 months were not different between IV CsA group and oral CsA group (p=0.795, p=0.079). However, CsA levels during initial 15 days were higher in response-achieved group than response-not-achieved group. Intensive IV CsA group maintained CsA level ≥ 300 ng/ml during 15 days had higher responses at 6 months than non-intensive IV CsA group and oral CsA group (p=0.009, p=0.021). Intensive IV CsA group (HR=3.239, 95% CI=1.095-8.997, p=0.013) independently predicted favorable the hematologic response at 6 months of IST. Early intensified CsA therapy was important to achieve favorable outcomes in IST including rATG.

Evolution of iron burden in acquired aplastic anemia: a cohort study of more than 3-year follow-up

Acquired aplastic anemia (AA) is the most common condition linked to transfusion dependence. We conducted a cohort study to explore patterns of the dynamic evolution of iron burden, and to identify the risk factors for iron overload (IO) in 550 AA patients. Of the participants, 13 % presented with IO when diagnosed, including 7 % of patients without a history of transfusion and 22 % of those receiving transfusions. Male patients [hazard ratio (HR) = 3.85, 95 % confidence interval (CI) 1.77-8.36], adults (HR = 3.04, 95 % CI 1.21-7.63), and patients with high transfusion burdens (more than eight units; HR = 11.30, 95 % CI 4.45-28.70) experienced a significantly higher risk of IO. Furthermore, we found a sharply increasing risk of IO within the first 2 years, especially in males, patients with large number of lifetime transfusions, and patients not responding to treatment. More interestingly, after transfusion independence, a significant seesaw effect between erythropoiesis and iron burden was not noted until 6 months later, which continued over 3 years. In contrast to female patients, children, and patients with lower transfusion burdens, male subjects, adults, and subjects with high transfusion burdens experienced a pattern of slow decline in iron burden. AA incurred a high risk of progression to IO and showed distinct patterns in the evolution of iron burden. In light of these data, we offer suggestions for decision-making regarding who should undergo iron chelation and when.

Ciclosporin use during pregnancy

Ciclosporin (cyclosporine) is an immunosuppressive drug first approved for use in organ transplantation to prevent rejection. Ciclosporin is also known to be used for the treatment of psoriasis, rheumatoid arthritis, systemic lupus erythematosus and inflammatory bowel disease, among other indications. While it is recommended that all medications that are not absolutely necessary should be avoided during pregnancy, this may not be an option for many women whose quality of life is significantly impacted without treatment, or for those who must continue immunosuppressive therapy to avoid organ rejection. The purpose of this review is to provide a comprehensive report from the literature of ciclosporin exposure during pregnancy. PubMed, MEDLINE and the Cochrane Database of Systematic Reviews were searched for English-language articles published from 1970 to 2012 that included reports of pregnant women treated at any time during pregnancy with ciclosporin. On an initial search, it was evident that much of the available information is limited to pregnancy after transplant, which suggests that ciclosporin use during pregnancy appears to be associated with premature delivery and low birthweight infants. Comorbidities such as hypertension, pre-eclampsia and gestational diabetes mellitus are also reported at higher incidences than the general population. Medical literature concerning women with autoimmune disorders exposed to ciclosporin during pregnancy are currently limited to case reports and registry data, and, as such, it is difficult to determine if any risks associated with ciclosporin therapy during pregnancy are due to exposure to the drug alone or to pre-existing maternal comorbidities. The literature suggests that ciclosporin therapy during pregnancy should be carefully considered by the treating physician, but may be a safe alternative for patients with autoimmune disease refractory to conventional treatment. Continued monitoring of this patient population remains a key component to understanding the risk factors associated with ciclosporin exposure during pregnancy.

First-line immunosuppressive treatment in children with aplastic anemia: rabbit antithymocyte globulin

Immunosuppressive therapy is the treatment of choice in children with acquired severe aplastic anemia (AA) and no HLA-matched family donor. The paper presents results of a multicenter study of 63 children with AA treated with rabbit antithymocyte globulin (r-ATG) and cyclosporine A as the first line treatment in the years 1996-2012. Therapeutic effects were evaluated at Days 112, 180, and 360. At Day 112, remission was achieved in 28 out of the 63 patients (44.4 %), complete remission in 10 patients (15.9 %), and partial remission in 18 (28.5 %). At Day 180, 31 patients (49.2 %) were in remission including 15 cases in complete (23.8 %), and 16 cases in partial remission (25.4 %). One year after therapy onset, 34 patients (64.9 %) were in remission including 24 patients (38.0 %) in complete and 10 (15.9 %) in partial remission. Relapse occurred in 4 patients, from 8 months up to 2 years and 2 months after remission. One child, 5 years after remission, was diagnosed with paroxysmal nocturnal hemoglobinuria. The estimated 10-year overall survival rate and 10-year event-free survival rate were 67 % and 57 %, respectively.

Outcomes of optimized over standard protocol of rabbit antithymocyte globulin for severe aplastic anemia: a single-center experience

BACKGROUND

Previous reports showed that outcome of rabbit antithymocyte globulin (rATG) was not satisfactory as the first-line therapy for severe aplastic anemia (SAA). We explored a modifying schedule of administration of rATG.

DESIGN AND METHODS

Outcomes of a cohort of 175 SAA patients, including 51 patients administered with standard protocol (3.55 mg/kg/d for 5 days) and 124 cases with optimized protocol (1.97 mg/kg/d for 9 days) of rATG plus cyclosporine (CSA), were analyzed retrospectively.

RESULTS

Of all 175 patients, response rates at 3 and 6 months were 36.6% and 56.0%, respectively. 51 cases received standard protocol had poor responses at 3 (25.5%) and 6 months (41.2%). However, 124 patients received optimized protocol had better responses at 3 (41.1%, P = 0.14) and 6 (62.1%, P = 0.01). Higher incidences of infection (57.1% versus 37.9%, P = 0.02) and early mortality (17.9% versus 0.8%, P<0.001) occurred in patients received standard protocol compared with optimized protocol. The 5-year overall survival in favor of the optimized over standard rATG protocol (76.0% versus. 50.3%, P<0.001) was observed. By multivariate analysis, optimized protocol (RR = 2.21, P = 0.04), response at 3 months (RR = 10.31, P = 0.03) and shorter interval (<23 days) between diagnosis and initial dose of rATG (RR = 5.35, P = 0.002) were independent favorable predictors of overall survival.

CONCLUSIONS

Optimized instead of standard rATG protocol in combination with CSA remained efficacious as a first-line immunosuppressive regimen for SAA.

The efficacy of rabbit antithymocyte globulin with cyclosporine in comparison to horse antithymocyte globulin as a first-line treatment in adult patients with severe aplastic anemia: a single-center retrospective study

Antithymocyte globulin (ATG) is the drug of choice for immunosuppressive therapy (IST) in patients with severe aplastic anemia (SAA) ineligible for allogeneic stem cell transplantation. Recently, rabbit ATG with cyclosporine A has been used as a first-line IST regimen in patients with SAA because of unavailability of horse ATG. We retrospectively analyzed adult SAA patients who were treated with horse ATG (n=46) or rabbit ATG (n=53) between Feb 2001 and May 2010 to compare hematologic response and survival. Overall response rates at 3, 6, 12, and 18 months were similar in both the horse and rabbit ATG groups: 28.3 versus 35.8 % (P=0.421), 39.1 versus 45.3 % (P=0.537), 45.7 versus 49.1 % (P=0.735), and 47.8 versus 50.9 % (P=0.757), respectively. The complete response (CR) rate at 6 months in the horse ATG was significantly superior in comparison with the rabbit ATG (13.0 versus 1.9 %, P=0.031). But CR rates became similar in both groups after 6 months: 17.4 versus 11.3 % (P=0.387) at 12 months and 21.7 versus 22.6 % (P=0.914) at 18 months. Lymphocyte depletion after ATG was more profound and protracted in the rabbit ATG group compared to the horse ATG group. Overall survival (P=0.460) and failure-free survival (P=0.911) were not significantly different between the two groups. Our retrospective study demonstrated that the efficacy of first-line IST with rabbit ATG is similar to that with horse ATG. However, the time from treatment to CR was longer with rabbit ATG than with horse ATG, partly due to more profound and protracted lymphocyte depletion.

Aplastic anemia: therapeutic updates in immunosuppression and transplantation

Advances in hematopoietic stem cell transplantation (HSCT) and immunosuppressive therapy (IST) have improved survival in severe aplastic anemia (SAA) from 10%-20% in the 1960s to 80%-90% today. A matched sibling HSCT is the treatment of choice in younger patients, whereas IST is often used in older patients or in those who lack a histocompatible sibling. Graft rejection, GVHD, and poor immune reconstitution (with associated infectious complications) limit the success of HSCT, whereas lack of response, relapse, and clonal evolution limit the success of IST. The historically high rate of graft rejection in SAA is now less problematic in the matched setting, but with greater rates observed with unrelated and umbilical cord donors. The correlation of increasing age with the risk of GVHD and the significant morbidity and mortality of this transplantation complication continue to affect the decision to pursue HSCT versus IST as initial therapy in adults with SAA. Outcomes with matched unrelated donor HSCT have improved, likely due to better donor selection, supportive care, and improved transplantation protocols. Results with mismatched unrelated donor and umbilical HSCT are not as favorable, with higher rates of graft rejection, GVHD, and infectious complications. Investigation of several upfront alternative IST protocols has not improved outcomes beyond horse antithymocyte globulin and cyclosporine. More recently, the role of alemtuzumab in SAA has been better defined and an oral thrombomimetic, eltrombopag, is showing promising activity in refractory cases. The most recent advances in HSCT and IST in SAA are discussed in this review.

Immunosuppressive treatment in children with acquired aplastic anemia

OBJECTIVE

Immunosuppressive treatment (IST) is an alternative for children with acquired aplastic anemia (AA) that do not have HLA-matched donors. The objective of this study was to evaluate the outcome of IST in children with acquired AA.

MATERIAL AND METHODS

The study included 18 pediatric acquired AA patients that were retrospectively evaluated. The patients either did not have an HLA-matched related donor or were unable to undergo transplantation within 6 months despite having an HLA-matched donor.

RESULTS

In all, 6 of the patients were characterized as very severe AA, 6 as severe AA, and 6 as moderate AA. Mean duration of follow-up was 44.5 months. In total, 9 patients that could not be treated with equine anti-thymocyte globulin (hATG) following diagnosis received high-dose methylprednisolone treatment. Among the 6 very severe AA patients, 2 achieved complete remission (22%); the other 16 patients received hATG+cyclosporine and short-term methylprednisolone. In total, 4 of the patients died during the first month of treatment. Of the remaining 12 patients, 3 responded to the treatment (25%). Of the 9 patients that did not respond after 3 months of treatment, 7 received a second course of immunosuppressive treatment with rabbit ATG (rATG)+cyclosporine and short-term methylprednisolone; 2 of the 7 patients responded (22%), but 5 did not respond to any treatment. Median survival among the patients was as 64 ± 8 months

CONCLUSION

Combination IST with ATG+cyclosporine and low-dose methylprednisolone was an effective treatment in the pediatric acquired AA patients with non-identical HLA donors. In the patients that couldn't be treated with ATG high-dose methylprednisolone treatment was safe and effective.

How I treat acquired aplastic anemia

Survival in severe aplastic anemia (SAA) has markedly improved in the past 4 decades because of advances in hematopoietic stem cell transplantation, immunosuppressive biologics and drugs, and supportive care. However, management of SAA patients remains challenging, both acutely in addressing the immediate consequences of pancytopenia and in the long term because of the disease's natural history and the consequences of therapy. Recent insights into pathophysiology have practical implications. We review key aspects of differential diagnosis, considerations in the choice of first- and second-line therapies, and the management of patients after immunosuppression, based on both a critical review of the recent literature and our large personal and research protocol experience of bone marrow failure in the Hematology Branch of the National Heart, Lung, and Blood Institute.

Excellent outcome of matched unrelated donor transplantation in paediatric aplastic anaemia following failure with immunosuppressive therapy: a United Kingdom multicentre retrospective experience

We retrospectively analysed the outcome of consecutive children with idiopathic severe aplastic anaemia in the United Kingdom who received immunosuppressive therapy (IST) or matched unrelated donor (MUD) haematopoietic stem cell transplantation (HSCT). The 6-month cumulative response rate following rabbit antithymocyte globulin (ATG)/ciclosporin (IST) was 32·5% (95% CI 19·3-46·6) (n = 43). The 5-year estimated failure-free survival (FFS) following IST was 13·3% (95% confidence interval [CI] 4·0-27·8). In contrast, in 44 successive children who received a 10-antigen (HLA-A, -B, -C, -DRB1, -DQB1) MUD HSCT there was an excellent estimated 5-year FFS of 95·01% (95% CI 81·38-98·74). Forty of these children had failed IST previously. HSCT conditioning was a fludarabine, cyclophosphamide and alemtuzumab (FCC) regimen and did not include radiotherapy. There were no cases of graft failure. Median donor chimerism was 100% (range 88-100%). A conditioning regimen, such as FCC that avoids total body irradiation is ideally suited in children. Our data suggest that MUD HSCT following IST failure offers an excellent outcome and furthermore, if a suitable MUD can be found quickly, MUD HSCT may be a reasonable alternative to IST.

Final results of the phase II study of rabbit anti-thymocyte globulin, ciclosporin, methylprednisone, and granulocyte colony-stimulating factor in patients with aplastic anaemia and myelodysplastic syndrome

This report describes the final results of a Phase II clinical trial investigating the efficacy of rabbit antithymocyte globulin (rATG), ciclosporin, steroids, and granulocyte colony-stimulating factor (GCSF) in patients with untreated aplastic anaemia (AA), or low to intermediate-risk and hypocellular myelodysplastic syndrome (MDS). We treated 24 patients each with AA and MDS with rATG (3·5 mg/kg/d × 5; reduced to 2·5 mg/kg/d × 5 in patients with MDS ≥ 55 years), ciclosporin (5 mg/kg orally daily × 6 months), steroids (1 mg/kg daily, tapered off over 1 month), and GCSF. The overall response rate in AA patients was 64% compared to 25% in MDS patients. The median time to response was 3 months in AA patients and 4 months in MDS patients. Pretreatment clinical characteristics, such as age, sex, blood counts, cellularity, cytogenetics, or HLA-DR15 status, did not predict for response. Response to therapy, however, predicted for improved overall survival (OS), with a 3-year OS of 89% vs. 43% in responders versus non-responders, respectively (P < 0·001). Infusion reactions occurred in about half the patients and were manageable. Myelosuppression, elevation in liver enzymes, and infections were common. The early mortality in MDS patients was 13% vs. 0% in AA patients.

Antibodies in the treatment of aplastic anemia

Antibodies have been the cornerstone of treatment of acquired aplastic anemia for more than 25 years. Treatment with antithymocyte globulin (ATG) is considered pivotal and the addition of cyclosporine improves the overall response rate. This antibody is heterogeneous and horse ATG is apparently more effective than rabbit ATG. Several issues remain unsolved in relation to the combination of ATG and cyclosporine: cost, toxicity and late clonal disorders. In recent years, alternative immunosuppressive therapy has been proposed and new antibodies have emerged: porcine ATG, alemtuzumab, daclizumab, and rituximab. Experience with these antibodies is limited to a few studies with alemtuzumab being the most promising, but the results are interesting and provocative. More studies are needed to find the perfect antibody.

Immunosuppressive therapies in the management of acquired immune-mediated marrow failures

PURPOSE OF REVIEW

Immunosuppression is a key treatment strategy for patients suffering from aplastic anemia or related immune-mediated bone marrow failure syndromes. Several attempts have been performed to improve the standard immunosuppression regimen of horse antithymocyte globulin (h-ATG) and cyclosporine A (CyA).

RECENT FINDINGS

The addition of a third immunosuppression agent to h-ATG + CyA did not result in any improvement. Antilymphocyte agents other than h-ATG have been investigated. A rabbit-ATG preparation, which was known to be more immunosuppressive than h-ATG, resulted in markedly inferior outcome in a large randomized study from the National Institutes of Health. These data seem to be confirmed in additional experiences with rabbit-ATG from other groups. Cyclophosphamide and alemtuzumab have been proven to be biologically active in small studies, but available data suggest inferior outcomes when compared with h-ATG. All these alternative agents result in a more pronounced lymphocyte depletion, suggesting that the actual mechanisms of action of immunosuppressive therapy in aplastic anemia are not fully understood.

SUMMARY

Immunosuppression by h-ATG and CyA remains the standard of care for aplastic anemia patients lacking a low-risk transplant procedure, resulting in a 60-70% response rate. Rabbit-ATG, cyclophosphamide and alemtuzumab demonstrated a biological activity, but resulted in inferior outcome as compared with h-ATG; thus, they are not recommended as front-line therapy of aplastic anemia.

Clonal Evolution in Aplastic Anemia

Current immunosuppressive treatment (IST) induces remissions in 50%-70% of patients with aplastic anemia (AA) and result in excellent long-term survival. In recent years, the survival of refractory patients has also improved. Apart from relapse and refractoriness to IST, evolution of clonal diseases, including paroxysmal nocturnal hemoglobinuria and myelodysplastic syndrome (MDS), are the most serious long-term complications and constitute a strong argument for definitive therapy with BM transplantation if possible. Consequently, the detection of diagnostic chromosomal abnormalities (mostly monosomy 7) is of great clinical importance. Newer whole-genome scanning technologies such as single nucleotide polymorphism (SNP) array–based karyotyping may be a helpful diagnostic test for the detection of chromosomal defects in AA due to its precision/resolution and lack of reliance on cell division.

Immunosuppressive therapy without hematopoietic growth factor exposure in pediatric acquired aplastic anemia

Immunosuppressive therapy (IST) is recommended for children with acquired aplastic anemia (AA) who lack a human leukocyte antigen (HLA)-matched sibling donor for hematopoietic cell transplantation (HCT). Hematopoietic growth factors have often been included in IST supportive care, but prolonged exposure may increase the risk of secondary clonal evolution. The authors evaluated response, survival, and the incidence of clonal evolution following cyclosporine-based IST without hematopoietic growth factor exposure in a population-based pediatric cohort, identified retrospectively. Forty-five patients with a median age of 7.3 years (range 1.2-17.0 years) were included. Partial (PR) and complete (CR) response was achieved in 82% and 64%, at a median of 55 days (range 11-414 days) and 7.6 months (range 2.8-82.2 months), respectively. Patients with associated seronegative hepatitis had an increased likelihood of PR and CR on multivariate analyses (PR: hazard ratio [HR] 3.15, 95% confidence interval [CI] 1.40, 7.11; CR: HR 2.99, 95% CI 1.35, 6.62), whereas older children were less likely to achieve IST response than children younger than 5 years at diagnosis. Five- and 10-year overall survival was 96% ± 4% and 90% ± 7%, respectively, and 5-year failure-free survival was 63% ± 8%. There was no infection-related mortality, although 16.4% of patients had at least 1 episode of documented bacteremia. The 5-year cumulative incidence of relapse was 12.9% and of clonal evolution was 3.2%. The authors conclude that children with AA who receive IST without hematopoietic growth factor support have excellent response and survival outcomes and a low incidence of clonal evolution.

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.

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).

A randomized controlled study in patients with newly diagnosed severe aplastic anemia receiving antithymocyte globulin (ATG), cyclosporine, with or without G-CSF: a study of the SAA Working Party of the European Group for Blood and Marrow Transplantation

We evaluated the role of granulocyte colony-stimulating factor (G-CSF) in patients with severe aplastic anemia (SAA) treated with antithymocyte globulin (ATG) and cyclosporine (CSA). Between January 2002 and July 2008, 192 patients with newly diagnosed SAA not eligible for transplantation were entered into this multicenter, randomized study to receive ATG/CSA with or without G-CSF. Overall survival (OS) at 6 years was 76% ± 4%, and event-free survival (EFS) was 42% ± 4%. No difference in OS/EFS was seen between patients randomly assigned to receive or not to receive G-CSF, neither for the entire cohort nor in subgroups stratified by age and disease severity. Patients treated with G-CSF had fewer infectious episodes (24%) and hospitalization days (82%) compared with patients without G-CSF (36%; P = .006; 87%; P = .0003). In a post hoc analysis of patients receiving G-CSF, the lack of a neutrophil response by day 30 was associated with significantly lower response rate (56% vs 81%; P = .048) and survival (65% vs 87%; P = .031). G-CSF added to standard ATG and CSA reduces the rate of early infectious episodes and days of hospitalization in very SAA patients and might allow early identification of nonresponders but has no effect on OS, EFS, remission, relapse rates, and mortality. This study was registered at www.clinicaltrials.gov as NCT01163942.

A comparison of Jurkat cell-reactive anti-T lymphocyte globulin and fetal anti-thymocyte globulin preparations in the treatment of aplastic anemia

OBJECTIVE

The aim of this study was to investigate the success rate and effects on survival of different anti-thymocyte globulin (ATG) preparations in patients diagnosed with aplastic anemia.

SUBJECTS AND METHODS

Of the total 24 patients included in the study, 12 were male and 12 female with a median age of 44 years (range 16-72). Nine patients received Lymphoglobulin®, 7 Thymoglobulin® and ATG-Fresenius® (ATG-F). There was no significant difference between the three treatment groups in terms of severity of aplastic anemia.

RESULTS

The estimated 6-month survival rates for ATG-F, Lymphoglobulin and Thymoglobulin groups were 42.9, 77.8 and 71.4%, respectively. The difference in overall survival rates between groups was not significant, most likely due to the low number of patients. The most striking result was that none of the patients in the ATG-F preparation group showed any response to treatment. The ATG-F group was found to have a significantly inferior response rate (p = 0.07).

CONCLUSION

Our data showed that none of the patients responded to ATG-F treatment. Hence, despite the small number of the patients, we recommend that ATG-F should not be used for treatment of severe aplastic anemia.

Aplastic Anemia: First-line Treatment by Immunosuppression and Sibling Marrow Transplantation

Newly diagnosed aplastic anemia is a serious condition, with more than 75% (higher in young patients) becoming long-term survivors if diagnosed and treated appropriately. First-line treatment approaches include immunosuppressive treatment using the combination of antithymocyte globulin and cyclosporine A for patients without a sibling donor and HLA identical sibling transplant for patients younger than age 40 with a donor. Best transplant strategies have been defined and include conditioning with cyclophosphamide and antithymocyte globulin, marrow as a stem cell source, and graft-versus-host diease prophylaxis using cyclosporine A and methotrexate. It is against these standard treatment approaches that any therapeutic progress has to be measured.

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.