Impact of age on outcomes after bone marrow transplantation for acquired aplastic anemia using HLA-matched sibling donors

Outcome of aplastic anemia in adolescence: a survey of the Severe Aplastic Anemia Working Party of the European Group for Blood and Marrow Transplantation

We analyzed the outcome of 537 adolescents (age 12-18 years) with idiopathic aplastic anemia included in the database of the Severe Aplastic Anemia Working Party of the European Group for Blood and Marrow Transplantation comparing: i) matched family donor hematopoietic stem cell transplantation performed as first-line treatment with ii) front-line immunosuppressive therapy not followed by subsequent transplant given for failure and with iii) hematopoietic stem cell transplantation performed after failed front-line immunosuppressive therapy. Overall survival was 86% in the matched family donor hematopoietic stem cell transplantation group, 90% in patients given front-line immunosuppressive alone (those who did not fail this treatment and who did not receive subsequent rescue with hematopoietic stem cell transplantation) and 78% in subjects who underwent hematopoietic stem cell transplantation post failed front-line immunosuppressive therapy (P=0.14). Event-free survival in the same groups was respectively 83%, 64% and 71% (P=0.04). Cumulative incidence of rejection was 8% in matched family donor hematopoietic stem cell transplantation and 9% in transplants post failed front-line immunosuppression (P=0.62). Cumulative incidence of acute graft-versus-host disease was 12% in matched family donor transplants and 18% in transplants post failed immunosuppression (P=0.18). Chronic graft-versus-host disease was higher in matched family donor hematopoietic stem cell transplantation (8%) than in transplants post failed immunosuppressive therapy (20%) (P=0.0009). Cumulative incidence of post-therapy malignancies was 0.7% in matched family donor transplantations, 7% in transplantations post failed immunosuppression and 21% after front-line immunosuppression (P=0.0017). In the whole cohort, under multivariate analysis, the diagnosis to treatment interval of two months or under positively affected overall survival whereas up-front immunosuppression alone (with no subsequent rescue transplants) negatively affected event-free survival. In transplanted patients an interval from diagnosis to treatment of 2 months or under, bone marrow as source of cells and first-line matched family donor transplants provided a significant advantage in overall and event-free survival. Aplastic anemia in adolescents has a very good outcome. If a matched family donor is available, hematopoietic stem cell transplantation using bone marrow cells is the first choice treatment. If such a donor is not available, immunosuppressive treatment may still be an acceptable second choice, also because, in case of failure, hematopoietic stem cell transplantation is a very good rescue option.

Outcomes of hematopoietic cell transplantation in adult patients with acquired aplastic anemia using intermediate-dose alemtuzumab-based conditioning

Graft-versus-host disease (GVHD) has no therapeutic benefit after hematopoietic cell transplantation (HCT) for patients with acquired aplastic anemia (AA), and its prevention is highly desirable. We designed a conditioning regimen using an intermediate dose of alemtuzumab (50 to 60 mg) and describe our institutional experience of 41 patients who underwent HCT for AA. The median age at HCT was 37 years (range, 17 to 59). The conditioning regimen was high-dose cyclophosphamide (n = 9) or fludarabine based (n = 32). Additional GVHD prophylaxis was with cyclosporine. With a median follow-up of 3.6 years, overall survival at 3 years was 85%. Survival in patients <40 years and ≥40 years was 96% and 67%, respectively (P = .04). Graft failure occurred in 4 (10%) patients; 2 primary and 2 secondary. The cumulative incidences of acute (grades 1 to 2) and chronic GVHD were 27% and 15%, respectively. No patients developed grade 3 to 4 acute GVHD or severe chronic GVHD. The following viral complications were frequent: cytomegalovirus reactivation (79%), herpes simplex (18%), varicella zoster (25%), and BK virus hemorrhagic cystitis (8%). The majority of patients had no significant long-term health issues. This intermediate-dose alemtuzumab-based conditioning regimen results in excellent survival with a favorable impact on GVHD and long-term health outcomes, but close monitoring for viral complications is important.

Allogeneic hematopoietic cell transplantation without total body irradiation from unrelated donor in adult patients with idiopathic aplastic anemia: fludarabine versus cyclophosphamide-ATG

Total body irradiation (TBI) has traditionally been used in the conditioning regimen for allogenetic hematopoietic stem cell transplantation (alloHCT) from an unrelated donor (u-HCT). However, patients are increasingly receiving a fludarabine-based conditioning regimen without TBI, as it seemed less toxic than TBI. We need to know the clinical results of non-TBI u-HCT treatments. We retrospectively investigated the clinical outcomes of allogenetic hematopoietic cell transplantation (alloHCT) from an unrelated donor without TBI (non-TBI u-HCT) and compared the clinical outcomes of fludarabine-based (FLU group) and cyclophosphamide-ATG (Cy-ATG group) conditioning regimens. Sixty-one patients received the non-TBI conditioning regimen for u-HCT (32 in the FLU group and 29 in the Cy-ATG group). The cumulative incidence of neutrophil engraftment at 30 days, platelet>20K/μL at 30 days, acute graft-versus host disease (aGvHD) at 100 days, and chronic GvHD (cGvHD) at 2 years were 87.01%, 65.57%, 35.20%, and 26.64%, respectively. However, transplantation outcomes and overall survival rates did not differ between the FLU and Cy-ATG groups. Only infused CD34+ cells >3×10(6)kg(-1) was identified as a favorable factor for survival in the multivariate analysis. In conclusion, non-TBI u-HCT was feasible and there was no difference between the FLU and Cy-ATG groups in terms of transplantation outcomes.

Haematopoietic stem cell transplantation for acquired aplastic anaemia

PURPOSE OF REVIEW

Survival outcomes from haematopoietic stem cell transplantation (HSCT) in severe aplastic anaemia (SAA) have improved steadily over the past decades, largely reflecting progress in supportive care and conditioning regimens. Here we review recently published data that highlight the improvements and current issues.

RECENT FINDINGS

Human leukocyte antigen (HLA)-matched sibling donor (MSD) HSCT remains the gold standard for SAA patients younger than 40-50 years, with HLA-matched unrelated donor (MUD) HSCT for second line after failure to respond to immunosuppressive therapy (IST). The use of alternative donor sources for aplastic anaemia patients remains limited and problematic, but novel conditioning regimens, particularly in the haploidentical setting, justify further evaluation. In recent studies when comparing alemtuzumab-based conditioning with standard antithymocyte globulin conditioning regimens, lower rates of acute and chronic graft-versus-host disease and better tolerance in older patients are seen.

SUMMARY

Improving outcomes may lead to an expanded frontline HSCT role in the future. In children lacking a MSD, increasingly MUD HSCT is being considered as first-line treatment and is also being considered more for young adults. Further research is needed to advance our understanding of the role HSCT has to play in SAA with particular emphasis on alternative donor sources and identifying optimal conditioning regimens.

Effect of race on outcomes after allogeneic hematopoietic cell transplantation for severe aplastic anemia

We compared outcomes after hematopoietic cell transplantation in patients of African American (n = 84) and Caucasian (n = 215) descent with severe aplastic anemia. African Americans and Caucasians were matched for age, donor-recipient human leukocyte antigen match, graft type, and transplantation year. The median follow-up of surviving patients was 5 years. In multivariate analysis, overall mortality risks were higher for African Americans compared to Caucasians (relative risk 1.73, P = 0.01). The 5-year probabilities of overall survival adjusted for interval from diagnosis to transplantation, and performance score was 58% for African Americans and 73% for Caucasians. The day-100 cumulative incidence of grade III-IV, but not grade II-IV acute graft-versus-host disease (GVHD), was higher in African Americans compared to Caucasians (29% vs. 13%, P = 0.006). Although the 5-year cumulative incidence of chronic GVHD was not significantly different between the racial groups, African Americans were more likely to have extensive chronic GVHD compared to Caucasians (72% vs. 49%, P = 0.06). Survival differences between Caucasians and African Americans can be attributed to multiple factors. Our data suggest that some of the observed survival differences between Caucasians and African Americans may be explained by higher rates of acute GVHD and severity of chronic GVHD.

Rapid donor T-cell engraftment increases the risk of chronic graft-versus-host disease following salvage allogeneic peripheral blood hematopoietic cell transplantation for bone marrow failure syndromes

The risk of graft-rejection after allogeneic hematopoietic cell transplantation using conventional cyclophosphamide-based conditioning is increased in patients with bone marrow failure syndromes (BMFS) who are heavily transfused and often HLA-alloimmunized. Fifty-six patients with BMFS underwent fludarabine-based reduced-intensity conditioning and allogeneic peripheral blood progenitor cell (PBPC) transplantation at a single institution. The conditioning regimen consisted of intravenous cyclophosphamide, fludarabine, and equine antithymocyte globulin. Graft-versus-host disease (GVHD) prophylaxis included cyclosporine A alone or in combination with either mycophenolate mofetil or methotrexate. To reduce the risk of graft-rejection/failure, unmanipulated G-CSF mobilized PBPCs obtained from an HLA-identical or single HLA-antigen mismatched relative were transplanted rather than donor bone marrow. Despite a high prevalence of pretransplant HLA-alloimmunization (41%) and a heavy prior transfusion burden, graft-failure did not occur with all patients having sustained donor lympho-hematopoietic engraftment. The cumulative incidence of grade II-IV acute-GVHD and chronic-GVHD was 51.8% and 72%, respectively; with 87.1% surviving at a median follow-up of 4.5 years. A multivariate analysis showed pretransplant alloimmunization and rapid donor T-cell engraftment (≥95% donor by day 30) were both significantly (P < 0.05) associated with the development of chronic-GVHD (adjusted HR 2.13 and 2.99, respectively). These data show fludarabine-based PBPC transplantation overcomes the risk of graft-failure in patients with BMFS, although rapid donor T-cell engraftment associated with this approach appears to increase the risk of chronic-GVHD. (Clinicaltrials.gov identifier: NCT00003838).

Retrospective study of alemtuzumab vs ATG-based conditioning without irradiation for unrelated and matched sibling donor transplants in acquired severe aplastic anemia: a study from the British Society for Blood and Marrow Transplantation

This retrospective national study compared the use of alemtuzumab-based conditioning regimens for hematopoietic SCT (HSCT) in acquired severe aplastic anemia with antithymocyte globulin (ATG)-based regimens. One hundred patients received alemtuzumab and 55 ATG-based regimens. A matched sibling donor (MSD) was used in 87 (56%), matched unrelated donor (MUD) in 60 (39%) and other related or mismatched unrelated donor (UD) in 8 (5%) patients. Engraftment failure occurred in 9% of the alemtuzumab group and 11% of the ATG group. Five-year OS was 90% for the alemtuzumab and 79% for the ATG groups, P=0.11. For UD HSCT, OS of patients was better when using alemtuzumab (88%) compared with ATG (57%), P=0.026, although smaller numbers of patients received ATG. Similar outcomes for MSD HSCT using alemtuzumab or ATG were seen (91% vs 85%, respectively, P=0.562). A lower risk of chronic GVHD (cGVHD) was observed in the alemtuzumab group (11% vs 26%, P=0.031). On multivariate analysis, use of BM as stem cell source was associated with better OS and EFS, and less acute and cGVHD; young age was associated with better EFS and lower risk of graft failure. This large study confirms successful avoidance of irradiation in the conditioning regimens for MUD HSCT patients.

First-line allogeneic hematopoietic stem cell transplantation of HLA-matched sibling donors compared with first-line ciclosporin and/or antithymocyte or antilymphocyte globulin for acquired severe aplastic anemia

BACKGROUND

Acquired severe aplastic anemia is a rare and potentially fatal disease, which is characterized by hypocellular bone marrow and pancytopenia. The major signs and symptoms are severe infections, bleeding, and exhaustion. First-line allogeneic hematopoietic stem cell transplantation (HSCT) of a human leukocyte antigen (HLA)-matched sibling donor (MSD) is a treatment for newly diagnosed patients with severe aplastic anemia. First-line treatment with ciclosporin and/or antithymocyte or antilymphocyte globulin (as first-line immunosuppressive therapy) is an alternative to MSD-HSCT and is indicated for patients where no MSD is found.

OBJECTIVES

To evaluate the effectiveness and adverse events of first-line allogeneic hematopoietic stem cell transplantation of HLA-matched sibling donors compared to first-line immunosuppressive therapy including ciclosporin and/or antithymocyte or antilymphocyte globulin in patients with acquired severe aplastic anemia.

SEARCH METHODS

We searched the electronic databases MEDLINE (Ovid), EMBASE (Ovid), and The Cochrane Library CENTRAL (Wiley) for published articles from 1946 to 22 April 2013. Further searches included trial registries, reference lists of recent reviews, and author contacts.

SELECTION CRITERIA

The following prospective study designs were eligible for inclusion: randomized controlled trials (RCTs) and non-randomized controlled trials if the allocation of patients to treatment groups was consistent with 'Mendelian randomization'. We included participants with newly diagnosed severe aplastic anemia who received MSD-HSCT or immunosuppressive therapy without prior HSCT or immunosuppressive therapy, and with a minimum of five participants per treatment group. We did not apply limits on publication year or languages.

DATA COLLECTION AND ANALYSIS

Two review authors abstracted the data on study and patient characteristics and assessed the risk of bias independently. We resolved differences by discussion or by appeal to a third review author. The primary outcome was overall mortality. Secondary outcomes were treatment-related mortality, graft failure, no response to first-line immunosuppressive therapy, graft-versus-host-disease (GVHD), relapse after initial successful treatment, secondary clonal and malignant disease, health-related quality of life, and performance score.

MAIN RESULTS

We identified three trials that met the inclusion criteria. None of these trials was a RCT. 302 participants are included in this review. The three included studies were prospectively conducted and had features consistent with the principle of 'Mendelian randomization' as defined in the present review. All studies had a high risk of bias due to the study design. All studies were conducted more than 10 years ago and may not be applicable to the standard of care of today. Primary and secondary outcome data showed no statistically significant difference between treatment groups. We present results for first-line allogeneic hematopoietic stem cell transplantation of an HLA-matched sibling donor, which we denote as the MSD-HSCT group, versus first-line treatment with ciclosporin and/or antithymocyte or antilymphocyte globulin, which we denote as the immunosuppressive therapy group in the following section.The pooled hazard ratio for overall mortality for the MSD-HSCT group versus the immunosuppressive therapy group was 0.95 (95% confidence interval 0.43 to 2.12, P = 0.90, low quality evidence). Therefore, overall mortality was not statistically significantly different between the groups. Treatment-related mortality ranged from 20% to 42% for the MSD-HSCT group and was not reported for the immunosuppressive therapy group (very low quality evidence). The authors reported graft failure from 3% to 16% for the MSD-HSCT group and GVHD from 26% to 51% (both endpoints not applicable for the immunosuppressive therapy group, very low quality evidence). The authors did not report any data on response and relapse for the MSD-HSCT group. For the immunosuppressive therapy group, the studies reported no response from 15% (not time point stated) to 64% (three months) and relapse in one of eight responders after immunosuppressive therapy at 5.5 years (very low quality evidence). The authors reported secondary clonal disease or malignancies for the MSD-HSCT group versus the immunosuppressive therapy group in 1 of 34 versus 0 of 22 patients in one study and in 0 of 28 versus 4 of 86 patients in the other study (low quality evidence). None of the included studies addressed health-related quality of life. The percentage of the evaluated patients with a Karnofsky performance status score in the range of 71% to 100% was 92% in the MSD-HSCT group and 46% in the immunosuppressive therapy group.

AUTHORS' CONCLUSIONS

There are insufficient and biased data that do not allow any conclusions to be made about the comparative effectiveness of first-line allogeneic hematopoietic stem cell transplantation of an HLA-matched sibling donor and first-line treatment with ciclosporin and/or antithymocyte or antilymphocyte globulin (as first-line immunosuppressive therapy). We are unable to make firm recommendations regarding the choice of intervention for treatment of acquired severe aplastic anemia.

Allogeneic stem cell transplantation using alemtuzumab-containing regimens in severe aplastic anemia

Alemtuzumab, a humanized anti-CD52, IgG1 monoclonal antibody, is used to reduce graft-versus- host disease (GVHD) and aid engraftment after allogeneic haemopoietic stem cell transplant (HSCT). Its associated low incidence of GVHD makes it an attractive alternative to anti-thymocyte globulin (ATG) in transplant conditioning regimen for severe aplastic anaemia (SAA). We have reviewed the use of alemtuzumab-based conditioning regimen for HSCT in SAA and show that it results in sustained haematological engraftment, a very low incidence of chronic GVHD without an increase in viral infections. Intriguingly, alemtuzumab appears to induce tolerance post-HSCT with the findings of stable mixed T cell chimerism with full donor myeloid chimerism and the absence of chronic GVHD, and which persist on withdrawal of post-graft immunosuppression. Finally, its low toxicity profile may permit future application of HSCT to older patients with SAA who fail to respond to immunosuppressive therapy.

Allogeneic BM transplantation for the treatment of aplastic anemia: current results and expanding donor possibilities

Allogeneic BM transplantation from an HLA-identical sibling donor leads to long-term survival in the majority of patients (>80%). Therefore, survival is no longer the sole concern and attention has to be paid to decreasing the incidence and severity of long-term complications. For patients without a sibling donor, transplantation from a well-matched unrelated donor can be considered after failure of a previous course of immunosuppressive therapy. After transplantation from an HLA-identical sibling donor or from an unrelated one, the use of peripheral blood stem cells must be strongly discouraged because they have been systematically associated with an increased incidence of chronic GVHD compared with the use of BM as a stem cell source, leading to an unacceptably higher risk of treatment-related mortality in this setting. For as yet unknown reasons, the age limit after which transplantation results are less satisfactory remains 40 years of age.

Management of adult patients older than 40 years refractory to at least one immunosuppressive course: HLA-identical sibling HSCT using fludarabine-based conditioning

Allogeneic hematopoietic SCT (HSCT) from an HLA-identical sibling donor is the recommended upfront therapeutic option for young patients with SAA. The outcome of allogeneic sibling HSCT has remarkably improved during the last decade as a function of improvement in transplantation supportive care. However, there is still much debate concerning the upper age limit for sibling HSCT in SAA, particularly in patients who are refractory to at least one immunosuppressive course. Recent studies suggest that fludarabine-based conditioning may improve HSCT outcome in older patients with SAA. This review discusses available data about the use of fludarabine-based conditioning in transplantation of older patients with SAA. More definitive conclusions are needed from larger studies before the wide adoption of fludarabine-based conditioning as an alternative to the standard CY and ATG-based conditioning.

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.

Late effects in hematopoietic cell transplant recipients with acquired severe aplastic anemia: a report from the late effects working committee of the center for international blood and marrow transplant research

With improvements in hematopoietic cell transplant (HCT) outcomes for severe aplastic anemia (SAA), there is a growing population of SAA survivors after HCT. However, there is a paucity of information regarding late effects that occur after HCT in SAA survivors. This study describes the malignant and nonmalignant late effects in survivors with SAA after HCT. A descriptive analysis was conducted of 1718 patients post-HCT for acquired SAA between 1995 and 2006 reported to the Center for International Blood and Marrow Transplant Research (CIBMTR). The prevalence and cumulative incidence estimates of late effects are reported for 1-year HCT survivors with SAA. Of the HCT recipients, 1176 (68.5%) and 542 (31.5%) patients underwent a matched sibling donor (MSD) or unrelated donor (URD) HCT, respectively. The median age at the time of HCT was 20 years. The median interval from diagnosis to transplantation was 3 months for MSD HCT and 14 months for URD HCT. The median follow-up was 70 months and 67 months for MSD and URD HCT survivors, respectively. Overall survival at 1 year, 2 years, and 5 years for the entire cohort was 76% (95% confidence interval [CI]: 74-78), 73% (95% CI: 71-75), and 70% (95% CI: 68-72). Among 1-year survivors of MSD HCT, 6% had 1 late effect and 1% had multiple late effects. For 1-year survivors of URD HCT, 13% had 1 late effect and 2% had multiple late effects. Among survivors of MSD HCT, the cumulative incidence estimates of developing late effects were all <3% and did not increase over time. In contrast, for recipients of URD HCT, the cumulative incidence of developing several late effects exceeded 3% by 5 years: gonadal dysfunction 10.5% (95% CI: 7.3-14.3), growth disturbance 7.2% (95% CI: 4.4-10.7), avascular necrosis 6.3% (95% CI: 3.6-9.7), hypothyroidism 5.5% (95% CI: 2.8-9.0), and cataracts 5.1% (95% CI: 2.9-8.0). Our results indicated that all patients undergoing HCT for SAA remain at risk for late effects, must be counseled about, and should be monitored for late effects for the remainder of their lives.

Etiology and survival of aplastic anemia: a study based on clinical investigation

BACKGROUND

Management of aplastic anemia is etiology driven, whether constitutional or acquired. Age, gender, and severity of disease also play crucial role in the survival of aplastic anemia. Since, inadequate data are available from India, the present study was conducted with the aim to evaluate the etiology and survival of aplastic anemia.

METHODS

Three hundred patients were enrolled between May 2007 and April 2010. Severity analysis and chromosomal breakage study was performed and patients were followed up to calculate the survival rate.

RESULTS

Only 9.4% of the cases demonstrated the evidence of constitutional disease. Patients with acquired disease showed a significantly higher odd ratio for hepatitis. Overall survival was found to be independent of the gender and inherited etiology. Phenotype resembling to constitutional disease was present in only 22.22% (6/27) of patients. Similar ratio of the constitutional and acquired disease in both the age groups was observed.

CONCLUSION

Irrespective of the age and phenotype, chromosomal breakage study should be mandatory for all patients with aplastic anemia. Hepatitis as a preceding event may be associated with the cause of aplastic anemia. Young age and less severe disease were strongly associated with better survival. Lack of tertiary care facility in the country, time lag between diagnosis and treatment, and unaffordability to abide the treatment cost could be the major contributory factors for poorer survival.

Last marrow standing: bone marrow transplantation for acquired bone marrow failure conditions

Paroxysmal nocturnal hemoglobinuria, aplastic anemia, and myelodysplastic syndrome are a spectrum of acquired marrow failure, having a common pathologic thread of both immune dysregulation and the development of abnormal hematopoiesis. Allogeneic hematopoietic cell transplantation plays a critical role in the treatment of these disorders and, for many patients, is the only treatment modality with demonstrated curative potential. In recent years, there have been many breakthroughs in the understanding of the pathogenesis of these uncommon disorders. The subsequent advances in non-transplant therapies, along with concurrent improvement in outcomes after hematopoietic cell transplantation, necessitate continual appraisal of the indications, timing, and approaches to transplantation for acquired marrow failure syndromes. We review here contemporary and critical new findings driving current treatment decisions.

Allogeneic transplantation for aplastic anemia

OBJECTIVE

To discuss the role of allogeneic transplantation for the treatment of severe aplastic anemia.

METHODS

Published reports for treatment of severe aplastic anemia were searched with Medline. Search terms included severe aplastic anemia, HLA-matched sibling, unrelated donor, hematopoietic stem cell transplantation.

RESULTS

Survival after HLA-matched sibling donor transplantation is approximately 80% in patients aged less than 20 years. Survival rates are lower in older patients ranging from 50-70%. The risks of transplant-related morbidity and mortality increase with age and explain the observed lower survival rates in older patients. Unrelated donor transplantation is reserved for patients who lack a matched related donor and have failed at least one course of immunosuppressive therapy. Survival after unrelated donor transplantation has also improved in recent years and largely attributed to the selection of donors who are fully HLA-matched to the patient. The risks of transplant-related complications are higher than after HLA-matched sibling transplantation. Graft-versus-host disease (GVHD) is higher; GVHD can lead to significant morbidity and mortality. Other frequent complications include graft failure and pulmonary complications. The use of peripheral blood progenitor cells has also contributed to higher GVHD risks and consequently excess deaths.

DISCUSSION

The results of allogeneic transplantation, from related and unrelated donors have improved substantially in the last decade. Early referral for transplantation, selection of HLA-matched donors and improved supportive care has contributed to the success of this treatment. The choice of graft used for transplantation is important regardless of donor type; bone marrow is the preferred graft.

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.

Allogeneic hematopoietic stem cell transplant for adults over 40 years old with acquired aplastic anemia

Although younger age is associated with favorable prognosis in adults undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) for aplastic anemia (AA), other pretransplantation factors may be more important than age. We retrospectively analyzed the impact of older age on transplantation outcomes and survival in a total of 225 adult patients with AA who underwent allo-HSCT: 57 patients >40 years old (older patient group [OPG]) and 168 patients ≤40 years old (younger patient group [YPG]). Age at allo-HSCT ≤40 years, time from diagnosis to allo-HSCT ≤6 months, and matched related donor (MRD) were favorable prognostic factors in all study patients. Risk analysis of survival in the OPG showed that age >50 years was the only poor prognostic factor. Survival did not differ significantly between the YPG and patients <50 years old in the OPG. In conclusion, patients between the ages of 41 and 50 years with severe AA and MRDs should undergo allo-HSCT as early as possible to optimize survival.

Bone marrow versus peripheral blood as the stem cell source for sibling transplants in acquired aplastic anemia: survival advantage for bone marrow in all age groups

BACKGROUND

Bone marrow has been shown to be superior to peripheral blood, as a stem cell source, in young patients (<20 years of age) with acquired aplastic anemia undergoing a matched sibling transplant. The aim of this study was to test whether this currently also holds true for older patients with acquired aplastic anemia.

DESIGN AND METHODS

We analyzed 1886 patients with acquired aplastic anemia who received a first transplant from a human leukocyte antigen identical sibling between 1999 and 2009, with either bone marrow (n=1163) or peripheral blood (n=723) as the source of stem cells.

RESULTS

In multivariate Cox analysis negative predictors for survival were: patient's age over 20 years (RR 2.0, P<0.0001), an interval between diagnosis and transplantation of more than 114 days (RR 1.3, P=0.006), no anti-thymocyte globulin in the conditioning (RR 1.6, P=0.0001), a conditioning regimen other than cyclophosphamide (RR=1.3, P=0.008) and the use of peripheral blood as the source of stem cells (RR 1.6, P<0.00001). The survival advantage for recipients of bone marrow rather than peripheral blood was statistically significant in patients aged 1-19 years (90% versus 76% P<0.00001) as well as in patients aged over 20 years (74% versus 64%, P=0.001). The advantage for recipients of bone marrow over peripheral blood was maintained above the age of 50 years (69% versus 39%, P=0.01). Acute and chronic graft-versus-host disease were more frequent in peripheral blood transplants. Major causes of death were graft-versus-host disease (2% versus 6% in bone marrow and peripheral blood recipients, respectively), infections (6% versus 13%), and graft rejection (1.5% versus 2.5%).

CONCLUSIONS

This study shows that bone marrow should be the preferred stem cell source for matched sibling transplants in acquired aplastic anemia, in patients of all age groups.

Alemtuzumab with fludarabine and cyclophosphamide reduces chronic graft-versus-host disease after allogeneic stem cell transplantation for acquired aplastic anemia

We evaluated a novel alemtuzumab-based conditioning regimen in HSCT for acquired severe aplastic anemia (SAA). In a multicenter retrospective study, 50 patients received transplants from matched sibling donors (MSD; n = 21) and unrelated donors (UD; n = 29), using fludarabine 30 mg/m2 for 4 days, cyclophosphamide 300 mg/m2 for 4 days, and alemtuzumab median total dose of 60 mg (range:40-100 mg). Median age was 35 years (range 8-62). Overall survival at 2 years was 95% ± 5% for MSD and 83% for UD HSCT (p 0.34). Cumulative incidence of graft failure was 9.5% for MSD and 14.5% for UD HSCT. Full-donor chimerism (FDC) in unfractionated peripheral blood was 42%; no patient achieved CD3 FDC. Acute GVHD was observed in only 13.5% patients (all grade I-II) and only 2 patients (4%) developed chronic GVHD. A low incidence of viral infections was seen. Factors influencing overall survival were HSCT comorbidity 2-year index (92% with score 0-1 vs 42% with score ≥ 2, P < .001) and age (92% for age < 50 years vs 71% ≥ 50 years, P < .001). Our data suggest that the use of an alemtuzumab-based HSCT regimen for SAA results in durable engraftment with a low incidence of chronic GVHD.

The EBMT risk score

The European Group for Blood and Marrow Transplantation (EBMT) risk score provides a simple tool to assess instantly chances and risks of hematopoietic SCT(HSCT) for an individual patient pre-transplant. Five factors, age of the patient, stage of the disease, time from diagnosis, donor type and donor recipient gender combination augment risk for an individual patient with increasing score from 0 as best to 7 as worst in an additive way. The score holds for all acquired hematological disorders, for allogeneic and autologous HSCT (score 0-5), is independent of the HSCT technology and is valid for standard or reduced intensity conditioning. Survival is uniformly worse for older patients, transplanted in advanced disease stage after a long-time interval and with a mismatched donor than for younger patients, transplanted soon in early stage with a well matched donor. Additional risk factors such as performance score, CMV serostatus or cytokine polymorphisms improve prediction but to different extents for low or high-risk patients. Comparative assessment of disease risk and global pre-transplant risk should guide decisions for each patient with his/her specific disease between HSCT and a non-transplant approach and replace the traditional 'donor vs no donor' with such a risk-adapted individualized strategy.