Fludarabine, cyclophosphamide plus thymoglobulin conditioning regimen for unrelated bone marrow transplantation in severe aplastic anemia

The state of the art in the treatment of severe aplastic anemia: immunotherapy and hematopoietic cell transplantation in children and adults

Acquired aplastic anemia (AA) is an immune-mediated bone marrow (BM) failure where marrow disruption is driven by a cytotoxic T-cell-mediated autoimmune attack against hematopoietic stem cells. The key diagnostic challenge in children, but also in adults, is to exclude the possible underlying congenital condition and myelodysplasia. The choice of treatment options, either allogeneic hematopoietic cell transplantation (alloHCT) or immunosuppressive therapy (IST), depends on the patient's age, comorbidities, and access to a suitable donor and effective therapeutic agents. Since 2022, horse antithymocyte globulin (hATG) has been available again in Europe and is recommended for IST as a more effective option than rabbit ATG. Therefore, an update on immunosuppressive strategies is warranted. Despite an improved response to the new immunosuppression protocols with hATG and eltrombopag, some patients are not cured or remain at risk of aplasia relapse or clonal evolution and require postponed alloHCT. The transplantation field has evolved, becoming safer and more accessible. Upfront alloHCT from unrelated donors is becoming a tempting option. With the use of posttransplant cyclophosphamide, haploidentical HCT offers promising outcomes also in AA. In this paper, we present the state of the art in the management of severe AA for pediatric and adult patients based on the available guidelines and recently published studies.

Outcomes of allogeneic haematopoietic stem cell transplantation for patients with severe aplastic anaemia using the porcine antilymphocyte globulin-containing conditioning regimen

Antithymocyte globulin (ATG) is widely used for allogeneic haematopoietic stem cell transplantation (allo-HSCT) in severe aplastic anaemia (SAA). Only rabbit-ATG (r-ATG) and porcine-antilymphocyte globulin (p-ALG) are available in China, but the p-ALG-containing conditioning regimen for allo-HSCT in SAA has seldom been reported. In this study, we retrospectively evaluated the outcomes of 41 SAA patients receiving allo-HSCT with a p-ALG-containing conditioning regimen in our transplantation centre. All patients engrafted, and no death during conditioning was observed. The actuarial 3-year overall survival (OS) rates were 95.1 ± 3.4%. The actuarial 3-year disease-free survival (DFS) rates were 85.0 ± 5.7%. Acute graft-versus-host disease (aGVHD) predicted inferior OS (p < 0.05). The interval from diagnosis to transplantation for more than 100 days predicted an inferior DFS rate (p < 0.05) and a higher graft rejection/poor graft function (GR/PGF) rate (p < 0.01). In conclusion, the p-ALG-containing regimen showed satisfactory effects and safety in allo-HSCT for SAA patients. P-ALG could be a potential alternative preparation for r-ATG in SAA allo-HSCT.

Successful preemptive therapy with single-dose rituximab for Epstein-Barr virus infection to prevent post-transplant lymphoproliferative disease after pediatric hematopoietic stem cell transplantation

BACKGROUND

The efficacy of preemptive treatment containing rituximab to prevent post-transplant lymphoproliferative disease (PTLD) in children has not yet been fully elucidated.

METHODS

We analyzed 19 pediatric patients who developed high Epstein-Barr virus (EBV) DNAemia (EBV viral load of greater than 40 000 copies/mL) after allogeneic hematopoietic stem cell transplantation (HSCT) and were preemptively administered rituximab. Rituximab was intravenously injected at a dose of 375 mg/m² once the EBV viral load was greater than 40 000 copies/mL.

RESULTS

In all 19 patients, EBV DNAemia was eradicated after a median of 9 days (range, 3-20 days), and PTLD did not occur. One patient had transient fever, and four patients did not fully recover B cell counts after transplantation. We suggested that delayed B cell recovery was caused by chronic graft-versus-host disease (GVHD) related drugs, not rituximab administration. And there were no other infection-related side effects.

CONCLUSIONS

In conclusion, preemptive therapy containing rituximab is expected to reduce the incidence of PTLD after HSCT and improve post-transplantation outcomes in children.

Aplastic Anemia Preconditioned with Fludarabine, Cyclophosphamide, and Anti-Thymocyte Globulin

Background

Graft rejection and graft versus host disease (GvHD) have impeded the success of hematopoietic cell transplantation for severe aplastic anemia (SAA) patients. There is no sufficient data to identify the outcomes of peripheral blood stem cell transplantation (PBSCT) in SAA patients, especially for adult SAA patients. The aim of this study was to evaluate the outcomes of adult SAA patients undergoing PBSCT with the FCA regimen. The FCA regimen includes fludarabine, cyclophosphamide, and anti-thymocyte globulin (ATG).

Material/Methods

We report our experience with 46 adult SAA patients who underwent PBSCT with the FCA regimen. Thirty SAA patients who received only cyclophosphamide and ATG (CA) regimen were used as controls. Complications and survival outcomes were evaluated and compared.

Results

There was a significantly higher percentage of patients who achieved >95% donor chimerism by day 30 in the FCA group. The 5-year event-free survival (EFS) rate in the FCA group was higher than that in the CA group (95.4% versus 73.3%). In addition, the 5-year rejection rate (RR) in the FCA group was lower than that in the CA group (4.6% versus 23.6%). A multivariable model identified the FCA regimen as an independent factor affecting EFS and RR. However, GvHD and serious infection did not differ between the 2 groups. For patients with an unrelated donor, the FCA regimen had a higher EFS and a lower RR than the CA regimen.

Conclusions

The FCA regimen for PBSCT in adult SAA patients compared favorably to the CA regimen. It can improve EFS and reduce graft rejection, especially for unrelated donor PBSCT.

Allogeneic Matched Related Donor Bone Marrow Transplantation for Pediatric Patients With Severe Aplastic Anemia Using "Low-dose" Cyclophosphamide, ATG Plus Fludarabine

BACKGROUND

The combination of cyclophosphamide (CY) and antithymocyte globulin (ATG) has been used as a standard conditioning regimen for matched related donor transplantation in patients with severe aplastic anemia.

PROCEDURE

To decrease the regimen-related toxicity while maintaining appropriate engraftment and survival rates, fludarabine (FLU) was added to the regimen. Four pediatric patients received matched related donor bone marrow transplantation with CY (50 mg/kg×2) (instead of the 50 mg/kg×4 standard dosing), equine ATG (30 mg/kg×3), with the addition of FLU (30 mg/m×4). Graft versus host disease (GvHD) prophylaxis included a calcineurin inhibitor and methotrexate.

RESULTS

No grade 4 acute toxicities occurred during the first 30 days after transplant. All patients engrafted with normalization of peripheral blood counts and transfusion independence. One patient developed grade 1 to 2 acute GvHD, followed by chronic GvHD that resolved. With a median follow-up of 41.7 months, all 4 patients are alive and transfusion free, with complete donor chimerism. This combination of a low-dose CY/ATG+FLU regimen was overall very well tolerated and contributed toward a successful outcome including engraftment, chimerism, and survival.

CONCLUSION

This small pilot study shows that this cytoreductive regimen could be considered as the standard of care for transplantation of pediatric patients with aplastic anemia from HLA-matched siblings.

Population pharmacokinetics of fludarabine in patients with aplastic anemia and Fanconi anemia undergoing allogeneic hematopoietic stem cell transplantation

Although hematopoietic stem cell transplantation (HSCT) with a conditioning regimen consisting of fludarabine (F-araA) and cyclophosphamide (Cy) is associated with improved outcome in young patients with aplastic anemia (AA) and Fanconi anemia (FA), several factors limit the success of the procedure. We evaluated the population pharmacokinetics (POPPK) of F-araA and its influence on HSCT outcome in patients (n=53) with AA and FA undergoing HSCT. Patients carrying a 5′-UTR polymorphism in NT5E gene (rs2295890 G>C) exhibited significantly lower plasma F-araA clearance compared to those with wild-type genotype (7.12 vs 5.03 L/h/m² (29%) P<0.05). F-araA clearance was significantly higher in patients with AA compared to FA (2.46 ×, P<1e−6). Of all the outcome parameters evaluated (engraftment, rejection/graft failure, GvHD, TRM, OS), high F-araA AUC (>29.4 μm*h) was the only significant factor associated with the development of aGvHD by both univariate and multivariate analysis (P=0.02). The influence of plasma F-araA levels need to be evaluated in a larger cohort of patients to propose the need for therapeutic drug monitoring.

Targeted busulfan and fludarabine-based conditioning for bone marrow transplantation in chronic granulomatous disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency disease caused by impaired phagocytic function. Hematopoietic stem cell transplantation (HSCT) is a definitive cure for CGD; however, the use of HSCT is limited because of associated problems, including transplantation-related mortality and engraftment failure. We report a case of a patient with CGD who underwent successful HSCT following a targeted busulfan and fludarabine reduced-toxicity myeloablative conditioning. Intravenous busulfan was administered once daily for 4 consecutive days (days -8 to -5), and the target area under the curve was 75,000 µg·hr/L. Fludarabine (40 mg/m²) was administered once daily for 6 consecutive days from days -8 to -3. Antithymocyte globulin (2.5 mg/kg/day) was administered from days -4 to -2. The patient underwent successful engraftment and did not have any severe toxicity related to the transplantation. Conditioning with a targeted busulfan and fludarabine regimen could provide a better outcome for HSCT in CGD, with close regulation of the busulfan dose.

Unmanipulated Haploidentical Reduced-Intensity Stem Cell Transplantation Using Fludarabine, Busulfan, Low-Dose Antithymocyte Globulin, and Steroids for Patients in Non-Complete Remission or at High Risk of Relapse: A Prospective Multicenter Phase I/II Study in Japan

This prospective, multicenter phase I/II study of unmanipulated HLA-haploidentical reduced-intensity stem cell transplantation using a low dose of anti-T lymphocyte globulin (ATG) and steroid was conducted in 5 institutions in Japan. Thirty-four patients with hematologic malignancies who were in an advanced stage or at a high risk of relapse at the time of transplantation were enrolled. Among them, 7 patients underwent transplantation as a second transplantation because of relapse after the previous allogeneic stem cell transplantation. The conditioning regimen consisted of fludarabine, busulfan, and ATG (Fresenius, 8 mg/kg), and graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus and methylprednisolone (1 mg/kg). All patients except 1 (97.1%) achieved donor-type engraftment. Rapid hematopoietic engraftment was achieved, with neutrophils > .5 × 10(9)/L on day 11 and platelets > 20 × 10(9)/L on day 17.5. Treatment was started for ≥grade I GVHD, and the cumulative incidences of acute grade I and grade II to IV GVHD were 27.5% and 30.7%, respectively. The incidence of chronic GVHD (extensive type) was 20%. Fourteen patients (41.2%) had a relapse. The cumulative incidence of transplantation-related mortality at 1 year after transplantation was 26.5%. The survival rate at day 100 was 88.2%. The survival rates at 1 year for patients with complete remission (CR)/chronic phase (n = 8) and non-CR (n = 26) status before transplantation were 62.5% and 42.3%, respectively. In the multivariate analysis, non-CR status before transplantation was the only factor significant prognostic factor of increased relapse (P = .0424), which tended to be associated with a lower survival rate (P = .0524). This transplantation protocol is safe and feasible, if a suitable donor is not available in a timely manner. As the main cause of death was relapse and not GVHD, more intensified conditioning or attenuation of GVHD prophylaxis and/or donor lymphocyte infusion may be desirable for patients with non-CR status.

Alternative donor transplant of benign primary hematologic disorders

Hematopoietic SCT is currently the only curative therapy for a range of benign inherited and acquired primary hematologic disorders in children, including BM failure syndromes and hemoglobinopathies. The preferred HLA-matched sibling donor is available for only about 25% of such children. However, there has been substantial progress over the last four decades in the use of alternative donors for those without a matched sibling-including HLA-matched unrelated donors, HLA-haploidentical related donors and unrelated-donor umbilical cord blood-so that it is now possible to find a donor for almost every child requiring an allograft. Below, we summarize the relative merits and limitations of the different alternative donors for benign hematologic conditions, first generally, and then in relation to specific disorders, and suggest recommendations for selecting such an alternative donor.

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.

Allogeneic stem cell transplantation for children with acquired severe aplastic anaemia: a retrospective study by the Viva-Asia Blood and Marrow Transplantation Group

We retrospectively analysed the outcomes of 127 children with acquired severe aplastic anaemia (SAA) who had received haematopoietic stem cell transplantation (HSCT) between 2000 and 2011 in one of the 10 Asia Pacific institutions. Fifty-three were matched sibling donor (MSD) and 74 were alternative donor (AD), including 22 matched unrelated donor, 32 mismatched unrelated donor and 20 mismatched related donor. With a median follow up 45.5 months (13-139) and when compared to the MSD group, AD recipients had more grade II-IV acute graft-versus-host disease (aGVHD; 14.3% vs. 32.8%, P = 0.029), but similar grade III-IV aGVHD (10.2% vs. 12.5%, P = 0.774), graft failure (GF) (15.1% vs. 15.5%, P = 0.658) and 5-year overall survival (90.6% vs. 83.7%, P = 0.251). As a source of stem cell, peripheral blood stem cells (PBSC) resulted in less GF (18% vs. 9.1% P = 0.013), similar grade II-IV aGVHD (28.1% vs. 17.4%, P = 0.258), chronic GVHD (25.8% vs. 29.3%, P = 0.822) and similar outcomes (89.7% vs. 82.4%, P =0.665) when compared to bone marrow (BM). In univariate analysis, GF (P < 0.001) and grade II-IV aGVHD (P = 0.009) were predictors of poor survival. In multivariate analysis, only GF was associated with poor survival (P = 0.012). The outcome of AD and PBSC HSCT were comparable to that of MSD and BM HSCT in the Asia Pacific region.

Peri-engraftment syndrome in allogeneic hematopoietic SCT

Engraftment syndrome (ES) and pre-engraftment syndrome (pre-ES) are both inflammatory conditions that occur after hematopoietic SCT (HSCT) and are characterized by non-infectious fever and skin rash. Although the pathogenesis is not fully understood, both syndromes are similar, and could be defined as a new clinical syndrome, named as peri-engraftment syndrome (peri-ES). We retrospectively analyzed the clinical records in 176 pediatric patients, following allogeneic HSCT. We utilized the definition of ES by Spitzer as the diagnostic criteria, excluding 'within 96 h of engraftment' criteria. Thirty cases developed peri-ES with a cumulative incidence of 17.0%. High cumulative incidence (50%) was seen in patients who underwent a double-unit cord blood transplantation (DUCBT; P<0.01). Clinical findings of peri-ES are similar, regardless of the onset day, and encephalopathy was the most severe complication. In the DUCBT cohort, the use of TBI and early complete chimerism (≤ day 21) were identified as risk factors that predispose the development of peri-ES. We determined that both, ES and pre-ES, might have similar causes, which could be included in peri-ES. Particularly, it occurred more in DUCBT patients, which means that not only neutrophil engraftment but also immune reactions within the two units might contribute to peri-ES.

A randomized comparison of cyclophosphamide vs. reduced dose cyclophosphamide plus fludarabine for allogeneic hematopoietic cell transplantation in patients with aplastic anemia and hypoplastic myelodysplastic syndrome

Recently, a less toxic regimen comprising reduced cyclophosphamide (Cy), fludarabine, and anti-thymocyte globulin (ATG) (Cy-Flu-ATG) was used to condition high-risk patients scheduled for allogeneic hematopoietic cell transplantation (alloHSCT) instead of standard Cy-ATG in patients with severe aplastic anemia (AA). We performed a randomized phase III study to compare the regimen-related toxicities (RRTs) of two different conditioning regimens: Cy-ATG vs. Cy-Flu-ATG. Patients in the Cy-ATG arm received Cy at 200 mg/kg. Those in the Cy-Flu-ATG arm received fludarabine (Flu) at 150 mg/m(2) and Cy at 100 mg/kg. A total of 83 patients (40 in the Cy-ATG and 43 in the Cy-Flu-ATG) were enrolled. Seventy-nine patients had AA and four had MDS. All predefined RRTs were significantly lower in patients of the Cy-Flu-ATG arm (23.3 vs. 55.0 %; p = 0.003). Infection with identified causative organism and sinusoidal obstruction syndrome, hematuria, febrile episodes, and death from any cause tended to be more frequent in Cy-ATG arm but did not differ significantly between arms. There was no difference in neutrophil engraftment failure (2.5 vs. 2.33 %; p = 0.959), acute graft-versus-host disease (GvHD) (15.0 vs. 23.3 %; p = 0.388), and chronic GvHD (16.7 vs. 16.2 %; p = 0.961) between Cy-ATG and Cy-Flu-ATG arms. The 4-year survival rate did not differ between the Cy-ATG and Cy-Flu-ATG arms. Preconditioning with Cy-Flu-ATG was superior to that afforded by Cy-ATG in terms of reducing RRT levels without increasing engraftment failure.

Favorable preliminary results using TLI/ATG-based immunomodulatory conditioning for matched unrelated donor allogeneic hematopoietic stem cell transplantation in pediatric severe aplastic anemia

To assess whether a tolerance-induction regimen could be applied for unrelated (MUD) HCT in SAA, we retrospectively reviewed our HCT experience using unmanipulated 10/10 HLA-matched bone marrow grafts from MSD vs. MUD donors. Conditioning was CTX 200 mg/kg (CTX) + rabbit ATG 10 mg/kg (ATG) for MSD (n = 9) and TLI (800 cGy) + CTX/ATG for MUD HCT ( n = 5). Immunoprophylaxis was CSA and short-course MTX. Median patient age was 14.7 yr, median time to HCT 1.5 yr, and median follow-up 3 yr. Outcome measures included EFS, time to engraftment, and cumulative incidence of GVHD (CIN of GVHD) for MSD and MUD cohorts. EFS and stable engraftment rate were 100%. CIN of acute GVHD was: MSD, Grade I-II: 1 (11%), Grade III-IV: 0%; MUD, Grade I-II: 1 (20%), Grade III-IV: 1 (20%). CIN of chronic GVHD was: MSD, limited: 1 (11%), extensive: 0%; MUD, limited: 0%, extensive: 0%. All immunosuppressive-compliant patients successfully weaned immunosuppression. Although in limited patients, our results suggest that immunomodulatory TLI added to backbone CTX/ATG conditioning is a promising option for MUD HCT in SAA patients, which we will examine in a prospective clinical trial.

Specific factors influence the success of autologous and allogeneic hematopoietic stem cell transplantation

Successful hematopoietic stem cell transplantation (HSCT), both autologous and allogeneic, requires a rapid and durable engraftment, with neutrophil (>500/µL) and platelet (>20,000/µL) reconstitution. Factors influencing engraftment after autologous or allogeneic HSCT were investigated in 65 patients: 25 autologous peripheral stem cell transplantation (PBSCT) and 40 allogeneic bone marrow transplantation (BMT) patients. The major factor affecting engraftment was the graft source for HSCT. Neutrophil and platelet recovery were more rapid in autologous PBSCT than in allogeneic BMT [neutrophil occurring in median on day 10.00 (09.00/11.00) and 19.00 (16.00/23.00) and platelet on day 11.00 (10.00/13.00) and 21.00 (18.00/25.00), respectively; p < 0.0001]. The type of disease also affected engraftment, where multiple myeloma (MM) and lymphoma showed faster engraftment when compared with leukemia, syndrome myelodysplastic (SMD) and aplastic anemia (AA) and MM presented the best overall survival (OS) in a period of 12 months. Other factors included the drug used in the conditioning regimen (CR), where CBV, melphalan (M-200) and FluCy showed faster engraftment and M-200 presented the best OS, in a period of 12 months and age, where 50–59 years demonstrated faster engraftment. Sex did not influence neutrophil and platelet recovery.

Successful bone marrow transplantation for children with aplastic anemia based on a best-available evidence strategy

  A best-available evidence strategy, i.e., the best-available donors, conditioning regimens and GVHD prophylaxis were chosen at the time of BMT for AA, was analyzed retrospectively. The outcomes for 18 children with AA who underwent allogeneic BMT were analyzed. The median age was 11 yr (range 4-16), and nine were men. As conditioning regimens, seven had low-dose irradiation + CY, six had ATG + CY + Flu, and five had ATG + CY. Donors were HLA-matched siblings in 10, HLA-mismatched family in one, HLA-matched unrelated in three, and HLA-mismatched unrelated in four. As GVHD prophylaxis, three received CsA alone, nine received CsA + MTX, and six received tacrolimus + MTX. All 18 patients showed engraftment. The median number of days until the neutrophil count exceeded 500/μL was 16 (range 11-21) post-transplant. Five developed more than grade 2 acute GVHD, and three developed extensive cGVHD. One patient died because of interstitial pneumonia complicated with cGVHD. Five-yr OS was 94% (95% CI: 83-105). These results suggest that a strategy of treating patients based on the best-available evidence is acceptable.

Fludarabine-based conditioning chemotherapy for allogeneic hematopoietic stem cell transplantation in acquired severe aplastic anemia

Thirty-eight patients who met the diagnostic criteria for severe aplastic anemia underwent allogeneic hematopoietic stem cell transplantation (HSCT). The median patient age was 20 years (range, 14-36 years). Twenty-four patients were treatment-naïve, 11 had failed one or more previous courses of immunosuppressive therapy, and 3 had failed a previous HSCT. The conditioning regimen included fludarabine 30 mg/m(2)/day for 3 days (days -9, -8, and -7) and cyclophosphamide 50 mg/kg/day for 4 days (days -5, -4, -3, and -2). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and short-course methotrexate. All patients underwent transplantation with unmanipulated bone marrow as the stem cell source. The median total nucleated cell (TNC) dose was 2.43 × 10(8)/kg (range, 0.60-6.7 × 10(8)/ kg). The conditioning regimen was well tolerated, with minimal treatment-related mortality. Engraftment was observed in all patients after transplantation; the median time to engraftment of neutrophils and platelets was 18 and 23 days, respectively. Twenty-five of the 27 patients with available chimeric studies at day 180 maintained donor chimerism. Acute GVHD grade ≥II was diagnosed in 4 patients (11%). Extensive chronic GVHD was observed in 8 patients (25%) who survived beyond day +100, at a median observation time of 43 months. Graft rejection with relapse of aplais was observed in one patient. The overall survival (OS) for the whole group was 79%. A trend toward improved OS was observed in the treatment-naïve patients (83% vs 71%), but this was statistically insignificant (P = .384). The fludarabine-based conditioning regimen used in this study with relatively young cohort of patients was well tolerated, with a low rate of rejection and treatment outcomes comparable to those seen in other, more intense and potentially more toxic conditioning regimens. Our results await validation in a larger study, optimally in a randomized controlled manner.

Is it time for a change? The case for early application of unrelated allo-SCT for severe aplastic anemia

Severe aplastic anemia (SAA) is a BM failure syndrome in which allo-SCT remains a highly effective curative option. Its application remains limited by donor availability and by the potential for treatment-related morbidity and mortality. The improved outcomes with unrelated transplantation are a result of the advent of molecular donor-recipient matching, generation of effective novel conditioning regimens, improvement of supportive care and expansion of the donor registry. Decision making regarding the earlier use of unrelated transplant procedures is rapidly evolving. This paper reviews critical data relevant to these treatment options and recommends early consideration of related SCT for patients with SAA who show failure of immune suppressive therapy.

Influence of nucleated cell dose on overall survival of unrelated cord blood transplantation for patients with severe acquired aplastic anemia: a study by eurocord and the aplastic anemia working party of the European group for blood and marrow transplantation

Information is scarce on outcomes after unrelated cord blood transplantation (UCBT) for patients with severe aplastic anemia (SAA). We retrospectively analyzed 71 patients (median age, 13 years; 28 adults) with SAA (9 with paroxysmal nocturnal hemoglobinuria [PNH]) who received a single-unit (n = 57; 79%) or double-unit UCBT (n = 14; 19%) in 32 centers between 1996 and 2009. A reduced-intensity conditioning regimen was provided in 68% of the patients. The cumulative incidence (CI) of neutrophil recovery was 51% ± 6% at day 60, with significantly better engraftment seen in recipients of higher prefreezing total nucleated cell (TNC) dose (>3.9 10(7)/kg; hazard ratio [HR], 1.5; P = .05). The CI of platelet engraftment at day 180 posttransplantation was 37% ± 7%, that of grade II-IV acute GVHD was 20% ± 5%, and that of chronic GVHD at 3 years was 18% ± 5%. At a median follow-up of 35 months (range, 3-83 months), the estimated probability of 3-year overall survival (OS) was 38% ± 6%. Significantly improved OS was seen in recipients of >3.9 10(7) TNCs/kg prefreezing (45%, compared with 18% for recipients of ≤ 3.9 10(7) TNC/kg; HR, 0.4; P = .007). These results highlight the fundamental role of cell dose for both engraftment and OS in patients with SAA undergoing UCBT.

Early pulmonary complications after hematopoietic stem cell transplantation in pediatric patients: association with cytomegalovirus infection

Pulmonary complications resulting in high morbidity and mortality occur in a substantial proportion of hematopoietic stem cell transplantation (HSCT) recipients. We investigated the incidence, causes, and risk factors of pulmonary complications, early after HSCT in pediatric patients, and patient outcomes by retrospective analysis of patients who underwent HSCT at Seoul National University Children's Hospital between September 2003 and June 2007. A total of 145 patients were evaluated of whom 15 (10.3%) developed pulmonary complications. Eight patients were suspected to have infection-related pulmonary complications and 7 had noninfectious causes. In a multivariate analysis of allogeneic transplantation recipients, detection of cytomegalovirus antigenemia was significantly associated with the development of both pulmonary complications and acute respiratory distress syndrome. Eleven (73.3%) of the 15 patients developed acute respiratory distress syndrome, required mechanical ventilation and eventually died. Early use of methylprednisolone in 3 patients decreased the oxygenation index. Sixteen patients died due to treatment-related complications early after HSCT, and pulmonary complications accounted for a substantial portion of the mortality. Thus, improvement of prophylaxis and management for pulmonary complications is crucial to improve the overall outcome of HSCT. More aggressive prophylaxis and treatment of cytomegalovirus infection and judicious use of methylprednisolone at the appropriate time could be the means for such improvement.

Successful salvage unrelated umbilical cord blood transplantation with two units after engraftment failure with single unit in severe aplastic anemia

Severe aplastic anemia (SAA) patients without an HLA-matched sibling donor need alternative treatment options. Umbilical cord blood transplantation (UCBT) has become an alternative means for treating various diseases, but it has not been proved to be a satisfactory method to treat SAA. Here, we report the case of a girl who underwent successful two-unit UCBT after engraftment failure with a single unit. Two-unit UCBT is proposed to have better engraftment potential and to offer a better chance of survival, according to some reports. Increased cell dose and graft-versus-graft reaction could contribute to these advantages. With this promising result, two-unit UCBT could be an alternative treatment option for patients with SAA without an HLA-matched donor.

Myelodysplasia and acute leukemia as late complications of marrow failure: future prospects for leukemia prevention

Patients who have acquired and inherited bone marrow failure syndromes are at risk for the development of clonal neoplasms including acute myeloid leukemia, myelodysplastic syndrome, and paroxysmal nocturnal hemoglobinuria. This article reviews the evidence supporting a model of clonal selection, a paradigm that provides a reasonable expectation that these often fatal complications might be prevented in the future.

Effect of iron overload and iron-chelating therapy on allogeneic hematopoietic SCT in children

Iron overload is known to increase complications of hematopoietic SCT (HSCT). We investigated the association of pre-transplant ferritin level with complications and survival after allogeneic HSCT, and evaluated the efficacy of iron-chelating therapy before HSCT. We retrospectively reviewed 101 patients who underwent allogeneic HSCT and divided these patients into three groups: F>1000, patients with ferritin level above 1000 ng/ml at the time of HSCT; F<1000, patients whose ferritin levels were maintained below 1000 ng/ml before HSCT without iron-chelating therapy; IC, patients with ferritin level decreased to less than 1000 ng/ml after iron-chelating therapy before HSCT. In the comparison between the F>1000 group and the F<1000 group, hyperbilirubinemia and treatment-related mortality (TRM) were significantly higher in the F>1000 group. The F>1000 group also showed decreased OS and EFS. In the comparison of the F<1000 and IC groups, there was no significant difference in complications and survival. When compared with the F>1000 group, the IC group showed lower TRM and higher survival. Elevated serum ferritin level was associated with increased TRM and decreased survival, and the analysis of the IC group suggested the benefit of iron-chelating therapy to improve the outcome of HSCT.

Reduced-intensity conditioning for severe aplasia using fludarabine and CY followed by infusion of ex vivo T-cell-depleted grafts leads to excellent engraftment and absence of GVHD

We studied the outcome of individuals with aplastic anaemia (AA) who received reduced-intensity conditioning followed by the infusion of stem cell grafts that had been T-cell depleted ex vivo with alemtuzumab. Consecutive patients with AA who had an HLA-identical sibling received conditioning with fludarabine 30 mg/m(2) daily for 5 days followed by CY 60 mg/kg on 2 consecutive days. Cytokine-mobilized blood grafts were incubated ex vivo with alemtuzumab 'in the bag' and infused without washing. CYA was prescribed until day +90. Engraftment rate, GVHD, EFS and overall survival were studied. Fifteen patients received PBPC grafts. It was the second graft in one of the patients. Ten patients were male and their median age was 23.5 years. The toxicity of the conditioning was minimal. One patient received 1 x 10(7)/kg donor lymphocytes for rising chimerism. At a median of 1107 (294-1778) days, all of them survived with normal blood parameters. None of them developed acute or chronic GVHD. In patients with AA the combination of purine analogue and alkylator leads to rapid engraftment despite T-cell depletion of grafts. This strategy of reduced-intensity conditioning has low toxicity, does not compromise engraftment and seems effective for prevention of GVHD.

Liposomal Coencapsulated Fludarabine and Mitoxantrone for Lymphoproliferative Disorder Treatment**Xiaobin Zhao and Jianmei Wu contributed equally to this study

Fludarabine (FLU)-based combination therapies are commonly used to treat low-grade lymphoma and chronic lymphocytic leukemia (CLL) patients. In vitro and clinical studies have indicated advantages when FLU and mitoxantrone (MTO) are applied in combination. To further enhance this effect, these two agents were coencapsulated in liposomes. FLU was passively encapsulated during liposome formation, and MTO was loaded with a transmembrane pH gradient. Entrapment efficiency, particle size, stability, and drug release kinetics were characterized. In vitro cytotoxicity study was carried out in two representative B-cell lines: Wac3CD5 and Raji. Synergism as measured by combination index (CI) was observed in cells treated with liposomes coencapsulating FLU and MTO. Annexin V/propidium iodide (PI) analysis further confirmed that coencapsulated FLU and MTO improved the percentage of apoptosis among primary CLL cells. These data suggest that adopting liposomes containing coencapsulated drug combinations constitutes a potential strategy to promote drug synergism and may have utility in the treatment of leukemia and lymphoma.

Unrelated bone marrow transplantation with a reduced toxicity myeloablative conditioning regimen in Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is an X-linked congenital immune-deficiency syndrome, and bone marrow transplantation (BMT) has become a curative modality. However, the transplant with the alternative donor needed more intensive conditioning with increased treatment-related toxicities. Recently, fludarabine-based reduced toxicity myeloablative conditioning regimens have been developed for adult myeloid malignancies with promising results of good engraftment and low treatment-related toxicities. To increase the engraftment potential without serious complications, a boy with WAS received successful unrelated BMT with a reduced toxicity myeloablative conditioning regimen composed of fludarabine (40 mg/m2) on days -8, -7, -6, -5, -4, -3), busulfan (0.8 mg/kg i. v. q 6 hr on days -6, -5, -4, -3), and thymoglobulin (2.5 mg/kg on days -4, -3, -2). This novel conditioning regimen could improve the outcome of allogeneic transplantation for other non-malignant diseases such as congenital immune-deficiency syndromes or metabolic storage diseases.

Allogeneic stem cell transplantation for aplastic anemia

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

Fludarabine and cyclophosphamide based reduced intensity conditioning (RIC) regimens reduce rejection and improve outcome in Indian patients undergoing allogeneic stem cell transplantation for severe aplastic anemia

Thirty-five patients (25 men and 10 women) with a median age of 20 years with severe aplastic anaemia (SAA) underwent HLA identical stem cell transplantation (HSCT) using a combination of fludarabine and cyclophosphamide +/- anti-thymocyte globulin between 2004 and 2006. Cyclosporine and mini methotrexate were used as GVHD prophylaxis. Graft source included peripheral blood stem cells (28) or G-CSF stimulated bone marrow (7). Two patients expired < 7 days post-HSCT while 32 (91.5%) patients engrafted with a median neutrophil and platelet engraftment time of 12 days each. Three patients (8.5%) developed veno-occlusive disease while acute GVHD occurred in 29% of evaluable patients, with chronic GVHD in 32%. At a mean follow-up of 22 months, 29 (82.8%) are alive and well. When compared with 26 patients previously transplanted using Cy200/antilymphocyte globulin, there was faster neutrophil engraftment (12 vs 16 days; P = 0.002) with significantly lower rejection rates (2.9 vs 30.7%; P = 0.003) and a superior event-free (82.8 vs 38.4%; P = 0.001) and overall survival (82.8 vs 46.1%; P = 0.005). A combination of fludarabine with cyclophosphamide +/- anti-thymocyte globulin reduces rejection and improves overall and event-free survival in Indian patients undergoing HSCT for severe aplastic anaemia.

Bone marrow transplantation in children with severe aplastic anemia using a conditioning regimen containing 3 Gy of total body irradiation, cyclophosphamide with or without antithymocyte globulin

We have employed the 3 Gy total body irradiation (TBI) containing conditioning regimen to bone marrow transplantation (BMT) for severe aplastic anemia (SAA) in pediatric patients irrespective of donor type since March 1986. The outcome of BMT for 17 SAA patients is favorable. Eight patients received BMT from human leukocyte antigen matched-related donors (MRD) and nine received BMT from alternative donors. The conditioning regimen consisted of 3-Gy TBI and cyclophosphamide of 200 mg/kg in the BMT from MRD. In the case of BMT from alternative donor, antithymocyte globulin 10 mg/kg was added to the regimen. Fifteen of 17 patients (88%) engrafted on median of day 18 (range, 11-26) and all 13 evaluable patients showed complete donor chimerism by median 30 (range, 13-47) days after BMT. Fourteen patients have survived with a median follow-up of 67 (range, 2-228) months and the probability of survival was 81.9% (95% CI, 63.3-100%). No late complications including second malignancies caused by TBI have been observed and all three female patients have regular menstruation. In conclusion, TBI of 3 Gy appears to be an appropriate dose regarding to ensure engraftment and avoid the risk of late adverse event for SAA patients.

Rabbit antithymocyte globulin inhibits monocyte-derived dendritic cells maturation in vitro and polarizes monocyte-derived dendritic cells towards tolerogenic dendritic cells expressing indoleamine 2,3-dioxygenase

BACKGROUND

Rabbit antithymocyte globulin (rATG) is a polyclonal mixture of immunoglobulin (Ig) G. It is used to prevent graft rejection and also graft versus host disease after transplantation. Its effect on lymphocyte function has been widely studied. Dendritic cells are central actors of the immune system. As antigen presenting cells, they are able to initiate, stimulate, and modulate immune responses.

METHODS

In this study, we investigated rATG effects on in vitro differentiation and maturation of monocyte-derived dendritic cells (Mo-DCs).

RESULTS

rATG inhibited maturation of immature Mo-DCs and allowed the generation of dendritic cells expressing ILT-3, CD123, CCR6 but not CCR7 and producing Indoleamine 2,3-dioxygenase mRNA as well as interferon-alpha.

CONCLUSION

rATG polarizes in vitro Mo-DCs towards tolerogenic dendritic cells.

Early engraftment kinetics of two units cord blood transplantation

Cord blood transplantation (CBT) is a promising alternative means of allogeneic stem cell transplantation. However, limited cell doses may compromise outcome. To enhance engraftment, CBT has been conducted using two units with promising results. However, little is known about the mechanism of engraftment. Here, we analyzed the early engraftment kinetics of eight patients given two unit umbilical CBT. Early engraftment kinetics revealed dominancy of one of two units from the day of engraftment (absolute neutrophil count > 0.5 x 10(9)/l). The median value of percentage of the predominant unit by chimerism analysis at the time of engraftment was 88% (60-100%). Two units CBT was found to be a safe, effective and promising alternative treatment option with good engraftment potential. Dominancy occurred early after CBT and is probably influenced by multiple factors.

Current concepts in the pathophysiology and treatment of aplastic anemia

Aplastic anemia, an unusual hematologic disease, is the paradigm of the human bone marrow failure syndromes. Almost universally fatal just a few decades ago, aplastic anemia can now be cured or ameliorated by stem-cell transplantation or immunosuppressive drug therapy. The pathophysiology is immune mediated in most cases, with activated type 1 cytotoxic T cells implicated. The molecular basis of the aberrant immune response and deficiencies in hematopoietic cells is now being defined genetically; examples are telomere repair gene mutations in the target cells and dysregulated T-cell activation pathways. Immunosuppression with antithymocyte globulins and cyclosporine is effective at restoring blood-cell production in the majority of patients, but relapse and especially evolution of clonal hematologic diseases remain problematic. Allogeneic stem-cell transplant from histocompatible sibling donors is curative in the great majority of young patients with severe aplastic anemia; the major challenges are extending the benefits of transplantation to patients who are older or who lack family donors. Recent results with alternative sources of stem cells and a variety of conditioning regimens to achieve their engraftment have been promising, with survival in small pediatric case series rivaling conventional transplantation results.

Overcoming graft rejection in heavily transfused and allo-immunised patients with bone marrow failure syndromes using fludarabine-based haematopoietic cell transplantation

Allogeneic haematopoietic cell transplantation (HCT) can cure a variety of non-malignant haematological disorders. Although transplant outcomes for selected patients with severe aplastic anaemia (SAA) and paroxysmal nocturnal haemoglobinuria (PNH) have improved, older age, allo-immunisation from transfusions, prior immunosuppressive therapy and a prolonged time from diagnosis to transplantation are associated with worse outcome. Because of its potent immunosuppressive effects, we investigated a fludarabine-based non-myeloablative conditioning regimen in patients with transfusion-dependent non-malignant haematological disorders at increased risk for graft rejection with conventional transplant conditioning. Twenty-six patients with transfusion dependent/anti-thymocyte globulin (ATG)-refractory SAA, PNH or pure red cell aplasia underwent HCT from a human leucocyte antigen (HLA)-compatible relative. Transplant conditioning consisted of cyclophosphamide (120 mg/kg) and fludarabine (125 mg/m2) with or without ATG. Ciclosporine, alone or combined with mycophenolate mofetil or methotrexate, was used as graft-versus-host disease (GVHD) prophylaxis. All patients achieved durable engraftment and transfusion-independence. Twenty-four of 26 patients are alive at a median of 21 months following transplantation. Although a high cumulative incidence of acute (65% grades II-IV, 54% grades III-IV) and chronic GVHD (56%) was observed, only one patient died from transplant-related causes (cumulative incidence 7%). These data show that HCT following fludarabine-based non-myeloablative conditioning results in durable engraftment and excellent survival in SAA and PNH patients at high risk for graft rejection.

Fludarabine, cyclophosphamide and horse antithymocyte globulin conditioning regimen for allogeneic peripheral blood stem cell transplantation performed in non-HEPA filter rooms for multiply transfused patients with severe aplastic anemia

Multiply transfused patients of severe aplastic anemia are at increased risk of graft rejection. Five such patients underwent peripheral blood stem cell transplantation from HLA-identical siblings with a fludarabine-based protocol. The conditioning consisted of fludarabine 30 mg/m(2)/day x 6 days, cyclophosphamide 60 mg/kg/day x 2 days and horse antithymocyte globulin (ATG) x 4 days. Two different ATG preparations were used: ATGAM (dose 30 mg/kg/day x 4 days) or Thymogam (dose 40 mg/kg/day x 4 days). Engraftment: median time to absolute neutrophil count (ANC) >0.5 x 10(9)/l was 11 days (range: 8-17) and median time to platelet count >20 x 10(9)/l was 11 days (range: 9-17). At a median follow-up of 171 days (range: 47-389), there has been no graft rejection and all patients are in complete remission. Acute GVHD (grade 1) occurred in one patient only. Chronic GVHD developed in two patients (extensive in one and limited in another). The transplants were performed in non-HEPA filter rooms. In only one patient, systemic antifungal therapy (voriconazole) was used. The use of Thymogam brand of ATG for conditioning is being reported for the first time. Our experience suggests that this fludarabine-based protocol allows rapid sustained engraftment in high-risk patients without significant immediate toxicity.