A fludarabine-based conditioning regimen for severe aplastic anemia

Long-term results of allogeneic peripheral blood hematopoietic stem cell transplantation for severe aplastic anemia

OBJECTIVE

Aplastic anemia (AA) is a life-threatening disorder and may be associated with significant morbidity and mortality Currently, the first treatment option is allogeneic hematopoietic stem cell transplant (allo-HSCT) for patients younger than 40 years. Bone marrow is recommended as the stem cell source due to less graft versus host disease (GVHD) risk and better outcomes than peripheral blood (PB)-derived stem cell. The aim of this study is to share the data of AA patients who have underwent PB-derived allo-HSCT in our bone marrow transplantation center.

METHODS

Twenty-seven patients who underwent PB-derived allo-HSCT from human leukocyte antigen matched sibling donors were analyzed retrospectively.

RESULTS

The median follow-up time was 95.2 months (range, 4.8-235 months). The 10-year survival was 89 %. The median neutrophil and platelet engraftment time was 11 days (range, 9-16 days) and 13 days (range, 11-29 days), respectively. Primary platelet engraftment failure was observed in 1 patient (3.7 %). Acute and chronic GVHD observed in 2 (7.4 %) and 3 (11.1 %) patients, respectively. Neutropenic fever was observed in 13 (44.8 %) of patients until the engraftment after allo-HSCT. One patient died due to CMV infections, two died due to septic shock secondary to fungal infection.

CONCLUSION

Although there is no prospective data directly comparing BM with PB as stem cell source in AA, observational studies indicates better OS with BM. PB can be used in certain situations such as higher risk for graft failure and donor preference. This study demonstrated that PB-derived stem cell seems to be a reasonable alternative to BM.

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.

Pilot trial of risk-adapted cyclophosphamide intensity based conditioning and HLA matched sibling and unrelated cord blood stem cell transplantation in newly diagnosed pediatric and adolescent recipients with acquired severe aplastic anemia

BACKGROUND

Cyclophosphamide-based conditioning regimens and allogeneic hematopoietic stem cell transplantation (AlloHSCT) from matched related donors (MRD) has resulted in the highest survival rates in children and adolescents with acquired severe aplastic anemia (SAA). Time to transplant has consistently been associated with decreased overall survival. Reduced toxicity conditioning and AlloHSCT has been used successfully in other pediatric non-malignant diseases.

PROCEDURE

We piloted a risk-adapted AlloHSCT approach, using fludarabine and anti-thymocyte globulin based conditioning with high (200 mg/kg) and low (60 mg/kg) dose cyclophosphamide as upfront treatment in newly diagnosed pediatric patients with acquired SAA incorporating alternative donor sources, including cord blood. Average risk for non-engraftment patients with <10 transfusions received low dose cyclophosphamide (60 mg/kg); High Risk, those with ≥10 transfusions received conditioning regimen with higher intensity cyclophosphamide (200 mg/kg).

RESULTS

Seventeen patients were enrolled and underwent AlloHSCT including 12 males and 5 females with mean age of 8 years (range 3-16), and median follow-up time of 39 months (range 1-135). Donor sources included MRD BM (6/6 [n = 9], 5/6 [n = 2]) and unrelated CB (5/6 [n = 4], 4/6 [n = 2]). Five year OS was 67.6% (37.9-85.4). Three secondary graft failures (17.6%) occurred in the low dose cyclophosphamide arm.

CONCLUSIONS

Upfront treatment with risk-adapted cyclophosphamide conditioning AlloSCT is well tolerated for the management of newly diagnosed pediatric and adolescent patients with acquired SAA. However, the increased risk of graft rejection in the lower dose arm warrants additional research regarding the optimal intensity of cyclophosphamide-based conditioning regimen to reduce toxicity without increasing graft failure.

A combination of fludarabine, half-dose cyclophosphamide, and anti-thymocyte globulin is an effective conditioning regimen before allogeneic stem cell transplantation for aplastic anemia

Conditioning regimens consisting of reduced-dose cyclophosphamide (CY) and fludarabine (FDR) have been investigated for use in allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with aplastic anemia to reduce the toxicities associated with CY. However, the ideal dose of CY has not been identified. In addition, little information is available regarding donor cell chimerism after allo-HSCT with these regimens. Therefore, we retrospectively analyzed 13 patients who underwent allo-HSCT with half-dose CY (100 mg/kg in total), FDR, and anti-thymocyte globulin at total doses of 2.5-10 mg/kg at our center. All the patients except one, who died due to encephalopathy on day 20, achieved neutrophil engraftment a median of 18.5 days after HSCT with complete donor-type chimerism. Two patients who received a graft from an HLA-matched donor subsequently developed mixed chimerism (MC) associated with transfusion-dependent cytopenia. One became transfusion-independent after donor lymphocyte infusion, but continues to exhibit MC. The other regained complete donor-type chimerism after the cessation of cyclosporine, but remains transfusion-dependent. These findings suggest that a conditioning regimen with half-dose CY and FDR is effective for achieving neutrophil engraftment and complete donor-type chimerism. However, subsequent MC may be observed, especially after HLA-matched HSCT.

Efficacy and safety of human umbilical cord derived mesenchymal stem cell therapy in children with severe aplastic anemia following allogeneic hematopoietic stem cell transplantation: a retrospective case series of 37 patients

The treatment of pediatric severe aplastic anemia (SAA) with allogeneic hematopoietic stem cell transplantation (allo-HSCT), presents major challenges including the risks of graft failure, septic complications, and graft-versus-host disease (GVHD). Additive infusions of human umbilical cord derived mesenchymal stem cell (hUC-MSC) may be administered to improve patient survival. We retrospectively examined 37 pediatric patients with SAA who received allo-HSCT and subsequent infusions of hUC-MSC suspension at a dose of 1.0 × 10(6 )/kg. The times and doses of hUC-MSC infusions were increased in patients with severe GVHD. All patients received hUC-MSC infusions. The median time to post-transplantation neutrophil count of greater than 0.5 × 10(9 )/L was 14 days (range, 11-20 days) and time to post-transplantation platelet count of greater than 20 × 10(9 )/L was 19 days (14-29 days). The overall frequency of acute GVHD (aGVHD) was 45.9% (17/37). These aGVHD episodes occurred at a median time of post-transplantation 47 days (15-83 days). The frequency of chronic GVHD (cGVHD) was 18.9% (7/37); cGVHD developed from aGVHD in 10.8% (4/37) of patients. The GVHD-associated mortality rate was 18.9% (7/37) and aGVHD-specific mortality rate was 8.1% (3/37). The median overall survival time was 35 months (9-67 months) and the three-year overall survival rate was 74.2% (28/37). Seven patients died of GVHD, one patient died of a severe invasive fungal infection, and one patient died of renal failure. In conclusion, post-transplantation hUC-MSC infusions seemed to be safely infused in children with SAA who have previously received allo-HSCT.

A novel protocol for haploidentical hematopoietic SCT without in vitro T-cell depletion in the treatment of severe acquired aplastic anemia

Mismatched related donors of hematopoietic SCT (HSCT) for severe aplastic anemia (SAA) present challenges mainly associated with graft failure and GVHD. The greater the HLA disparity, the poorer the OS. About 19 consecutive SAA/very SAA (VSAA) patients who received HSCT from haploidentical family donors in our center are reported in this study, 18/19 pairs had 2-3 loci mismatched. All 19 cases failed to respond to previous therapy and were heavily transfused before transplantation. The conditioning regimen before HSCT included BU, CY and thymoglobulin. The recipients received CsA, mycophenolate mofetil (MMF) and short-term MTX for GVHD prophylaxis. The source of stem cell grafts was a combination of G-CSF-primed BM and G-CSF-mobilized peripheral blood stem cells. All patients achieved 100% donor myeloid engraftment; the median time for myeloid engraftment was 12 days (ranging from 10-29 days) and for platelets was 18 days (ranging from 8-180 days) with a cumulative platelet engraftment incidence of 84.21 ± 10.53%. The cumulative incidence was 42.1 ± 11.3% for grade II-IV acute GVHD and 56.2 ± 12.4% for chronic GVHD. The OS was 64.6 ± 12.4% with a median 746-day (90-1970) follow-up for surviving patients. These limited retrospective analysis data suggest that HLA-haploidentical HSCT for SAA patients without an HLA-identical sibling donor might be feasible. Further research to increase OS by decreasing GVHD while maintaining stable engraftment will be needed in the future.

Mechanisms of alloimmunization and subsequent bone marrow transplantation rejection induced by platelet transfusion in a murine model

For many nonmalignant hematological disorders, HLA-matched bone marrow transplantation (BMT) is curative. However, due to lack of neoplasia, the toxicity of stringent conditioning regimens is difficult to justify, and reduced intensity conditioning is used. Unfortunately, current reduced intensity regimens have high rates of BMT rejection. We have recently reported in a murine model that mHAs on transfused platelet products induce subsequent BMT rejection. Most nonmalignant hematological disorders require transfusion support prior to BMT and the rate of BMT rejection in humans correlates with the number of transfusions given. Herein, we perform a mechanistic analysis of platelet transfusion-induced BMT rejection and report that unlike exposure to alloantigens during transplantation, platelet transfusion primes alloimmunity but does not stimulate full effector function. Subsequent BMT is itself an additional and distinct immunizing event, which does not induce rejection without antecedent priming from transfusion. Both CD4(+) and CD8(+) T cells are required for priming during platelet transfusion, but only CD8(+) T cells are required for BMT rejection. In neither case are antibodies required for rejection to occur.

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.

Disease-specific hematopoietic cell transplantation: nonmyeloablative conditioning regimen for dyskeratosis congenita

Dyskeratosis congenita (DC) is characterized by reticular skin pigmentation, oral leukoplakia and abnormal nails. Patients with DC have very short telomeres and approximately one-half have mutations in telomere biology genes. A majority of patients with DC develop BM failure (BMF). Hematopoietic cell transplantation (HCT) represents the only known cure for BMF in DC, but poses significant toxicities. We report six patients who underwent allogeneic HCT with a novel nonmyeloablative conditioning regimen specifically designed for DC patients. Graft sources included related PBSCs (1), unrelated BM (2) and unrelated double umbilical cord blood (3). Complete donor engraftment was achieved in five of six patients. One patient had initial autologous hematopoietic recovery, which was followed by a second transplant that resulted in 88% donor chimerism. With a median follow-up of 26.5 months, four patients are alive, three of whom were recipients of unrelated grafts. We conclude with this small study that encouraging short-term survival can be achieved with HCT in patients with DC using a preparative regimen designed to promote donor engraftment and minimize life-threatening disease-specific complications such as pulmonary fibrosis. Long-term follow-up will be crucial with respect to individualized patient care with each of the transplanted individuals.

Allogeneic haemopoietic stem cell transplantation in children: what alternative donor should we choose when no matched sibling is available?

Allogeneic haemopoietic stem cell transplantation has provided curative therapy for life-threatening malignant and non-malignant diseases in children for over 40 years. Only 25% of children in whom an allograft is indicated have the ideal option of a human leucocyte antigen-identical sibling donor. Substantial advances in the use of alternative donors (unrelated volunteer donors, haploidentical family donors and unrelated umbilical cord blood donors) now make it possible for almost all children to benefit from this life-saving treatment. Each donor choice is associated with distinct advantages and disadvantages, which have greater or lesser importance in different diseases. We review the current status of alternative donor transplantation for haematological malignancies, primary immunodeficiencies, inherited metabolic disorders and bone marrow failure syndromes and outline the current UK consensus donor selection algorithms for these disease groups.

Hematopoietic stem cell transplantation for bone marrow failure syndromes in children

Bone marrow failure (BMF) syndromes include a broad group of diseases of varying etiologies, in which hematopoeisis is abnormal or completely arrested in one or more cell lines. BMF can be an acquired aplastic anemia (AA) or can be congenital, as part of such syndromes as Fanconi anemia (FA), Diamond Blackfan anemia, and Schwachman Diamond syndrome (SDS). In this review, we first address the evolution and current status of bone marrow transplantation (BMT) in the pediatric population in the most common form of BMF, acquired AA. We then discuss pediatric BMT in some of the more common inherited BMF syndromes, with emphasis on FA, in which experience is greatest. It is important to consider the possibility of a congenital etiology in every child (and adult) with marrow failure, because identification of an associated syndrome provides insight into the likely natural history of the disease, as well as prognosis, treatment options for the patient and family, and long-term sequelae both of the disease itself and its treatment.

Results of unrelated cord blood transplant in fanconi anemia patients: risk factor analysis for engraftment and survival

We retrospectively analyzed results of unrelated cord blood transplantation (UCBT) in 93 Fanconi anemia (FA) patients. Median age at transplantation was 8.6 years (1-45). The units transplanted were HLA-A, -B, or -DRB1 identical in 12 cases, 1 HLA mismatch in 35 cases, and 2 or 3 HLA differences in 45 cases. The median number of nucleated cells (NC) and CD34+ cells infused of recipient weight was 4.9x10(7)/kg and 1.9x10(5)/kg, respectively. Participating centers selected the preparative regimen of their choice, in 57 patients (61%), it included Fludarabine. Graft-versus-host disease (GVHD) prophylaxis consisted mostly of cyclosporine with prednisone. Cumulative incidence (CI) of neutrophil recovery was 60+/-5% at day +60. In multivariate analysis, Fludarabine containing regimen and NC infused>or=4.9x10(7)/kg were associated with higher probability of recovery. CI of grade II-IV acute and of chronic GVHD (aGVHD, cGVHD) was 32%+/-5% and 16%+/-4%, respectively. Overall survival (OS) was 40%+/-5%. In multivariate analysis, factors associated with favorable outcome were use of Fludarabine in the conditioning regimen, number of NC infused>or=4.9x10(7)/kg, and negative cytomegalovirus (CMV) serology in the recipient. In conclusion, factors easily modifiable such as donor selection and a Fludarabine-containing regimen can considerably improve survival in FA patients given a UCBT. These data are the basis for designing prospective protocols.

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.

Allografting in patients with severe, refractory aplastic anemia using peripheral blood stem cells and a fludarabine-based conditioning regimen: the Mexican experience

We studied the effectiveness of a fludarabine/cyclophosphamide-based conditioning regimen without anti-thymocyte globulin in 23 aplastic anemia patients who had no response to previous conventional pharmacologic treatment. Patients received oral busulphan 4 mg/kg/day/2 days, IV cyclophosphamide 350 mg/m(2)/day/3 days, and fludarabine 30 mg/m(2)/day/3 days. For GVHD prophylaxis, patients received MTX 5 mg/m(2) days +1, +3, +6, and +11 and oral cyclosporin A (CyA) 5 mg/kg/day, starting on day -1. Peripheral blood stem cell products were used with a median dose of 5.5 x 10(6) CD34(+)/kg. The patients were followed for an average of 25 months. By a median of day +11, an ANC > 0.5 x 10(9)/L was reached; and by day +12, the platelet count had reached >20,000 x 10(9)/L. Acute grade I-II GVHD occurred in 4 patients, whereas limited chronic GVHD presented in 6 cases. Twenty-one patients (91.3%) achieved engraftment. Two patients failed to engraft, and 4 developed late rejection; 2 of these individuals died, 2 have survived with high transfusion requirements, whereas 2 received a second peripheral blood stem cell infusion and achieved sustained engraftment. Currently 21 (91%) of the 23 patients are alive, whereas 19 of 21 (90%) remain in complete remission. The average cost was about USD 15,000 for this kind of reduced-intensity allotransplant. Reduced-intensity stem cell transplantation represents an affordable alternative to traditional more cytotoxic conditioning for severe aplastic anemia (SAA) patients. Long-term effects however, remain to be evaluated.

Alemtuzumab, fludarabine and melphalan as a conditioning therapy in severe aplastic anemia and hypoplastic myelodysplastic syndrome--single center experience

BACKGROUND

Allogeneic hematopoietic stem cell transplantation is the treatment of choice in young patients with severe aplastic anemia. The main causes of failure after this procedure are graft versus host disease, infections and graft failure, often exacerbated by large numbers of transfusions and prolonged disease duration before transplant.

METHODS

We report the results of allografting following conditioning with fludarabine, alemtuzumab and melphalan in: five patients with severe aplastic anemia and one with hypoplastic myelodysplastic syndrome. All patients had matched sibling donors. Source of hematopoietic stem cell was: bone marrow-2, blood-3, bone marrow and blood-1. The age of recipients was 18-26 years. Four patients received their graft as the first line therapy and two after failure of cyclosporine and antithymocyte globulin treatment. Number of transfused units including red blood cells and platelets before transplantation was 8-100 (median: 22) and 10-32 (median: 11), respectively. All donors and recipients were CMV-seropositive. Conditioning consisted of: alemtuzumab 30 mg/d (day -7 to -5), fludarabine 30 mg/m(2) (days -7 to -3) and melphalan 140 mg/m(2) at the day -2.

RESULTS

The time to granulocytes and platelets recovery was 15 and 25 days, respectively. All patients achieved full donor chimerism on day +60. Only two patients needed ganciclovir as preemptive therapy. Recurrent parvovirus B19 infection with pure red cell aplasia and acute viral B hepatitis was observed in one case. Pure red cell aplasia was successfully treated with immunoglobulins and cyclosporine discontinuation. With a follow-up of 16-39 (median: 29) months all patients are alive, and neither graft failure nor graft versus host disease, or any no other severe complications, was observed.

CONCLUSIONS

Our study suggests that transplantation of hematopoietic stem cell using alemtuzumab, fludarabine and melphalan as a conditioning therapy is safe, inexpensive and effective treatment for patients with severe aplastic anemia, including multi-transfused adults having their disease for a long time.

Haematopoietic stem cell transplantation to treat aplastic anaemia

Aplastic anaemia (AA) consists of pancytopenia and empty bone marrow. Its incidence varies worldwide but predominates in developing countries. Diverse aetiologies are involved, with autoimmunity at the centre of the picture. For the 70% of patients with the severe and very severe forms of AA and who lack a human leukocyte antigen (HLA)-matched sibling, immunosuppressive therapy (IST) is key in treating the disease, with a remission rate close to 70%, an 80-90% 5-year survival rate in responding patients and a relapse rate close to 10%. For the 30% with a sibling donor available, haematopoietic stem cell transplant (HSCT) from bone marrow or peripheral blood has up to a 90% chance of cure, with a 5-10% graft rejection/failure rate. Patients who fail IST (25-30%) and lack a sibling donor can benefit from CD34(+)-enriched, partially T cell-depleted unrelated stem cell transplants, with a general survival rate up to 37%, the newest source of stem cells for this modality being cord blood. Non-myeloablative, irradiation-free conditioning regimens offer appreciable benefits, and new immunosuppressive agents, such as fludarabine and alemtuzumab, have been incorporated with promising preliminary results. Graft-versus-host disease, graft failure and infections remain significant challenges in HSCT for which innovative treatment strategies are being developed at present.

Reduced intensity hematopoietic stem-cell transplantation across human leukocyte antigen barriers in a patient with congenital amegakaryocytic thrombocytopenia and monosomy 7

Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare inherited bone marrow failure syndrome that has the potential to progress to pancytopenia and acute myeloid leukemia. Hematopoietic stem-cell transplantation (HSCT) is presently the only curative treatment approach. We used a reduced intensity transplantation regimen in a CAMT patient with aplastic anemia and monosomy 7 who had no matched related donor. The patient had rapid and durable engraftment with minimal complications and is well 24 months post-transplantation. Thus, reduced intensity conditioning might be a feasible approach to stem-cell transplantation in patients with CAMT who do not have a related donor and who are at increased risk of toxicity from standard conditioning regimens.

Non-total body irradiation containing preparative regimen in alternative donor bone marrow transplantation for severe aplastic anemia

Using non-total body irradiation (TBI) containing preparative regimens, 13 patients with severe aplastic anemia (SAA) were transplanted from an alternative donor in a single institute. In total, 12 donors were unrelated volunteers and one was an HLA one-locus mismatched sibling. Median time from diagnosis of SAA to bone marrow transplantation (BMT) was 10.1 months (range, 1.6-180.1). Nine patients had received immunosuppressive treatment with ATG before BMT, while four had not. Preparative regimens consisted of cyclophosphamide plus ATG in nine patients, cyclophosphamide plus fludarabine in two patients, and cyclophosphamide plus fludarabine plus ATG in two patients. All patients received non-T-cell depleted bone marrow from the donor. Cyclosporine plus methotrexate were given for GVHD prophylaxis. All patients engrafted on a median of day 21 (range, 15-27). Grade III-IV acute GVHD developed in three (23%) of 13 patients and extensive chronic GVHD in four (31%) of 12 evaluable patients. With a median follow-up duration of 1138 days (range, 118-1553), 10 patients are alive with durable engraftment showing 74.6% (95% confidence interval, 49.5-99.7%) of survival rate. Cause of the deaths was CNS bleeding in one and chronic GVHD in two. In conclusion, non-TBI containing preparative regimen could ensure durable engraftment in alternative donor BMT for SAA and showed promising results.

Successful bone marrow transplantation in a patient with c-mpl-mutated congenital amegakaryocytic thrombocytopenia from a carrier donor

Congenital amegakaryocytic thrombocytopenia (CAMT) is characterized by severe thrombocytopenia and the absence of megakaryocytes in bone marrow. Furthermore, mutation of the c-mpl gene has been identified as a cause of this disorder. The only curative treatment is allogeneic stem cell transplantation (SCT). The current report describes a patient exhibiting c-mpl mutation in both alleles who underwent transplantation of allogeneic bone marrow donated by her brother, a c-mpl mutated carrier, employing a fludarabine-based conditioning regimen. Engraftment and reconstitution of hematopoietic cells was rapid and without complications. These findings suggest that the carrier donor displaying the c-mpl mutation can serve as a donor source for SCT.

Non-radiotherapy conditioning with stem cell transplantation from alternative donors in children with refractory severe aplastic anemia

Conditioning including total body/lymphoid irradiation is widely used to prevent graft rejection in patients with refractory severe aplastic anemia (SAA) undergoing hemopoietic cell transplantation (HCT) from alternative donors and or after graft manipulation. To reduce regimen-related toxicity we transplanted three children with refractory SAA after conditioning with radiotherapy-free regimens. Conditioning included fludarabine 175-180 mg/m2 in all patients. In addition, patient 1 (failing two previous grafts) received thiotepa 10 mg/kg and Campath-1H 60 mg/m2; patient 2 cyclophosphamide 120 mg/kg, thiotepa 15 mg/kg and OKT-3 0.1 mg/kg/day for 4 weeks; and patient 3 cyclophosphamide 120 and ATG 90 mg/kg. Stem cell source was unmanipulated marrow from the same unrelated donor as for the two previous transplantations in patient 1 and CD34+-purified peripheral blood stem cells from an HLA-matched unrelated donor and from the haploidentical mother in patients 2 and 3. Only patient 1 received graft-versus-host disease (GVHD) prophylaxis with cyclosporine A and mycophenolate mofetil. Follow-up is now 30, 51, and 15 months. None of the patients developed GVHD. All patients have normal counts with complete donor chimerism. Fludarabine-based conditioning is powerfully immunosuppressive and may be used for children with refractory SAA undergoing HCT from alternative donors even after rejection following previous HCT.

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

Antithymocyte globulin (ATG) has been used in severe aplastic anemia (SAA) as a part of the conditioning regimen. Among the many kinds of ATG preparations, thymoglobulin had been found to be more effective in preventing GVHD and rejection of organ transplants. As the fludarabine-based conditioning regimens without total body irradiation have been reported to be promising for bone marrow transplantation (BMT) from alternative donors in SAA, thymoglobulin was added to fludarabine and cyclophosphamide conditioning to reduce GVHD and to allow good engraftment in unrelated BMT. Five patients underwent BMT with cyclophosphamide (50 mg/kg once daily i.v. on days -9, -8, -7 and -6), fludarabine (30 mg/m2 once daily i.v. on days -5, -4, -3 and -2) and thymoglobulin (2.5 mg/kg once daily i.v. on days -3, -2 and -1) from HLA-matched unrelated donors. Complete donor type hematologic recovery was achieved in all patients. No serious complication occurred during BMT. Only one patient developed grade I acute GVHD resolved spontaneously. Except for one who had rupture of hepatic adenoma 78 days after BMT, all the other four patients are still alive with median 566 days. Fludarabine, cyclophosphamide plus thymoglobulin conditioning allows for the promising results of good engraftment, tolerable toxicity and minimal GVHD.

Preclinical experiments

The clinical use of autologous stem cell transplants for the treatment of refractory severe autoimmune diseases was preceded by convincing proof of its underlying principle in animal models. The various categories of experimental autoimmune disease in laboratory rodents are briefly described here, and the rationale that was used in the selection of suitable experimental autoimmune diseases for translational research is explained. The two models that provided the bulk of the data needed for designing the initial clinical treatment protocols were adjuvant arthritis (AA) and experimental allergic encephalomyelitis (EAE), which were both induced in Buffalo rats. In this strain, AA is manifested as a chronic, progressive, systemic polyarthritis and EAE as a chronic, remitting/relapsing form of encephalomyelitis resembling multiple sclerosis. Both diseases can be cured with autologous stem cell transplantation provided that adequate conditioning is given and that the disease has not yet progressed to the stage of 'scarring'. It is basically the inflammatory stages that respond well to this therapy. The success of treatment depends on how completely the autoantigen-specific activated T-lymphocytes and memory cells are eradicated. Because of a lack of information on the nature of the autoantigens involved in human disease and on the size of those cell populations in the animal models as well as in humans, this aspect of translation is difficult. The experiments have, however, provided important guidelines. High-dose conditioning regimens yield better results than low-dose conditioning, certain conditioning agents perform better than others, and care should be taken not to reintroduce too many T-cells with the autologous graft. The clinical results obtained so far indicate a high predictive power of these two animal models, which are therefore recommended strongly for additional preclinical studies.

Acute graft-versus-host disease in patients with Fanconi anemia or acquired aplastic anemia undergoing bone marrow transplantation from HLA-identical sibling donors: risk factors and influence on outcome

To assess whether Fanconi anemia (FA) patients might be at risk for acute graft-versus-host disease (AGvHD) despite using low-intensity conditionings, we retrospectively analyzed the incidence of AGvHD and its impact on outcome in 37 FA patients and 73 patients with acquired aplastic anemia (AAA) that received transplants at Saint Louis Hospital from HLA-genotypic identical siblings with similar conditionings (thoraco-abdominal irradiation plus cyclophosphamide 20 [FA] or 150 mg/kg [AAA]). Despite being younger, FA patients had an increased risk of grades II to IV AGvHD (relative risk [RR], 2.00; P =.021), especially in younger patients (RR, 7.93; P =.014). The risks of requiring systemic corticosteroids to treat AGvHD and experiencing cortico-resistant AGvHD were significantly increased in FA patients. Although non-FA and FA patients had similar 10-year outcomes, acute and chronic GvHD had a biphasic effect on FA patient outcome with an additional cluster of lethal events starting by 5 years after transplantation. This late survival fall, restricted to FA patients, was closely related to head and neck carcinomas (15-year incidence: 53%). FA patients represent a group at risk regarding AGvHD when using irradiation-based conditionings. The impact of AGvHD on survival may not be limited to the early posttransplantation period and may be a major risk factor for head and neck carcinomas and late mortality in FA patients.

Low-intensity hematopoietic stem-cell transplantation across human leucocyte antigen barriers in dyskeratosis congenita

Since the results of conventional hematopoietic stem-cell transplantation (HSCT) for patients with dyskeratosis congenita (DC) are poor owing to the high incidence of transplant-related complications, we explored the use of a low-intensity HSCT regimen. We report two children with DC with severe cytopenia, who underwent successful HSCT from a matched unrelated donor after conditioning with fludarabine, cyclophosphamide, and antithymocyte globulin. Graft-versus-host-disease (GVHD) prophylaxis consisted of corticosteroids and cyclosporin A. The regimen was well tolerated, no significant transplant-related complications were observed, and engraftment was rapid and complete. At 15 and 16 months after HSCT, the children were fully engrafted, in excellent clinical condition, full-donor chimerism, and no signs of GVHD. We conclude that a low-intensity regimen is sufficient to induce durable engraftment using matched unrelated donor HSCT in DC patients, with minimal 1-year transplant-related toxicity. Longer follow-up will determine whether this regimen also reduces long-term toxicity.

Successful allogeneic blood stem cell transplantation for aplastic anemia in a patient with renal insufficiency requiring dialysis

A 27-year-old man with aplastic anemia and renal insufficiency requiring dialysis underwent allogeneic PBSCT. The preparative regimen consisted of melphalan, ATG and TLI. GVHD prophylaxis consisted of cyclosporine and prednisolone. He was dialyzed prior to administration of melphalan and at 24 and 72 h after it. Otherwise, the dialysis schedule was unchanged, at three times a week. Engraftment was rapid. Regimen-related toxicity was minimal. Pharmacokinetic parameters of melphalan were not significantly altered with its plasma half-life 1.5 h. Patients with renal failure can receive allogeneic HSCT, and a combination of melphalan, ATG and TLI may serve as an alternative to CY and ATG.