Risk-adapted procedures for HSCT from alternative donor in children with severe aplastic anaemia

Combination of HLA-Matched Sibling Allogeneic Hematopoietic Stem Cell Transplantation With Unrelated Cord Blood Unit in Patients Aged 35 to 50 Years With Severe Aplastic Anemia: Preliminary Summary of a Single-Arm Trial

This study reports a single-arm trial in the interim phase in 4 patients with median age of 40.5 years who have undergone combined HLA-matched sibling donor (MSD) stem cell graft and an unrelated cord blood (UCB) unit for the treatment of severe aplastic anemia (SAA). The median time was 10 days for neutrophil engraftment (9-18 days) and 17 days for platelets (12-24 days). Median follow-up of 22 months (ranging from 16 to 29 months) showed survival of the 4 patients with complete hematological response. Acute graft-vs-host disease (GVHD) (grade II) occurred only in 1 patient, yet chronic GVHD was free. One patient showed a pattern of transient MSD graft followed by dominant UCB chimerism, and another 1 achieved mixed chimerism in the first 6 months after allogeneic hematopoietic stem cell transplantation (allo-HSCT) then evolved to a stable MSD graft. The other 2 patients sustained a full MSD graft during the post-HSCT period. Nevertheless, none of the patients developed primary and secondary graft failure up to the final follow-up. Although this is a small cohort, the dual transplantation combining HLA-matched sibling allogeneic hematopoietic stem cell transplantation with unrelated cord blood unit may deserve further exploration for treatment of SAA patients aged 35 to 50 years old.

Hematopoietic stem cell transplantation without in vivo T-cell depletion for pediatric aplastic anemia: A single-center experience

For young patients, HLA-MRD HSCT is the first-line treatment of SAA. However, due to China's birth control policy, few patients could find suitable sibling donors and HLA-MUD. More and more transplantation centers have used Haplo-D as the donor source for young adult and pediatric patients. However, studies with larger amount of pediatric patients are rare. We retrospectively analyzed the data of children with AA who were treated with allogeneic HSCT and compared the therapeutic efficacy of Haplo-HSCT and MRD/MUD group. A total of 62 patients were enrolled. Implantation was successfully performed in 58 patients. There was no significant difference in the time for reconstruction of hematopoietic function between patients in the two groups. Thirty-two had grade I-IV aGVHD with incidence of 51.61%. The incidence of aGVHD was 79.41% for patients in the Haplo-HSCT, significantly higher than that of 17.86% for patients in the MRD/MUD group (P < .01). However, the incidence of cGVHD was not significantly different between patients in the two groups (26.47% vs 10.71%, P = .09), the incidence of CMV infection was 28.57% and 52.94% for patients in the MRD/MUD and Haplo group, respectively, showing no significant difference (P = .053). The incidence of EBV infection was 47.06% for patients in the Haplo group and 28.57% for patients in the MRD/MUD group, showing no significant difference (P = .11). However, the 3- and 5-year cumulative OS and FFS rates showed statistically significant difference in the two groups, P = .012 and .045, respectively. Compared to Haplo-HSCT, MRD/MUD is more economic. In this study, we achieved good Haplo transplantation results. The incidences of cGVHD and CMV/EBV were not significantly different between Haplo group and MRD/MUD group. Although OS and FFS of the Haplo group were not as good as those of the MRD/MUD group, it is still acceptable as an alternative treatment under emergency.

Cotransplantation of bone marrow-derived mesenchymal stem cells in haploidentical hematopoietic stem cell transplantation in patients with severe aplastic anemia: an interim summary for a multicenter phase II trial results

This corrects the article DOI: 10.1038/bmt.2016.347.

Haploidentical transplantation for pediatric patients with acquired severe aplastic anemia

Techniques for haploidentical hematopoietic stem cell transplantation (haplo-HSCT) to treat severe aplastic anemia (SAA) have recently improved, but no protocol has been evaluated in a large number of pediatric patients. Fifty-two children with SAA received haplo-HSCT in our center. The treatment protocol used G-CSF-primed bone marrow with G-CSF-mobilized PBSCs without in vitro T-cell depletion. The conditioning regimen included busulfan/cyclophosphamide and antithymocyte globulin. Fifty-one patients achieved primary engraftment; one child died of regimen-related toxicity on the day +1. Secondary graft failure occurred in three patients. The cumulative incidences of aGVHD grade II-IV and grade III-IV were 39.2±0.5 and 13.7±0.2%, respectively. The cumulative incidence of cGVHD was 34.2±0.5%. The 3-year overall and failure-free survival rates were 84.5±5.0 and 82.7±5.2%, respectively, with a median follow-up time of 744.5 days (100-3294) for surviving patients. The Eastern Cooperative Oncology Group score was the only predictor of overall and failure-free survival rates. Clinical outcomes were similar between the upfront and salvage group. This result suggests that both newly diagnosed and refractory pediatric SAA patients benefit from haplo-HSCT, especially when patients are in good general condition. Therefore, haplo-HSCT might be an alternative therapy for pediatric SAA patients without HLA-matched sibling donors.

Missing Cells: Pathophysiology, Diagnosis, and Management of (Pan)Cytopenia in Childhood

Peripheral blood cytopenia in children can be due to a variety of acquired or inherited diseases. Genetic disorders affecting a single hematopoietic lineage are frequently characterized by typical bone marrow findings, such as lack of progenitors or maturation arrest in congenital neutropenia or a lack of megakaryocytes in congenital amegakaryocytic thrombocytopenia, whereas antibody-mediated diseases such as autoimmune neutropenia are associated with a rather unremarkable bone marrow morphology. By contrast, pancytopenia is frequently associated with a hypocellular bone marrow, and the differential diagnosis includes acquired aplastic anemia, myelodysplastic syndrome, inherited bone marrow failure syndromes such as Fanconi anemia and dyskeratosis congenita, and a variety of immunological disorders including hemophagocytic lymphohistiocytosis. Thorough bone marrow analysis is of special importance for the diagnostic work-up of most patients. Cellularity, cellular composition, and dysplastic signs are the cornerstones of the differential diagnosis. Pancytopenia in the presence of a normo- or hypercellular marrow with dysplastic changes may indicate myelodysplastic syndrome. More challenging for the hematologist is the evaluation of the hypocellular bone marrow. Although aplastic anemia and hypocellular refractory cytopenia of childhood (RCC) can reliably be differentiated on a morphological level, the overlapping pathophysiology remains a significant challenge for the choice of the therapeutic strategy. Furthermore, inherited bone marrow failure syndromes are usually associated with the morphological picture of RCC, and the recognition of these entities is essential as they often present a multisystem disease requiring different diagnostic and therapeutic approaches. This paper gives an overview over the different disease entities presenting with (pan)cytopenia, their pathophysiology, characteristic bone marrow findings, and therapeutic approaches.

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.

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.

Aplastic anemia: pathophysiology and treatment

An immune basis for most patients with aplastic anemia (AA) provides a rationale for immunosuppressive therapy (IST), using antithmyocyte globulin and cyclosporine as one therapeutic modality; hematologic response is observed in up to 75% of patients. Recent advances in understanding the pathogenesis of AA have identified defective telomere maintenance as an important explanation for the onset of marrow failure, relapse and clonal evolution after IST, in some patients with AA. The finding of inherited mutations in the telomerase gene complex in patients with apparent acquired AA has important implications for clinical management. Hematopoietic stem cell transplantation (HSCT) for acquired AA, whether from an HLA identical sibling or an unrelated donor, provides an excellent chance of long term cure. Current issues with HSCT include graft rejection, chronic GVHD and poor outcome in older patients. The lack of a suitable bone marrow donor for all patients who need a transplant, illustrates the need for novel transplant procedures, such as cord blood transplantation.