Management of acquired aplastic anemia in children

Romiplostim for Treatment of Children and Young Adults With Severe Aplastic Anemia and Myelodysplastic Syndrome

Thrombopoietin receptor agonists (TPO-RAs) induce trilineage hematopoiesis under conditions with acquired hematopoietic failure. We evaluated safety, tolerability, and preliminary efficacy of a TPO-RA, romiplostim (Nplate), with or without standard-of-care immunosuppressive therapy (±IST) for children (ages < 21 y) with newly diagnosed and relapsed/refractory severe aplastic anemia (SAA) and myelodysplastic syndrome (MDS). Data were collected from an observational study and a single arm interventional pilot study. The safety outcome was treatment-related adverse events (AEs). Efficacy was evaluated by complete hematopoietic response (CHR) at week 24. Romiplostim was commenced at 5 µg/kg/week, with dose escalation of 2.5 µg/kg/week (maximum, 20 µg/kg/dose) based on platelet response. Romiplostim was continued until CHR was observed. Ten subjects (SAA, 9 [IST, 4; without IST, 5]; MDS, 1) completed the study (median age: 9.2 y). Median romiplostim dose was 10 µg/kg/week (range: 5 to 17.5 µg/kg/week). The cumulative incidence of CHR was 70.4% (95% CI, 20.2%-92.6%). Among 21 AEs (Grade 1 to 3), 3 were attributed to romiplostim. At a median posttherapy follow-up of 10.9 months (range: 0.7 to 77.5), no clonal evolution, bone marrow fibrosis or mortality was reported. This proof-of-concept study provides data about short-term safety, tolerability, and preliminary efficacy of romiplostim (±IST) for treatment of pediatric SAA/MDS.

Diagnosis and management of acquired aplastic anemia in childhood. Guidelines from the Marrow Failure Study Group of the Pediatric Haemato-Oncology Italian Association (AIEOP)

Acquired aplastic anemia (AA) is a rare heterogeneous disorder characterized by pancytopenia and hypoplastic bone marrow. The incidence is 2-3 per million population per year in the Western world, but 3 times higher in East Asia. Survival in severe aplastic anemia (SAA) has improved significantly due to advances in hematopoietic stem cell transplantation (HSCT), immunosuppressive therapy, biologic agents, and supportive care. In SAA, HSCT from a matched sibling donor (MSD) is the first-line treatment. If a MSD is not available, options include immunosuppressive therapy (IST), matched unrelated donor, or haploidentical HSCT. The purpose of this guideline is to provide health care professionals with clear guidance on the diagnosis and management of pediatric patients with AA. A preliminary evidence-based document prepared by a group of pediatric hematologists of the Bone Marrow Failure Study Group of the Italian Association of Pediatric Hemato-Oncology (AIEOP) was discussed, modified and approved during a series of consensus conferences that started online during COVID 19 and continued in the following years, according to procedures previously validated by the AIEOP Board of Directors.

Outcomes and risk factors of hemorrhagic cystitis in pediatric allogeneic hematopoietic stem cell transplantation recipients using different graft source and condition with severe aplastic anemia

BACKGROUND

Hemorrhagic cystitis (HC) is a severe complication of allo-HSCT, characterized by irritative symptoms of the urinary tract and a higher morbidity rate. The risk factors and prognosis of HC are still unclear.

OBJECTIVE

The objective of this study is to identify risk factors and outcomes to improve treatment in pediatric SAA patients undergoing HSCTs in the Children's Hospital of Soochow University.

METHODS

A total of 97 SAA patients as a cohort were enrolled from 2010 to 2019 in the Children's Hospital of Soochow University and a number of factors related to HC and outcomes were analysed. In all transplants (except UCBT), patients received a combination of G-CSF stimulated bone marrow (BM) and peripheral blood stem cell (PBSC). The minimum number of CD34 + cells is 5 × 10⁶ cells/kg.

RESULTS

Mononuclear cells dose (MNC, cut off: 8.53 × 10⁸/kg) and grade II-IV acute graft versus host disease (aGVHD) were identified as independent risk factors for HC. Patients without HC had better overall survival (OS) than with HC (No HC: 98.6%±1.4% vs HC: 87.4% ± 6.8%, p = 0.03).

CONCLUSION

We concluded that aGVHD and MNC dose in graft might play an important role in the development of HC in pediatric SAA patients undergoing allo-HSCT. HC is also a key complication affecting the prognosis of children with SAA after allo-HSCT.

Clinical Outcome of Acquired Post-Immunosuppressive-Therapy Aplastic Anemia in Pediatric Patients: A 13-Year Experience in Two Southern China Tertiary Care Centers

Objective

The aim of the present study is to evaluate the efficacy, complications, and contributing factors of immunosuppressive therapy (IST) response in children with acquired aplastic anemia (AA) and to explore optimal therapeutic methods for different clinical AA types.

Methods

A total of 130 children diagnosed with acquired AA underwent IST in the Department of Pediatrics at Sun Yat-sen Memorial Hospital and the Department of Pediatrics at Seventh Affiliated Hospital, Sun Yat-sen University, between January 1, 2006, and July 15, 2020. The overall survival (OS), response rates, complications, and response predictors were analyzed. The response rates were compared according to clinical AA type.

Results

All 130 children with AA were followed up with for a median of 50.6 months. Among the patients, 25 had non-severe AA (NSAA), 64 had severe AA (SAA), and 41 had very severe AA (VSAA). All patients initially received IST. In 13 patients, the IST failed; these patients received an allo-hematopoietic stem cell transplant as a salvage regimen. The OS rate was 90.3% ± 2.8%, and the response rates at 3, 6, 9, and 12 months were 34.19%, 39.32%, 49.57%, and 66.67%, respectively. The prolonged follow-up period might have led to higher response rates, especially in patients with SAA and VSAA. A multivariate logistic regression analysis of prognostic factors was conducted; the results showed that high red blood cell (RBC) and platelet (PLT) counts were associated with a high overall response rate and that the RBC count at diagnosis is a major contributing factor.

Conclusion

With the use of rabbit anti-thymocyte globulin, proper cyclosporine management, and a prolonged IST follow-up period, a higher number of patients with acquired AA than normal achieved response. Proportionally, the number of patients who achieved remission within 12 months was higher in the SAA group (38.18%→63.64%) and VSAA group (28.95%→65.79%) than in the NSAA group (58.33%→75%). Higher RBC and PLT counts at diagnosis can predict a favorable outcome.

miR-146b-5p regulates bone marrow mesenchymal stem cell differentiation by SIAH2/PPARγ in aplastic anemia children and benzene-induced aplastic anemia mouse model

This study aimed to reveal the mechanism of miR-146b-5p in the differentiation of bone marrow mesenchymal stem cells (BMSCs) derived from children with aplastic anemia (AA). Here, we found that miR-146b-5p was highly expressed in BMSCs from children with AA, and the BMSCs surface markers expressions in BMSCs derived from children with AA and the healthy controls exerted no significant differences. Besides, the overexpression of miR-146b-5p in normal human-derived BMSCs promoted the adipogenic differentiation of BMSCs. Furthermore, miR-146b-5p negatively regulated SIAH2 luciferase activity, and the interference with miR-146b-5p reduced the stability of PPARγ protein and inhibited SIAH2-mediated ubiquitination of PPARγ protein. Besides, the interference with miR-146b-5p was beneficial for ameliorating AA in a mouse model of AA. Overall, our results found that miR-146b-5p was highly expressed in BMSCs from children with AA, and our further studies indicated that miR-146b-5p improved AA via promoting SIAH2-mediated ubiquitination of PPARγ protein.

Second allogeneic hematopoietic stem cell transplantation in children with severe aplastic anemia

The outcome of 55 children with severe aplastic anemia (SAA) who received a second hematopoietic stem cell transplantation (HSCT) was retrospectively analyzed using the registration data of the Japanese Society for Hematopoietic Cell Transplantation. The 5-year overall survival (OS) and failure-free survival (FFS) after the second transplantation were 82.9% (95% confidence interval (CI), 69.7-90.8)) and 81.2% (95% CI, 67.8-89.4), respectively. FFS was significantly better when the interval between the first and second transplantation was >60 days (88.9%; 95% CI, 73.0-95.7) than when it was ⩽60 days (61.4%; 95% CI, 33.3-80.5; P=0.026). All 12 patients who were conditioned with regimens containing fludarabine and melphalan were alive with hematopoietic recovery. These findings justify the recommendation of a second HSCT for children with SAA who have experienced graft failure after first HSCT.

New directions for rabbit antithymocyte globulin (Thymoglobulin(®)) in solid organ transplants, stem cell transplants and autoimmunity

In the 30 years since the rabbit antithymocyte globulin (rATG) Thymoglobulin^® was first licensed, its use in solid organ transplantation and hematology has expanded progressively. Although the evidence base is incomplete, specific roles for rATG in organ transplant recipients using contemporary dosing strategies are now relatively well-identified. The addition of rATG induction to a standard triple or dual regimen reduces acute cellular rejection, and possibly humoral rejection. It is an appropriate first choice in patients with moderate or high immunological risk, and may be used in low-risk patients receiving a calcineurin inhibitor (CNI)-sparing regimen from time of transplant, or if early steroid withdrawal is planned. Kidney transplant patients at risk of delayed graft function may also benefit from the use of rATG to facilitate delayed CNI introduction. In hematopoietic stem cell transplantation, rATG has become an important component of conventional myeloablative conditioning regimens, following demonstration of reduced acute and chronic graft-versus-host disease. More recently, a role for rATG has also been established in reduced-intensity conditioning regimens. In autoimmunity, rATG contributes to the treatment of severe aplastic anemia, and has been incorporated in autograft projects for the management of conditions such as multiple sclerosis, Crohn’s disease, and systemic sclerosis. Finally, research is underway for the induction of tolerance exploiting the ability of rATG to induce immunosuppresive cells such as regulatory T-cells. Despite its long history, rATG remains a key component of the immunosuppressive armamentarium, and its complex immunological properties indicate that its use will expand to a wider range of disease conditions in the future.

Allogeneic hematopoietic stem cell transplantation for non-malignant hematological disorders

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) from a geno-identical matched sibling (MSD) is one of the most successful therapies in patients with non-malignant hematological disorders. This study included 273 patients with severe aplastic anemia (SAA), 152 patients with B-Thalassemia major (BTM), 31 patients with Fanconi's anemia (FA), 20 patients with congenital immunodeficiency diseases (ID), and 13 patients with inherited metabolic disorders (IMD) allografted from a MSD. In SAA, the 8-year overall survival (OS) of the whole group patients was 74%. OS was significantly better in patients conditioned with fludarabine and cyclophosphamide (Flu/Cy) than in those who received cyclophosphamide and antithymocyte globulin (Cy/ATG) (p = 0.021). Acute graft-versus-host disease (aGVHD) grade II-IV occurred in 15% while chronic GVHD (cGVHD) occurred in 28%. In BTM, the 12-year disease-free survival (DFS) of the whole group of BTM patients was 72.4%. DFS was 74% for peripheral blood stem cell (PBSC) group compared to 64% in the BM stem cell group. The incidence of graft rejection was significantly lower in patients who received PBSC than in those who received BM (9% vs 25%) (p = 0.036). AGVHD grade II-IV and cGVHD occurred in 15% and 12% of the whole group of BTM patients respectively. In FA, the 5-year OS was 64.5%. Graft rejection occurred in 10% of patients. Grade II-IV aGVHD occurred in 16% while cGVHD occurred in 4%. In ID, the 5-year OS was 62%. Graft rejection occurred in two (10%) patients. Three patients (15%) developed grade II-IV aGVHD, 2 of them progressed to secondary cGVHD. In IMD, OS was 46% at 5 years. Graft rejection occurred in 8% of patients. AGVHD grade II-IV occurred in 15% while cGVHD occurred in 14%. In conclusion, Allo-HSCT provides a higher DFS rate over conventional therapies for patients with non-malignant hematological disorders with prolonged survival.

Outcome of aplastic anaemia in children. A study by the severe aplastic anaemia and paediatric disease working parties of the European group blood and bone marrow transplant

This study analysed the outcome of 563 Aplastic Anaemia (AA) children aged 0-12 years reported to the Severe Aplastic Anaemia Working Party database of the European Society for Blood and Marrow Transplantation, according to treatment received. Overall survival (OS) after upfront human leucocyte antigen-matched family donor (MFD) haematopoietic stem cell transplantation (HSCT) or immunosuppressive treatment (IST) was 91% vs. 87% (P 0·18). Event-free survival (EFS) after upfront MFD HSCT or IST was 87% vs. 33% (P 0·001). Ninety-one of 167 patients (55%) failed front-line IST and underwent rescue HSCT. The OS of this rescue group was 83% compared with 91% for upfront MFD HSCT patients and 97% for those who did not fail IST up-front (P 0·017). Rejection was 2% for MFD HSCT and HSCT post-IST failure (P 0·73). Acute graft-versus-host disease (GVHD) grade II-IV was 8% in MFD graft vs. 25% for HSCT post-IST failure (P < 0·0001). Chronic GVHD was 6% in MFD HSCT vs. 20% in HSCT post-IST failure (P < 0·0001). MFD HSCT is an excellent therapy for children with AA. IST has a high failure rate, but remains a reasonable first-line choice if MFD HSCT is not available because high OS enables access to HSCT, which is a very good rescue option.

Outcome of patients activating an unrelated donor search for severe acquired aplastic anemia

Patients with severe aplastic anemia (SAA) without a sibling donor receive immunosuppressive treatment (IST) with anti-thymocyte globulin (ATG). In the case of no response to IST, a voluntary unrelated donor (VUD) search is usually started. This study analyzes the outcome of ATG-refractory SAA patients activating a VUD search. Of 179 patients, 68 had at least one HLA-A, -B, and -DR matched donor identified and underwent HSCT while 50 also with a donor were not transplanted because of early death (8), late response to IST (34), transplant refusal (1), or other (7). Conversely, 61 had no matched donor, 13 of those ultimately received a mismatched HSCT. All but one received marrow stem cells. Among patients aged <17 years, those with at least one matched donor had a significant higher 4-year survival as compared to others (79% ± 6% versus 53% ± 10%, P = 0.01). There was also a survival advantage independent of recipient age when the donor search was initiated in the recent 2000-2005 study-period (74% ± 6% versus 47% ± 10%, P < 0.05). In multivariate analysis, the identification of a matched VUD tended to impact favourably on survival in patients with a recent donor search (P = 0.07). This study provides evidence for the use of unrelated donor HSCT in children and adults with IST-refractory SAA.

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.