Long-Term Outcomes of Cord Blood Transplantation from an HLA-Identical Sibling for Patients with Bone Marrow Failure Syndromes: A Report From Eurocord, Cord Blood Committee and Severe Aplastic Anemia Working Party of the European Society for Blood and Marrow Transplantation

Treatment of newly diagnosed severe aplastic anemia in children: Evidence-based recommendations

Severe aplastic anemia (SAA) is a rare potentially fatal hematologic disorder. Although overall outcomes with treatment are excellent, there are variations in management approach, including differences in treatment between adult and pediatric patients. Certain aspects of treatment are under active investigation in clinical trials. Because of the rarity of the disease, some pediatric hematologists may have relatively limited experience with the complex management of SAA. The following recommendations reflect an up-to-date evidence-based approach to the treatment of children with newly diagnosed SAA.

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.

Upfront Umbilical Cord Blood Transplantation Versus Immunosuppressive Therapy for Pediatric Patients With Idiopathic Severe Aplastic Anemia

Umbilical cord blood transplantation (UCBT) has been rarely reported as a first-line treatment for idiopathic severe aplastic anemia (SAA) patients lacking HLA-matched sibling donors (MSD). Our study aimed to compare the clinical outcomes of pediatric SAA patients who received UCBT and immunosuppressive therapy (IST) upfront. A retrospective analysis was performed on 43 consecutive patients who received frontline IST (n = 17) or UCBT (n = 26) between July 2017 and April 2022. The 3-year overall survival (OS) was comparable between the UCBT and IST groups (96.2% versus 100%, P = .419), while the 3-year event-free survival (EFS) was significantly better in the former than in the latter (88.5% versus 58.8%, P = .048). In the UCBT group, 24 patients achieved successful engraftment, 2 patients developed severe acute graft-versus-host disease (aGVHD), no extensive chronic GVHD (cGVHD), and a high GVHD-free, failure-free survival (GFFS) of 84.6% at 3 years. After 1 year of treatment, 12 patients in the IST group responded, while 5 patients did not achieve remission and 2 patients had disease relapse. At both 3 and 6 months after treatment, the proportion of transfusion-independent patients was higher in the UCBT group than in the IST group. Faster immune recovery and earlier transfusion independence further reduced the risk of infection and bleeding, thereby improving health-related quality of life in the UCBT-treated group. Our results suggested that UCBT as upfront therapy may be an effective and safe option for pediatric SAA patients, with favorable outcomes in experienced centers.

Outcome of first or second transplantation using unrelated umbilical cord blood without ATG conditioning regimen for pediatric bone marrow failure disorders

BACKGROUND

Unrelated umbilical cord blood transplantation (UCBT) for bone marrow failure (BMF) disorders using conditioning regimens without Anti-Thymocyte Globulin (ATG) has been used as an alternative transplantation for emerging patients without matched-sibling donors. Experience with this transplant modality in children is limited, especially as a secondary treatment for transplant failure patients.

PROCEDURE

We retrospectively reviewed 17 consecutive bone marrow failure patients who underwent unrelated umbilical cord blood transplantation in our center and received conditioning regimens of Total Body Irradiation (TBI) or Busulfan (BU) + Fludarabine (FLU) + Cyclophosphamide (CY).

RESULTS

Among the 17 BMF patients, 15 patients were treated with first cord blood transplantation and another 2 with secondary cord blood transplantation because of graft failure after first haploidentical stem cell transplantation at days +38 and +82. All patients engrafted with a median donor cell chimerism of 50 % at days +7 (range, 16 %-99.95 %) and finally rose to 100 % at days +30. Median time to neutrophil engraftment was 19 days (range, 12-30) and time to platelet engraftment was 32 days (range, 18-61). Pre-engraftment syndrome (PES) was found in 16 patients (94.11 %, 16/17). Cumulative incidence of grades II to IV acute GVHD was 58.8 % (95 % CI: 32.7-84.9 %), and 17.6 % (95 % CI: 2.6-37.9 %) of patients developed chronic GVHD. The 3-year overall survival (OS) and failure-free survival (FFS) rates were 92.86 ± 6.88 %.

CONCLUSION

UCBT is an effective alternative treatment for bone marrow failure pediatric patients. TBI/BU + FLU + CY regimen ensure a high engraftment rate for unrelated umbilical cord blood transplantation, which overcomes the difficulty of graft failure. Secondary salvage use of cord blood transplantation may still be useful for patients who have failed after other transplantation.

Poor Outcome After Hematopoietic Stem Cell Transplantation Of Patients With Unclassified Inherited Bone Marrow Failure Syndromes

Classification of inherited bone marrow failure syndromes (IBMFSs) according to clinical and genetic diagnoses enables proper adjustment of treatment. Unfortunately, 30% of patients enrolled in the Canadian Inherited Marrow Failure Registry (CIMFR) with features suggesting hereditability could not be classified with a specific syndromic diagnosis. We analyzed the outcome of hematopoietic stem cell transplantation (HSCT) in unclassified IBMFSs (uIBMFSs) and the factors associated with outcome. Twenty-two patients with uIBMFSs and 70 patients with classified IBMFSs underwent HSCT. Five-year overall survival of uIBMFS patients after HSCT was inferior to that of patients with classified IBMFSs (56% vs 76.5%). The outcome of patients with uIBMFS who received cord blood was significantly lower than that of patients who received other stem cell sources (14.8% vs 90.9%). Engraftment failure was higher among patients with uIBMFS who received cord blood than those who received bone marrow. None of the following factors was significantly associated with poor survival: transfusion load, transplant indication, the intensity of conditioning regimen, human leukocyte antigen-identical sibling/alternative donor. We suggest that identifying the genetic diagnosis is essential to modulate the transplant procedure including conditioning agents and stem cell sources for better outcome and the standard CBT should be avoided in uIBMFS.

Outcomes of haploidentical bone marrow transplantation in patients with severe aplastic anemia-II that progressed from non-severe acquired aplastic anemia

Severe aplastic anemia II (SAA-II) progresses from non-severe aplastic anemia (NSAA). The unavailability of efficacious treatment has prompted the need for haploidentical bone marrow transplantation (haplo-BMT) in patients lacking a human leukocyte antigen (HLA)-matched donor. This study aimed to investigate the efficacy of haplo-BMT for patients with SAA-II. Twenty-two patients were included and followed up, and FLU/BU/CY/ATG was used as conditioning regimen. Among these patients, 21 were successfully engrafted, 19 of whom survived after haplo-BMT. Four patients experienced grade II-IV aGvHD, including two with grade III-IV aGvHD. Six patients experienced chronic GvHD, among whom four were mild and two were moderate. Twelve patients experienced infections during BMT. One was diagnosed with post-transplant lymphoproliferative disorder and one with probable EBV disease, and both recovered after rituximab infusion. Haplo-BMT achieved 3-year overall survival and disease-free survival rate of 86.4% ± 0.73% after a median follow-up of 42 months, indicating its effectiveness as a salvage therapy. These promising outcomes may support haplo-BMT as an alternative treatment strategy for patients with SAA-II lacking HLA-matched donors.

Allogeneic hematopoietic stem cell transplantation in aplastic anemia: current indications and transplant strategies

Treatment options for newly diagnosed aplastic anemia (AA) patient includes upfront allogeneic hematopoietic stem cell transplant (HSCT) or immunosuppressive therapy (IST). With recent advances in supportive care, conditioning regimens and post-transplant immunosuppression the overall survival for HSCT approaches 70-90%. Transplant eligibility needs to be assessed considering age, comorbidities, donor availability and probability of response to immunosuppressive therapy (IST). Upfront HSCT should be offered to children and young adults with matched related donor (MRD). Upfront HSCT may also be offered to children and young adults with rapidly available matched unrelated donor (MUD) who require urgent HSCT. Bone marrow (BM) graft source and cyclosporine (CsA) plus methotrexate (MTX) as graft versus host disease (GVHD) prophylaxis are preferable when using anti-thymocyte globulin (ATG) based conditioning regimens. Alemtuzumab is an acceptable alternative to ATG and is used with CsA alone and with either BM or peripheral blood stem cells (PBSC). Cyclophosphamide (CY) plus ATG conditioning is preferable for patients receiving MRD transplant, while Fludarabine (Flu) based conditioning is reserved for older adults, those with risk factors of graft failure and those receiving MUD HSCT. For haploidentical transplant, use of low dose radiotherapy and post-transplant cyclophosphamide has resulted in a marked reduction in graft failure and GVHD.

Aplastic anaemia: Current concepts in diagnosis and management

Aplastic anaemia is a rare, previously fatal condition with a significantly improved survival rate owing to advances in understanding of the pathophysiology and improved treatment strategies including haematopoietic stem cell transplantation. Although a rare condition, aplastic anaemia continues to present a high burden for affected patients, their families and the health system due to the prolonged course of disease often associated with high morbidity and the uncertainty regarding clinical outcome. Modern molecular and genetic techniques including next-generation sequencing have contributed to a better understanding of this heterogeneous group of conditions, albeit at a cost of increased complexity of clinical decision-making regarding prognosis and choice of treatment for individual patients. Here we present a concise and comprehensive review of aplastic anaemia and closely related conditions based on extensive literature review and long-standing clinical experience. The review takes the reader across the complex pathophysiology consisting of three main causative mechanisms of bone marrow destruction resulting in aplastic anaemia: direct injury, immune mediated and bone marrow failure related including inherited and clonal disorders. A comprehensive diagnostic algorithm is presented and an up-to-date therapeutic approach to acquired immune aplastic anaemia, the most represented type of aplastic anaemia, is described. Overall, the aim of the review is to provide paediatricians with an update of this rare, heterogeneous and continuously evolving condition.

Subsequent neoplasms and late mortality in children undergoing allogeneic transplantation for nonmalignant diseases

We examined the risk of subsequent neoplasms (SNs) and late mortality in children and adolescents undergoing allogeneic hematopoietic cell transplantation (HCT) for nonmalignant diseases (NMDs). We included 6028 patients (median age, 6 years; interquartile range, 1-11; range, <1 to 20) from the Center for International Blood and Marrow Transplant Research (1995-2012) registry. Standardized mortality ratios (SMRs) in 2-year survivors and standardized incidence ratios (SIRs) were calculated to compare mortality and SN rates with expected rates in the general population. Median follow-up of survivors was 7.8 years. Diagnoses included severe aplastic anemia (SAA; 24%), Fanconi anemia (FA; 10%), other marrow failure (6%), hemoglobinopathy (15%), immunodeficiency (23%), and metabolic/leukodystrophy syndrome (22%). Ten-year survival was 93% (95% confidence interval [95% CI], 92% to 94%; SMR, 4.2; 95% CI, 3.7-4.8). Seventy-one patients developed SNs (1.2%). Incidence was highest in FA (5.5%), SAA (1.1%), and other marrow failure syndromes (1.7%); for other NMDs, incidence was <1%. Hematologic (27%), oropharyngeal (25%), and skin cancers (13%) were most common. Leukemia risk was highest in the first 5 years posttransplantation; oropharyngeal, skin, liver, and thyroid tumors primarily occurred after 5 years. Despite a low number of SNs, patients had an 11-fold increased SN risk (SIR, 11; 95% CI, 8.9-13.9) compared with the general population. We report excellent long-term survival and low SN incidence in an international cohort of children undergoing HCT for NMDs. The risk of SN development was highest in patients with FA and marrow failure syndromes, highlighting the need for long-term posttransplantation surveillance in this population.

Cord blood transplantation for bone marrow failure syndromes: state of art

Hematopoietic stem cell transplantation (HSCT) and immunosuppressive therapy (IST) represent the milestones of the treatment algorithm for idiopathic and inherited bone marrow failure (BMF) disorders. However, patients lacking a suitable donor or failing IST still have a poor prognosis. Cord blood transplantation (CBT) has extended the possibility of HSCT for many patients in case of the absence of an eligible donor, and although in the last years, this procedure is less used in several hematological diseases, it remains an option for the treatment of patients with BMF syndromes. Nevertheless, optimization of conditioning regimen and cord blood unit selection is warranted to reduce the risk of graft failure and transplant-related mortality. This review summarizes the state of art of CBT in the field of BMF diseases, focusing on historical and recent issues in idiopathic aplastic anemia and inherited disorders.

Current status of umbilical cord blood transplantation in children

The first umbilical cord blood (UCB) transplantation was performed 30 years ago. UCB transplantation (UCBT) is now widely used in children with malignant and non-malignant disorders who lack a matched family donor. UCBT affords a lower incidence of graft-versus-host disease compared to alternative stem cell sources, but also presents a slower immune recovery and a high risk of infections if serotherapy is not omitted or targeted within the conditioning regimen. The selection of UCB units with high cell content and good human leucocyte antigen match is essential to improve the outcome. Techniques, such as double UCBT, ex vivo stem cell expansion and intra-bone injection of UCB, have improved cord blood engraftment, but clinical benefit remains to be demonstrated. Cell therapies derived from UCB are under evaluation as potential novel strategies to reduce relapse and viral infections following transplantation. In recent years, improvements within haploidentical transplantation have reduced the overall use of UCBT as an alternative stem cell source; however, each may have its relative merits and disadvantages and tailored use of these alternative stem cell sources may be the optimal approach.

Indications for haematopoietic stem cell transplantation for haematological diseases, solid tumours and immune disorders: current practice in Europe, 2019

This is the seventh special EBMT report on the indications for haematopoietic stem cell transplantation for haematological diseases, solid tumours and immune disorders. Our aim is to provide general guidance on transplant indications according to prevailing clinical practice in EBMT countries and centres. In order to inform patient decisions, these recommendations must be considered together with the risk of the disease, the risk of the transplant procedure and the results of non-transplant strategies. In over two decades since the first report, the EBMT indications manuscripts have incorporated changes in transplant practice coming from scientific and technical developments in the field. In this same period, the establishment of JACIE accreditation has promoted high quality and led to improved outcomes of patient and donor care and laboratory performance in transplantation and cellular therapy. An updated report with operating definitions, revised indications and an additional set of data with overall survival at 1 year and non-relapse mortality at day 100 after transplant in the commonest standard-of-care indications is presented. Additional efforts are currently underway to enable EBMT member centres to benchmark their risk-adapted outcomes as part of the Registry upgrade Project 2020 against national and/or international outcome data.

Severe aplastic anemia: allogeneic bone marrow transplantation as first-line treatment

Treatment of severe aplastic anemia has improved significantly over the past 4 decades. This review will summarize the key areas of progress in the use of allogeneic hematopoietic cell transplantation and nontransplant immunosuppressive therapy (IST) for the treatment of aplastic anemia and then summarize the recommendations for first-line treatment. Based on recent data, we argue that guidelines for the initial treatment of patients with newly diagnosed severe aplastic anemia require revision. At the time of diagnosis, before beginning treatment, HLA typing should be done to identify a marrow donor among family members or in the unrelated donor registries, and a marrow transplant should be considered first-line therapy. The priority order of donor source for bone marrow transplantation is: (1) HLA-identical sibling, (2) HLA-matched unrelated donor, and (3) HLA-haploidentical donor if an HLA-matched unrelated donor is not rapidly available. Each of these donor marrow sources may be preferable to nontransplant IST. We make this recommendation because of the long-term persistent risk for disease relapse and secondary myelodysplastic syndrome or acute myeloid leukemia with the use of nontransplant IST for patients with aplastic anemia. In contrast, marrow transplantation is associated with high cure rates of aplastic anemia and a relatively low risk for graft-versus-host disease, with many patients now living for decades without the risk for disease recurrence or the development of clonal disorders. Implementation of this first-line treatment strategy will provide patients with severe aplastic anemia the best chance of long-term disease-free survival.