Comparing Outcomes with Bone Marrow or Peripheral Blood Stem Cells as Graft Source for Matched Sibling Transplants in Severe Aplastic Anemia across Different Economic Regions

Long-Term Follow-Up of Abatacept, Post-Transplantation Cyclophosphamide, and Sirolimus-Based Haploidentical Transplantation in Younger Patients with Nonmalignant Diseases

Haploidentical (haplo) hematopoietic cell transplantation (HCT) for nonmalignant disease (NMD) carries inherent challenges of both alloreactivity and graft failure. Building on promising results from pilot studies in which abatacept was combined with post-transplantation cyclophosphamide (PTCy) and sirolimus (AbaCyS) in younger NMD patients undergoing haplo-HCT, we present the long-term outcomes of this protocol. On the back of uniform disease-specific conditioning regimens containing antithymocyte globulin 4.5 mg/kg from day -9 to day -7, GVHD prophylaxis with AbaCyS consisted of abatacept administered on days 0, +5, +20, +35, and monthly until 180 days with PTCy and sirolimus. The patients were followed up with longitudinal assessment of immune reconstitution, growth, and reproductive development and quality of life (QoL) analyses. Among 40 patients (aplastic anemia, n = 24; hemoglobinopathies, n = 14; and primary immunodeficiencies, n = 2) with a median age of 10 years (range, 2 to 25 years), 95% achieved sustained engraftment. Post-transplantation hemophagocytic syndrome was detected in 3 patients, leading to graft failure in 2 cases. The incidence of acute graft-versus-host disease (GVHD) was 2.6%, and that of chronic GVHD (cGVHD) was 14.3%. Cytomegalovirus, adenovirus, and Epstein-Barr virus infections were observed in 45%, 5%, and 0% respectively. Rates of nonrelapse mortality, overall survival, event-free survival, and GVHD-free, event-free survival were 5%, 95%, 90%, and 82%, respectively, at a median follow-up of 4.6 years. Absence of cGVHD correlated with younger patient age and early sustained recovery of regulatory T cells and mature natural killer cells, which in turn was associated with improved QoL and lack of late infections. The AbaCyS protocol was associated with excellent long-term survival, with attenuation of both early and late alloreactivity in >80% of younger patients undergoing haplo-HCT for NMD. This study sheds light on predispositions to cGVHD and its impact on QoL, warranting further optimization of this approach.

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.

Guidelines for the diagnosis and management of adult aplastic anaemia: A British Society for Haematology Guideline

Pancytopenia with hypocellular bone marrow is the hallmark of aplastic anaemia (AA) and the diagnosis is confirmed after careful evaluation, following exclusion of alternate diagnosis including hypoplastic myelodysplastic syndromes. Emerging use of molecular cyto-genomics is helpful in delineating immune mediated AA from inherited bone marrow failures (IBMF). Camitta criteria is used to assess disease severity, which along with age and availability of human leucocyte antigen compatible donor are determinants for therapeutic decisions. Supportive care with blood and platelet transfusion support, along with anti-microbial prophylaxis and prompt management of opportunistic infections remain key throughout the disease course. The standard first-line treatment for newly diagnosed acquired severe/very severe AA patients is horse anti-thymocyte globulin and ciclosporin-based immunosuppressive therapy (IST) with eltrombopag or allogeneic haemopoietic stem cell transplant (HSCT) from a matched sibling donor. Unrelated donor HSCT in adults should be considered after lack of response to IST, and up front for young adults with severe infections and a readily available matched unrelated donor. Management of IBMF, AA in pregnancy and in elderly require special attention. In view of the rarity of AA and complexity of management, appropriate discussion in multidisciplinary meetings and involvement of expert centres is strongly recommended to improve patient outcomes.

Haploidentical Hematopoietic Stem Cell Transplantation for Patients with Severe Aplastic Anemia-Single-Centre Experience

Severe aplastic anemia (SAA) is a life-threatening type of aplastic anemia for which allogeneic stem cell transplantation or immunosuppressive therapy are the principal treatment modalities. Only about 25-30% of patients have a matched sibling donor, and finding an unrelated donor in ethnic minorities is a challenge. The use of related haploidentical donor transplants in severe aplastic anemia is uncommon. We would like to report our experience with the first four patients who underwent haploidentical transplants for severe aplastic anemia. This is a retrospective study. We collected data from our transplant database of all haploidentical hematopoietic stem cell transplants for SAA from 1 January 2020 to 31 December 2021. The transplant protocol used was the Hopkins' protocol. There were three patients who underwent haploidentical transplants as primary therapy for SAA. A fourth patient received a haploidentical transplant after immunosuppressive therapy failure. The median age of the patients at transplant was 24 y (range 20-29). All patients were engrafted. Neutrophil engraftment occurred at a median of 21 days (range 17-22). Any active infections resolved with the recovery of blood counts. The median hospitalization time was 27 days (range 22-41). Only one patient had grade 2 acute GVHD involving the skin. There was no chronic GVHD. All patients had complete lymphoid and myeloid donor chimerism on day 60. Based on our experience and the emerging literature, haplo-identical transplantation should be considered for select young patients with SAA who have low chances of responding to immunosuppressive therapy.

Comparison of Haploidentical Stem Cell Transplantation with Post-Transplantation Cyclophosphamide versus Umbilical Cord Blood Transplantation in Adult Patients with Aplastic Anemia

Aplastic anemia patients who are refractory to immunosuppressive therapy or with very low neutrophil counts require allogeneic hematopoietic stem cell transplantation (HSCT). Umbilical cord blood transplantation (UCBT) has been a treatment option when an HLA-matched donor is not available, and HSCT from a related haploidentical donor using post-transplantation cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis (PTCy-haplo) recently became another important approach. We aimed to compare the outcomes of PTCy-haplo and UCBT in adult patients with aplastic anemia to identify more effective and safer approaches for alternative donor transplantation. Data in a nationwide registry were analyzed retrospectively to assess the outcomes of aplastic anemia patients age ≥16 years who underwent PTCy-haplo or UCBT as their first HSCT between 2016 and 2020. The primary endpoint was 1-year overall survival (OS) after HSCT. Secondary endpoints included 1-year failure-free survival (FFS), neutrophil and platelet engraftment, and acute and chronic GVHD. Eighty-three patients who underwent PTCy-haplo (n = 24) or UCBT (n = 59) were eligible. The 1-year OS rate was 78.5% (95% confidence interval [CI], 55.7% to 90.5%) in the PTCy-haplo group and 77.5% (95% CI, 64.5% to 86.3%; P = .895) in the UCBT group. The 1-year FFS rate was 78.7% (95% CI, 56.1% to 90.6%) in the PTCy-haplo group and 62.2% (95% CI, 48.5% to 73.3%; P = .212) in the UCBT group. Among patients age <40 years, the PTCy-haplo group had a significantly higher FFS rate (92.9% [95% CI, 59.1% to 99.0%]) vs 63.9% [95% CI, 43.2% to 78.7%]; P = .047). Neutrophil engraftment and platelet engraftment rates were significantly higher in the PTCy-haplo group compared with the UCBT group: 95.8% (95% CI, 73.9% to 99.4%) vs 78.0% (95% CI, 65.1% to 86.6%, P < .001) and 83.3% (95% CI, 61.5% to 93.4%) vs 72.9% (95% CI, 59.6% to 82.4%; P = .025). No significant difference was observed in the cumulative incidence of grade II-IV acute GVHD and chronic GVHD between the 2 groups. Aplastic anemia patients achieved significantly higher neutrophil and platelet engraftment rates with PTCy-haplo than with UCBT. OS and the incidences of acute and chronic GVHD were similar between the 2 groups. In patients age <40 years, the FFS rate was higher in the PTCy-haplo group. PTCy-haplo is promising for alternative donor transplantation in adult patients with aplastic anemia.

Combining post-transplant cyclophosphamide with antithymocyte globulin for graft-versus-host disease prophylaxis in hematological malignancies

In search of an ideal partner or alternative to conventional immunosuppressive agents, rabbit anti-thymocyte globulin (ATG) and, more recently, post-transplant cyclophosphamide (PT-Cy) have both emerged as valid and efficient options for preventing graft-versus-host disease (GvHD). To further reduce the risk of GvHD, strategies combining ATG and PT-Cy have recently been investigated. In a haploidentical setting, retrospective studies suggest that combining PT-Cy and ATG may result in a lower incidence of chronic GvHD without increasing the risks of infection or relapse, when compared to PT-Cy without ATG. In haploidentical or unrelated donor settings, adding reduced doses of PT-Cy to ATG may reduce the risk of acute and chronic GvHD and improve survival, particularly GvHD-free, relapse-free survival (GRFS), when compared to ATG without PT-Cy. Overall, the combination of PT-Cy and ATG is a safe and promising approach for patients with hematological malignancies undergoing allogeneic hematopoietic stem cell transplantation (HSCT).

Haematopoietic Stem Cell Transplant Trends in Pakistan: Activity Survey from Pakistan Bone Marrow Transplant Group

Pakistan is the fifth most populous country with a population of 225 million and has health expenditure accounting for only 2.8 percent of gross domestic product (GDP). Accordingly, there are a limited number of haematology-oncology and transplant centers in the country. The Pakistan Blood and Marrow Transplant (PBMT) group was established in 2020, and this report is the first activity survey from January 2021 to December 2022 focusing on the trends of matched-related donor, haploidentical, and autologous transplants in a developing country. A total of 12 transplant centers contributed data on the modified PBMT survey form retrospectively and 806 haematopoietic stem cell transplants (HSCTs) were carried out during the study duration. Allogeneic HSCT constituted 595 (73.8%) of all the transplants; this is in stark contrast to Western data, where autologous HSCT accounts for the majority of transplants. ß-thalassemia major and aplastic anemia were the commonest indications for allogeneic HSCT, in contrast to Western data, where acute leukemia is the leading transplant indication. Autologous transplants were more frequently performed for Hodgkin's lymphoma as compared to non-Hodgkin's lymphoma and multiple myeloma. The use of peripheral and bone marrow stem cells was comparable. A myeloablative conditioning regimen was routinely used in patients with acute leukemia. This report provides an insight of HSCT trends in Pakistan which are different from those of Western centers contributing to transplant data from South Asia.

Outcome of peripheral blood stem cell transplantation from HLA-identical sibling donors for adult patients with aplastic anemia

Although bone marrow transplantation is the recommended form of allogeneic hematopoietic stem cell transplantation for aplastic anemia, some patients undergo peripheral blood stem cell transplantation (PBSCT). Therefore, there is critical demand to identify factors affecting transplantation outcomes. Using the Japanese registry database, we retrospectively analyzed outcomes of 94 adult patients with aplastic anemia who underwent PBSCT from HLA-identical sibling donors. The cumulative incidence of neutrophil engraftment was 94% (95% confidence interval [CI] 86-97%), and was significantly higher in patients who received anti-thymocyte globulin (ATG) in conditioning. The cumulative incidence rate was 26% (95% CI 17-35%) in grades II-IV acute graft-versus-host disease (GVHD) and 20% (95% CI 13-29%) in extensive chronic GVHD, and tended to be lower in patients with chronic GVHD who received ATG-based conditioning. The 5-year overall survival (OS) rate was 70% (95% CI 59-78%). In multivariate analysis, patient age < 40 years, shorter period from diagnosis to transplantation, better performance status, and ATG-based conditioning were significantly correlated with favorable OS. In conclusion, PBSCT from HLA-identical sibling donors for aplastic anemia would result in acceptable outcomes. Several risk factors identified in our study should be considered when selecting a stem cell source.

Impact of Conditioning Regimen and Graft-versus-Host Disease Prophylaxis on The Outcome of Haploidentical Peripheral Blood Stem Cell Transplantation for High-Risk Severe Aplastic Anemia in Children and Young Adults: A Report from the Pediatric Severe Aplastic Anemia Consortium of India

Allogenic hematopoietic cell transplantation (HCT) is the best curative approach for patients with severe aplastic anemia (SAA). The outcomes of HCT from haploidentical family donors (HFDs) have improved, making it a feasible option for patients lacking an HLA-identical donor. However, data on HFD-HCT for younger patients with SAA is sparse. In this multicenter retrospective study, we evaluated the outcomes of 79 patients undergoing HFD-HCT for SAA. All the patients were heavily pretransfused, the median time to HCT was >12 months, and 67% had failed previous therapies. Conditioning was based on fludarabine (Flu)-cyclophosphamide (Cy)-antithymocyte globulin (ATG)/total body irradiation (TBI) with or without thiotepa/melphalan (TT/Mel). Post-transplantation Cy (PTCy) and calcineurin inhibitors (CNIs)/sirolimus were used as graft-versus-host disease (GVHD) prophylaxis with or without abatacept. The rate of primary graft failure (PGF) was 16.43% overall, lower in patients conditioned with TT/Mel. The incidences of acute and chronic GVHD were 26.4% and 18.9%, respectively. At a median follow-up of 48 months, the overall survival (OS) and event-free survival (EFS) were 61.6% and 58.1%, respectively. Both OS and EFS were better in the TT/Mel recipients and with abatacept as GVHD prophylaxis. On multivariate analysis, the use of abatacept was found to favorably impact the outcome variables, including GVHD and EFS. Our study suggests that PTCy-based HFD-HCT is a reasonable option for young patients with high-risk SAA, in whom optimization of conditioning and GVHD prophylaxis might further improve outcomes.

T Cell-Depleted Peripheral Blood versus Unmanipulated Bone Marrow in Matched Sibling Transplantation for Aplastic Anemia

Bone marrow (BM) is the recommended stem cell source for hematopoietic stem cell transplantation (HSCT) from matched sibling donors (MSDs) in patients with severe aplastic anemia (SAA) for its superior survival and graft-versus-host disease (GVHD) outcomes compared to recipients of unmanipulated peripheral blood (PB) HSCT. Nevertheless, no studies comparing BM with ex vivo T cell-depleted (TCD) PB have been reported to date. The aim of the present study was to compare the transplantation outcomes of MSD HSCT recipients with SAA using PB (with partial ex vivo TCD targeted cell dose grafts) with those of MSD HSCT recipients with SAA using unmanipulated BM. We performed a matched-pair analysis of MSD-HSCT using TCD PB in a single institution with unmanipulated BM MSD-HSCT in the United States between 2013 and 2019 reported to the Center for International Blood and Marrow Transplant Research. We compared 23 recipients of TCD PB HSCT for SAA (cases) and 69 recipients of unmanipulated BM grafts (controls) matched for age, Karnofsky Performance Status, Hematopoietic Cell Transplantation-Specific Comorbidity Index, time from diagnosis to transplantation, and recipient cytomegalovirus serostatus. We found significantly faster neutrophil and platelet recovery in the TCD PB cohort (P < .001 and P = .03, respectively), as well as a lower incidence of grade II-IV acute GVHD (0% versus 17%; P = .05) and similar overall survival (96% versus 97% at 3 years; P = .8). Our study shows that TCD PB can be considered a safe source for MSD-HSCT in patients with SAA, with potential advantages in engraftment and GVHD that could challenge the standard with BM. These findings provide a basis for future research in a prospective controlled clinical trial.

Emerging approaches to improve allogeneic hematopoietic cell transplantation outcomes for nonmalignant diseases

Many congenital or acquired nonmalignant diseases (NMDs) of the hematopoietic system can be potentially cured by allogeneic hematopoietic cell transplantation (HCT) with varying types of donor grafts, degrees of HLA matching, and intensity of conditioning regimens. Unique features that distinguish the use of allogeneic HCT in this population include higher rates of graft failure, immune-mediated cytopenias, and the potential to achieve long-term disease-free survival in a mixed chimerism state. Additionally, in contrast to patients with hematologic malignancies, a priority is to completely avoid graft-versus-host disease in patients with NMD because there is no theoretical beneficial graft-versus-leukemia effect that can accompany graft-versus-host responses. In this review, we discuss the current approach to each of these clinical issues and how emerging novel therapeutics hold promise to advance transplant care for patients with NMDs.

Radiation-sparing reduced-intensity unrelated umbilical cord blood transplantation for rare hematological disorders in children

Graft failure is a major pitfall of unrelated umbilical cord blood transplantation (CBT) in children with rare hematological disorders other than acute leukemia, such as acquired and inherited bone marrow failure, myelodysplastic syndrome, juvenile myelomonocytic leukemia, and chronic myeloid leukemia. We developed a less-toxic conditioning regimen for CBT that achieves a higher rate of complete donor chimerism, and retrospectively compared it against two other conditioning regimens for CBT performed at our single institution. The engraftment rate with complete donor chimerism was 100% and 5-year event-free survival (5y-EFS) was 90.9% in patients using our latest regimen (n = 11) of reduced-intensity conditioning (RIC) containing fludarabine (Flu) 180 mg/m², melphalan (MEL) 210 mg/m², and low-dose rabbit anti-thymocyte globulin (LD-rATG) 2.5 mg/kg without irradiation (regimen C). Outcomes were better than in patients (n = 10) treated with previous regimens involving irradiation (5y-EFS 30.0%, p = 0.004): regimen A, consisting of myeloablative conditioning containing cyclophosphamide (CY) and total body irradiation (TBI) with 8-12 Gy, or regimen B, consisting of RIC with Flu, CY, horse ATG, and thoracoabdominal irradiation (TAI) with 6 Gy. In conclusion, Flu/MEL/LD-rATG (regimen C) without TBI/TAI may be preferable as RIC for unrelated CBT in children with rare hematological disorders.

Special issues related to the diagnosis and management of acquired aplastic anemia in countries with restricted resources, a report on behalf of the Eastern Mediterranean blood and marrow transplantation (EMBMT) group and severe aplastic anemia working party of the European Society for blood and marrow transplantation (SAAWP of EBMT)

Aplastic anemia is a relatively rare but potentially fatal disorder, with a reported higher incidence in developing countries in comparison to the West. There are significant variations in epidemiological as well as etiological factors of bone marrow failure syndromes in the developing countries in comparison to the developed world. Furthermore, the management of bone marrow failure syndromes in resource constraint settings has significant challenges including delayed diagnosis and referral, limited accessibility to healthcare facilities, treatment modalities as well as limitations related to patients who require allogeneic stem cell transplantation. Here we will provide a review of the available evidence related to specific issues of aplastic anemia in the developing countries and we summarize suggested recommendations from the Eastern Mediterranean blood and bone marrow transplantation (EMBMT) group and the severe aplastic anemia working party of the European Society of blood and marrow transplantation (SAAWP of EBMT) related to the diagnosis and therapeutic options in countries with restricted resources.

An Antithymocyte Globulin-Free Conditioning Regimen Using Fludarabine and Cyclophosphamide Is Associated with Good Outcomes in Patients Undergoing Matched Related Family Donor Transplantation for Aplastic Anemia

Allogeneic hematopoietic stem cell transplantation (HSCT) using fludarabine (Flu)-based conditioning regimens are being increasingly being used in patients with aplastic anemia (AA). We describe an antithymocyte globulin (ATG)-free conditioning regimen consisting of Flu and cyclophosphamide (Cy) in patients undergoing matched related donor (MRD) HSCT for AA. Between 2004 and 2019, 212 patients underwent MRD HSCT using Flu (30 mg/m²/day for 6 days) and Cy (60 mg/kg/day for 2 days) for conditioning. The graft source was peripheral blood stem cells in all patients. Graft-versus-host disease (GVHD) prophylaxis consisted mainly of cyclosporine and methotrexate, although 41 patients received post-transplantation Cy as part of a study. Engraftment occurred in 91% of patients at a median of 16 days, whereas 4 patients (1.8%) experienced primary graft failure and 15 (7.1%) died before achieving engraftment. Toxicity was minimal. The incidence of grade II-IV acute GVHD (aGVHD) was 27.9%, and that of grade III-IV aGVHD was 11.3%. Chronic GVHD occurred in 41.6%. 80% were free of immunosuppression at 60 months and long-term complications were seen in 8.4%. At a median of 46 months, 158 patients were alive and well, with a 5-year overall survival (OS) of 75.3 ± 3.0%. The 5-year OS was 80.6 ± 4.1% for patients age <20 years (n = 93), 74.5 ± 4.6% for those age 20 to 40 years (n = 91), and 59.7 ± 9.5% for those age >40 years (n = 28) (P = .11). Patients classified as low risk had better OS compared with those at high risk (93.2 ± 2.9% versus 65.7 ± 4.1%; P = .000). Factors affecting OS on multivariate analysis included aGVHD (P = .02) and graft failure (P = .000). This large series using Flu/Cy for conditioning before MRD HSCT confirms good outcomes in patients with AA, with excellent outcomes in low-risk patients. Suitable modifications are needed to improve outcomes in high-risk patients.

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.

Safety of peripheral blood stem cell harvest in children under anaesthesia in the day care setting - A single centre experience

The use of cytokine mobilized peripheral blood stem cells (PBSC) for stem cell transplantation offers early engraftment, and less early transplant related mortality and morbidity. This can be done easily in the out-patient setting in an adult donor, but is difficult in children. The safety and efficacy of general anaesthesia outside the controlled operation room setting is quite challenging and demanding. We present our experience with paediatric PBSC harvest done under anaesthesia in the out-patient setting between January 2009 to June 2017. A total of 158 children underwent 164 PBSC harvests during the study period. Donors were predominantly females with a median age of 5 years (1-12) and a median weight of 17.5 kg (9.4-51). In 50% of the cases, induction of anaesthesia was by sevoflurane followed by total intravenous anaesthesia (TIVA) while in 32% it was sevoflurane induction followed by sedation. Hudson mask (48.5%) and laryngeal mask airway (50%) were the most common modes of airway and all patients were ventilated in the spontaneous mode. Propofol was the most commonly used maintenance agent (67%). There were no major complications except for acute pulmonary edema secondary to infusion of blood products requiring a short stay in ICU for one donor. All donors were discharged on the next day of harvest. No long term complications have been reported in any of these donors. Paediatric PBSC harvest can be safely done under anaesthesia with due precautions in the day care setting.

Transplant in Aplastic Anemia Using Combined Granulocyte Colony-Stimulating Factor Primed Blood and Bone Marrow Stem Cells: A Retrospective Analysis

INTRODUCTION

Aplastic anemia (AA) is characterized by diminished hematopoietic precursors in the bone marrow, most often due to injury to the pluripotent stem cell. In Pakistan, AA is not uncommon, and allogeneic hematopoietic stem cell transplant remains the only curative option for these patients.

OBJECTIVE

The objective of this study was to determine the transplant outcome of combined granulocyte colony-stimulating factor (G-CSF) primed blood and bone marrow grafts in adult and pediatric patients with AA.

METHODS

We retrospectively collected the data of all transplant procedures performed from 2004 to 2019 at Aga Khan University in Karachi, Pakistan. Variables analyzed included age, sex, type of stem cells used, conditioning regimens, and overall survival for patients undergoing transplant in AA.

RESULTS

A total of 351 transplants were performed during the study period. Out of these, 239 were allogeneic transplants, whereas 112 were autologous procedures. We performed 70 transplants for AA during the study period, of which 52 were male patients and 18 were female patients. The median age ± standard deviation (SD) was 17.5 ± 9.4 years (range, 2-43 years). Cyclophosphamide/antithymocyte globulin (ATG) was used as a conditioning regimen in 65 patients, while ATG/cyclophosphamide/fludarabine was used in 5 patients. In 60 patients, a combination of G-CSF primed blood and bone marrow stem cells were used. The mean CD34 count was 5.2 × 10⁶/kg. Graft-vs-host disease (GVHD) prophylaxis was done with cyclosporine and methotrexate. All patients received standard infection prophylaxis. Engraftment was achieved in 86% of patients. The median day of myeloid engraftment was 15 (range, 10-22 days). Chronic GVHD was present in 3 patients while 4 had acute GVHD. The overall survival was 71.2% (median duration of 80 months). The main cause of mortality was gram-negative sepsis.

CONCLUSION

A combination of blood and bone marrow stem cells results in early engraftment with decreased frequency of GVHD in AA. The overall survival was comparable to international literature.

High Overall and GVHD-Free Survival in Patients with Aplastic Anemia Receiving in vivo T-cell Depletion Transplants and Long-Term Complications

We report a single-center experience of allogeneic hematopoietic stem cell transplant for patients with severe aplastic anemia over 13 years of age. Fifty-eight patients were included, and in vivo T-cell depletion was used in all cases. Fifty-one (88%) received alemtuzumab and 7 (12%) were given rabbit anti-thymocyte globulin. The median follow-up period was 6 years (range: 0-13.5). Data was collected retrospectively and updated in April 2019. The median age was 31 years (range: 18-67). Forty (69%) recipients received grafts from related donors and 18 (31%) received them from unrelated donors. Peripheral blood grafts were infused in 12 (20.7%) patients. Five-year overall survival (OS) was 80.7%. Five-year graft-versus-host disease (GVHD)/rejection-free survival was 56%. Eight (13.8%) patients experienced graft failure. The cumulative incidence of grade II-IV acute GVHD at day 100 was 14% and that of chronic GVHD at 1 year was 7%. The selection of unrelated donors and the use of peripheral blood grafts were not significant risk factors for clinically relevant GVHD or for lower OS. Recipients older than 40 years showed significantly worse OS, as observed from the results of univariate analysis. T-cell depletion in severe aplastic anemia shows low rates of GVHD and high OS, but older patients remain a group with higher risk of mortality. Long-term complications were mainly autoimmune in character.

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.

Hematopoietic Stem Cell Transplantation in Thalassemia Patients: a Jordanian Single Centre Experience

Introduction:

Beta thalassemia major is the commonest inherited hematological disorder worldwide which needs lifelong sufficient supportive management. Hematopoietic stem Cell transplantation (HSCT) is the only curative treatment available till now.

Aim:

To evaluate the outcome of children who underwent allogenic hematopoietic stem Cell transplantation as a curative approach for Thalassemia Major, treated at Queen Rania AL- Abdullah children Hospital (QRCH)

Methods:

A retrospective review of the medical files was conducted for all children (< 15 years) who had thalassemia major and received HSCT between January, 2010 and January, 2019. The following variables were studied for all patients: age , gender, Pesaro classifications, the count of infused raw bone marrow stem cell (CD34), engraftment time, outcome and complications.

Results:

A total of 34 children were transplanted for thalassemia major, at an average of 4 cases per year. All underwent allogenic raw bone marrow transplantation from matched related donors. Thirteen patients (38.2%) were males and twenty one (61.2%) were females. The age ranged between 2 and 15 years, with a median age of 6.5 years. According to Pesaro classification, 31 patients were class 2 (91.2%) and 3 patients were class 3 (8.8%) while no single case met the criteria for class 1 Pesaro classification. The median CD34 count was 3.5 million/Kg of recipient weight (range, 1.5*10⁶-7*10⁶ /kg). The median time for neutrophil engraftment was 15.5 days. At a median follow up of 5 years (range 1- 9.5), 33 patients were alive. One patient died before 100 days post transplantation due to grade IV acute gastrointestinal Graft Versus Host Disease (GVHD). Three patients had secondary graft failure (8.8%). Six patients (17.5 %) developed mild grade 1-2 skin GVHD while another patient developed hemorrhagic cystitis due to BK virus and cytomegalovirus (CMV) which reactivated simultaneously, and was successfully managed.

Conclusion:

The outlook for Thalassemia major has dramatically changed after HSCT, with a considerable success in Jordan and results comparable to international data.

Partial T Cell-Depleted Peripheral Blood Stem Cell Transplantation from HLA-Identical Sibling Donors for Patients with Severe Aplastic Anemia

We analyzed the outcomes of 26 consecutive patients with acquired severe aplastic anemia (SAA) undergoing peripheral blood stem cell transplantation (PBSCT) with partial ex vivo T cell depletion with a targeted T cell dose from HLA-identical sibling donors. The median patient age was 37 years (range, 3 to 63 years). Four patients with uncontrolled pneumonia at the time of transplantation died, on days +1, +2, +21, and +26. All evaluable patients engrafted, with a median time to neutrophil recovery of 11 days (range, 10 to 14 days) and a median time to platelet recovery of 19 days (range, 8 to 53 days). Two patients had transient grade I acute graft-versus-host disease (GVHD) with skin involvement, but no patients developed grade II-IV acute GVHD. Two patients had mild skin chronic GVHD, and 1 patient had moderate chronic GVHD with ocular involvement. No relapse was observed after a median follow-up of 114 months (range, 4 to 233 months). The overall cumulative incidence of TRM at 10 years was 19%, whereas it was 5% for those with a Karnofsky Performance Status (KPS) score >60 at the time of transplantation. Disease-free survival, overall survival, and GVHD and relapse-free survival at 10 years were 81%, 81%, and 80%, respectively, for all patients and 95%, 95%, and 90%, respectively, for patients with a KPS score >60 at transplantation. Our data indicate that PBSCT with partial ex vivo T cell-depleted targeted cell dose grafts from an HLA-identical sibling donor is a feasible, safe, and effective approach to reduce GVHD and cure patients with SAA.

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.

Effect of Stem Cell Source and Dose on Allogeneic Hematopoietic Stem Cell Transplantation in Adult Patients with Idiopathic Aplastic Anemia: Data from the Korean Aplastic Anemia Trials

OBJECTIVE

We aimed to evaluate the effect of stem cell source and dose on the survival of various donor subgroups, such as matched sibling donor (MSDs) and alternative donors (ADs), upon bone marrow (BM) or peripheral blood stem cell (PBSC) infusion in aplastic anemia (AA).

METHODS

We retrospectively investigated the effects of stem cell source and dose on allogeneic hematopoietic stem cell transplantation (alloHSCT) in AA.

RESULTS

A total of 267 patients were included in this analysis. The BM-treated group showed an association with low incidence of any-grade acute graft versus host disease (GvHD) (p < 0.001). A higher stem cell dose was related with a low incidence of extensive chronic GvHD in MSDs (p = 0.025). Multivariate analysis for overall survival (OS) revealed that only age at alloHSCT <31 years (p = 0.010) and prior platelet transfusion <86 U (p = 0.046) in MSDs and higher stem cell dose (hazard ratio = 2.596, p = 0.045) in ADs were favorable prognostic factors.

CONCLUSION

PBSCs could be preferred in AD because high stem cell dose may be easily achieved to improve the OS at the expense of acute GvHD. However, BM stem cells are preferred in MSDs.

[Improved outcome by optimized conditioning regimens with an increased dose of cyclophosphamide in allogeneic peripheral blood stem cell transplantation for severe aplastic anemia]

Objective: To respectively analyze the impact of conditioning regimens with a dose-decreased cyclophosphamide (Cy) on the outcome in fully matched sibling donor (MSD) peripheral blood stem cell transplantation (PBSCT) for severe aplastic anemia (SAA) . Methods: Two conditioning regimens with different doses of Cy (150 mg/kg or 120 mg/kg) in combination with fludarabine (Flu) and antithymocyte globulin (ATG) for MSD-PBSCT were investigated in 51 patients with acquired SAA. Results: Overall survival and failure-free survival in patients received 150 mg/kg of Cy (Cy150 cohort) or 120 mg/kg (Cy120 cohort) were 93.5% vs 90.0% (χ(2)=0.170, P=0.680) and 90.3% vs 85.0% (χ(2)=0.285, P= 0.594) respectively. However, either acute or chronic graft-versus-host disease risks were higher in Cy120 cohort than in Cy150 cohort (HR=3.89, 95% CI 1.21-12.53, P=0.023; HR=4.48, 95% CI 1.40-14.32, P= 0.011, respectively) . No difference was found for opportunistic infections or graft failure between two cohorts. Conclusion: Cy at a dose of 150 mg/kg, in combination with Flu and ATG, was more effective than that of 120 mg/kg Cy to produce improved clinical outcome in the setting of acquired SAA patients after MSD-PBSCT.

The Concentration of Total Nucleated Cells in Harvested Bone Marrow for Transplantation Has Decreased over Time

Bone marrow (BM) is an essential source of hematopoietic stem cell grafts for many allogeneic hematopoietic cell transplant (HCT) recipients, including adult patients (for specific diseases and transplantation strategies) and the majority of pediatric recipient. However, since the advent of granulocyte colony-stimulating factor-mobilized peripheral blood stem cell (PBSC) grafts, there has been a significant decrease in the use of BM in HCT, thought to be due mainly to the increased logistical challenges in harvesting BM compared with PBSCs, as well as generally no significant survival advantage of BM over PBSCs. The decreased frequency of collection has the potential to impact the quality of BM harvests. In this study, we examined >15,000 BM donations collected at National Marrow Donor Program centers between 1994 and 2016 and found a significant decline in the quality of BM products, as defined by the concentration of total nucleated cells (TNCs). The mean TNC concentration in BM donations dropped from 21.8 × 10⁶ cells/mL in the earliest era (1994 to 1996) to 18.7 × 10⁶ cells/mL in the most recent era (2012 to 2016) (means ratio, .83; P < .001). This decline in BM quality was seen despite the selection of more donors perceived to be optimal (eg, younger and male). Multivariate regression analysis showed that higher-volume centers (performing >30 collections per era) had better-quality harvests with higher concentrations of TNCs collected. In conclusion, we have identified a significant decrease in the quality of BM collections over time, and lower-volume collection centers had poorer-quality harvests. In this analysis, we could not elucidate the direct cause for this finding, suggesting the need for further studies to investigate the key factors responsible and to explore the impact on transplant recipients.

Country-Level Macroeconomic Indicators Predict Early Post-Allogeneic Hematopoietic Cell Transplantation Survival in Acute Lymphoblastic Leukemia: A CIBMTR Analysis

For patients with acute lymphoblastic leukemia (ALL), allogeneic hematopoietic cell transplantation (alloHCT) offers a potential cure. Life-threatening complications can arise from alloHCT that require the application of sophisticated health care delivery. The impact of country-level economic conditions on post-transplantation outcomes is not known. Our objective was to assess whether these variables were associated with outcomes for patients transplanted for ALL. Using data from the Center for Blood and Marrow Transplant Research, we included 11,261 patients who received a first alloHCT for ALL from 303 centers across 38 countries between the years of 2005 and 2013. Cox regression models were constructed using the following macroeconomic indicators as main effects: Gross national income per capita, health expenditure per capita, and Human Development Index (HDI). The outcome was overall survival at 100 days following transplantation. In each model, transplants performed within lower resourced environments were associated with inferior overall survival. In the model with the HDI as the main effect, transplants performed in the lowest HDI quartile (n = 697) were associated with increased hazard for mortality (hazard ratio, 2.42; 95% confidence interval, 1.64 to 3.57; P < .001) in comparison with transplants performed in the countries with the highest HDI quartile. This translated into an 11% survival difference at 100 days (77% for lowest HDI quartile versus 88% for all other quartiles). Country-level macroeconomic indices were associated with lower survival at 100 days after alloHCT for ALL. The reasons for this disparity require further investigation.

Hematopoietic cell transplantation for aplastic anemia

PURPOSE OF REVIEW

Improvements in allogeneic hematopoietic cell transplantation (HCT) with better donor selection, conditioning regimens and graft vs. host disease prophylaxis make it reasonable to move HCT earlier in the algorithm for management of severe aplastic anemia (SAA). Recent progress in transplantation is reviewed whereas issues related to developing countries are also addressed.

RECENT FINDINGS

Multiple research centers are reporting on clonality, mutations and telomere disorders in SAA, which may help to choose the most appropriate therapy upfront. Eltrombopag, in combination with immunosuppressive therapy (IST), has shown remarkable improvement over historical IST, and long-term follow-up is awaited. In younger patients and in experienced centers, matched unrelated-donor (MUD) and related haploidentical transplants (haplo-HCT) are being reported with survival approaching that seen with sibling transplants. Literature from resource-limited countries highlight the need to modify guidelines to make them affordable and cost-effective. Bone marrow remains the graft source of choice; peripheral blood stem cells may be acceptable in special circumstances in resource-constrained countries.

SUMMARY

The potential of novel research findings and new therapeutic trials should be maximized by validation in different centers, countries and patient populations to provide personalized care to patients with aplastic anemia.

Post-Transplant Cyclophosphamide as Sole Graft-versus-Host Disease Prophylaxis Is Feasible in Patients Undergoing Peripheral Blood Stem Cell Transplantation for Severe Aplastic Anemia Using Matched Sibling Donors

High-dose cyclophosphamide (PTCY) after allogeneic hematopoietic cell transplantation (HSCT) has been shown to be effective in preventing graft-versus-host disease (GVHD) after HLA-matched bone marrow transplantation. We performed a phase II study of PTCY given at 50 mg/kg i.v. on days 3 and 4 as the sole GVHD prophylaxis after HSCT for severe aplastic anemia (SAA) in patients receiving granulocyte colony-stimulating factor-mobilized peripheral blood stem cell (PBSC) grafts from HLA-matched related donors after conditioning with fludarabine, CY, and single-dose total body irradiation. Thirty patients with a median age of 29 years (range, 16 to 49) were enrolled in this study. Engraftment was seen in 27 patients (90%) at a median of 16 days (range, 12 to 21) post-HSCT. None of the patients developed veno-occlusive disease of the liver or hemorrhagic cystitis. Grades II to IV acute GVHD was seen in 22% of patients with grades III to IV GVHD in 11.1%. The 2-year cumulative incidence of chronic GVHD was 22.7%. Fourteen patients (46.6%) did not require any further immunosuppression after receiving PTCY. Comparing with 2 historical cohorts of 30 patients each who received cyclosporine and methotrexate (MTX; at 15 mg/m² [MTX15] and 10 mg/m² [MTX10]), the incidence of grades II to IV acute GVHD was lower, albeit not significantly, with the use of PTCY (PTCY, 22.2%, vs MTX15, 37.1%, vs MTX10, 53.8%; P = .056), whereas rates of chronic GVHD were significantly reduced (PTCY, 22.7%, vs MTX15, 63.6%, vs MTX10, 76.2%; P = .013). Viral infections including cytomegalovirus were significantly higher with the use of PTCY (60%) compared with cyclosporine and MTX (MTX15, 23.3%, vs MTX10, 33.3%; P = .008). Overall survival was similar between the 3 groups. We conclude that PTCY as the sole GVHD prophylaxis is associated with low rates of acute and chronic GVHD in patients undergoing PBSC transplant for SAA using HLA-matched donors. This trial is registered at CTRI/2010/091/001480.

ATG vs thiotepa with busulfan and cyclophosphamide in matched-related bone marrow transplantation for thalassemia

Matched-related bone marrow transplantation (BMT) may cure >80% of low-risk children with severe thalassemia (ST). Very long-term follow-up studies have shown how the standard busulfan-cyclophosphamide (BuCy) regimen may be associated with normalization of health-related quality of life, no second malignancies in the absence of chronic graft-versus-host disease, and fertility preservation in many patients. However, because BuCy may be associated with high rejection rates, some centers incorporate thiotepa (Tt) in busulfan- or treosulfan-based regimens, a combination that may increase the risk of permanent infertility. This study retrospectively compares matched-related BMT outcomes in 2 groups of low-risk ST patients conditioned with either Tt or anti-thymocyte globulin (ATG) in addition to BuCy. A total of 81 consecutive first BMTs were performed in 5 collaborating startup BMT centers in the Indian subcontinent between January 2009 and January 2016; 30 patients were transplanted after conditioning with Tt-BuCy between January 2009 and July 2013, whereas between August 2013 and January 2016, 51 patients received ATG-BuCy. All patients were <15 years and had no hepatomegaly (liver ≤2 cm from costal margin). Actuarial overall survival in the Tt-BuCy and ATG-BuCy groups was 87% and 94% and thalassemia-free survival was 80% and 85% at a median follow-up of 37 and 17 months, respectively, with no significant differences by log-rank statistics. Substituting Tt with ATG in the standard BuCy context seems safe and effective and may decrease transplant-related mortality. Higher fertility rates are expected for patients who received ATG-BuCy.