Who is the best haploidentical donor for acquired severe aplastic anemia? Experience from a multicenter study

Recent infection with SARS-CoV-2 in donors was associated with a higher incidence of acute graft-versus-host disease in recipients undergoing allogeneic haematopoietic stem cell transplantation

The global pandemic has resulted in the common occurrence of SARS-CoV-2 infection in the population. In the post-pandemic era, it is imperative to understand the influence of donor SARS-CoV-2 infection on outcomes after allogeneic haematopoietic stem cell transplantation (allo-HSCT). We retrospectively analysed allo-HSCTs from donors with mild SARS-CoV-2 infection or early recovery stage (ERS) (group 1, n = 65) and late recovery stage (group 2, n = 120). Additionally, we included allo-HSCT from donors without prior SARS-CoV-2 infection as group 0 (n = 194). Transplants from donors with different SARS-CoV-2 infection status had comparable primary engraftment and survival rates. However, group 1 had higher incidences of acute graft-versus-host disease (aGvHD), grade II-IV (41.5% vs. 28.1% in group 0 [p = 0.014] and 30.6% in group 2 [p = 0.067]) and grade III-IV (22.2% vs. 9.6% [p = 0.004] in group 0 and 12.2% in group 2 [p = 0.049]). Conversely, the risk of aGvHD in group 2 was similar to that in group 0 (p > 0.5). Multivariable analysis identified group 1 associated with grade II-IV (hazard ratio [HR] 2.307, p = 0.010) and grade III-IV (HR 2.962, p = 0.001) aGvHD, which yielded no significant risk factors for survival. In conclusion, we preliminarily demonstrated donors in the active infection state or ERS of mild SARS-CoV-2 infection were associated with higher incidences of aGvHD in transplants from related donors.

The Role of Pre-existing Anti-HLA Antibodies in Severe Aplastic Anemia Patients Undergoing Allogenic Hematopoietic Stem Cell Transplantation

The objective is to underscore the significance of pre-existing anti-HLA Abs in the context of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for SAA. A retrospective analysis was conducted using data from 244 SAA patients who underwent allo-HSCT between January 2016 and October 2022. The patient cohort was divided into 2 groups based on the presence of pre-existing anti-HLA Abs. Out of 244 SAA patients, 82 were tested positive for anti-HLA Abs. Seventeen patients were tested with DSA in haplo-HSCT. We found that the presence of pre-existing anti-HLA Abs did not influence neutrophil engraftment (P = .600); however, it resulted in delayed platelet recovery (P = .006). Comparatively, patients with anti-HLA Abs demonstrated lower overall survival (OS) compared to their counter parts without anti-HLA Abs (P = .001), with a correspondingly elevated transplant-related mortality (TRM) in the former group (P = .002). Multivariate analysis established pre-existing anti-HLA Abs as an independent risk factor for impaired platelet recovery (HR 1.67, 95% CI 1.16 to 2.44, P = .006) and OS (HR 2.19, 95% CI 1.03 to 4.67, P = .043). However, there were no differences between DSA and non-DSA patients after desensitization in haplo-HSCT. In summary, the presence of pre-existing anti-HLA Abs in SAA patients undergoing allo-HSCT appears to detrimentally affect platelet recovery and overall prognosis.

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.

Allogeneic bone marrow transplantation for aplastic anemia

After more than 60 years of intense research in allogeneic hematopoietic cell transplantation (HCT), this therapy has progressed from one that was fraught with seemingly insurmountable complications to a standard treatment of patients with aplastic anemia. During the 1970s and 1980s, HCT donors were almost exclusively HLA-identical siblings. Subsequent advances in the understanding of the complexity of the HLA region along with the development of molecular HLA typing and the establishment of unrelated volunteer donor registries have resulted in an ever-increasing use of such donors. Most recent breakthroughs have enabled HLA-haploidentical HCT and, thereby, finding donors for nearly every patient. The outstanding outcomes reported with any of the donor options have made allogeneic HCT the preferred treatment over immunosuppressive therapy.

Repair of dysfunctional bone marrow endothelial cells alleviates aplastic anemia

Aplastic anemia (AA) is a life-threatening disease characterized by bone marrow (BM) failure and pancytopenia. As an important component of the BM microenvironment, endothelial cells (ECs) play a crucial role in supporting hematopoiesis and regulating immunity. However, whether impaired BM ECs are involved in the occurrence of AA and whether repairing BM ECs could improve hematopoiesis and immune status in AA remain unknown. In this study, a classical AA mouse model and VE-cadherin blocking antibody that could antagonize the function of ECs were used to validate the role of BM ECs in the occurrence of AA. N-acetyl-L-cysteine (NAC, a reactive oxygen species scavenger) or exogenous EC infusion was administered to AA mice. Furthermore, the frequency and functions of BM ECs from AA patients and healthy donors were evaluated. BM ECs from AA patients were treated with NAC in vitro, and then the functions of BM ECs were evaluated. We found that BM ECs were significantly decreased and damaged in AA mice. Hematopoietic failure and immune imbalance became more severe when the function of BM ECs was antagonized, whereas NAC or EC infusion improved hematopoietic and immunological status by repairing BM ECs in AA mice. Consistently, BM ECs in AA patients were decreased and dysfunctional. Furthermore, dysfunctional BM ECs in AA patients led to their impaired ability to support hematopoiesis and dysregulate T cell differentiation toward proinflammatory phenotypes, which could be repaired by NAC in vitro. The reactive oxygen species pathway was activated, and hematopoiesis- and immune-related signaling pathways were enriched in BM ECs of AA patients. In conclusion, our data indicate that dysfunctional BM ECs with impaired hematopoiesis-supporting and immunomodulatory abilities are involved in the occurrence of AA, suggesting that repairing dysfunctional BM ECs may be a potential therapeutic approach for AA patients.

Time-dependent analysis of the impact on early cytomegalovirus reactivation of HLA mismatch and acute graft-versus-host disease after allogeneic hematopoietic cell transplantation from related donors in acquired aplastic anemia

Cytomegalovirus (CMV) reactivation is an important issue in allogeneic hematopoietic cell transplantation (HCT). The incidence of early CMV reactivation is notably high in HLA-mismatched HCT. However, the interactions between HLA mismatch and acute graft-versus-host disease (aGvHD), a time-dependent event, make it methodologically challenging to evaluate the independent impact on CMV reactivation of the two variables. We retrospectively analyzed 355 patients with acquired aplastic anemia who received related donor transplants using a unified antithymocyte globulin-based platform. Patients were divided into group 1 (6/6 HLA match), group 2 (1-2/6 HLA allelic mismatch), and group 3 (3/6 HLA allelic mismatch). The impact of covariates was analyzed through two models: (1) time-dependent Cox and (2) dynamic landmarking analysis. The time-dependent Cox model showed that the HLA mismatch of 3/6 alleles (hazard ratio (HR) =1.852, P = .004) and aGvHD (HR = 1.009, P = .019) were independent risk factors for CMV reactivation. With the dynamic landmarking analysis, a higher HLA disparity correlated to increased early CMV reactivation (HR = 1.606, P = .001) at all time points. Developing aGvHD following HCT was generally associated with a higher incidence of CMV reactivation (HR = 1.623, P = .013), though its impact decreased with successive later landmark time points. In conclusion, our data suggest that the higher HLA disparity and aGvHD increases susceptibility to early CMV reactivation. In particular, the dynamic landmarking analysis demonstrated the time-varying effect of aGvHD on CMV reactivation, and HLA mismatch showed a profound impact over time following HCT.

Busulfan for Allogeneic Hematopoietic Stem Cell Transplantation in Children with Severe Aplastic Anemia: A Retrospective Study

INTRODUCTION

This retrospective study aimed to compare a range of conditioning regimens in children with severe aplastic anemia (SAA) undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) at the Seventh Medical Center of PLA General Hospital between January 2008 and June 2017.

METHODS

Patients were categorized into the Bu (Bu + Flu + Cy + ATG-F regimen) and control (Flu + Cy + ATG-F) groups, with a median follow-up time after HSCT of 3.5 (range, 3.1-6.2) and 3.7 (3.2-5.9) years in the Bu and control groups, respectively.

RESULTS

No differences were observed between the two groups regarding the median time of peripheral blood neutrophil and platelet engraftment (p = 0.538 and p = 0.491); the 28-day engraftment rates of neutrophils were similar (p = 0.199), although higher for platelets with Bu (p = 0.044). Additionally, graft failure was 0% and 20.0% in the Bu and control groups, respectively (p = 0.004). In both groups, the incidence of grades III-IV (or grades II-IV) acute graft-versus-host disease (GVHD) and chronic GVHD was not significantly different (p > 0.05). Moreover, the 3-year overall survival and failure-free survival did not show significant differences (p = 0.670 and p = 0.908).

DISCUSSION

In children with SAA undergoing allo-HSCT, conditioning regimen with Bu + Flu + Cy + ATG-F is capable of enhancing the myeloablation effect, promoting donor hematopoietic stem cell engraftment, and reducing the graft failure rate. Furthermore, it does not increase the incidence of complications, including GVHD.

Comparison of haploidentical-allogeneic hematopoietic stem cell transplantation and intensive immunosuppressive therapy for patients with severe aplastic anemia with an absolute neutrophil count of zero: a retrospective study

A retrospective analysis was conducted based on the clinical data from 60 patients older than 16 years from January 2016 to January 2021. All the patients were newly diagnosed with severe aplastic anemia (SAA) with an absolute neutrophil count (ANC) of zero. We compared the hematological response and survival of haploidentical-allogeneic hematopoietic stem cell transplantation (HID-HSCT) (n = 25) and intensive immunosuppressive therapy (IST) (n = 35) treatments. At six months, the overall response rate and complete response were significantly higher in the HID-HSCT group than those in the IST group (84.0% vs. 40.0%, P = 0.001; 80.0% vs. 17.1%, P = 0.001). With a median follow-up of 18.5 months (4.3~30.8 months), patients in the HID-HSCT group had longer overall survival and event-free survival (80.0% vs. 47.9%, P = 0.0419; 79.2% vs. 33.5%, P = 0.0048). These data suggested that HID-HSCT might be an effective alternative treatment option for adult patients with SAA with an ANC of zero, which requires further validation in an additional prospective study.

Low-dose post-transplant cyclophosphamide with G-CSF/ATG based haploidentical protocol provides favorable outcomes for SAA patients

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT), as one of the life-saving treatments for severe aplastic anemia (SAA), is widely used because of its great donor availability. Over decades, granulocyte colony-stimulating factor (G-CSF)/antithymocyte globulin (ATG)-based protocol (the so-called Beijing Protocol) has achieved favorable engraftment and survival outcomes. In this study, we modified the conventional Beijing Protocol: the full-dose Cyclophosphamide (Cy) (200 mg/kg in total) was divided into 42.75 mg/kg Cy on day -5 to day -2 and Low dose post-transplant Cy (PTCy) (14.5 mg/kg on days +3 and +4), hoping to reduce the incidence of severe acute graft-versus-host disease (aGVHD) and to guarantee successful and stable engraftment. Here we retrospectively reported and analyzed the data of first 17 patients with SAA who had received haplo-HSCT using this novel regimen between August 2020 and August 2022. The median follow-up was 522 days (range, 138-859 days). No patient developed primary graft failure. Four (23.5%) patients developed grade II bladder toxicity, two (11.8%) patients developed grade II cardiotoxicity. All patients achieved neutrophil and platelet engraftment at median times of 12 days (range, 11-20 days) and14 days (range, 8-36 days). During our follow-up, no patients developed grade III-IV aGVHD. The cumulative incidence of grade II and grade I aGVHD at 100 days was 23.5% (95% CI, 6.8%-49.9%) and 47.1% (95% CI, 23.0%-72.2%). Three patients (17.6%) developed chronic GVHD of skin, mouth, and eyes and all of which were mild. All patients are alive by the end of the follow-up, with a failure-free survival of 100%, which was defined as survival without treatment failures, such as death, graft failure, or relapse rate. The rate of cytomegalovirus (CMV) reactivation was 82.4% (95% CI, 64.3%-100%). The rate of Epstein-Barr virus (EBV) reactivation was 17.6% (95% CI, 3.8%-43.4%). No CMV disease and post-transplantation lymphoproliferative disorder (PTLD) occurred among these patients. In conclusion, the encouraging results of prolonged survival outcomes and reduced incidence of GVHD suggest promising effect of this novel regimen in haplo-HSCT for patients with SAA. Larger-sample prospective clinical trials are needed to confirm the effectiveness of this regimen.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

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.

Low-Dose Anti-Thymocyte Globulin Plus Low-Dose Posttransplant Cyclophosphamide as an Effective Regimen for Prophylaxis of Graft Versus Host Disease After Haploidentical Peripheral Blood Stem Cell Transplantation With Maternal/Collateral Related Donors

Maternal and collateral donors were associated with a higher incidence of graft-versus-host disease (GvHD) after haploidentical hematopoietic stem cell transplantation (haplo-HSCT). A more effective regimen for GvHD prophylaxis after haplo-HSCT with maternal/collateral donors needed to be explored. A retrospective study was performed on 62 patients after haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) with maternal/collateral donors, which included 35 patients with low-dose antithymocyte globulin (ATG) plus low-dose posttransplant cyclophosphamide-based (low-dose ATG/PTCy-based) and 27 with ATG-based regimens for GvHD prophylaxis. The 180-day cumulative incidences (CIs) of grades II-IV and III-IV acute GvHD (aGvHD) were 17.7% and 6.8% in low-dose ATG/PTCy-based group, which were significantly lower than that in ATG-based group (55.4% and 31.9%) (P = 0.003 for grade II-IV and P = 0.007 for III-IV aGvHD). In low-dose ATG/PTCy-based group, the 1-year overall survival (OS) and relapse-free survival (RFS) were 80.0%and 80.4%, which were higher than that in ATG-based group with OS of 59.4% and RFS of 62.0%. In multivariate analysis, the low-dose ATG/PTCy-based regimen significantly reduced the risk of grade II-IV (HR = 0.357; P = 0.049) and grade III-IV aGvHD (HR = 0.190; P = 0.046) as an independent risk factor. The results suggested that the low-dose ATG/PTCy-based regimen could effectively prevent the occurrence of aGvHD after haplo-PBSCT with maternal/collateral donors compared with the ATG-based regimen.

The impact of pretransplant serum ferritin on haploidentical hematopoietic stem cell transplant for acquired severe aplastic anemia in children and adolescents

Haploidentical hematopoietic stem cell transplant (haplo-HSCT) provides an important alternative for children and adolescents with acquired severe aplastic anemia (SAA) lacking matched donors. To test whether pretransplant serum ferritin (SF) represents a candidate predictor for survival and a potential biomarker for graft-versus-host disease (GvHD) in pediatric haplo-HSCT, we retrospectively evaluated 147 eligible patients with SAA who underwent haplo-HSCT. The patients were divided into the low-SF group (< 1000 ng/mL) and the high-SF group (≥ 1000 ng/mL). We found that SF ≥1000 ng/mL independently increased the risk of grade II-IV aGvHD (HR = 2.596; 95% CI, 1.304-5.167, P = 0.007) and grade III-IV aGvHD (HR = 3.350; 95% CI, 1.162-9.658, P = 0.025). Similar probabilities of transplant-related mortality at 100 days were observed in the two groups (6.19 ± 2.45% vs 8.00 ± 3.84%, P = 0.168). The two-year overall survival (85.29 ± 3.89% vs 92.00% ± 3.84%, P = 0.746) and failure-free survival (83.23% ± 4.08% vs 83.37% ± 6.27%, P = 0.915) were comparable. GvHD-/failure-free survival were 60.06 ± 5.10% and 75.56 ± 6.87%, respectively (P = 0.056). In conclusion, elevated pretransplant SF level is associated with higher incidences of grade II-IV aGvHD and grade III-IV aGvHD. However, it is not associated with worse survival after haplo-HSCT for children and adolescent patients with SAA.

Unmanipulated haploidentical haematopoietic cell transplantation with radiation-free conditioning in Fanconi anaemia: A retrospective analysis from the Chinese Blood and Marrow Transplantation Registry Group

Haematopoietic cell transplantation (HCT) is the only curative treatment for haematological complications in patients with Fanconi anaemia (FA). Haploidentical (haplo-) HCT is a promising alternative for FA. We aimed to analyse the outcomes of unmanipulated haplo-HCT in patients with FA with radiation-free conditioning. A total of 56 patients from 11 centres between 2013 and 2021 in China were retrospectively analysed. The mean (SD) cumulative incidence was 96.4% (0.08%) for 30-day neutrophil engraftment and 85.5% (0.24%) for 100-day platelet engraftment. With a median (range) follow-up of 2.4 (0.2-5.8) years, favourable mean (SD) overall survival of 80.9% (5.5%) and event-free survival of 79.3% (5.6%) were achieved. The mean (SD) incidences of acute graft-versus-host disease (aGvHD) Grade II-IV and Grade III-IV were 55.4% (0.45%) and 42.9 (0.45%) respectively. The mean (SD) cumulative incidence of 3-year chronic graft-versus-host disease (cGvHD) was 34.7% (0.86%) and that of moderate-to-severe cGvHD was 9.0% (0.19%). Our data demonstrate that in unmanipulated haplo-HCT for patients with FA, radiation-free regimens based on fludarabine and low-dose cyclophosphamide ± busulfan achieved favourable engraftment and survival with relatively high incidences of aGvHD and cGvHD. These results prompt the use of low-intensity conditioning without radiation and intensive GvHD prophylaxis when considering unmanipulated haplo-HCT in patients with FA.

Comparisons Between modified PTCY and G-CSF/ATG Regimens for Haploidentical Transplantation in Patients with Aplastic Anemia

BACKGROUND

Haploidentical transplantation has become an alternative treatment option for aplastic anemia patients without matched sibling donors or matched unrelated donors. Recently, the post-transplantation cyclophosphamide (PTCY) regimen and granulocyte colony-stimulating factor (G-CSF)/antithymocyte globulin (ATG) regimen have become the most common protocols used worldwide.

OBJECTIVE

We designed this retrospective study to compare the outcomes of patients receiving a modified post-transplantation cyclophosphamide (mPTCY) regimen versus the G-CSF/ATG regimen.

STUDY DESIGN

We retrospectively reviewed and analyzed the clinical data of 130 aplastic anemia patients who underwent haplo-HSCT and received the mPTCY regimen (n=55) or G-CSF/ATG regimen (n=75) between Jan 2013 and Jun 2021 across seven transplant centers.

RESULTS

Neutrophil engraftment was successful in all patients within 30 days in the G-CSF/ATG group. The cumulative neutrophil engraftment rate in the mPTCY group was 96.36% (95% CI, 94.57-97.57, P=0.010). The median time of neutrophil engraftment in the G-CSF/ATG group was 10 (7-28) days, which was more rapid than that observed in the mPTCY group (P <0.001). There were no significant differences in the incidence of graft versus host disease (GVHD) between the two groups. The cumulative incidence of II-IV acute GVHD was 18.40% (95% CI, 4.27-40.31) in the mPTCY group and 19.32% (95% CI, 5.86-38.58) in the G-CSF/ATG group, while the cumulative incidence of III-IV acute GVHD was 7.31% (95% CI, 0.09-37.48) in the mPTCY group and 7.57% (95% CI, 0.20-34.19) in the G-CSF/ATG group. Similarly, no significant difference was observed between the two groups in terms of overall survival (OS), failure-free survival (FFS), and GVHD relapse-free survival (GRFS). The 2-year OS, FFS and GRFS rates were 95.91% (95% CI, 84.59-98.96), 92.25% (95% CI, 80.59-97.03) and 86.68% (95% CI, 73.98-93.44), respectively, in the mPTCY group and 86.67% (95% CI, 76.64-92.59), 81.28% (95% CI, 70.45-88.46) and 77.20% (95% CI, 65.89-85.16), respectively, in the G-CSF/ATG group. The transplantation-related mortality (TRM) rate was significantly higher in the G-CSG/ATG group than in the mPTCY group (13.33% in the G-CSG/ATG group versus 1.96% in the mPTCY group, P=0.022). In multivariate analysis, female donors, a higher hematopoietic cell transplantation comorbidity index (HCT-CI) and III-IV aGVHD were associated with worse survival outcomes.

CONCLUSIONS

In conclusion, the mPTCY and G-CSF/ATG regimens led to similar outcomes in AA patients, but quicker engraftment was observed with the ATG/G-CSF regimen, and a lower incidence of TRM was observed with the mPTCY regimen.

Development and validation of a mortality predicting scoring system for severe aplastic anaemia patients receiving haploidentical allogeneic transplantation

Haploidentical allogeneic haematopoietic stem cell transplantation (haplo-HSCT) is a significant alternative treatment for severe aplastic anaemia (SAA). To improve this process by modifying the risk stratification system, we conducted a retrospective study using our database. 432 SAA patients who received haplo-HSCT between 2006 and 2020 were enrolled. These patients were divided into a training (n = 288) and a validation (n = 144) subset randomly. In the training cohort, longer time from diagnosis to transplantation, poorer Eastern Cooperative Oncology Group (ECOG) status and higher haematopoietic cell transplantation-specific comorbidity index (HCT-CI) score were independent risk factors for worse treatment-related mortality (TRM) in the final multivariable model. The haplo-HSCT scoring system was developed by these three parameters. Three-year TRM after haplo-HSCT were 6% [95% confidence interval (CI), 1-21%], 21% (95% CI, 7-40%), and 47% (95% CI, 20-70%) for the low-, intermediate-, and high-risk group, respectively (P < 0·0001). In the validation cohort, the haplo-HSCT scoring system also separated patients into three risk groups with increasing risk of TRM: intermediate-risk [hazard ratio (HR) 2·45, 95% CI, 0·92-6·53] and high-risk (HR 11·74, 95% CI, 3·07-44·89) compared with the low-risk group (P = 0·001). In conclusion, the haplo-HSCT scoring system could effectively predict TRM after transplantation.

The consensus from The Chinese Society of Hematology on indications, conditioning regimens and donor selection for allogeneic hematopoietic stem cell transplantation: 2021 update

The consensus recommendations in 2018 from The Chinese Society of Hematology (CSH) on indications, conditioning regimens and donor selection for allogeneic hematopoietic stem cell transplantation (allo-HSCT) facilitated the standardization of clinical practices of allo-HSCT in China and progressive integration with the world. There have been new developments since the initial publication. To integrate recent developments and further improve the consensus, a panel of experts from the CSH recently updated the consensus recommendations, which are summarized as follows: (1) there is a new algorithm for selecting appropriate donors for allo-HSCT candidates. Haploidentical donors (HIDs) are the preferred donor choice over matched sibling donors (MSDs) for patients with high-risk leukemia or elderly patients with young offspring donors in experienced centers. This replaces the previous algorithm for donor selection, which favored MSDs over HIDs. (2) Patients with refractory/relapsed lymphoblastic malignancies are now encouraged to undergo salvage treatment with novel immunotherapies prior to HSCT. (3) The consensus has been updated to reflect additional evidence for the application of allo-HSCT in specific groups of patients with hematological malignancies (intermediate-risk acute myeloid leukemia (AML), favorable-risk AML with positive minimal residual disease, and standard-risk acute lymphoblastic leukemia). (4) The consensus has been updated to reflect additional evidence for the application of HSCT in patients with nonmalignant diseases, such as severe aplastic anemia and inherited diseases. (5) The consensus has been updated to reflect additional evidence for the administration of anti-thymocyte globulin, granulocyte colony-stimulating factors and post-transplantation cyclophosphamide in HID-HSCT.

Research advances on haploidentical hematopoietic stem cell transplantation in the treatment of severe aplastic anemia in children

Haploidentical hematopoietic stem cell transplantation is a recommended alternative therapy for children with severe aplastic anemia who lack a human leukocyte antigen (HLA)-identical sibling donor and do not respond well to immunosuppressive therapy; however, due to non-identical HLA, the patients may have donor-specific anti-HLA antibody, which may lead to a relatively high incidence rate of poor graft function. Compared with HLA-identical transplantation, conditioning regimen for haploidentical transplantation still needs to be explored. This article reviews the detection and treatment of donor-specific anti-HLA antibody, the selection of conditioning regimen, and the mechanism and treatment of poor graft function in haploidentical hematopoietic stem cell transplantation.

Optimizing outcomes for haploidentical hematopoietic stem cell transplantation in severe aplastic anemia with intensive GVHD prophylaxis: a review of current findings

Introduction: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has resulted in increased levels of disease-free survival in severe aplastic anemia (SAA). Haploidentical transplantation (haplo-SCT) was previously not recommended due to unacceptable incidences of graft-versus-host disease (GvHD) and graft failures. With the advent of intensive GvHD prophylaxis strategies, the outcomes obtained with haplo-SCT for SAA have gradually improved.Areas covered: A comprehensive search considered PubMed reported articles before 1 February 2021, presented abstracts, and clinical trials pertaining to haplo-HSCT for SAA. This manuscript covers modern approaches with intensive GvHD prophylaxis in haplo-SCT for SAA. The representative methods consist of granulocyte colony stimulating factor (G-CSF) plus ATG-based and posttransplantation cyclophosphamide (PT-Cy)-based protocols.Expert opinion: Currently, haplo-SCT has become a feasible option for treating SAA. The G-CSF/ATG-based protocol included the largest sample size and reported comparable survival rates with identical siblings. The PT-Cy protocol resulted in a relatively lower incidence of GvHD and seemingly poorer but continuously improved engraftment with augmented conditioning. The optimized outcomes are constantly updated with the modification of the conditioning regimen, donor selection, graft source and GvHD prophylaxis. In the future, we should pay more attention to quality of life in addition to survival, and personalized haplo-SCT may improve outcomes.

Mesenchymal stromal cells as prophylaxis for graft-versus-host disease in haplo-identical hematopoietic stem cell transplantation recipients with severe aplastic anemia?-a systematic review and meta-analysis

BACKGROUND

Mesenchymal stromal cells (MSCs) are an emerging prophylaxis option for graft-versus-host disease (GVHD) in haplo-identical hematopoietic stem cell transplantation (haplo-HSCT) recipients with severe aplastic anemia (SAA), but studies have reported inconsistent results. This systematic review and meta-analysis evaluates the efficacy of MSCs as prophylaxis for GVHD in SAA patients with haplo-HSCT.

METHODS

Studies were retrieved from PubMed, EMBASE, Cochrane, Web of Science, and http://clinicaltrials.gov from establishment to February 2020. Twenty-nine single-arm studies (n = 1456) were included, in which eight (n = 241) studies combined with MSCs and eleven (n = 1215) reports without MSCs in haplo-HSCT for SAA patients. The primary outcomes were the incidences of GVHD. Other outcomes included 2-year overall survival (OS) and the incidence of cytomegalovirus (CMV) infection. Odds ratios (ORs) were calculated to compare the results pooled through random or fixed effects models.

RESULTS

Between MSCs and no MSCs groups, no significant differences were found in the pooled incidences of acute GVHD (56.0%, 95% CI 48.6-63.5% vs. 47.2%, 95% CI 29.0-65.4%; OR 1.43, 95% CI 0.91-2.25; p = 0.123), grade II-IV acute GVHD (29.8%, 95% CI 24.1-35.5% vs. 30.6%, 95% CI 26.6-34.6%; OR 0.97, 95% CI 0.70-1.32; p = 0.889), and chronic GVHD (25.4%, 95% CI 19.8-31.0% vs. 30.0%, 95% CI 23.3-36.6%; OR 0.79, 95% CI 0.56-1.11; p = 0.187). Furtherly, there was no obvious difference in 2-year OS (OR 0.98, 95% CI 0.60-1.61; p = 1.000) and incidence of CMV infection (OR 0.61, 95% CI 0.40-1.92; p = 0.018).

CONCLUSIONS

Our meta-analysis indicates that the prophylactic use of MSC co-transplantation is not an effective option for SAA patients undergoing haplo-HSCT. Hence, the general co-transplantation of MSCs for SAA haplo-HSCT recipients may lack evidence-based practice.

Haploidentical stem cell transplantation for aplastic anemia: the current advances and future challenges

Haematopoietic stem cell transplantation (HSCT) is a curative option for severe aplastic anemia (SAA). Finding a suitable matched donor in a timely manner is a challenge. The availability of haploidentical donors and their successful use in transplantation have expanded valid choices for SAA. In recent decades, haploidentical HSCT (haplo-HSCT) for the treatment of SAA has been continuously attempted, and great strides have been made. Nowadays, haplo-HSCT using different regimens has overcome the difficulty of graft failure and severe graft-versus-host disease (GvHD), and achieved inspiring survival outcomes in SAA. The regimens consist mainly of granulocyte colony-stimulating factor (G-CSF) plus antithymocyte globulin (ATG), posttransplantation cyclophosphamide (PT-Cy), and ex vivo graft T-cell depletion (TCD). In particular, the G-CSF and ATG-based regimen includes the largest sample size and the successful wide use of the G-CSF and ATG-based regimen has promoted haplo-HSCT a higher priority in SAA patients without matched related or unrelated donors in China. Recent studies have also indicated that haplo-HSCT using PT-Cy or TCD regimen is a practicable alternative, but the sample size is relatively small. Here, we offer an overview of clinical results obtained through the use of haploidentical transplantation in SAA, mainly focusing on current advances and future challenges.

History of hematopoietic cell transplantation: challenges and progress

After more than 60 years of research in allogeneic hematopoietic cell transplantation (HCT), this therapy has advanced from one that was declared dead in the 1960s to a standard treatment of otherwise fatal malignant and non-malignant blood diseases. To date, close to 1.5 million hematopoietic cell transplants have been performed in more than 1,500 transplantation centers worldwide. This review will highlight the enormous efforts by numerous investigators throughout the world who have brought the experimental field of HCT to clinical reality, examine ongoing challenges, and provide insights for the future.

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.

Mechanisms and rejuvenation strategies for aged hematopoietic stem cells

Hematopoietic stem cell (HSC) aging, which is accompanied by reduced self-renewal ability, impaired homing, myeloid-biased differentiation, and other defects in hematopoietic reconstitution function, is a hot topic in stem cell research. Although the number of HSCs increases with age in both mice and humans, the increase cannot compensate for the defects of aged HSCs. Many studies have been performed from various perspectives to illustrate the potential mechanisms of HSC aging; however, the detailed molecular mechanisms remain unclear, blocking further exploration of aged HSC rejuvenation. To determine how aged HSC defects occur, we provide an overview of differences in the hallmarks, signaling pathways, and epigenetics of young and aged HSCs as well as of the bone marrow niche wherein HSCs reside. Notably, we summarize the very recent studies which dissect HSC aging at the single-cell level. Furthermore, we review the promising strategies for rejuvenating aged HSC functions. Considering that the incidence of many hematological malignancies is strongly associated with age, our HSC aging review delineates the association between functional changes and molecular mechanisms and may have significant clinical relevance.