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

Acquired severe aplastic anaemia: how medical therapy evolved in the 20th and 21st centuries

The progress in aplastic anaemia (AA) management is one of success. Once an obscure entity resulting in death in most affected can now be successfully treated with either haematopoietic stem cell transplantation (HSCT) or immunosuppressive therapy (IST). The mechanisms that underly the diminution of haematopoietic stem cells (HSCs) are now better elucidated, and include genetics and immunological alterations. Advances in supportive care with better antimicrobials, safer blood products and iron chelation have greatly impacted AA outcomes. Working somewhat 'mysteriously', anti-thymocyte globulin (ATG) forms the base for both HSCT and IST protocols. Efforts to augment immunosuppression potency have not, unfortunately, led to better outcomes. Stimulating HSCs, an often-sought approach, has not been effective historically. The thrombopoietin receptor agonists (Tpo-RA) have been effective in stimulating early HSCs in AA despite the high endogenous Tpo levels. Dosing, timing and best combinations with Tpo-RAs are being defined to improve HSCs expansion in AA with minimal added toxicity. The more comprehensive access and advances in HSCT and IST protocols are likely to benefit AA patients worldwide. The focus of this review will be on the medical treatment advances in AA.

The impact of donor total estimated blood volume on nucleated cell yield in bone marrow harvests for hematopoietic stem cell transplantation

BACKGROUND

Nucleated cell yields of marrow harvests depend on factors related to donors, the procedure itself, and the volume of marrow harvested. Few attempts have been made to relate donor characteristics to harvest volume. We hypothesize that the percentage of total donor blood volume accessed for harvesting impacts the nucleated cell yield per ml of marrow collected.

METHODS AND MATERIALS

We investigated 481 consecutive unrelated marrow harvests from a single center. Donor characteristics including weight, body mass index (BMI), white blood cells (WBCs), hemoglobin (Hgb), and platelet counts, as well as estimated total blood volume, were recorded and compared with nucleated cell yields and harvest volumes.

RESULTS

The percentage of donor blood volume accessed for marrow harvesting was inversely related to nucleated cell yields (r = -0.57). The donor-recipient weight differential impacted cell yields as well (r = 0.35), with heavier recipients requiring increased marrow volumes from smaller donors to satisfy their nucleated cell needs. 3.73 × 10⁸ /kg of recipient weight could be collected with 95% certainty when harvest volumes did not exceed 16.1% of donor total blood volume. In a stepwise multiple regression analysis, 45.4% of cell yield variance was explained by blood volume percentage accessed for harvesting, donor weight, and WBC. Donor sex, BMI, and platelet counts did not contribute further to cell yield variance. Smokers had higher cell yields than nonsmokers (20.4 vs. 18.3 × 10⁶ /ml; 95% confidence interval 0.62, 3.47) independent of other parameters.

CONCLUSION

Establishing the relationship between percentage of estimated donor total blood volume and recipient cell needs can facilitate donor selection for successful hematopoietic cell (HPC) transplants.

Natural Antioxidants in Anemia Treatment

Anemia, characterized by a decrease of the hemoglobin level in the blood and a reduction in carrying capacity of oxygen, is a major public health problem which affects people of all ages. The methods used to treat anemia are blood transfusion and oral administration of iron-based supplements, but these treatments are associated with a number of side effects, such as nausea, vomiting, constipation, and stomach pain, which limit its long-term use. In addition, oral iron supplements are poorly absorbed in the intestinal tract, due to overexpression of hepcidin, a peptide hormone that plays a central role in iron homeostasis. In this review, we conducted an analysis of the literature on biologically active compounds and plant extracts used in the treatment of various types of anemia. The purpose of this review is to provide up-to-date information on the use of these compounds and plant extracts, in order to explore their therapeutic potential. The advantage of using them is that they are available from natural resources and can be used as main, alternative, or adjuvant therapies in many diseases, such as various types of anemia.

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.

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.

Feasibility of reduced-dose posttransplant cyclophosphamide and cotransplantation of peripheral blood stem cells and umbilical cord-derived mesenchymal stem cells for SAA

Posttransplant cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis is an effective strategie for patients receiving matched sibling donor hematopoietic stem cell transplantation (MSD-HSCT) and haploidentical HSCT (haplo-HSCT). We evaluated the effectiveness and safety of reduced-dose cyclophosphamide, 20 mg/kg for 13 patients in MSD-HSCT cohort and 25 mg/kg for 22 patients in haplo-HSCT cohort, on days + 3, + 4 combined with cotransplantation of peripheral blood stem cells (PBSCs) and human umbilical cord-derived mesenchymal stem cells (UC-MSCs) for severe aplastic anemia (SAA). In MSD-PTCy cohort, the times to neutrophil and platelet engraftment were significantly shorter than those in the MSD-control cohort (P < 0.05). The cumulative incidence of acute GVHD (aGVHD) at day + 100 (15.4%) was lower than that in the MSD-control cohort (P = 0.050). No patient developed chronic GVHD (cGVHD). The 1-year overall survival (OS) and event-free survival (EFS) rates were 100% and 92.3%. In haplo-PTCy cohort, the times to neutrophil and platelet engraftment were significantly shorter than those in the haplo-control cohort (P < 0.05). The cumulative incidences of aGVHD at day + 100 and 1-year cGVHD were 31.8% and 18.2%, and the 1-year OS and EFS rates were 81.8% and 66.9%. Reduced-dose PTCy and cotransplantation of PBSCs and UC-MSCs is an acceptable alternative to patients with SAA.

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.

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.

Cyclosporine/methotrexate versus tacrolimus/methotrexate with or without anti-thymocyte globulin as GVHD prophylaxis in adult patients with aplastic anemia

The impact of calcineurin inhibitor types and anti-thymocyte globulin (ATG) in conditioning on overall survival (OS) and GVHD-free, relapse-free survival (GRFS) has not yet been analyzed in detail for aplastic anemia. We herein examined 517 adult patients with aplastic anemia who underwent BMT from HLA-matched sibling donors (MSD, n = 255) and unrelated donors (UD, n = 262) and were treated with cyclosporine A (CSA) + methotrexate (MTX) (n = 258) and tacrolimus (TAC) + MTX (n = 259). In total, 330 patients received ATG in conditioning. CSA + MTX versus TAC + MTX did not have a significant impact on acute and chronic GVHD, OS, or GRFS in each donor type. The use of ATG in conditioning reduced the risk of grade II-IV acute GVHD in the MSD and UD cohorts (HR 0.42, P = 0.014, and HR 0.3, P < 0.001, respectively); however, a differential impact on GRFS was identified, namely, better GRFS in MSD recipients (HR 0.56, P = 0.016), but not in UD recipients (HR 1.1, P = 0.657). In conclusion, CSA + MTX and TAC + MTX were similar as GVHD prophylaxis regardless of the donor type, and ATG in conditioning increased GRFS in MSD transplants, but not in UD transplants.

A study of human leukocyte antigen-haploidentical hematopoietic stem cells transplantation combined with allogenic mesenchymal stem cell infusion for treatment of severe aplastic anemia in pediatric and adolescent patients

The clinical applications of human leukocyte antigen (HLA) haploidentical hematopoietic stem cells transplantation (haplo‐HSCT) have offered most of the young severe aplastic anemia (SAA) patients an opportunity to accept curative therapy at the early stage of bone marrow lesions. However, the outcome of juvenile SAA patients received haplo‐HSCT remain to be improved due to high incidence of graft failure and graft vs host disease (GVHD). Mesenchymal stem cells (MSCs) have been characterized by their hematopoiesis‐supporting and immunomodulatory properties. In the current study, we designed a combination of haplo‐HSCT with allogenic MSC for treatment of SAA in pediatric and adolescent patients and evaluated its effects. Juvenile patients (<18 years) with SAA (n = 103) were given HLA‐haploidentical HSC combined with allogenic MSC after a conditioning regimen consisting of busulfan, cyclophosphamide, fludarabine, and antithymocyte globulin and an intensive GVHD prophylaxis, including cyclosporine, short‐term methotrexate, mycophenolate mofetil, and basiliximab. Neutrophil engraftment was achieved in 102 of 103 patients in a median time of 14.3 days (range 9‐25 days). The median time of platelet engraftment was 25.42 days (range 8‐93 days). The cumulative incidence of II‐IV acute GVHD at day +100 was 26.32% ± 0.19% and III‐IV acute GVHD was 6.79% ± 0.06% at day +100, respectively. The cumulative incidence of chronic GVHD was 25.56% ± 0.26%. The overall survival was 87.15% ± 3.3% at a median follow‐up of 40 (1.3‐98) months. Our data suggest that cotransplantation of HLA‐haploidentical HSC and allogenic mesenchymal stem cell may provide an effective and safe treatment for children and adolescents with SAA who lack matched donors.

Very long-term follow-up of aplastic anemia treated with immunosuppressive therapy or allogeneic hematopoietic cell transplantation

Introduction

Since the 1970s outcome of aplastic anemia (AA) patients has improved significantly due to the introduction of immunosuppressive therapy (IST) and allogeneic hematopoietic transplantation (HCT). However, patients may suffer from persistent disease, relapse, clonal evolution, graft-versus-host disease and other late effects. Here, we analyse very long-term outcome of all AA patients at our institution comparing not only survival, but also response status and complications.

Methods

Patient charts of all 302 AA patients treated between 1973 and 2017 at the University Hospital Basel, Switzerland, were retrospectively analysed.

Results

First line treatment was IST in 226 (75%) and HCT in 76 (25%) patients. Overall survival at 30 years was similar in patients treated initially by HCT and IST (44% (±14%), and 40% (± 9%) respectively, with better results in more recent years. Partial and no response occurred more frequently after IST, relapse incidence after IST was 24 %, whereas non-engraftment and graft failure was documented in 15 patients (19 %) after HCT. Clonal evolution to myelodysplastic syndrome / acute myeloid leukemia was 16 % at 25 years in IST patients, 1.3 % in HCT patients, iron overload (18 versus 4 %, p = 0.002) and cardiovascular events (11 versus 1 %, p=0.011) occured significantly more often in IST than HCT treated patients. The majority of long-term survivors, 96% of those alive at 25 years, were in complete remission at last follow up, irrespective of the initial treatment modality.

Conclusion

Very long term survivors after AA are those with stable hematopoietic recovery.

Impact of CD34 Cell Dose and Conditioning Regimen on Outcomes after Haploidentical Donor Hematopoietic Stem Cell Transplantation with Post-Transplantation Cyclophosphamide for Relapsed/Refractory Severe Aplastic Anemia

Severe aplastic anemia (SAA) is a life-threatening disease that can be cured with allogeneic cell transplantation (HCT). Haploidentical donor transplantation with post-transplantation cyclophosphamide (haplo-PTCy) is an option for patients lacking an HLA-matched donor. We analyzed 87 patients who underwent haplo-PTCy between 2010 and 2019. The median patient age was 14 years (range, 1 to 69 years), most were heavily transfused, and all received previous immunosuppression (25% without antithymocyte globulin). Almost two-thirds (63%) received standard fludarabine (Flu)/cyclophosphamide (Cy) 29/total body irradiation (TBI) 200 cGy conditioning, and the remaining patients received an augmented conditioning: Flu/Cy29/TBI 300-400 (16%), Flu/Cy50/TBI 200 (10%), or Flu/Cy50/TBI 400 (10%). All patients received PTCy-based graft-versus-host disease (GVHD) prophylaxis. Most grafts (93%) were bone marrow (BM). The median duration of follow-up was 2 years and 2 months. The median time to neutrophil recovery was 17 days. Primary graft failure occurred in 15% of the patients, and secondary or poor graft function occurred in 5%. The incidences of grade II-IV acute GVHD was 14%, and that of chronic GVHD was 9%. Two-year overall survival and event-free survival (EFS) were 79% and 70%, respectively. EFS was higher for patients who received augmented Flu/Cy/TBI (hazard ratio [HR], .28; P = .02), and those who received higher BM CD34 cell doses (>3.2 × 10E6/kg) (HR, .29; P = .004). The presence of donor-specific antibodies before HSCT was associated with lower EFS (HR, 3.92; P = .01). Graft failure (HR, 7.20; P < .0001) was associated with an elevated risk of death. Cytomegalovirus reactivation was frequent (62%). Haploidentical HCT for SAA is a feasible procedure; outcomes are improved with augmented conditioning regimens and BM grafts with higher CD34 cell doses.

Similar outcomes of alemtuzumab-based hematopoietic cell transplantation for SAA patients older or younger than 50 years

Survival after allogeneic hematopoietic cell transplantation (HSCT) for severe aplastic anemia (SAA) among older patients remains poor and associated with increased risk for graft-versus-host disease (GVHD). In this retrospective study of 65 consecutive patients with acquired SAA who were transplanted using fludarabine, low-dose cyclophosphamide, and alemtuzumab (FCC), outcomes of 27 patients aged at least 50 years were compared with those of 38 patients younger than 50 years. The median age of the older cohort was 61 years (range, 51-71 years); 21 (78%) patients were transplanted from unrelated donors (3 of 21 from HLA 9/10 mismatch donors) and 6 from matched sibling donors. One-year GVHD-free, relapse-free survival (GRFS) was comparable to that of patients younger than 50 years (84% vs 94%, respectively; P = .23). Both groups showed low rates of acute (5% vs 4%) and chronic (18% vs 14%) GVHD, with no cases of severe GVHD among matched donor transplants, and similar 1-year transplant-related mortality (14% vs 5.4%, older vs younger; P = .23). HSCT comorbidity index (HTC-CI) scores were similar between the groups, but overall survival with an HCT-CI of at least 3 was lower compared with a score less than 3 (76% vs 98%; P = .005). Median donor T-cell chimerism among older patients was 64% and 60% at 1 and 3 years, respectively, and was similar to that of younger patients. Increased B regulatory cells potentially contributed to low alloreactivity and mutual donor-recipient tolerance in older patients. Effect of comorbidities rather than age alone may be a more important determinant of suitability for FCC HSCT in older patients.

Evolution of the role of haploidentical stem cell transplantation: past, present, and future

INTRODUCTION

The accessibility to haplo-donors has led to an increase in the number of haplo-HSCT worldwide. A systematic search of the PubMed database between 2000 to present was performed.

AREAS COVERED

In this review, the authors discussed the most used approaches to perform haplo-HSCT and its results: T-cell depletion (TCD, including Perugia platform and its modifications) and T-cell repleted haplo (TCR, including the high-dose post-transplant cyclophosphamide strategy (Baltimore protocol) and the Beijing protocol). The improvements and modifications made to the different strategies have increased the indications of haplo-HSCT, including both malignant and nonmalignant disorders. Focusing on the Baltimore protocol, the authors review the results of the retrospective studies that have compared it to other donor transplants. The limitations of this strategy in terms of toxicity, graft complications, and GVHD are also discussed in detail. Finally, possible approaches to improve the outcomes of TCR haplo-HSCT are presented.

EXPERT OPINION

The recent advances in the field of haplo-HSCT have allowed a large number of patients with incurable diseases to benefit from this procedure despite not having a matched donor. With all available strategies, virtually no patient who needs an allogeneic transplant should be excluded by the absence of a donor.

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.

Allogeneic Hematopoietic Stem Cell Transplantation for Paroxysmal Nocturnal Hemoglobinuria: Multicenter Analysis by the Polish Adult Leukemia Group

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the sole potential cure for paroxysmal nocturnal hemoglobinuria (PNH); however, the data on its utility in PNH are limited. This retrospective analysis of patients with PNH who underwent allo-HSCT in 11 Polish centers between 2002 and 2016 comprised 78 patients with PHN, including 27 with classic PNH (cPNH) and 51 with bone marrow failure-associated PNH (BMF/PNH). The cohort was 59% male, with a median age of 29 years (range, 12 to 65 years). There was a history of thrombosis in 12% and a history of hemolysis in 81%, and 92% required erythrocyte transfusions before undergoing allo-HSCT. No patient received eculizumab, and 26% received immunosuppressive treatment. The median time from diagnosis to allo-HSCT was 12 months (range, 1 to 127 months). Almost all patients (94%) received reduced-toxicity conditioning, 66% with treosulfan. The stem cell source was peripheral blood in 72% and an identical sibling donor in 24%. Engraftment occurred in 96% of the patients. With a median follow-up of 5.1 years in patients with cPNH and 3.2 years in patients with BMF/PNH, 3-year overall survival (OS) was 88.9% in the former and 85.1% in the latter (P = not significant [NS]). The 3-year OS for patients with/without thrombosis was 50%/92% (P = NS) in the cPNH group and 83.3%/85.3% (P = NS) in the BMF/PNH group. The 3-year OS for in the BMF/PNH patients with/without hemolysis was 93.9%/62.9% (hazard ratio, .13; P = .016). No other factors impacted OS. After allo-HSCT, the frequency of the PNH clone was reduced to 0%, <1%, and <2.4% in 48%, 48%, and 4% of cPNH patients and in 84%, 11%, and 5% of BMF/PNH patients, respectively. The frequency of acute graft-versus-host disease (GVHD) grade II-IV was 23%, and the cumulative 1-year incidence of extensive chronic GVHD was 10.8% in the BMF/PNH group and 3.7% in the cPNH group. Allo-HSCT is a valid option for PNH patients, effectively eliminating the PNH clone with satisfactory overall survival and acceptable toxicity. Reduced-toxicity conditioning with treosulfan is effective and safe in patients with cPNH and BMF/PNH.

Haploidentical hematopoietic stem cell transplantation in aplastic anemia: a systematic review and meta-analysis of clinical outcome on behalf of the severe aplastic anemia working party of the European group for blood and marrow transplantation (SAAWP of EBMT)

Aplastic anemia (AA) is a serious hematological disorder, which is solely cured by hematopoietic stem cell transplantation (HSCT). Haploidentical HSCT is an emerging modality with encouraging outcomes in several blood conditions. The present study aims to comprehensively assess the feasibility and safety of haploidentical HSCT in patients with severe and very severe AA. It is a systematic review and meta-analysis of studies related to haploidentical stem cell transplantation in idiopathic AA investigating rates of successful engraftment, acute graft-versus-host disease (aGvHD), chronic GvHD (cGvHD), transplant-related mortality (TRM), and posttransplantation viral infections (including cytomegalovirus [CMV]) in patients with AA. The effects of reduced-intensity conditioning (RIC) and nonmyeloablative conditioning (NMA), as well as various GvHD prophylaxis regimens on these outcomes were evaluated. In total 15 studies were identified, (577 patients, 58.9% males), successful engraftment was observed in 97.3% of patients (95% CI, 95.9-98.7) while grades II-IV aGvHD and cGvHD were reported in 26.6% and 25.0%, respectively. The pooled incidence of TRM was 6.7% per year (95% CI, 4.0-9.4). RIC regimens were associated with higher proportions of successful engraftment (97.7% vs 91.7%, P = 0.03) and aGvHD (29.5% vs 18.7%, P = 0.008) when compared with NMA regimens with no differences in cGvHD or mortality incidence. When compared with methotrexate-containing regimens and other regimens, posttransplant cyclophosphamide-containing regimens reduced the rates of aGvHD (28.6%, 27.8%, and 12.8%, respectively, P = 0.02), CMV viremia (55.7%, 38.6%, and 10.4%, respectively, P < 0.001), and CMV disease in initially viremic patients (2.1%, 33.0%, and 0%, respectively, P < 0.001). We have concluded that Haploidentical HSCT was associated with promising outcomes in terms of successful engraftment and reduced complications. Future prospective trials are needed to identify the preferred conditioning regimen, GvHD prophylaxis, and graft source in the setting of haploidentical transplant for AA.

Stem Cells: A Review Encompassing the Literature with a Special Focus on the Side-Lined Miraculous Panacea; Pre-Morula Stem Cells

Stem cells are the undifferentiated cells in the body that possess the ability to differentiate and give rise to any type of cells in the body. In recent years, there has been a growing interest in therapies involving stem cells as different treatment methods got developed. Depending on the source, there are two major kinds of stem cells, embryonic and adult stem cells. The former type is found in the embryo at the different developmental stages before the implantation and excels the latter owing to pluripotency. On the premise of the attributes of stem cells, they are touted as the "panacea for all ills" and are extensively sought for their potential therapeutic roles. There are a lot of robust pieces of evidence that have proved to cure the different ailments in the body like Huntington disease, Parkinson's disease, and Spinal cord injury with stem cell therapy but associated with adverse effects like immune rejection and teratoma formation. In this regard, the pre-morula (isolated at an early pre-morula stage) stem cells (PMSCs) are one of its kind of embryonic stem cells that are devoid of the aforementioned adverse effects. Taking the beneficial factor into account, they are being used for the treatment of disorders like Cerebral palsy, Parkinson's disorder, Aplastic anemia, Multiple sclerosis and many more. However, it is still illegal to use stem cells in the abovementioned disorders. This review encompasses different stem cells and emphasizes on PMSCs for their uniqueness in therapy as no other previously published literature reviews have taken these into consideration. Later in the review, current regulatory aspects related to stem cells are also considered.

Allo-HSCT compared with immunosuppressive therapy for acquired aplastic anemia: a system review and meta-analysis

Background

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) and immunosuppressive therapy (IST) are two major competing treatment strategies for acquired aplastic anemia (AA). Whether allo-HSCT is superior to IST as a front-line treatment for patients with AA has been a subject of debate. To compare the efficacy and safety of allo-HSCT with that of IST as a front-line treatment for patients with AA, we performed a meta-analysis of available studies that examined the impact of the two major competing treatment strategies for AA.

Results

Fifteen studies including a total of 5336 patients were included in the meta-analysis. The pooled hazard ratio (HR) for overall survival (OS) was 0.4 (95% CI 0.074–0.733, P = 0.016, I² = 58.8%) and the pooled HR for failure-free survival (FFS) was 1.962 (95% CI 1.43–2.493, P = 0.000, I² = 0%). The pooled relative risk (RR) for overall response rate (ORR) was 1.691 (95% CI 1.433–1.996, P = 0.000, I² = 11.6%).

Conclusion

Although survival was significantly longer among AA patients undergoing first-line allo-HSCT compared to those undergoing first-line IST, the selection of initial treatment for patients with newly diagnosed AA still requires comprehensive evaluation of donor availability, patient age, expected quality of life, risk of disease relapse or clonal evolution after IST, and potential use of adjunctive eltrombopag.

Comparable survival outcome between transplantation from haploidentical donor and matched related donor or unrelated donor for severe aplastic anemia patients aged 40 years and older: A retrospective multicenter cohort study

This retrospective multicenter cohort study aimed to compare the outcome of haploidentical hematopoietic stem cell transplantation (HID-HSCT) with matched sibling donor (MSD) and unrelated donor (URD) transplantation in severe aplastic anemia (SAA) patients 40 years of age and older. With a median follow-up time of 17.6 months, 85 consecutive patients were enrolled in the study, and the median patient age was 45 years (40, 58). The cumulative engraftment rates of neutrophil and platelet were 98.8 ± 0.0% and 92.9 ± 0.1%. The cumulative incidences of Grade 2-4 acute graft-versus-host disease (aGvHD) and chronic graft-versus-host disease (cGvHD) at 3 years were 14.1 ± 0.1% and 17.3 ± 0.2%. The 3-year estimated overall survival (OS) and failure-free survival (FFS) were 91.2 ± 3.2% and 89.7 ± 3.5%. In multivariate analysis, the only factor associated with inferior survival was an ECOG score ≥2. HID-HSCT was associated with a higher incidence of GvHD, but the difference of 3-year estimated OS between HID group and the other two cohorts was not significant (86.7 ± 6.4% for HID vs 92.1% ± 4.4% for MSD and 100% for URD, P = .481). HID-HSCT might be a feasible alternative option for selected SAA patients aged 40 years and older without a matched donor.

Multifaceted characterization of the signatures and efficacy of mesenchymal stem/stromal cells in acquired aplastic anemia

Background

Longitudinal studies have verified the pivotal role of mesenchymal stem/stromal cells (MSCs) in the bone marrow microenvironment for hematopoiesis and coordinate contribution to leukemia pathogenesis. However, the precise characteristics and alternation of MSCs during acquired aplastic anemia (AA) remain obscure.

Methods

In this study, we originally collected samples from both healthy donors (HD) and AA patients to dissect the hematological changes. To systematically evaluate the biological defects of AA-derived MSCs (AA-MSCs), we analyzed alterations in cellular morphology, immunophenotype, multi-lineage differentiation, cell migration, cellular apoptosis, and chromosome karyocyte, together with the immunosuppressive effect on the activation and differentiation of lymphocytes. With the aid of whole genome sequencing and bioinformatic analysis, we try to compare the differences between AA-MSCs and HD-derived MSCs (HD-MSCs) upon the molecular genetics, especially the immune-associated gene expression pattern. In addition, the efficacy of umbilical cord-derived MSC (UC-MSC) transplantation on AA mice was evaluated by utilizing survivorship curve, histologic sections, and blood cell analyses.

Results

In coincidence with the current reports, AA patients showed abnormal subsets of lymphocytes and higher contents of proinflammatory cytokines. Although with similar immunophenotype and chromosome karyotype to HD-MSCs, AA-MSCs showed distinguishable morphology and multiple distinct characteristics including genetic properties. In addition, the immunosuppressive effect on lymphocytes was significantly impaired in AA-MSCs. What is more, the cardinal symptoms of AA mice were largely rescued by systemic transplantation of UC-MSCs.

Conclusions

Herein, we systematically investigated the signatures and efficacy of MSCs to dissect the alterations occurred in AA both at the cellular and molecular levels. Different from HD-MSCs, AA-MSCs exhibited multifaceted defects in biological characteristics and alterative molecular genetics in the whole genome. Our findings have provided systematic and overwhelming new evidence for the defects of AA-MSCs, together with effectiveness assessments of UC-MSCs on AA as well.

Allogeneic Bone Marrow Transplants for Pediatric Severe Aplastic Anemia: Real-world Data comparing Matched Related and Unrelated Donors in a Developing Country. Retrospective study on behalf of the Pediatric Hematopoietic Stem Cell Transplant Working Group of the Brazilian Bone Marrow Transplantation Society (SBTMO) and the Brazil-Seattle Consortium (Gedeco)

In this study, we report on major MRD or URD BMT outcomes in pediatric patients with SAA in Brazil. This was a retrospective study, which included 106 patients ≤18 years old who received a first BMT for SAA. All patients received bone marrow as graft source from an MRD (n = 69) or a URD (n = 37). Conditioning regimen was non-myeloablative in 73.6% of cases, and GVHD prophylaxis comprised a calcineurin inhibitor plus methotrexate in 89.6% of patients. After a median follow-up of 4.5 years after BMT, 81 patients are alive, with a 4-year OS of 77% and no statistically significant difference between the MRD and URD groups (82% vs. 69%, respectively; P = .08). Grade III-IV aGVHD at 6 months and cGVHD at 2 years were observed in 8% and 14% of cases, respectively, and were not statistically different between the groups. Twenty-five (23%) patients died at a median of 2.9 months after BMT. Our study showed that 4-year OS after BMT was not statistically different between MRD and URD recipients. This study shows that the outcomes of pediatric patients transplanted for SAA with a URD in Brazil are approaching those of MRD transplants. In contrast, OS after MRD BMT was lower than we would expect based on previous reports. The wide range of preparatory regimens used by the study centers highlights the need for standardized protocols for these children. Our findings provide a benchmark for future studies focused on improving BMT outcomes in this setting in Brazil.

Posttransplant cyclophosphamide in allogeneic bone marrow transplantation for the treatment of nonmalignant hematological diseases

We present a single-center retrospective series of allogeneic bone marrow transplantation (BMT) with the use of posttransplant cyclophosphamide (PTCy) in the setting of nonmalignant hematological conditions. Nine patients were treated between 2013 and 2019. Nonmyeloablative conditioning consisted of antithymocyte globulin, fludarabine, low-dose cyclophosphamide, and total body irradiation (200cGy) followed by allogeneic bone marrow infusion. Post-BMT GVHD prophylaxis was with PTCy, tacrolimus, and mycophenolate mofetil. At a median follow-up of 24 months (range 4, 63), all patients are alive, with donor-derived hematopoiesis and free of significant acute or chronic GVHD. Donors were haploidentical (n = 6), fully matched unrelated (n = 2), and fully matched sibling (n = 1). Neutrophil and platelet engraftment occurred at a median of 21 days and 33 days, respectively, after transplantation. Three patients (3/9, 33%) experienced stage 1-2 acute skin GVHD. The only cases of chronic GVHD are in three patients (3/9, 33%) with ocular disease (two mild, one moderate). No patient has required systemic immunosuppression beyond 12 months after BMT. PTCy-based nonmyeloablative allogeneic BMT is safe and effective for nonmalignant hematologic conditions and should be prospectively compared with historical regimens.

The Case for Upfront HLA-Matched Unrelated Donor Hematopoietic Stem Cell Transplantation as a Curative Option for Adult Acquired Severe Aplastic Anemia

The improved success of HLA-matched unrelated donor (MUD) hematopoietic stem cell transplantation (HSCT) for severe aplastic anemia (SAA) in recent decades has had an impact on the indications for and timing of this treatment modality. In the absence of a matched sibling donor (MSD), historically MUD HSCT was reserved as an option after failure to respond to at least 2 courses of immunosuppressive therapy (IST) in adults with SAA, but with improved outcomes over time, it is now considered following failure to respond to 1 course of IST. Recent national and international studies and guidelines now recommend upfront MUD HSCT as an option for children for whom an MUD is readily available, because outcomes are similar to those for MSD HSCT. Fludarabine-based conditioning and the use of in vivo T cell depletion with antithymocyte globulin or alemtuzumab has been associated with a reported overall survival (OS) of >85% in adult patients undergoing MUD HSCT. However, the recent introduction of eltrombopag for patients with SAA has transformed the treatment landscape, and there is currently much interest in its use with IST as upfront treatment, which showed a high response rate in an early-phase study. The risks of HSCT, especially graft-versus-host disease (GVHD), need to be carefully balanced against the concerns of IST, namely relapse and later clonal evolution to myelodysplastic syndrome (MDS)/acute myelogenous leukemia (AML). In the absence of a current prospective randomized trial comparing these 2 approaches, in this review we examine the evidence supporting consideration of early MUD HSCT in adults with SAA who would have been considered for MSD HSCT but who lack a MSD and for whom an MUD is readily available, especially using an irradiation-free conditioning regimen, with a low risk of GVHD, as another treatment option. This option may be offered to patients to provide them with an informed choice, with the aim of curing disease rather than achieving freedom from disease, relapse-free survival, or OS. Furthermore, understanding the immune signature for the response to IST and the immunologic responses to somatic mutations and clonal progression to MDS/AML may help define the future indications for upfront HSCT and a more precise medical approach to therapy.

Haploidentical donor transplants for severe aplastic anemia

Haploidentical stem cell transplantation (HAPLO) is being increasingly used, and significant progress has been made both with ex vivo T-cell depleted grafts as well as with unmanipulated marrow or peripheral blood grafts. We here review the current status of HAPLO grafts in patients with acquired severe aplastic anemia. Several transplant platforms have been tested, to overcome graft severe rejection and graft vs host disease (GvHD): these include differences in the conditioning regimen, in graft source and graft manipulation, and in GvHD prophylaxis. The latter include ex vivo T-cell depletion and/or antithymocyte globulin and/or high dose post-transplant cyclophosphamide. Some programs also include the use of marrow or cord blood mesenchymal stem cells, infused at the time of transplantation. Extremely encouraging results are being reported especially in the pediatric population, but also in young adults: we will review reports on 375 patients, with an average rejection rate of 6%, grade II-IV GvHD of 23% and 1-year survival of 80%. Finally we will discuss the place of HAPLO transplants in the context of alternative donor grafts for acquired aplastic anemia.