Comparative study of porcine anti-human lymphocyte immunoglobulin and rabbit anti-human thymocyte immunoglobulin as a first-line treatment of acquired severe aplastic anemia

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.

The long-term outcomes and safety of severe aplastic anemia treated with porcine antilymphocyte globulin plus cyclosporine, with or without thrombopoietin receptor agonists: a double-center retrospective study

BACKGROUND

Porcine antilymphocyte globulin (p-ALG) combined with cyclosporine (CsA) has been commonly used for severe aplastic anemia (SAA) patients, but few studies on the combination of p-ALG and thrombopoietin receptor agonist (TPO-RA).

RESEARCH DESIGN AND METHODS

We retrospectively analyzed the data of 85 people with diagnosed SAA who underwent p-ALG plus CsA, with or without TPO-RA from 2014 to 2023.

RESULTS

The overall response rates were 55.3% and 65.9% at 3 and 6 months, and the TPO-RA group were 66.7% and 72.3% at 3 and 6 months, without TPO-RA group were 27.8% and 55.6%. In multivariate analysis, baseline platelet count of > 10 × 109/L was a simple predictor of favorable response at 6 months (p = 0.015). The median follow-up time for all patients was 39 months (range 0.4 ~ 104), the 5-year overall survival (OS) rate was 90.6% [95% CI = 82.1-95.2%], and the failure-free survival (FFS) rate was 68.9% [95% CI = 56.6-78.4%]. Having hematologic responses in 6 months was an independent positive predictor for FFS (p = 0.000). Twelve patients (14.1%) suffered from serum sickness, and 9.5% of patients had mild hepatic impairment.

CONCLUSIONS

p-ALG along with CsA is an effective choice for patients with SAA. p-ALG combined with TPO-RA may contribute to the early restoration of hematopoiesis.

Eltrombopag with or without Tacrolimus for relapsed/refractory acquired aplastic anaemia: a prospective randomized trial

This trial compared eltrombopag (EPAG)+tacrolimus and EPAG monotherapy in patients with refractory/relapsed acquired aplastic anaemia (AA). Patients with refractory/relapsed AA were randomly assigned to receive either EPAG+tacrolimus or EPAG monotherapy at a ratio of 2:1. Patient response, safety, clonal evolution and survival were compared. In total, 114 patients were included in the analysis, with 76 patients receiving EPAG+tacrolimus and 38 receiving EPAG only. With a median follow-up of 18 (6-24) months, the overall response rate (ORR) for patients treated with EPAG+tacrolimus and EPAG alone was 38.2% vs. 31.6% (P = 0.490) at the 3rd month, 61.8% vs. 39.5% (P = 0.024) at the 6th month, 64.5% vs. 47.1% (P = 0.097) at the 12th month, and 60.5% vs. 34.2% (P = 0.008) at the last follow-up. The rate of each adverse event, overall survival curves (P = 0.635) and clonal evolution rate (P = 1.000) were comparable between the groups. A post hoc subgroup analysis showed that EPAG+tacrolimus could have advantage over EPAG monotherapy in terms of the ORR at the 6th month (P = 0.030)/last follow-up (P = 0.013) and the cumulative relapse-free survival (RFS) curves (P = 0.048) in patients <60 years old.

[The effect of on-demand glucocorticoid strategy on the occurrence and outcome of p-ALG-associated serum sickness in aplastic anemia]

Objective: To investigate the effect of on-demand glucocorticoid strategy on the occurrence and outcome of porcine anti-lymphocyte globulin (p-ALG) -associated serum sickness in aplastic anemia (AA) . Methods: The data of AA patients who received in the Anemia Diagnosis and Treatment Center of Haematology Hospital, CAMS & PUMC from January 2019 to January 2022 were collected. Among them, 35 patients were enrolled in the on-demand group, with the glucocorticoid strategy adjusted based on the occurrence and severity of serum sickness; 105 patients were recruited in the usual group by matching the age and disease diagnosis according to 1∶3 ratio in patients who received a conventional glucocorticoid strategy in the same period. The incidences, clinical manifestations, treatment outcomes of serum sickness, and glucocorticoid dosage between the two groups were analyzed. Results: The incidences of serum sickness in the on-demand group and the usual group were 65.7% and 54.3% (P=0.237) , respectively. The median onset of serum sickness was the same [12 (9, 13) d vs the 12 (10, 13) d, P=0.552], and clinical symptoms and signs, primarily joint, and/or muscle pain, fever, and rash were similar. Severity grades were both dominated by Grades 1-2 (62.8% vs 51.4%) , with only a few Grade 3 (2.9% vs 2.9%) , and no Grades 4-5. No significant difference in the serum sickness distribution (P=0.530) . The median duration of serum sickness was the same [5 (3, 7) d vs 5 (3, 6) d, P=0.529], and all patients were completely cured after glucocorticoid therapy. In patients without serum sickness, the average dosage of prophylactic glucocorticoid per patient in the usual group was (469.48 ±193.57) mg (0 in the on-demand group) . When compared to the usual group, the average therapeutic glucocorticoid dosage per patient in the on-demand group was significantly lower [ (125.91±77.70) mg vs (653.90±285.56) mg, P<0.001]. Conclusions: In comparison to the usual glucocorticoid strategy, the on-demand treatment strategy could significantly reduce glucocorticoid dosage without increasing the incidence of serum sickness; in addition, the duration of serum sickness and the incidence of above Grade 2-serum sickness were similar.

Porcine anti-human lymphocyte immunoglobulin depletes the lymphocyte population to promote successful kidney transplantation

Introduction

Porcine anti-human lymphocyte immunoglobulin (pALG) has been used in kidney transplantation, but its impacts on the lymphocyte cell pool remain unclear.

Methods

We retrospectively analyzed 12 kidney transplant recipients receiving pALG, and additional recipients receiving rabbit anti-human thymocyte immunoglobulin (rATG), basiliximab, or no induction therapy as a comparison group.

Results

pALG showed high binding affinity to peripheral blood mononuclear cells (PBMCs) after administration, immediately depleting blood lymphocytes; an effect that was weaker than rATG but stronger than basiliximab. Single-cell sequencing analysis showed that pALG mainly influenced T cells and innate immune cells (mononuclear phagocytes and neutrophils). By analyzing immune cell subsets, we found that pALG moderately depleted CD4+T cells, CD8+T cells, regulatory T cells, and NKT cells and mildly inhibited dendritic cells. Serum inflammatory cytokines (IL-2, IL-6) were only moderately increased compared with rATG, which might be beneficial in terms of reducing the risk of untoward immune activation. During 3 months of follow-up, we found that all recipients and transplanted kidneys survived and showed good organ function recovery; there were no cases of rejection and a low rate of complications.

Discussion

In conclusion, pALG acts mainly by moderately depleting T cells and is thus a good candidate for induction therapy for kidney transplant recipients. The immunological features of pALG should be exploited for the development of individually-optimized induction therapies based on the needs of the transplant and the immune status of the patient, which is appropriate for non-high-risk recipients.

Antihuman T lymphocyte porcine immunoglobulin combined with cyclosporine as first-line immunosuppressive therapy for severe aplastic anemia in China: a large single-center, 10-year retrospective study

Background

Antihuman T lymphocyte porcine immunoglobulin (p-ATG) has been the most common ATG preparation in immunosuppressive therapy (IST) in Chinese patients with severe aplastic anemia (SAA) since 2009.

Objectives

This study aimed to evaluate the early hematologic response and long-term outcomes of a large cohort of patients with SAA who received p-ATG plus cyclosporine (CsA) as first-line therapy from 2010 to 2019.

Design

This is a single-center retrospective study of medical records.

Methods

We analyzed the data of 1023 consecutive patients with acquired aplastic anemia (AA) who underwent p-ATG combined with CsA as a first-line IST treatment from 2010 to 2019 at our department.

Results

The median age of the patients was 24 (4-75) years, and the median follow-up time was 57.2 months (3 days-137.5 months). There was an early mortality rate of 2.8% with a median death time of 0.9 months (3 days-2.9 months). The overall response rates were 40.6% and 56.1% at 3 and 6 months, respectively. The 5-year cumulative incidences of relapse and clonal evolution were 9.0% [95% confidence interval (CI) = 4.2-16.0%] and 4.5% (95% CI = 1.4-10.6%), respectively. The 5-year overall survival (OS) and event-free survival rates were 83.7% (95% CI = 81.1-86.0%) and 50.4% (95% CI = 47.1-53.5%), respectively.

Conclusion

p-ATG combined with CsA for the treatment of AA is effective and safe, and p-ATG can be used as an alternative ATG preparation for the standard IST regimen in areas in which h-ATG is not available.

Retrospective Comparison of Efficacy and Safety of Rabbit Anti-Thymocyte Globulin and Porcine Anti-Lymphocyte Globulin in Patients With Acquired Aplastic Anemia Undergoing Hematopoietic Stem Cell Transplantation From Matched Sibling Donors

We compared the efficacy and safety of porcine anti-lymphocyte globulin (pALG) (n=140) and rabbit anti-thymocyte globulin (rATG) (n=86) in patients with acquired aplastic anemia (AA) receiving hematopoietic stem cell transplantation (HSCT) from matched sibling donors (MSD) in two transplantation centers in China ranging from 2005 to 2020. The groups had similar baseline characteristics except for a higher number of infused mononuclear cells (P<0.001) and a higher proportion of peripheral blood stem cells as graft sources (P=0.003) in the pALG group. The rates of neutrophil engraftment at day 28 (P=1), platelet engraftment at day 28 (P=0.228), bloodstream infection before engraftment (P=0.867), invasive fungal diseases (P=0.362), cytomegalovirus viremia (P=0.667), and graft rejection (P=0.147) were similar in the two groups. A higher cumulative incidence of grades II-IV acute graft versus host disease (aGvHD) at 100 days occurred in the pALG group (19% vs. 8%, P=0.035) while no significant differences in grades III-IV aGvHD (P=0.572), mild to severe chronic GvHD (cGvHD) (P=0.181), and moderate to severe cGvHD (P=0.586) were observed. The actuarial 5-year overall survival (OS), failure-free survival (FFS), and GvHD-free, FFS rates of the pALG group were 87% (95% confidence interval [CI], 82-93), 85% (95% CI, 80-92), and 78% (95% CI, 72-92) versus 91% (95% CI, 86-99) (P=0.33), 88% (95% CI, 82-97) (P=0.428), and 79% (95% CI, 72-90) (P=0.824) in the rATG group, respectively. A busulfan-containing conditioning regimen was the only adverse risk factor for OS and FFS in multivariate analysis. In conclusion, pALG is an alternative to rATG in patients with severe AA receiving MSD-HSCT. A prospective, large-sample study is needed to explore this therapy further.

New Trends of Nontransplant therapy for Acquired Aplastic Anemia

Aplastic anemia (AA) is a hematological disease that is characterized by pancytopenia and hypofunctional bone marrow hematopoiesis. Patients with AA are treated with either immunosuppressive therapy (IST) using anti-thymocyte globulin (ATG) and Cyclosporine (CsA) or hematopoietic stem cell transplantation (HSCT), if a matched donor is available. The standard IST regimen for AA patients which results in response rates up to 70%, and even higher overall survival. However, primary and secondary failures after IST remain frequent, and to date all attempts aiming to overcome this problem have been unfruitful. The nontransplant therapeutic options for AA have significantly expanded during the last few years. Here, we review the new trends of nontransplant therapy for AA and summarize the current therapeutic effect of AA.

Comparison of porcine ALG and rabbit ATG on outcomes of HLA-haploidentical hematopoietic stem cell transplantation for patients with acquired aplastic anemia

Objective

To evaluate the efficacy and safety of P-ALG (porcine anti-lymphocyte globulin) and R-ATG (rabbit anti-thymocyte globulin) in the conditioning regime for patients with acquired aplastic anemia who underwent HLA-haploidentical hematopoietic stem cell transplantation (halpo-HSCT).

Methods

A total of 91 patients with acquired aplastic anemia who received haplo-HSCT at our center between January 2014 and December 2020 were retrospectively reviewed. Twenty-eight patients were in the P-ALG group while sixty-three patients were in the R-ATG group.

Results

The median time was 11 versus 13 days (P = 0.294) for myeloid engraftment and 12.5 versus 15 days (P = 0.465) for platelet engraftment in the P-ALG and R-ATG groups, respectively. There were no significant difference in 5-year overall survival (74.83% ± 8.24% vs 72.29% ± 6.26%, P = 0.830), GVHD-free, failure-free survival (71.05% ± 8.65% vs 62.71% ± 6.22%, P = 0.662), failure-free survival (74.83% ± 8.24% vs 66.09% ± 5.84%, P = 0.647) and transplantation-related mortality (25.17% ± 8.24% vs 26.29% ± 6.22%, P = 0.708) between the two groups. The incidence of aGVHD (acute graft versus host disease) (65.39% ± 9.33% vs 62.71% ± 6.30%, P = 0.653), II–IV aGVHD (38.46% ± 9.54% vs 35.64% ± 6.24%, P = 0.695), III–IV aGVHD (19.23% ± 7.73% vs 10.53% ± 4.07%, P = 0.291), cGVHD (chronic graft versus host disease) (22.22% ± 12.25% vs 22.31% ± 6.30%, P = 0.915), and moderate to severe cGVHD (5.56% ± 5.40% vs 9.28% ± 4.46%, P = 0.993) were not significantly different. Similar outcomes were observed between the P-ALG and R-ATG groups for severe bacterial infection (17.9% vs 25.4%, P = 0.431), invasive fungal diseases (3.6% vs 9.5%, P = 0.577) and graft rejection (0% vs 9.5%, P = 0.218). However, the incidence of cytomegalovirus infection and Epstein-Barr virus infection was significantly lower in the P-ALG group (46.4% vs 71.4%, P = 0.022; 3.6% vs 25.4%, P = 0.014).

Conclusion

The efficacy and safety of P-ALG were similar with R-ATG in the setting of haplo-HSCT for patients with acquired aplastic anemia patients. P-ALG could be an alternative for R-ATG.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02410-z.

Relationship between immune status after ATG treatment and PNH clone evolution in patients with severe aplastic anemia

OBJECTIVES

To investigate the relationship between immune status and paroxysmal nocturnal hemoglobinuria (PNH) clonal evolution of severe aplastic anemia (SAA) patients who received anti-human thymocyte globulin (ATG) treatment.

METHODS

The clinical data of 102 SAA patients who received ATG were collected and retrospectively analyzed. The remission rate, remission time, response rate, hematopoietic, and immune status were compared. Malignant clones were also observed.

RESULTS

The remission rate of the group with PNH clones appeared after treatment was significantly higher than the group without PNH clones. The response rate at 12 months of the groups with PNH clones was significantly higher than the group without PNH clones. The recovery of Hb and Ret % of patients with PNH clones was earlier than the patients without PNH clones. The reduction of percentage of CD8⁺ HLA-DR⁺ /CD8⁺ and Th1/Th2 ratio of patients with PNH clones was both earlier than the patients without PNH clones. Six patients developed myelodysplastic syndromes (MDS).

CONCLUSION

In SAA patients with PNH clones, the cytotoxic T-cell function and Th1 cell number recovered more quickly and had better response to IST. A small number of SAA patients with or without PNH clones developed MDS malignant clones.

[Clinical study of anti-human T cell porcine immunoglobulin with recombinant human tumor necrosis factor-α receptor II: IgG Fc in the treatment of 35 cases of grade III/IV acute graft-versus-host disease after allo-HSCT]

Objective: To evaluate the efficacy and safety of anti-human T lymphocyte porcine immunoglobulin (P-ATG) with recombinant human tumor necrosis factor-α receptor Ⅱ:IgG Fc fusion protein (rhTNFR∶Fc, Etanercept) on grade Ⅲ/Ⅳ acute graft-versus-host disease (aGVHD) after allogenic hematopoietic stem cell transplantation (allo-HSCT) . Methods: Thirty-five patients with Grade Ⅲ/Ⅳ aGVHD who received P-ATG with etanercept therapy after allo-HSCT were retrospectively analyzed. P-ATGs (5 mg·kg(-1)·d(-1)) were administrated for 3 to 5 days, and then 5mg/kg was sequentially administrated, QOD to BIW. Etanercepts were administrated 25 mg, twice a week (12.5 mg, BIW for pediatric patients) . Results: Among the 35 patients with grade Ⅲ/Ⅳ aGVHD, 21 were males and 14 females, with a median age of 10 (3-54) years. A total of 19 cases of acute myeloid leukemia, 13 of acute lymphoblastic leukemia, 1 of severe aplastic anemia, 1 of myelodysplastic syndrome, and 1 of mixed phenotypic acute leukemia were noted. The overall response (OR) rate of P-ATG with etanercept was 85.7% (30/35) , with complete response (CR) and partial response (PR) rates of 34.3% (12/35) and 51.4% (18/35) , respectively, on day 28. The OR rate of grade Ⅲ aGVHD group was higher than of grade IV aGVHD group [100% (19/19) vs. 68.8% (11/16) , P=0.004]. On day 56, the OR rate became 77.2% (27/35) , with CR and PR rates of 62.9% (22/35) and 14.3% (5/35) , respectively. The OR rate of grade Ⅲ aGVHD group was also higher than of grade Ⅳ aGVHD group [89.5% (17/19) vs. 62.5% (10/16) , P=0.009]. Thirty-five patients had no adverse effects such as fever, chills, and rash during the P-ATG infusion, and no obvious liver and kidney function damage was observed after treatment. The main treatment-related complication was infection. The reactivation rates of CMV and EBV were 77.1% (27/35) and 22.9% (8/35) , respectively, and the bacterial infection rate was 48.6% (17/35) . With a median follow-up time of 13 (1-55) months after HSCT, the 1-year and 2-year OS rates were (68.1±8.0) % and (64.3±8.4) % , respectively. The 1-year OS rate of grade Ⅲ aGVHD group was superior to grade Ⅳ aGVHD group [ (84.2±8.4) % vs. (47.6±13.1) % , χ(2)=3.38, P=0.05]. Conclusion: This study demonstrated that P-ATG with etanercept was effective and safe in treating grade Ⅲ-Ⅳ aGVHD after allo-HSCT.

Current insights into the treatments of severe aplastic anemia in China

Recently, several studies have been conducted to generate considerable evidence regarding unique treatments for severe aplastic anemia (SAA) in China. Haploidentical donor hematopoietic stem cell transplantation (HID-HSCT) showed an overall survival rate (80.3-86.1%) comparable to those with immunosuppressive therapy (IST) and matched related donor (MRD)- and matched unrelated donor (MUD)-HSCT. Failure-free survival of HID-HSCT was also comparable (76.4-85.0%) to those of MRD- and MUD-HSCT and better than IST in patients < 40 years. Although these results are promising, HID-HSCT should be regarded as a salvage therapy when young patients fail to respond to IST. Porcine anti-human lymphocyte immunoglobulin (pALG) showed similar or superior overall response at 6 months compared to rabbit anti-human thymocyte immunoglobulin (rATG) (64.0-79.4% in the pALG-group vs.48.1-64.7% in the rATG-group) as a first-line IST. Promising hematological response (28.4-33.3%) was observed in patients with refractory AA following infusion of the mesenchymal stromal cells (MSCs) derived from the bone marrow of allogeneic donors. pALG can replace rATG as an immunosuppressive drug and MSCs infusion can be used as a second-line treatment for refractory SAA. We believe that this review contributes to refine the global practices for SAA treatment.

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.

Treatment of Severe Aplastic Anemia with Porcine Anti-Human Lymphocyte Globulin

Aplastic anemia (AA) is a bone marrow failure syndrome characterized by pancytopenia. Decreased numbers of hematopoietic stem cells and impaired bone marrow microenvironment caused by abnormal immune function describe the major pathogenesis of AA. Hematopoietic stem cell transplantation and immunesuppressive therapy are the first-line treatments for AA. Porcine anti-lymphocyte globulin (p-ALG) is a new product developed in China. Several studies have shown that p-ALG exhibited good therapeutic effects in AA.

Efficacy and safety of porcine ALG compared to rabbit ATG as first-line treatment for children with acquired aplastic anemia

OBJECTIVE

To assess the outcomes of children with acquired aplastic anemia (AA) treated in China with first-line porcine anti-lymphocyte immunoglobulin (p-ALG)/rabbit anti-thymocyte immunoglobulin (r-ATG) combined with cyclosporine A (CSA).

METHODS

We performed a single-center, non-randomized, retrospective cohort study to assess the outcomes of 189 children with AA treated in China with first-line p-ALG/r-ATG combined with CSA between 2014 and 2018.

RESULTS

No significant differences were observed in the overall response rates at 3, 6, 12, or 24 months (3 months: 61.9% vs 67.4%, P = .5; 6 months: 70.9% vs 73.9%, P = .69; 12 months: 77.3% vs 73.3%, P = .58; 24 months: 81.6% vs 78.6%, P = .59) after either p-ALG- or r-ATG-based immunosuppressive therapy. No significant differences were observed in overall survival or failure-free survival between the p-ALG group and the r-ATG group.

CONCLUSION

Our results reveal that the therapeutic efficacy and safety of p-ALG combined with CSA did not differ significantly from those of r-ATG combined with CSA as first-line therapy for pediatric patients with AA. Moreover, p-ALG has the advantage of significantly lower cost compared with r-ATG.

Comparison of frontline treatment with intensive immunosuppression therapy and HLA-haploidentical hematopoietic stem cell transplantation for young patients with severe aplastic anemia - A meta analysis

AIM

To compare the survivals and treatment related complications between immunosuppression therapy (IST) and haploidentical hematopoietic stem cell transplantation (haplo-HSCT) on children and young adults with severe aplastic anemia (SAA) in East Asia during the last 10 years.

METHODS

After looking through Pubmed, Embase, Web of Science and Wanfang Data, a total of 491 patients from 7 retrospective studies conducted in East-Asia were included for meta-analysis based on Stata program. Publication bias was measured by Begger and Egger tests. 1/3/5/10 years overall survivals (OS), failure free survivals (FFS), incidence rates of adverse events and their 95% confidence intervals (CI) were pooled and compared.

RESULTS

There was no difference of 1/3/5/10 years OS between IST group and haplo-HSCT group, but the 1/3/5/10 years FFS were significantly better in haplo-HSCT group compared with IST group (p < 0.01). However, higher incidence of infections was observed in haplo-HSCT group compared with IST group (76% versus 45%, p < 0.001). The pooled estimates for acute graft versus host disease (aGVHD) and chronic graft versus host disease (cGVHD) were 54% (95% Cl, 43%～64%) and 43% (95% CI, 18%～68%), respectively for haplo-HSCT group. Among them 38% (95%CI, 22%～54%) was grade III aGVHD and 11% (95% Cl, 0%～22%) was grade III-IV aGVHD. Death causes included severe infection, bleeding in IST group and infection, GVHD in haplo-HSCT group.

CONCLUSIONS

The long-term survivals were similar for young patients with SAA who received IST or haplo-HSCT as the frontline treatment. The haplo-HSCT group showed a better FFS, on the other hand, had higher incidence of infection and GVHD.