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Articles

Randomized trial of anti-thymocyte globulin plus lowdose post-transplant cyclophosphamide to prevent graft-versus- host disease in haploidentical transplantation

Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing
Peking University People’s Hospital, Peking University Institute of Hematology, National Clinical Research Center for Hematologic Disease, Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Collaborative Innovation Center of Hematology, Peking University, Beijing
Vol. 110 No. 12 (2025): December, 2025 https://doi.org/10.3324/haematol.2025.287504

Abstract

The combination of anti-thymocyte globulin (ATG) and posttransplant cyclophosphamide (PTCy) appears to be a potentially effective graft-versus-host disease (GVHD) prevention strategy for haploidentical transplantation. However, the majority of the evidence originated from retrospective studies without uniform protocols. Our previous findings indicated that 10 mg/kg ATG plus low-dose PTCy could decrease GVHD among high-risk populations transplanted from maternal or collateral relatives. We designed an open-label, phase III, randomized controlled trial to compare patients receiving granulocyte colony-stimulating factor (G-CSF)/ATG-based haploidentical transplantation with or without low-dose PTCy (14.5 mg/kg on days 3 and 4) in non-maternal, non-collateral haploidentical transplants from fathers, children or siblings. A total of 66 patients were randomly assigned to ATG-PTCy (N=44) or ATG (N=22) when the first interim analysis was performed. The interim analysis revealed that the 100-day cumulative incidences of grade 2-4 (18.2%, 95% confidence interval [CI]: 6.6-29.7 vs. 18.2%, 95% CI: 1.7-34.7; P=0.996) and 3-4 acute GVHD (2.3%, 95% CI: 0-6.7 vs. 0; P=0.480) were comparable between the ATG-PTCy and ATG cohorts, as was chronic GVHD at 1 year. The estimated 1-year disease-free survival (DFS) rates were also similar between ATG-PTCy and ATG cohorts (95.5%, 95% CI: 89.5–100 vs. 95.2%, 95% CI: 86.6–100; P=0.979). These results suggested that ATG/PTCy (low-dose) had no advantage over 10 mg/kg ATG-based prophylaxis in patients with haploidentical transplantation other than that of maternal donors or collateral relatives. Future work needs to focus on identifying which populations might benefit from the combined strategy in the context of G-CSF/ATG-based protocols (clinicaltrials gov. Identifier: NCT 06108739).

Introduction

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) from haploidentical donors has made significant progress over the past 20 years. Two mainstream haploidentical protocols without in vitro T-cell depletion include granulocyte colony-stimulating factor (G-CSF)/ antithymocyte globulin (ATG)-based and posttransplant cyclophosphamide (PTCy)-based protocols.1-3 Although both protocols overcome the HLA barrier and achieve acceptable incidences of severe graft-versus-host disease (GVHD), the optimization of GVHD prophylaxis, including the combination of the two protocols, is continuously being explored.4,5 Previously published studies have demonstrated that PTCy plus ATG rather than PTCy alone limits the incidence of acute grade II-IV GVHD after reduced-intensity conditioning haploidentical transplantation, likely due to the combined effect of T and NK cell reconstitution.6,7

The G-CSF and ATG were two major elements in Beijing Protocol.3,8-10 In the context of G-CSF/ATG-based haploidentical transplantation, maternal donor or collateral relatives have been proven to be associated with increased incidence of GVHD.11 Previously, a novel regimen consisting of low-dose PTCy (14.5 mg/kg on days 3 and 4 after transplantation) in combination with 10 mg/kg ATG was designed. The addition of such a low dose PT-Cy was designed based on previous animal model and single-arm clinical cohort.12 Published data have demonstrated that ATG plus low-dose PTCy could significantly reduce both grade 3-4 acute GVHD (aGVHG) (5% vs. 18%) and 2-year chronic GVHD (cGVHD) (30% vs. 44%) compared with 10 mg/kg ATG-based prophylaxis among patients with maternal donor or collateral relatives at particularly high risk of GVHD.13 With respect to the mechanism of action of low-dose PTCy in conjunction with ATG, in vivo immune reconstitution analysis revealed that a low dose of PTCy is sufficient for lymphopenia-induced regulatory T-cell (Treg) proliferation and that the effect on Treg becomes more obvious when low-dose PTCy is combined with ATG.12

Thus, the combination of ATG with low-dose PTCy has a synergistic mechanism to reduce GVHD through animal experiments, which has also been found to decrease GVHD among high-risk populations transplanted from maternal or collateral relatives. However, it is unclear whether the combination of ATG with low-dose PTCy could decrease GVHD in non-maternal, non-collateral haploidentical transplants. On the basis of these findings, we designed a prospective randomized controlled clinical study to explore this question.

Methods

Study design and participants

This study was an open-label, phase III, randomized controlled trial conducted at Peking University People’s Hospital. The protocol was approved by the institutional review board of the participating centers. All of the patients or their legal guardians signed informed consent forms in accordance with the Declaration of Helsinki. This study was registered at (clinicaltrials gov. Identifier: NCT 06108739).

Patients were eligible if they had acute leukemia in complete remission and/or myelodysplastic syndrome and were indicated for allo-HSCT. Eligibility also included haploidentical donors other than maternal or collateral relatives, age between 12 and 55 years, an Eastern Cooperative Oncology Group (ECOG) score less than or equal to 3 and adequate basic organ function. The exclusion criteria were substantial vital organ function impairment, previous allo-HSCT, refractory malignant disease state, other malignant tumors requiring treatment, and active and non-controlled infectious diseases under treatment.

Randomization and protocols

The design was a superiority trial study. Randomization was performed with a central interactive response technology system. Patients were randomly assigned 2:1 to either the ATG-PTCy cohort or the ATG cohort. The conditioning regimen and GVHD prophylaxis were previously reported in detail.1 4,1 5 All transplant recipients received busulfan-cyclophosphamide (Bu-Cy) myeloablative conditioning regimens.11,16-18 In both cohorts, the Bu-Cy plus ATG conditioning regimen was applied as follows: cytarabine, 4 g/m2/day intravenously (i.v.) on day -9; Bu, 3.2 mg/kg/ day i.v. on days -8 to -6; Cy, 1.8 g/m2/day i.v. on days -5 to -4; Me-CCNU, 250 mg/m2/day orally on day -3; and rabbit ATG (Sangstat-Genzyme), 2.5 mg/kg/day i.v. on days -5 to -2. The GVHD prophylaxis regimen consisted of cyclosporine A, mycophenolate mofetil (MMF), and short-term methotrexate (MTX).16 CsA (1.5 mg/kg, every 12 hours, i.v.) was given from day -3 and the target concentration was adjusted to 200-250 ng/mL. Administration was oral once the patient’s bowel function returned to normal. The target concentration of CsA was required for up to 100 days post HSCT, CsA was then gradually reduced and discontinued about 6-9 months post transplantation (balanced between the relapse risk and GVHD status). MMF (0.5 g every 12 hours) was administered orally from day -3 and discontinued upon myeloid engraftment. The dosage of MTX was 15 mg/m2, administered i.v. on day +1, followed by 10 mg/m2 on days 3, 6, and 11 after transplantation. In the ATG-PTCy cohort, two doses of 14.5 mg/kg Cy were given on days 3 and 4 posttransplantation. The G-CSF (5 ug/kg/day) were administered to donors from day -3 for consecutive 5 days, and the first apheresis was started on the morning of the fourth day after the start of the G-CSF administration.19-22 All patients received peripheral blood as graft source. All patients enrolled in the study had donor-specific antibody (DSA) levels less than 2,000, and desensitization methods were not utilized.23,24 Letermovir has been commonly used during transplant course from day +7 to day +100 in this study.

Outcome evaluation

The primary endpoint was the cumulative incidence of grade 2-4 aGVHD. The secondary endpoints included engraftment, the cumulative incidence of 3-4 aGVHD and cGVHD, infections, non-relapse mortality (NRM), disease relapse, overall survival (OS), and disease-free survival (DFS). Myeloid engraftment was defined as the first of 3 consecutive days with an ANC ≥0.5×109/L, and platelet engraftment was defined as the day the platelet count met or exceeded 20×109/L without transfusion for 7 days. aGVHD and cGVHD were assessed according to the international consensus, with Mount Sinai Acute GVHD International Consortium (MAGIC) criteria for aGVHD and the National Institutes of Health 2014 criteria for cGVHD.25,26 Epstein-Barr virus (EBV) reactivation was defined based on titer ≥500 copies/mL. OS was calculated as the time from transplantation to death from any cause, and DFS was defined as the time from transplantation to relapse or death. GVHD and relapse-free survival (GRFS) events were defined as grade 3-4 aGVHD, intermediate-severe cGVHD, disease relapse, or death from any cause during follow-up after transplantation.27

Statistical analysis

Power calculations dictated that 196 subjects were necessary to detect a 20% difference between groups in grade 2-4 aGVHD on the basis of our previous results (from 45% to 25%), with a one-sided difference of 0.025 and a power of 0.80. The interim analysis was performed after one third, half and two thirds of the 196 cases was specified, and the conditional power for success was defined as 0.10. After the 66th patient was enrolled in this study, we performed the first interim analysis. As the conditional power was 0.025, which was less than the prespecified cutoff of 0.10, the Data and Safety Monitoring Board recommended halting the study owing to futility after the first interim analysis in August 2024. Data were collected on case report forms by medical record reviews.

The surviving patients were followed-up, and the results of the follow-up examinations were analyzed on December 31, 2024. Survival outcomes were estimated with the Kaplan-Meier method and compared using the log-rank test. The cumulative incidences of relapse, TRM, and GVHD were estimated while accounting for competing events and compared using Gray’s test. SPSS 21.0 (Mathsoft, Seattle, WA, USA) and R version 3.4.4 (The R Foundation for Statistical Computing) were used for data analyses.

Results

Basic characteristics

Between November 30, 2023, and August 21, 2024, 66 patients were randomly assigned to the ATG-PTCy (N=44) or ATG (N=22) groups. The median follow-up was 264 days (range, 141-399) for the ATG-PTCy cohort and 257 days (range, 132-393) for the ATG cohort (P=0.915) post-transplantation. The baseline characteristics are presented in Table 1. The distribution of those patients was balanced in terms of patient age at transplantation, donor-recipient sex, disease type, and the kinship of haploidentical donors between the ATG-PTCy and ATG cohorts. The mean counts of lymphocytes pre-ATG were 1.07×109/L (range, 0.30-2.34) in the ATG-PTCy and 0.88×109/L (range, 0.18-2.26) in the ATG cohorts without significance (P=0.170). The median donor age was 34 (range, 16-59) versus 39.5 (range, 15-57) in the ATG-PTCy and ATG cohorts (P=0.414).

Engraftment and graft-versus-host disease

On day 28 after HSCT, 97.7% (95% CI: 92.1-100) of patients in the ATG-PTCy cohort and 100% of patients in the ATG cohort achieved neutrophil engraftment (P=0.206; Figure 1A). The median time to neutrophil engraftment was 14 (range, 12-28) versus 14 (range, 9-21) days posttransplantation in the ATG-PTCy and ATG cohorts, respectively (P=0.269). On day 30 after HSCT, 68.2% (95% CI: 54.1-82.3) of patients in the ATG-PTCy cohort and 81.8% (95% CI: 64.6-99.1) of patients in the ATG cohort achieved platelet engraftment (P=0.115). On day 100 after HSCT, 95.5% (95% CI: 88.1-100) of patients in the ATG-PTCy cohort and 100% of patients in the ATG cohort achieved platelet engraftment (P=0.084; Figure 1B). The median time to platelet engraftment was 20 (range, 12-267) versus 14.5 (range, 12-65) days posttransplantation in the ATG-PTCy and ATG cohorts, respectively (P=0.113). All of the patients achieved full donor chimerism during the follow-up.

The 100-day cumulative incidences of grade 2-4 (18.2%, 95% CI: 6.6-29.7 vs. 18.2%, 95% CI: 1.7-34.7; P=0.996; Figure 2A) and grade 3-4 aGVHD (2.3%, 95% CI: 0-6.7 vs. 0; P=0.480; Figure 2B) were comparable between the ATG-PTCy and ATG cohorts. Five patients (11.3%) in the ATG-PTCy cohort and one patient (4.5%) in the ATG cohort suffered steroid-refractory aGVHD (P=0.364). The 6-month cumulative incidences of cGVHD (34.4%, 95% CI: 19.4-49.3% vs. 23.5%, 95% CI: 4.9-42.2%) and moderate to severe cGVHD (20.0%, 95% CI: 7.3-32.6% vs. 9.1%, 95% CI: 0-21.4%) were similar between the ATG-PTCy and ATG cohorts. The estimated 1-year cumulative incidences of cGVHD (45.5%, 95% CI: 28.2-62.7 vs. 44.8%, 95% CI: 19.1-70.5; P=0.721; Figure 3A) and moderate to severe cGVHD (23.2%, 95% CI: 9.5-36.8 vs. 15.6%, 95% CI: 0-32.7; P=0.468; Figure 3B) were also similar between the ATG-PTCy and ATG cohorts.

Cytomegalovirus and Epstein-Barr virus infection

On day 100 after HSCT, a total of 9.1% (95% CI: 0.5-17.7) of the ATG-PTCy cohort and 9.1% (95% CI: 0-21.4) of the ATG cohort developed cytomegalovirus (CMV) viremia (P=1.000). A total of 20.5% (95% CI: 8.4-32.5) of the patients in the ATG-PTCy cohort and 27.3% (95% CI: 8.2-6.4) of the patients in the ATG cohort were diagnosed with EBV viremia (P=0.438). None of the patients in the two cohorts developed CMV disease. Two patients (4.5%) in the ATG-PTCy cohort and one patient (4.5%) in the ATG cohort had EBV-associated posttransplant lymphoproliferative disorders (P=1.000). Besides, the dynamic immune reconstitution between the two cohorts have been presented in Table 2 and Table 3. We have further analyzed the impact of CD3, CD4, CD19 and immunoglobulin at +1 month on clinical outcomes, and found no statistically significant differences.

Table 1.Patient characteristics between the two groups.

Figure 1.The cumulative incidence of engraftment between ATG-PTCy and ATG groups. (A) The cumulative incidence of neutrophil engraftment and (B) platelet engraftment. allo-HSCT: allogeneic hematopoietic stem cell transplantation; ATG: anti-thymocyte globulin; PTCy: posttransplant cyclophosphamide.

Figure 2.The 100-day cumulative incidences of acute graft-versus-host disease between ATG-PTCy and ATG groups. (A) The 100-day cumulative incidences of grade 2-4 and (B) grade 3-4 acute graft-versus-host disease (GVHD). allo-HSCT: allogeneic hematopoietic stem cell transplantation; ATG: anti-thymocyte globulin; PTCy: posttransplant cyclophosphamide.

Regimen related toxicity

All patients received the conditioning regimen according to a pre-defined schedule. Two patients (4.5%) in the ATG-PTCy group and two patients (9.1%) in the ATG group suffered grade 1-2 hemorrhagic cystitis (P=0.466). Four patients (9.1%) in the ATG-PTCy group and two patients (9.1%) in the ATG group suffered grade 1 cardiotoxicity (P=1.000). Besides, there were five patients and two patients who developed oral mucositis in the ATG-PTCy and ATG groups, respectively (P=0.777).

Survival and relapse

Two patients in the whole cohort died during our follow-up due to relapse (1 in the ATG cohort) and thrombotic microangiopathy (1 in the ATG plus PTCy cohort). No significant difference in the cumulative incidence of relapse was observed between the ATG-PTCy (2.3%, 95% CI: 0-6.7%) and ATG cohorts (4.8%, 95% CI: 0-14.1%; P=0.582; Figure 4A). The cumulative incidence of transplantation-related mortality (TRM) was also similar between the ATG-PTCy (2.3%, 95% CI: 0-6.7%) and ATG (0%; P=0.480) cohorts (Figure 4B).

Figure 3.The cumulative incidences of chronic acute graft-versus-host disease between ATG-PTCy and ATG groups. (A) The cumulative incidences of chronic graft-versus-host disease (GVHD) and (B) moderate to severe chronic GVHD. allo-HSCT: allogeneic hematopoietic stem cell transplantation; ATG: anti-thymocyte globulin; PTCy: posttransplant cyclophosphamide.

At 1 year after HSCT, the estimated overall survival rate was 97.7% (95% CI: 93.4-100) for the ATG-PTCy cohort and 83.3% (95% CI: 58.3-100) for the ATG cohort (P=0.666; Figure 5A). The estimated 1-year DFS rates were also similar between the ATG-PTCy and ATG cohorts (95.5% CI: 89.5-100 vs. 95.2%, 95% CI: 86.6-100; P=0.979; Figure 5B). The estimated GRFS was 70.5% (95% CI: 61.0-81.4) for the ATG-PTCy cohort and 79.5±9.4% (95% CI: 66.0-95.5) for the ATG cohort (P=0.422).

Discussion

The optimization of GVHD prevention strategies in haploidentical transplantation has been under continuous exploration. To the best of our knowledge, this is the first prospective randomized controlled study to compare the efficacy of ATG-PTCy versus 10 mg/kg ATG protocols for GVHD prophylaxis. The current interim analysis revealed no statistically significant differences in terms of aGVHD, cGVHD, CMV, EBV, TRM, relapse or survival between the two cohorts.

A series of previous studies failed to reach a consensus on whether PTCy plus low-dose ATG can decrease the incidence of GVHD and improve prognosis compared with PTCy alone. Retrospective comparative studies partially support the notion that PTCy combined with low-dose ATG can reduce acute or cGVHD compared with PTCy alone,6,28-32 but other studies do not support this finding.4 The latest published report from the European Society for Blood and Marrow Transplantation (EBMT) Acute Leukemia Working Party enrolled 3,649 adult AML patients who underwent haplo-HSCT and who received either PTCy (N=2999), ATG (N=358), or combination prophylaxis (N=292). The combination of PTCy and ATG, however, led to significantly decreased rates of grade 2-4 (19.6% vs. 27.5%) and grade 3-4 (6.8% vs. 9.6%) aGVHD but did not affect survival or relapse outcomes compared with PTCy alone.7 Another recent report from the Chinese Bone Marrow Transplantation Registry Group (CBMTRG) compared the clinical outcomes of G-CSF/ ATG (N=572), PTCy (N=123) and PTCy combined with low-dose ATG (N=123). Compared with PTCy alone, PTCy plus ATG was not associated with fewer cases of 2-4 (28.7% vs. 27.9%) or 3-4 aGVHD (13.1% vs. 14.8%). Compared with the PTCy or PTCy plus ATG group, the G-CSF/ATG group led to faster engraftment, lower TRM and greater survival.4 The inconsistency in conclusions from these studies may be related to the differences in the enrolled populations; the various combinations with other drugs, such as calcineurin inhibitors, methotrexate or mycophenolate mofetil; and the retrospective nature of these studies.

Table 2.The CD3, CD4, and CD19 cell immune reconstitution between ATG-PTCy and ATG groups.

Similarly, there are no consistent and definite outcomes concerning whether the addition of PTCy can reduce the incidence of GVHD in the context of an ATG-based protocol. Several studies have indicated that the combination of reduced-dose ATG (5-7.5 mg/kg) and intermediate-dose PTCy (50-80 mg/kg) can reduce the incidence of aGVHD, with some potentially translating into a survival advantage.33-36 Previously, our team published a nationwide mul ticenter prospective clinical study that revealed that the combination of 10 mg/kg rabbit ATG (r-ATG) plus low-dose PTCy (14.5 mg/kg, +3/+4) could significantly reduce GVHD among patients transplanted from maternal donors or collateral relatives who are considered to be at high risk of developing aGVHD.13 The cumulative incidence of 100-day grade 3-4 aGVHD (5% vs. 18%) and TRM (6% vs. 15%) in the prospective ATG-PTCy cohort was significantly lower than that in the 10 mg/kg ATG group from the external control cohort. With respect to the mechanism of low-dose PTCy in combination with ATG, in vivo experiments have suggested that low-dose PTCy is sufficient to decrease aGVHD in a mouse model, partly because of the enhancement of rapid Treg reconstitution.12

Table 3.Humoral immune reconstitution between ATG-PTCy and ATG groups.

Figure 4.The comparisons of relapse and transplantation-related mortality between ATG-PTCy and ATG groups. (A) The cumulative incidence of relapse and (B) transplantation-related mortality (TRM). allo-HSCT: allogeneic hematopoietic stem cell transplantation; ATG: anti-thymocyte globulin; PTCy: posttransplant cyclophosphamide.

Figure 5.The survival outcomes between ATG-PTCy and ATG groups. The estimated rates of (A) overall survival (OS) and (B) disease-free survival (DFS). allo-HSCT: allogeneic hematopoietic stem cell transplantation; ATG: anti-thymocyte globulin; PTCy: posttransplant cyclophosphamide.

Notably, none of the aforementioned studies were prospective randomized controlled trials. Whether the combined strategy is more optimized for GVHD prophylaxis requires higher-level evidence-based medical evidence. In the current prospective randomized controlled study, ATG plus low-dose PTCy failed to decrease aGVHD or cGVHD among patients transplanted from haploidentical donors other than maternal donors or collateral relatives; thus, the trial stopped recruiting at the interim analysis. The reason why ATG-PTCy could reduce GVHD in maternal donors or collateral relatives but not in other haploidentical donors remains unclear. It is speculated that the combination strategy of ATG plus low-dose PTCy might be beneficial for patients at increased risk of developing GVHD. Most likely, transplants from maternal donors or collateral relatives might inherently be different from those from other donors in the reconstruction of T-cell subsets. In addition to defining populations that could benefit, perhaps modulation of the regimens or doses could also have benefit in some settings, which needed further research. Nowadays, the combinations of different doses of ATG and PTCy are being tested, including 6 mg/kg ATG plus 40 mg/kg PTCy as reported.37 Perhaps these different dose combinations are suitable for different populations and transplant scenarios. Whether the combined strategy with double T-cell depletion might delay immune reconstitution and increase the risk of viral infection should be considered. The current study revealed that the combined strategy did not increase the risk of CMV or EBV infection or affect survival outcomes. It is worth noting that 4.5% of patients in the ATG-PTCy cohort had EBV-associated PTLD. The latest published research indicates that letermovir prophylaxis for CMV may increase the risk of EBV-associated PTLD. The incidences of PTLD in the letermovir and the non-letermovir group were 9.9% and 2.6% (P=0.001).38 In the current study, patients routinely received letermovir, which appears to result in a somewhat higher incidence compared to previous observations.

The interim analysis outcomes of the control group are extremely good. It is therefore not possible to expect to design a study with outcomes that would be better than this control group. This limits the interpretation of the study. However, the examination of outcomes at later time points might reveal differences between ATG and ATG with low-dose PT-Cy in addition to the need for randomized studies and studies of dose variation.

In summary, the interim analysis of this prospective multicenter randomized controlled study indicated that the ATG plus low-dose PTCy and ATG cohorts had similar GVHD incidences and survival outcomes, with no additional adverse events. Future work needs to focus on identifying which populations can benefit from the combined strategy, aiming to improve the efficacy of haploidentical donor transplantation among the specific population.

Footnotes

  • Received February 14, 2025
  • Accepted June 6, 2025

Correspondence

Y. Wang ywyw3172@sina.com

Disclosures

No conflicts of interest to disclose.

Contributions

YW X-JH designed the research. Z-LX and YW analyzed the data and wrote the manuscript. All authors provided patient data and gave final approval for the manuscript.

Funding

This work was partly supported by the National Key Research and Development Program of China (no. 2023YFC2508905 & 2022YFA1103300), the National Natural Science Foundation of China (82470214&82270227), Major Program of the National Natural Science Foundation of China (no. 82293630), Beijing Municipal Science & Technology Commission (no. Z211100002921071), Peking University Medicine Fund for world’s leading discipline or discipline cluster development (no. 71003Y3035).

Acknowledgments

The authors would like to thank American Journal Experts for assistance with English editing.

References

  1. Xu ZL, Huang XJ. Haploidentical transplants with a G-CSF/ ATG-based protocol: experience from China. Blood Rev. 2023; 62:101035. Google Scholar
  2. Nagler A, Kanate AS, Labopin M. Post-transplant cyclophosphamide versus anti-thymocyte globulin for graft-versus-host disease prevention in haploidentical transplantation for adult acute lymphoblastic leukemia. Haematologica. 2021; 106(6):1591-1598. Google Scholar
  3. Wang Y, Chang YJ, Chen J. Consensus on the monitoring, treatment, and prevention of leukaemia relapse after allogeneic haematopoietic stem cell transplantation in China: 2024 update. Cancer Lett. 2024; 605:217264. Google Scholar
  4. Xu ZL, Ji J, Wang SB. Clinical outcomes of three haploidentical transplantation protocols for hematologic malignancies based on data from the Chinese Bone Marrow Transplantation Registry Group. Haematologica. 2025; 110(3):629-639. Google Scholar
  5. Dulery R, Brissot E, Mohty M. Combining post-transplant cyclophosphamide with antithymocyte globulin for graft-versus-host disease prophylaxis in hematological malignancies. Blood Rev. 2023; 62:101080. Google Scholar
  6. Makanga DR, Guillaume T, Willem C. Posttransplant cyclophosphamide and antithymocyte globulin versus posttransplant cyclophosphamide as graft-versus-host disease prophylaxis for peripheral blood stem cell haploidentical transplants: comparison of T cell and NK effector reconstitution. J Immunol. 2020; 205(5):1441-1448. Google Scholar
  7. Bazarbachi AH, Labopin M, Raiola AM. Posttransplant cyclophosphamide versus anti-thymocyte globulin versus combination for graft-versus-host disease prevention in haploidentical transplantation for adult acute myeloid leukemia: a report from the European Society for Blood and Marrow Transplantation Acute Leukemia Working Party. Cancer. 2024; 130(18):3123-3136. Google Scholar
  8. Guo H, Li R, Wang M. Multiomics analysis identifies SOCS1 as restraining T cell activation and preventing graft-versus-host disease. Adv Sci (Weinh). 2022; 9(21):e2200978. Google Scholar
  9. Wang Y, Liu QF, Wu DP. Mini-dose methotrexate combined with methylprednisolone for the initial treatment of acute GVHD: a multicentre, randomized trial. BMC Med. 2024; 22(1):176. Google Scholar
  10. Li M, Li Y, Qu Q. Clinical features and prognostic nomogram for therapy-related acute myeloid leukemia after allogeneic hematopoietic stem cell transplantation. Cancer Lett. 2025; 612:217460. Google Scholar
  11. Wang Y, Chang YJ, Xu LP. Who is the best donor for a related HLA haplotype-mismatched transplant?. Blood. 2014; 124(6):843-850. Google Scholar
  12. Wang Y, Chang YJ, Chen L. Low-dose post-transplant cyclophosphamide can mitigate GVHD and enhance the G-CSF/ ATG induced GVHD protective activity and improve haploidentical transplant outcomes. Oncoimmunology. 2017; 6(11):e1356152. Google Scholar
  13. Wang Y, Wu DP, Liu QF. Low-dose post-transplant cyclophosphamide and anti-thymocyte globulin as an effective strategy for GVHD prevention in haploidentical patients. J Hematol Oncol. 2019; 12(1):88. Google Scholar
  14. Chang YJ, Wang Y, Mo XD. Optimal dose of rabbit thymoglobulin in conditioning regimens for unmanipulated, haploidentical, hematopoietic stem cell transplantation: Longterm outcomes of a prospective randomized trial. Cancer. 2017; 123(15):2881-2892. Google Scholar
  15. Chang YJ, Xu LP, Wang Y. Controlled, randomized, open-label trial of risk-stratified corticosteroid prevention of acute graft-versus-host disease after haploidentical transplantation. J Clin Oncol. 2016; 34(16):1855-1863. Google Scholar
  16. Zhang XH, Chen J, Han MZ. The consensus from The Chinese Society of Hematology on indications, conditioning regimens and donor selection for allogeneic hematopoietic stem cell transplantation: 2021 update. J Hematol Oncol. 2021; 14(1):145. Google Scholar
  17. Xu L, Chen H, Chen J. The consensus on indications, conditioning regimen, and donor selection of allogeneic hematopoietic cell transplantation for hematological diseases in China-recommendations from the Chinese Society of Hematology. J Hematol Oncol. 2018; 11(1):33. Google Scholar
  18. Wang Y, Chen H, Chen J. The consensus on the monitoring, treatment, and prevention of leukemia relapse after allogeneic hematopoietic stem cell transplantation in China. Cancer Lett. 2018; 438:63-75. Google Scholar
  19. Machaczka M, Hagglund H, Staver E. G-CSF mobilized peripheral blood stem cell collection for allogeneic transplantation in healthy donors: Analysis of factors affecting yield. J Clin Apher. 2017; 32(6):384-391. Google Scholar
  20. Shier LR, Schultz KR, Imren S. Differential effects of granulocyte colony-stimulating factor on marrow- and blood-derived hematopoietic and immune cell populations in healthy human donors. Biol Blood Marrow Transplant. 2004; 10(9):624-634. Google Scholar
  21. Teipel R, Schetelig J, Kramer M. Prediction of hematopoietic stem cell yield after mobilization with granulocyte-colony-stimulating factor in healthy unrelated donors. Transfusion. 2015; 55(12):2855-2863. Google Scholar
  22. Xu ZL, Huang XJ. Haploidentical transplants with a G-CSF/ ATG-based protocol: Experience from China. Blood Rev. 2023; 62:101035. Google Scholar
  23. Chang YJ, Zhao XY, Xu LP. Donor-specific anti-human leukocyte antigen antibodies were associated with primary graft failure after unmanipulated haploidentical blood and marrow transplantation: a prospective study with randomly assigned training and validation sets. J Hematol Oncol. 2015; 8:84. Google Scholar
  24. Liu J, Zhao XY, Xu LP. The impact of donor-specific anti-HLA antibody levels on primary poor graft function and graft rejection in rituximab desensitized haploidentical stem cell transplantation. HLA. 2024; 103(1):e15300. Google Scholar
  25. Schoemans HM, Lee SJ, Ferrara JL. EBMT-NIH-CIBMTR Task Force position statement on standardized terminology & guidance for graft-versus-host disease assessment. Bone Marrow Transplant. 2018; 53(11):1401-1415. Google Scholar
  26. Jagasia MH, Greinix HT, Arora M. National Institutes of Health Consensus Development Project on criteria for clinical trials in chronic graft-versus-host disease: I. The 2014 Diagnosis and Staging Working Group report. Biol Blood Marrow Transplant. 2015; 21(3):389-401. Google Scholar
  27. Huang T, Xu L, Zhang X. Haploidentical haematopoietic stem cell transplantation for TP53-mutated acute myeloid leukaemia. Br J Haematol. 2023; 200(4):494-505. Google Scholar
  28. El-Cheikh J, Devillier R, Dulery R. Impact of adding antithymocyte globulin to posttransplantation cyclophosphamide in haploidentical stem-cell transplantation. Clin Lymphoma Myeloma Leuk. 2020; 20(9):617-623. Google Scholar
  29. Xue E, Lorentino F, Lupo Stanghellini MT. Addition of a single low dose of anti T-lymphocyte globulin to post-transplant cyclophosphamide after allogeneic hematopoietic stem cell transplant: a pilot study. J Clin Med. 2022; 11(4):1106. Google Scholar
  30. Dulery R, Goudet C, Mannina D. Reduced post-transplant cyclophosphamide doses in haploidentical hematopoietic cell transplantation for elderly patients with hematological malignancies. Bone Marrow Transplant. 2023; 58(4):386-392. Google Scholar
  31. Battipaglia G, Labopin M, Blaise D. Impact of the addition of antithymocyte globulin to post-transplantation cyclophosphamide in haploidentical transplantation with peripheral blood compared to post-transplantation cyclophosphamide alone in acute myelogenous leukemia: a retrospective study on behalf of the acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation. Transplant Cell Ther. 2022; 28(9):587.e1-587.e7. Google Scholar
  32. Jullien M, Le Bourgeois A, Peterlin P. Addition of ATG to non-myeloablative peripheral blood haploidentical transplant with PTCY decreases acute GVHD rates and improves GVHD-relapse free survival. Bone Marrow Transplant. 2023; 58(6):723-726. Google Scholar
  33. Xu X, Yang J, Cai Y. Low dose anti-thymocyte globulin with low dose posttransplant cyclophosphamide (low dose ATG/ PTCy) can reduce the risk of graft-versus-host disease as compared with standard-dose anti-thymocyte globulin in haploidentical peripheral hematopoietic stem cell transplantation combined with unrelated cord blood. Bone Marrow Transplant. 2021; 56(3):705-708. Google Scholar
  34. Barkhordar M, Kasaeian A, Janbabai G. Modified combination of anti-thymocyte globulin (ATG) and post-transplant cyclophosphamide (PTCy) as compared with standard ATG protocol in haploidentical peripheral blood stem cell transplantation for acute leukemia. Front Immunol. 2022; 13:921293. Google Scholar
  35. Cao J, Pei R, Lu Y. Fludarabine and antithymocyte globulin-based conditioning regimen combined with posttransplantation cyclophosphamide for haploidentical allogeneic hematopoietic stem cell transplantation in patients with high-risk acute myeloid leukemia and myelodysplastic syndrome. Curr Res Transl Med. 2023; 71(1):103360. Google Scholar
  36. Hu M, Li J, Hu T. Anti-thymocyte globulin combined with post-transplantation cyclophosphamide reduce graft-versus-host disease in hematopoietic stem cell transplantation for pediatric leukemia. Leuk Lymphoma. 2024; 65(12):1801-1810. Google Scholar
  37. Zu Y, Li Z, Gui R. Low-dose post-transplant cyclophosphamide with low-dose antithymocyte globulin for prevention of graft-versus-host disease in first complete remission undergoing 10/10 HLA-matched unrelated donor peripheral blood stem cell transplants: a multicentre, randomized controlled trial. Bone Marrow Transplant. 2022; 57(10):1573-1580. Google Scholar
  38. Pei XY, Huang Q, Luo LJ. Letermovir prophylaxis for cytomegalovirus is associated with risk of post-transplant lymphoproliferative disorders after haploidentical stem cell transplantation. Haematologica. 2025; 110(4):1005-1009. Google Scholar

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Vol. 110 No. 12 (2025): December, 2025 : Articles
 
DOI
https://doi.org/10.3324/haematol.2025.287504
Pubmed
40534493
 
Published
2025-06-19
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Ferrata Storti Foundation, Pavia, Italy
Print ISSN
0390-6078
Online ISSN
1592-8721
 
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