The role of collateral related donors in haploidentical hematopoietic stem cell transplantation

Prior cytomegalovirus reactivation may lead to worse bacterial bloodstream infection outcomes in HSCT patients

BACKGROUND

Cytomegalovirus (CMV) reactivation is common after transplantation, and may further augment natural killer (NK) cell activity, which has a protective role through both innate and adaptive immune responses. Bacterial bloodstream infections (BBSIs) are a common cause of morbidity and mortality in patients following allo-HSCT. Therefore, we hypothesized that CMV reactivation might play a role in the outcomes of patients with BBSI after allo-HSCT.

OBJECTIVES

We investigated the role of CMV reactivation in the clinical outcomes of patients with BBSI after allo-HSCT.

STUDY DESIGN

A total of 101 BBSI patients (45 non-CMV reactivation [NCR] and 56 CMV reactivation [CR]) were included in the study following allo-HSCT. Clinical and laboratory findings were reviewed, and differences were tested using the Chi-square (χ2) test. Multivariate Cox regression analysis was used to calculate hazard ratios for between-group comparisons of clinical outcomes.

RESULTS

CMV reactivation had a negative prognostic impact on the clinical outcomes of BBSI patients following allo-HSCT with regard to the 1-year overall survival time (HR, 3.583; 95% CI, 1.347-9.533; P = 0.011). In 56 BBSI patients with CMV reactivation following allo-HSCT, the 1-year mortality among those in whom CMV was reactivated first (CRF) was significantly elevated (56.5% vs. 18.2%, P = 0.003) compared with patients in whom the BBSIs occurred first (BOF).

CONCLUSIONS

CMV reactivation in BBSI patients is related to higher mortality 1-year after allo-HSCT. Further studies on a larger cohort are needed to better understanding the mechanism of CMV reactivation influence.

Clinical characteristics and outcomes of allogeneic hematopoietic stem cell transplantation recipients with coronavirus disease 2019 caused by the Omicron variant: a prospective, observational cohort study

We aimed to describe the clinical characteristics, particularly the occurrence and risk factors of severe/critical illness, in allogeneic hematopoietic stem cell (allo-HSCT) recipients infected with coronavirus disease 2019 (COVID-19) caused by Omicron variant in an observational prospective study (n = 311). The median time from allo-HSCT to COVID-19 diagnosis was 8.5 months (range 0.8-106.1) months. Four patients (1.3%) were reported to be asymptomatic during Omicron variant infection, and 135 (43.4%) patients showed lower respiratory tract disease. Thirty-four (10.9%) patients were categorized into serious infection (severe illness n = 25; critical illness n = 9) and the median duration from COVID-19 diagnosis to serious infections was 6 days (range, 0-29) days. Thirteen (4.2%) and 6 (1.9%) patients required intensive care unit care and invasive mechanical ventilation, respectively. Receiving more than 1 type of immunosuppressive therapies at COVID-19 diagnosis was associated with severity and persistence of infection. Six patients (1.9%) died after diagnosis of COVID-19 infection. The 4-week probability of overall survival after COVID-19 diagnosis was 98.7%, which was 100% and 88.2% for non-serious and serious infection group (P < 0.001), respectively. Thus, we observed a relatively low serious infection and mortality rate in allo-HSCT recipients infected with COVID-19 caused by Omicron variant.

Peripheral blood stem cell transplantation from haploidentical related donor could achieve satisfactory clinical outcomes for intermediate- or high-risk adult acute myeloid leukemia patients

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the most important curative method for intermediate- and high-risk adult acute myeloid leukemia (AML) patients. We aimed to identify the clinical outcomes of haploidentical related donor (HID) peripheral blood stem cell transplantation (PBSCT) who receiving peripheral blood (G-PB) harvest, and the patients receiving bone marrow (BM) plus G-PB harvest (BM + PB) as grafts were enrolled as control. The engraftments of neutrophil and platelet in G-PB group were both faster than those in BM + PB group. The cumulative incidences of grade II-IV acute graft-versus-host disease (aGVHD), and moderate to severe chronic GVHD (cGVHD) were all comparable between G-PB and BM + PB groups. The cumulative incidence of relapse and non-relapse mortality at 3 years after HID HSCT was 12.6% versus 13.7% (p = 0.899) and 3.6% versus 7.3% (p = 0.295), respectively, in G-PB and BM + PB group. While the probabilities of GVHD-free/relapse-free survival, leukemia-free survival, and overall survival at 3 years after HID HSCT were 60.6% versus 53.4% (p = 0.333), 83.8% versus 79.0% (p = 0.603), and were 87.3% versus 82.9% (p = 0.670), respectively. We confirmed the safety and efficacy of HID PBSCT in intermediate- and high-risk AML patients in a large cohort.

Similar outcomes following non-first-degree and first-degree related donor haploidentical hematopoietic cell transplantation for acute leukemia patients in complete remission: a study from the Global Committee and the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

There are situations where non-first-degree (NFD) related donors have to be considered as alternatives to first-degree (FD) related donors for haploidentical hematopoietic cell transplantation (HAPLO). However, the efficacy of these NFD related transplants remains uncertain. All consecutive adult patients (≥ 18 years) with acute myelogenous leukemia (AML) or acute lymphocytic leukemia (ALL) in CR who underwent a first HAPLO between 2010 and 2021 in the European Society for Blood and Marrow Transplantation (EBMT) registry were analyzed. Exact matching and propensity score matching was used. The NFD-to-FD ratio was 1:3. 2703 patients (AML: n = 2047; ALL: n = 656) in CR received a first HAPLO from either NFD (n = 154) or FD (n = 2549) related donors in 177 EBMT centers. 123 NFD and 324 FD HAPLO were included for analysis after matching. Median patient age was 35.6 and 37.2 for the NFD and FD cohorts, respectively. Both cohorts reached good engraftment rates (NFD: 95.7% vs. FD, 95.6%; p = 0.78). The 2-year relapse incidence (NFD, 21.1% vs. FD, 22.6%; p = 0.84) and non-relapse mortality (NRM) (NFD, 13.2% vs. FD, 17.7%; p = 0.33) were not significantly different. The 2-year overall survival (OS) (NFD, 71.8% vs. FD, 68.3%; p = 0.56), leukemia-free survival (LFS) (NFD, 65.7% vs. FD, 59.7%; p = 0.6) and graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS) (NFD, 50.9% vs. FD, 47.8%; p = 0.69) also showed no significant differences. The two cohorts showed no difference in terms of cumulative day 180 grade II-IV, grade III-IV acute GVHD, 2-year cumulative incidences of chronic and extensive chronic GVHD. For HAPLO in patients with acute leukemia, NFD related donors could be equivalent substitutions when FD related donors are not available.

Preemptive interferon-α therapy could prevent relapse of acute myeloid leukemia following allogeneic hematopoietic stem cell transplantation: A real-world analysis

Introduction

Measurable residual disease (MRD)-directed interferon-a treatment (i.e. preemptive IFN-α treatment) can eliminate the MRD in patients with acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Therefore, this study aimed to further assess its efficacy in a multicenter retrospective study in a real-world setting.

Methods

A total of 247 patientswho received preemptive IFN-α treatment were recruited from 4 hospitals in China. The protocols for MRD monitoring mainly based on quantitative polymerase chain reaction [qPCR] and multiparameter flow cytometry [MFC].

Results

The median duration of IFN-α treatment was 56 days (range, 1-1211 days). The cumulative incidences of all grades acute graft-versus-host disease (aGVHD), all grades chronic graft-versus-host disease (cGVHD), and severe cGVHD at 3 years after IFN-α therapy were 2.0% (95% confidence interval [CI], 0.3-3.8%), 53.2% (95% CI, 46.8-59.7%), and 6.2% (95% CI, 3.1-9.2%), respectively. The cumulative incidence of achieving MRD negative state at 2 years after IFN-α treatment was 78.2% (95% CI, 72.6-83.7%). The 3-year cumulative incidences of relapse and non-relapse mortality following IFN-α therapy were 20.9% (95% CI, 15.5-26.3%) and 4.9% (95%CI, 2.0-7.7%), respectively. The probabilities of leukemia-free survival and overall survival at 3 years following IFN-α therapy were 76.9% (95% CI, 71.5-82.7%) and 84.2% (95% CI, 78.7-90.1%), respectively. Multivariable analysis showed that MRD positive state by qPCR and MFC before IFN-α treatment, high-risk disease risk index before allo-HSCT, and receiving identical sibling donor HSCT were associated with a higher risk of relapse and a poorer leukemia-free survival. Severe cGVHD was associated with an increased risk of non-relapse mortality.

Discussion

Thus, real-world data suggest that preemptive IFN-α is effective for treating patients with AML with MRD after allo-HSCT.

Impact of second-degree related donor on the outcomes of T cell-replete haploidentical transplantation with post-transplant cyclophosphamide

Donor selection may contribute to improve clinical outcomes of T cell-replete haploidentical stem cell transplantation (Haplo-SCT) with post-transplant cyclophosphamide (PT-Cy). Impact of second-degree related donor (SRD) was not fully elucidated in this platform. We retrospectively compared the outcome of patients receiving Haplo-SCT either from a SRD (n = 31) or a first-degree related donor (FRD, n = 957). Median time to neutrophil and platelet recovery did not differ between a SRD and a FRD transplant (p = 0.599 and 0.587). Cumulative incidence of grade II-IV acute graft-versus host disease (GVHD) and moderate-severe chronic GVHD was 13% and 19% after SRD vs 24% (p = 0.126) and 13% (p = 0.395) after FRD transplant. One-year cumulative incidence of non-relapse mortality (NRM) was 19% for SRD and 20% for FRD (p = 0.435) cohort. The 3-year probability of overall survival (OS) and progression-free survival (PFS) was 42% vs 55% (p = 0.273) and 49% vs 35% (p = 0.280) after SRD and FRD transplant, respectively. After propensity score adjustment or matched pair analysis, the outcome of patients receiving Haplo-SCT from a SRD or a FRD did not differ in terms of NRM, OS, PFS, acute and chronic GVHD. Our results suggest that a SRD is a viable option for Haplo-SCT with PT-Cy when a FRD is not available.

A comprehensive model to predict severe acute graft-versus-host disease in acute leukemia patients after haploidentical hematopoietic stem cell transplantation

BACKGROUND

Acute graft-versus-host disease (aGVHD) remains the major cause of early mortality after haploidentical related donor (HID) hematopoietic stem cell transplantation (HSCT). We aimed to establish a comprehensive model which could predict severe aGVHD after HID HSCT.

METHODS

Consecutive 470 acute leukemia patients receiving HID HSCT according to the protocol registered at https://clinicaltrials.gov (NCT03756675) were enrolled, 70% of them (n = 335) were randomly selected as training cohort and the remains 30% (n = 135) were used as validation cohort.

RESULTS

The equation was as follows: Probability (grade III-IV aGVHD) = [Formula: see text], where Y = -0.0288 × (age) + 0.7965 × (gender) + 0.8371 × (CD3 + /CD14 + cells ratio in graft) + 0.5829 × (donor/recipient relation) - 0.0089 × (CD8 + cell counts in graft) - 2.9046. The threshold of probability was 0.057392 which helped separate patients into high- and low-risk groups. The 100-day cumulative incidence of grade III-IV aGVHD in the low- and high-risk groups was 4.1% (95% CI 1.9-6.3%) versus 12.8% (95% CI 7.4-18.2%) (P = 0.001), 3.2% (95% CI 1.2-5.1%) versus 10.6% (95% CI 4.7-16.5%) (P = 0.006), and 6.1% (95% CI 1.3-10.9%) versus 19.4% (95% CI 6.3-32.5%) (P = 0.017), respectively, in total, training, and validation cohort. The rates of grade III-IV skin and gut aGVHD in high-risk group were both significantly higher than those of low-risk group. This model could also predict grade II-IV and grade I-IV aGVHD.

CONCLUSIONS

We established a model which could predict the development of severe aGVHD in HID HSCT recipients.

A Predicted Model for Refractory/Recurrent Cytomegalovirus Infection in Acute Leukemia Patients After Haploidentical Hematopoietic Stem Cell Transplantation

Objective

We aimed to establish a model that can predict refractory/recurrent cytomegalovirus (CMV) infection after haploidentical donor (HID) hematopoietic stem cell transplantation (HSCT).

Methods

Consecutive acute leukemia patients receiving HID HSCT were enrolled (n = 289). We randomly selected 60% of the entire population (n = 170) as the training cohort, and the remaining 40% comprised the validation cohort (n = 119). Patients were treated according to the protocol registered at https://clinicaltrials.gov (NCT03756675).

Results

The model was as follows: Y = 0.0322 × (age) - 0.0696 × (gender) + 0.5492 × (underlying disease) + 0.0963 × (the cumulative dose of prednisone during pre-engraftment phase) - 0.0771 × (CD34+ cell counts in graft) - 1.2926. The threshold of probability was 0.5243, which helped to separate patients into high- and low-risk groups. In the low- and high-risk groups, the 100-day cumulative incidence of refractory/recurrent CMV was 42.0% [95% confidence interval (CI), 34.7%-49.4%] vs. 63.7% (95% CI, 54.8%-72.6%) (P < 0.001) for total patients and was 50.5% (95% confidence interval (CI), 40.9%-60.1%) vs. 71.0% (95% CI, 59.5%-82.4%) (P = 0.024) for those with acute graft-versus-host disease. It could also predict posttransplant mortality and survival.

Conclusion

We established a comprehensive model that could predict the refractory/recurrent CMV infection after HID HSCT.

Clinical Trial Registration

https://clinicaltrials.gov, identifier NCT03756675.

Preemptive Interferon-α Therapy Could Protect Against Relapse and Improve Survival of Acute Myeloid Leukemia Patients After Allogeneic Hematopoietic Stem Cell Transplantation: Long-Term Results of Two Registry Studies

For allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients, preemptive interferon-α (IFN-α) therapy is considered as a useful method to eliminate the minimal residual disease (MRD). Our purpose is to assess the long-term efficacy of preemptive IFN-α therapy in acute myeloid leukemia (AML) patients following allo-HSCT based on two registry studies (#NCT02185261 and #NCT02027064). We would present the final data and unpublished results of long-term clinical outcomes with extended follow-up. We adopted polymerase chain reaction (PCR) and multiparameter flow cytometry (MFC) to monitor MRD, and a positive result of bone marrow specimen examined by either of them would be identified as the MRD-positive status. Subcutaneous injections of recombinant human IFN-α-2b were performed for 6 cycles, and prolonged IFN-α therapy could be permitted at the request of patients. The median cycles were 3.5 (range, 0.5-30.5) cycles. A total of 9 patients suffered from grade ≥3 toxicities (i.e., infectious: n = 6; hematologic: n = 3). The 6-year cumulative incidences of relapse and non-relapse mortality following IFN-α therapy were 13.0% (95% confidence interval [CI], 5.4-20.6%) and 3.9% (95%CI, 0.0-17.6%), respectively. The probability of disease-free survival at 6 years following IFN-α therapy was 83.1% (95%CI, 75.2-91.9%). The probability of overall survival at 6 years following IFN-α therapy was 88.3% (95%CI, 81.4-95.8%). The cumulative incidences of total chronic graft-versus-host disease (cGVHD) and severe cGVHD at 6 years following IFN-α therapy were 66.2% (95%CI, 55.5-77.0%) and 10.4% (95%CI, 3.6-17.2%), respectively. Multivariable analysis showed that an alternative donor was associated with a lower risk of relapse and the better disease-free survival. Thus, preemptive IFN-α therapy could clear MRD persistently, prevent relapse truly, and improve long-term survival in AML patients following allo-HSCT.

Efficacy and safety of mesenchymal stem cells treatment for multidrug-resistant graft-versus-host disease after haploidentical allogeneic hematopoietic stem cell transplantation

PURPOSE

Graft-versus-host disease (GVHD) is an important complication after human leukocyte antigen (HLA) haploidentical donor (HID) hematopoietic stem cell transplantation (HSCT), which may lead to poor prognosis. Our study intends to identify the efficacy and safety of mesenchymal stem cells (MSCs) for multidrug-resistant (MDR)-GVHD after HID HSCT.

METHODS

MDR-GVHD was referring to GVHD remaining no response to at least two types of therapy, and hUCB-MSCs were given at the dose of (1.0-2.0) × 106/kg once a week.

RESULTS

A total of 21 patients were enrolled in this retrospective study (acute GVHD (aGVHD): n = 14, chronic GVHD (cGVHD): n = 7). The median dose of MSCs was 1.2 × 106 cells/kg (range, 0.8-1.8 × 106) cells/kg, and the median numbers of infusion were 2 (range, 1-7) and 3 (range, 2-12) for MDR-aGVHD and MDR-cGVHD patients, respectively. In MDR-aGVHD patients, the overall response rate (ORR) was 57.1%, including 50.0% complete response (CR) and 7.1% partial response (PR), and the median time to response was 49.5 days (range, 16-118) days. The 2-year probability of overall survival after MSCs was 64.3%. Five patients (35.7%) developed infections after MSCs, and no obvious hematologic toxicities were observed. Five MDR-aGVHD patients died after MSCs treatments because of GVHD progression (n = 1), severe infection (bacterial central nervous system infection: n = 1; fungal pneumonia: n = 2), and poor graft function (n = 1). In MDR-cGVHD patients, three patients (42.9%) achieved PR after MSCs and the median time to response was 56 days (22-84) days. The ORRs for moderate and severe cGVHD were 50.0% and 33.3%, respectively. Four MDR-cGVHD patients died after MSCs treatments because of GVHD progression (n = 2), severe fungal pneumonia (n = 1), and relapse (n = 1).

CONCLUSION

MSCs treatment may be safe and effective for MDR-GVHD after HID HSCT.

Preemptive Immunotherapy for Minimal Residual Disease in Patients With t(8;21) Acute Myeloid Leukemia After Allogeneic Hematopoietic Stem Cell Transplantation

In patients with t(8;21) acute myeloid leukemia (AML), recurrent minimal residual disease (MRD) measured by RUNX1-RUNX1T1 transcript levels can predict relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT). This study aimed to compare the efficacy of preemptive interferon (IFN)-α therapy and donor lymphocyte infusion (DLI) in patients with t(8;21) AML following allo-HSCT. We also evaluated the appropriate method for patients with different levels of RUNX1-RUNX1T1 transcripts. In this retrospective study, consecutive patients who had high-risk t(8;21) AML and received allo-HSCT were enrolled. The inclusion criteria were as follows: (1) age ≤65 years; (2) regained MRD positive following allo-HSCT. MRD positive was defined as the loss of a ≥4.5-log reduction and/or <4.5-log reduction in the RUNX1-RUNX1T1 transcripts, and high-level, intermediate-level, and low-level MRDs were, respectively, defined as <2.5-log, 2.5-3.5-log, and 3.5-4.5-log reductions in the transcripts compared with the pretreatment baseline level. Patients with positive RUNX1-RUNX1T1 could receive preemptive IFN-α therapy or DLI, which was primarily based on donor availability and the intentions of physicians and patients. The patients received recombinant human IFN-α-2b therapy by subcutaneous injection twice a week every 4 weeks. IFN-α therapy was scheduled for six cycles or until the RUNX1-RUNX1T1 transcripts were negative for at least two consecutive tests. The rates of MRD turning negative for patients with low-level, intermediate-level, and high-level RUNX1-RUNX1T1 receiving IFN-α were 87.5%, 58.1%, and 22.2%, respectively; meanwhile, for patients with intermediate-level and high-level RUNX1-RUNX1T1 receiving DLI, the rates were 50.0% and 14.3%, respectively. For patients with low-level and intermediate-level RUNX1-RUNX1T1, the probability of overall survival at 2 years was higher in the IFN-α group than in the DLI group (87.6% vs. 55.6%; p = 0.003). For patients with high levels of RUNX1-RUNX1T1, the probability of overall survival was comparable between the IFN-α and DLI groups (53.3% vs. 83.3%; p = 0.780). Therefore, patients with low-level and intermediate-level RUNX1-RUNX1T1 could benefit more from preemptive IFN-α therapy compared with DLI. Clinical outcomes were comparable between preemptive IFN-α therapy and DLI in patients with high-level RUNX1-RUNX1T1; however, they should be further improved.

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

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

Optimizing antithymocyte globulin dosing in haploidentical hematopoietic cell transplantation: long-term follow-up of a multicenter, randomized controlled trial

Given that randomized studies testing the long-term impact of antithymocyte globulin (ATG) dosing are scarce, we report the results of an extended follow-up from the original trial. In our prospective, multicenter, randomized trial, 408 leukemia patients 14-65 years of age who underwent haploidentical hematopoietic cell transplantation (haplo-HCT) under our original "Beijing Protocol" were randomly assigned one-to-one to ATG doses of 7.5 mg/kg (n = 203, ATG-7.5) or 10 mg/kg (n = 205, ATG-10.0) at four sites. Extended follow-up (median 1968 d (range: 1300-2710 d) indicated comparable 5-year probabilities of moderate-to-severe chronic graft-versus-host disease (GVHD) (hazard ratio (HR): 1.384, 95% confidence interval (CI): 0.876-2.189, P = 0.164), nonrelapse mortality (HR: 0.814, 95% CI: 0.526-1.261, P = 0.357), relapse (HR: 1.521, 95% CI: 0.919-2.518, P = 0.103), disease-free survival (HR: 1.074, 95% CI: 0.783-1.473, P = 0.658), and GVHD-free/relapse-free survival (HR: 1.186, 95% CI: 0.904-1.555, P = 0.219) between groups (ATG-7.5 vs. ATG-10.0). The 5-year rate of late effects did not differ significantly. However, the cytomegalovirus/Epstein-Barr virus-related death rate was much higher in the ATG-10.0 cohort than in the ATG-7.5 cohort (9.8% vs. 1.5%; P = 0.003). In summary, patients undergoing haplo-HCT benefit from 7.5 mg/kg ATG compared to 10.0 mg/kg ATG based on a balance between GVHD and infection control. ATG (7.5 mg/kg) is potentially regarded as the standard regimen in the platform. These results support the optimization of ATG use in the "Beijing Protocol", especially considering the potential economic advantage in developing countries.

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

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

Association Between Measurable Residual Disease in Patients With Intermediate-Risk Acute Myeloid Leukemia and First Remission, Treatment, and Outcomes

Importance

Measurable residual disease (MRD) is widely used as a therapy-stratification factor for acute myeloid leukemia (AML), but the association of dynamic MRD with postremission treatment (PRT) in patients with intermediate-risk AML (IR-AML) has not been well investigated.

Objective

To investigate PRT choices based on dynamic MRD in patients with IR-AML.

Design, Setting, and Participants

This cohort study examined 549 younger patients with de novo IR-AML in the South China Hematology Alliance database during the period from January 1, 2012, to June 30, 2016, including 154 who received chemotherapy, 116 who received an autologous stem cell transplant (auto-SCT), and 279 who received an allogeneic SCT (allo-SCT). Subgroup analyses were performed according to dynamic MRD after the first, second, and third courses of chemotherapy. The end point of the last follow-up was August 31, 2020. Statistical analysis was performed from December 1, 2019, to September 30, 2020.

Exposures

Receipt of chemotherapy, auto-SCT, or allo-SCT.

Main Outcomes and Measures

The primary end points were 5-year cumulative incidence of relapse and leukemia-free survival.

Results

Subgroup analyses were performed for 549 participants (314 male participants [57.2%]; median age, 37 years [range, 14-60 years]) according to the dynamics of MRD after 1, 2, or 3 courses of chemotherapy. Comparable cumulative incidences of relapse, leukemia-free survival, and overall survival were observed among participants who had no MRD after 1, 2, or 3 courses of chemotherapy. Participants who underwent chemotherapy and those who underwent auto-SCT had better graft-vs-host disease-free, relapse-free survival (GRFS) than those who underwent allo-SCT (chemotherapy: hazard ratio [HR], 0.35 [95% CI, 0.14-0.90]; P = .03; auto-SCT: HR, 0.07 [95% CI, 0.01-0.58]; P = .01). Among participants with MRD after 1 course of chemotherapy but no MRD after 2 or 3 courses, those who underwent auto-SCT and allo-SCT showed lower cumulative incidence of relapse (auto-SCT: HR, 0.25 [95% CI, 0.08-0.78]; P = .01; allo-SCT: HR, 0.08 [95% CI, 0.02-0.24]; P < .001), better leukemia-free survival (auto-SCT: HR, 0.26 [95% CI, 0.10-0.64]; P = .004; allo-SCT: HR, 0.21 [95% CI, 0.09-0.46]; P < .001), and overall survival (auto-SCT: HR, 0.22 [95% CI, 0.08-0.64]; P = .005; allo-SCT: HR, 0.25 [95% CI, 0.11-0.59]; P = .001) vs chemotherapy. In addition, auto-SCT showed better GRFS than allo-SCT (HR, 0.45 [95% CI, 0.21-0.98]; P = .04) in this group. Among participants with MRD after 1 or 2 courses of chemotherapy but no MRD after 3 courses, allo-SCT had superior cumulative incidence of relapse (HR, 0.10 [95% CI, 0.06-0.94]; P = .04) and leukemia-free survival (HR, 0.18 [95% CI, 0.05-0.68]; P = .01) compared with chemotherapy, but no advantageous cumulative incidence of relapse (HR, 0.15 [95% CI, 0.02-1.42]; P = .10) and leukemia-free survival (HR, 0.23 [95% CI, 0.05-1.08]; P = .06) compared with auto-SCT. Among participants with MRD after 3 courses of chemotherapy, allo-SCT had superior cumulative incidences of relapse, leukemia-free survival, and overall survival compared with chemotherapy (relapse: HR, 0.16 [95% CI, 0.08-0.33]; P < .001; leukemia-free survival: HR, 0.19 [95% CI, 0.10-0.35]; P < .001; overall survival: HR, 0.29 [95% CI, 0.15-0.55]; P < .001) and auto-SCT (relapse: HR, 0.25 [95% CI, 0.12-0.53]; P < .001; leukemia-free survival: HR, 0.35 [95% CI, 0.18-0.73]; P = .004; overall survival: HR, 0.54 [95% CI, 0.26-0.94]; P = .04). Among participants with recurrent MRD, allo-SCT was also associated with advantageous cumulative incidence of relapse, leukemia-free survival, and overall survival compared with chemotherapy (relapse: HR, 0.12 [95% CI, 0.04-0.33]; P < .001; leukemia-free survival: HR, 0.24 [95% CI, 0.10-0.56]; P = .001; overall survival: HR, 0.31 [95% CI, 0.13-0.75]; P = .01) and auto-SCT (relapse: HR, 0.28 [95% CI, 0.09-0.81]; P = .02; leukemia-free survival: HR, 0.30 [95% CI, 0.12-0.76]; P = .01; overall survival: HR, 0.26 [95% CI, 0.10-0.70]; P = .007).

Conclusions and Relevance

This study suggests that clinical decisions based on dynamic MRD might be associated with improved therapy stratification and optimized PRT for patients with IR-AML. Prospective multicenter trials are needed to further validate these findings.

M2 macrophages, but not M1 macrophages, support megakaryopoiesis by upregulating PI3K-AKT pathway activity

Dysfunctional megakaryopoiesis hampers platelet production, which is closely associated with thrombocytopenia (PT). Macrophages (MФs) are crucial cellular components in the bone marrow (BM) microenvironment. However, the specific effects of M1 MФs or M2 MФs on regulating megakaryocytes (MKs) are largely unknown. In the current study, aberrant BM-M1/M2 MФ polarization, characterized by increased M1 MФs and decreased M2 MФs and accompanied by impaired megakaryopoiesis-supporting abilities, was found in patients with PT post-allotransplant. RNA-seq and western blot analysis showed that the PI3K-AKT pathway was downregulated in the BM MФs of PT patients. Moreover, in vitro treatment with PI3K-AKT activators restored the impaired megakaryopoiesis-supporting ability of MФs from PT patients. Furthermore, we found M1 MФs suppress, whereas M2 MФs support MK maturation and platelet formation in humans. Chemical inhibition of PI3K-AKT pathway reduced megakaryopoiesis-supporting ability of M2 MФs, as indicated by decreased MK count, colony-forming unit number, high-ploidy distribution, and platelet count. Importantly, genetic knockdown of the PI3K-AKT pathway impaired the megakaryopoiesis-supporting ability of MФs both in vitro and in a MФ-specific PI3K-knockdown murine model, indicating a critical role of PI3K-AKT pathway in regulating the megakaryopoiesis-supporting ability of M2 MФs. Furthermore, our preliminary data indicated that TGF-β released by M2 MФs may facilitate megakaryopoiesis through upregulation of the JAK2/STAT5 and MAPK/ERK pathways in MKs. Taken together, our data reveal that M1 and M2 MФs have opposing effects on MKs in a PI3K-AKT pathway-dependent manner, which may lead to new insights into the pathogenesis of thrombocytopenia and provide a potential therapeutic strategy to promote megakaryopoiesis.

Hepatitis B Seropositive Status in Recipients or Donors Is Not Related to Worse Outcomes after Haploidentical Hematopoietic Stem Cell Transplantation

Hepatitis B virus (HBV) has a high rate of chronic infection in Asian populations, and only limited studies have been performed to analyze the impact of HBV-seropositive haploidentical hematopoietic stem cell transplantation (haplo-HSCT) recipients and donors. The present study aimed to evaluate the effect on clinical outcomes in those patients. We conducted a retrospective study enrolling 237 consecutive patients undergoing first haplo-HSCT. The patients were classified into 3 groups: recipient HBV-positive group (R+D-; n = 62), donor HBV-positive group (D+; n = 83), and HBV-negative group (R-D-; n = 92). Corresponding prophylactic antiviral treatment was given in the R+D- and D+ groups. The results were compared among the 3 groups using the Kruskal-Wallis test for continuous variables, Pearson's chi-square test for categorical variables, the competing-risk method to evaluate cumulative incidence, Kaplan-Meier curves to estimate overall survival (OS) and disease-free survival (DFS), and a Cox proportional hazard model to analyze multivariable influences. The 3-year cumulative HBV reactivation rate was 4.2%. The median time to HBV reactivation was 845 days (range, 545 to 1439 days) after haplo-HSCT. The R+D- group tended to have a higher cumulative incidence of HBV reactivation compared with the D+ group (11.8% versus 3.1%; P = .080). Significant differences in the causes of hepatic damage were observed among the 3 groups (P = .017), and all patients with acute hepatitis B after haplo-HSCT were from the R+D- group. Multivariate analysis showed that pretransplantation HBV status was associated with cytomegalovirus reactivation (R+D- versus R-D-: hazard ratio, 1.514; 95% confidence interval, 1.060 to 2.163; P = .023). The 3-year OS and DFS, 3-year cumulative incidence of nonrelapse mortality (NRM), rates of relapse and graft-versus-host disease (GVHD), and causes of death were comparable among the 3 groups. Pretransplantation HBV serostatus had no significant effect on OS, DFS, NRM, relapse, or GVHD in the multivariate analysis. Based on our data, seropositivity for hepatitis B surface antigen (HbsAg) or core antibody (HBcAb) in donors or recipients before transplantation did not negatively affect the overall outcome after haplo-HSCT under the premise of proper antiviral prophylaxis along with regular post-transplantation surveillance, and HBV seropositivity should not be considered a contraindication to haplo-HSCT.

Wilms' tumor gene 1 is an independent prognostic factor for pediatric acute myeloid leukemia following allogeneic hematopoietic stem cell transplantation

BACKGROUND

Sequential monitoring of Wilms' tumor gene 1 (WT1) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) could predict relapse in adult acute myeloid leukemia (AML). However, the prognostic role of WT1 in pediatric AML after allo-HSCT is unclear. Thus, we determined to see whether sequential monitoring of WT1 after allo-HSCT could predict relapse in AML children.

METHODS

Pediatric AML patients receiving allo-HSCT from January 21, 2012 to December 20, 2018 at the Peking University Institute of Hematology were included in this study. WT1 expression level was determined by TaqMan-based reverse transcription-polymerase chain reaction. WT1 sequential monitoring was performed 1, 2, 3, 4.5, 6, 9, and 12 months post-transplantation and at 6-month intervals thereafter. The primary end point was relapse. The secondary end points included disease-free survival (DFS), overall survival (OS), and non-relapse mortality (NRM). Kaplan-Meier analysis was used for DFS and OS estimates, while competing risk analysis was used for estimating relapse and NRM.

RESULTS

Of the 151 consecutive patients included, the median age was 10 years (range, 1-17). The optimal cutoff value of WT1 within 1 year after allo-HSCT to predict relapse was 0.8% (80 WT1 copies/104 ABL copies), with a sensitivity of 60% and specificity of 79%. Compared with WT1 expression < 0.8%, WT1 expression ≥0.8% indicated significantly higher 5-year cumulative incidence of relapse (CIR, 35.1% vs. 11.3%; P = 0.001), lower 5-year disease-free survival (DFS, 60.4% vs. 80.8%; P = 0.009), and lower 5-year overall survival (OS, 64.9% vs. 81.6%; P = 0.038) rates. Multivariate analyses showed that WT1 was an independent risk factor for relapse (HR 2.89; 95% confidence interval (CI), 1.25-6.71; P = 0.014). Both the CIR (5-year CIR: 8.3% vs. 11.3%; P = 0.513) and DFS (5-year DFS: 91.7% vs. 80.8%; P = 0.208) were comparable between patients achieving minimal residual disease (MRD) negativity after preemptive interferon-α (IFN-α) treatment and those without MRD after allo-HSCT, which were better than those of MRD-positive patients without preemptive therapies.

CONCLUSIONS

Sequential monitoring of WT1 could predict relapse in pediatric AML after allo-HSCT. WT1-directed immunotherapy may have the potential to prevent relapse and improve survival.

G-CSF-Primed Peripheral Blood Stem Cell Haploidentical Transplantation Could Achieve Satisfactory Clinical Outcomes for Acute Leukemia Patients in the First Complete Remission: A Registered Study

G-CSF-mobilized peripheral blood (G-PB) harvest is the predominant graft for identical sibling donor and unrelated donor allogeneic hematopoietic stem cell transplantation (HSCT) recipients, but it was controversial in haploidentical related donor (HID) HSCT. In this registry study, we aimed to identify the efficacy of HID G-PB HSCT (HID-PBSCT) for acute leukemia (AL) patients in first complete remission (CR1). Also, we reported the outcomes for the use of G-PB grafts in comparison with the combination of G-BM and G-PB grafts in HID HSCT recipients. Sixty-seven AL patients in CR1 who received HID-PBSCT were recruited at Institute of Hematology, Peking University. Patients who received haploidentical HSCT using the combination of G-BM and G-PB harvests in the same period were enrolled as controls (n=392). The median time from HSCT to neutrophil and platelet engraftment was 12 days (range, 9-19 days) and 12 days (range, 8-171 days), respectively. The 28-day cumulative incidence of neutrophil and platelet engraftment after HSCT was 98.5% and 95.5%, respectively. The cumulative incidences of grade II-IV and grade III-IV acute graft-versus-host disease (GVHD) were 29.9% (95%CI 18.8-40.9%) and 7.5% (95%CI 1.1-13.8%), respectively. The cumulative incidences of total and moderate-severe chronic GVHD were 54.9% (95%CI 40.9-68.8%) and 17.4% (95%CI 6.7-28.0%), respectively. The cumulative incidences of relapse and non-relapse mortality were 13.9% (95%CI 5.4-22.5%) and 3.4% (95%CI 0-8.1%), respectively. The probabilities of overall survival (OS) and leukemia-free survival (LFS) were 84.7% (95%CI 74.7-94.7%) and 82.7% (95%CI 73.3-92.1%) respectively. Compared with the HID HSCT recipients using the combination of G-BM and G-PB grafts, the engraftments of neutrophil and platelet were both significantly faster for the G-PB group, and the other clinical outcomes were all comparable between the groups. In multivariate analysis, graft types did not influence the clinical outcomes. Overall, for the patients with AL CR1, G-PB graft could be considered an acceptable graft for HID HSCT recipients. This study was registered at https://clinicaltrials.gov as NCT03756675.

Minimal residual disease monitoring and preemptive immunotherapies for frequent 11q23 rearranged acute leukemia after allogeneic hematopoietic stem cell transplantation

The prognosis of 11q23/KMT2A-rearranged (KMT2A-r) acute leukemia (AL) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is poor. Minimal residual disease (MRD) is an important prognostic factor for relapse. Thus, we aimed to identify the evolution of KMT2A before and after allo-HSCT and the efficacy of preemptive immunotherapies for KMT2A-r AL patients receiving allo-HSCT. KMT2A expression was determined through TaqMan-based RQ-PCR technology. Preemptive immunotherapies included interferon-α and donor lymphocyte infusion. We collected 1751 bone marrow samples from 177 consecutive KMT2A-r AL patients. Pre-HSCT KMT2A positivity was correlated with post-HSCT KMT2A positivity (correlation coefficient=0.371, P<0.001). The rates of achieving KMT2A negativity after allo-HSCT were 96.6%, 92.9%, and 68.8% in the pre-HSCT low-level group (>0, <0.1%), intermediate-level group (≥ 0.1%, <1%), and high-level group (≥1%), respectively. The rates of regaining KMT2A positivity after allo-HSCT were 7.7%, 35.7%, 38.5%, and 45.5% for the pre-HSCT KMT2A-negative, low-level, intermediate-level, and high-level groups, respectively (P<0.001). The 4-year cumulative incidence of relapse after allo-HSCT was as high as 53.7% in the pre-HSCT KMT2A expression ≥ 0.1% group, which was compared to the KMT2A-negative group (15.1%) and KMT2A <0.1% group (31.2%). The clinical outcomes of patients with post-HSCT KMT2A positivity were poorer than those of patients with persistent KMT2A negativity. Although post-HSCT preemptive immunotherapies might help to achieve KMT2A negativity, the long-term efficacy was unsatisfactory. Thus, pre-HSCT KMT2A positivity was significantly associated with post-HSCT KMT2A positivity. The clinical outcomes of patients with post-HSCT KMT2A positivity were poor, which might not be overcome by commonly used immunotherapies.

Preemptive interferon-α treatment could protect against relapse and improve long-term survival of ALL patients after allo-HSCT

Relapse was the major cause of treatment failure in patients with acute lymphoblastic leukemia (ALL) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We aimed to identify the efficacy and safety of preemptive interferon-α (IFN-α) treatment in ALL patients who had minimal residual disease (MRD) after allo-HSCT. Multiparameter flow cytometry and polymerase chain reaction assays were applied for MRD monitoring. Recombinant human IFN-α-2b injections were administered subcutaneously twice weekly in every 4 weeks cycle. Twenty-four (35.3%), 5 (7.4%), 6 (8.8%), and 13 (19.1%) patients achieved MRD negativity at 1, 2, 3, and > 3 months, respectively, after treatment. Seven patients showed grade ≥ 3 toxicities after IFN-α treatment. The 4-year cumulative incidence of total acute graft-versus-host disease (aGVHD), severe aGVHD, total chronic GVHD (cGVHD), and severe cGVHD after treatment was 14.7%, 2.9%, 40.0%, and 7.5%, respectively. The 4-year cumulative incidences of relapse and non-relapse mortality after treatment was 31.9% and 6.0%, respectively. The 4-year probabilities of disease-free survival and overall survival after IFN-α treatment were 62.1% and 71.1%, respectively. Thus, preemptive IFN-α treatment could protect against relapse and improve long-term survival for ALL patients who had MRD after allo-HSCT. The study was registered at https://clinicaltrials.gov as #NCT02185261 (09/07/2014).

Ruxolitinib is an effective salvage treatment for multidrug-resistant graft-versus-host disease after haploidentical allogeneic hematopoietic stem cell transplantation without posttransplant cyclophosphamide

The purpose of our study is to identify the efficacy of ruxolitinib in human leukocyte antigen (HLA) haploidentical hematopoietic stem cell transplantation (haplo-HSCT) recipients with multidrug-resistant (MDR)-graft-versus-host disease (GVHD, n = 34). MDR-GVHD was defined as GVHD showing no improvement after at least 3 types of treatments. The median number of previous GVHD-therapies was 4 for both MDR-acute GVHD (aGVHD) and MDR-chronic GVHD (cGVHD). For MDR-aGVHD (n = 15), the median time to response was 10 days (range 2 to 65), and the overall response rate (ORR) was 60.0% (9/15), including 40.0% (6/15) complete response (CR) and 20.0% (3/15) partial response (PR). The 1-year probability of overall survival after ruxolitinib was 66.7%. The rates of hematologic and infectious toxicities were 73.3% and 46.7% after ruxolitinib treatment. For MDR-cGVHD (n = 19), the median time to response was 29 days (range 6 to 175), and the ORR was 89.5% (17/19), including 26.3% (5/19) CR and 63.2% (12/19) PR. All patients remained alive until our last follow-up. The rates of hematologic and infectious toxicities were 36.8% and 47.4% after ruxolitinib treatment. Ruxolitinib is an effective salvage treatment for MDR-GVHD in haplo-HSCT recipients.

Prognostic factors and long-term follow-up of basiliximab for steroid-refractory acute graft-versus-host disease: Updated experience from a large-scale study

Acute graft-vs-host disease (aGVHD) is one of the most important causes of early mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT), particularly for those with steroid-refractory (SR)-aGVHD. We aimed to identify the prognostic factors and long-term clinical outcomes of basiliximab treatment for SR-aGVHD. Basiliximab was administered on days 1, 3, and 8, and repeated weekly until aGVHD was less than grade II, or patients showed no response after four doses. Out of 1498 patients receiving allo-HSCT, 230 patients with SR-aGVHD were enrolled. Grade III to IV aGVHD before basiliximab treatment significantly and independently predicted a poorer response to basiliximab in multivariate analysis. And, the cumulative incidence of overall response at 14 days, 28 days, and 56 days after treatment was 41.4% vs 23.1% (P = .023), 70.2% vs 43.6% (P = .002), and 80.1% vs 66.7% (P = .013), respectively. This was for those with grade II and grade III to IV aGVHD. Patients receiving more than four doses of basiliximab had higher rates of infections. The 4-year cumulative incidence of total and severe chronic GVHD after basiliximab treatment was 44.8% (95% CI 38.3%-51.3%) and 2.2% (95% CI 0.3%-4.1%), respectively. The 4-year cumulative incidence of relapse, non-relapse mortality, disease-free survival, and overall survival after basiliximab treatment was 11.3% (95% CI 7.2%-15.4%), 30.0% (95% CI 24.1%-35.9%), 58.7% (95% CI 52.3%-65.1%), and 61.7% (95% CI 55.4%-68.0%), respectively. Comorbidities before allo-HSCT and refined Minnesota aGVHD risk score at diagnosis had significant influences on long-term survival. Thus, basiliximab was a safe and effective treatment for patients with SR-aGVHD.

Risk factors for chronic graft-versus-host disease after anti-thymocyte globulin-based haploidentical hematopoietic stem cell transplantation in acute myeloid leukemia

Chronic graft-versus-host disease (cGVHD) is a major complication following unmanipulated haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We aimed to identify the risk factors for cGVHD in patients who underwent anti-thymocyte globulin-based haplo-HSCT for acute myeloid leukemia (n = 280). The diagnosis of cGVHD was in accordance with the National Institutes of Health consensus criteria. A total of 169 patients suffered from cGVHD. The patients who had 3 loci mismatched had a higher 8-year incidence of cGVHD (total, 66.0% vs. 53.7%, P = 0.031; moderate to severe, 42.4% vs. 30.1%, P = 0.036) than the patients who had 1 to 2 loci mismatched. The patients who had maternal donors had a higher 8-year incidence of moderate to severe cGVHD (49.2% vs. 32.9%, P = 0.024) compared with the patients who had other donors. The patients who had grades III to IV acute GVHD (aGVHD) had higher 8-year incidence of cGVHD (total, 88.0% vs. 50.4%, P < 0.001; moderate to severe, 68.0% vs. 27.0%, P < 0.001) compared with the patients without aGVHD. In multivariate analysis, grades III to IV aGVHD was the only independent risk factor for cGVHD. Thus, further interventions should be considered in patients with severe aGVHD to prevent cGVHD.

Low-dose post-transplant cyclophosphamide and anti-thymocyte globulin as an effective strategy for GVHD prevention in haploidentical patients

BACKGROUND

Low-dose post-transplant cyclophosphamide (PTCy) in conjunction with anti-thymocyte globulin (ATG) appears as a potentially effective graft-versus-host disease (GVHD) prevention strategy in haploidentical hematopoietic cell transplant (haplo-HCT). Our study aims to assess the efficacy of this regimen.

METHODS

We extended our prospective study in patients treated with low-dose PTCy (14.5 mg/kg on days 3 and 4) in ATG/granulocyte colony-stimulating factor (G-CSF)-based regimen and compared the results to the contemporary cohort of patients without low-dose PTCy (ATG cohort). Both study cohort and control are transplanted from maternal donor or collateral relatives.

RESULTS

We identified 239 consecutive patients (ATG-PTCy cohort = 114; ATG cohort = 125). All patients but one in ATG cohort achieved myeloid engraftment by day 30 post-HCT. We found that both the cumulative incidence of 100-day grade III-IV aGvHD and non-relapse-mortality (NRM) in the ATG-PTCy cohort was significantly reduced than that in the ATG group (5% vs 18%; P = 0.003; and 6% vs 15%; P= 0.045); the 2-year cumulative incidences of relapse and overall survival were comparable between the two cohorts (13% vs 14%; P = 0.62; and 83% vs 77%; P = 0.18, respectively). Furthermore, GVHD-free, relapse-free survival (GRFS) was significantly improved in the ATG-PTCy arm (63% vs 48%; P = 0.039). In multivariate analysis, the joint treatment resulted in lower grade II-IV acute GVHD (HR 0.58; P = 0.036), grade III-IV aGvHD (HR 0.28; P = 0.006), chronic GVHD (HR 0.60; P = 0.047), NRM (HR 0.26; P = 0.014), and higher GRFS (HR 0.59; P = 0.021) but slower myeloid and platelet recovery (HR 0.29 and 0.30; both P < 0.001).

CONCLUSIONS

These results suggested that ATG/PTCy (low-dose) can reduce both acute and chronic GVHD as compared with standard ATG-based prophylaxis using maternal donor or collateral relatives at particular high GVHD risk.