Haploidentical stem cell transplantation: anti-thymocyte globulin-based experience

Female-to-male allogeneic transplantation affects outcomes differently according to the type of haplo-transplantation

Allogeneic hematopoietic stem cell transplantation from a female donor to a male recipient (female-to-male allo-HCT) is a well-established risk factor for chronic graft-versus-host disease (GVHD) and non-relapse mortality (NRM). The inferior outcomes of female-to-male allo-HCT are considered to be due to allo-immunity against H-Y antigens. However, the influence of minor histocompatibility antigens in haplo-identical allo-HCT remains to be elucidated. We investigated the impact of female-to-male allo-HCT according to the haplo-HCT subtype. In the post-transplant cyclophosphamide (PTCY) cohort (n = 660), a female-to-male sex-mismatch was significantly associated with a decreased risk of relapse (HR: 0.70 [95% CI: 0.49-0.99], P = 0.045), but not with overall survival (OS) or NRM (HR: OS 0.89 [95% CI: 0.68-1.16], P = 0.40; NRM 0.98 [95% CI: 0.68-1.41], P = 0.90). On the other hand, in the non-PTCY cohort (n = 219), a female-to-male sex-mismatch was associated with inferior risks of OS and NRM, but was not associated with relapse. These results suggested that the survival impact of the haplo-HCT subtype differed according to the presence of a sex-mismatch. PTCY might be feasible for overcoming the inferiority of female-to-male allo-HCT and might preserve a GVL effect against H-Y antigens.

Recent advancements in hematopoietic stem cell transplantation in Taiwan

Hematopoietic stem cell transplantation (HSCT) can cure malignant and nonmalignant hematological disorders. From 1983 to 2022, Taiwan performed more than 10,000 HSCT transplants. The Taiwan Blood and Marrow Transplantation Registry collects clinical information to gather everyone's experience and promote the advances of HSCT in Taiwan to gather everyone's experience and promote advances of HSCT in Taiwan. Compared with matched sibling donors, transplants from matched unrelated donors exhibited a trend of superior survival. In Taiwan, transplant donors showed remarkable growth from unrelated (24.8%) and haploidentical (10.5%) donors. The number of older patients (17.4%; aged ≥61 years) who underwent transplantation has increased markedly. This review summarizes several significant developments in HSCT treatment in Taiwan. First, the use of Anti-thymocyte globulin (ATG) and intravenous busulfan regimens were important risk factors for predicting hepatic sinusoidal obstruction syndrome. Second, a new, machine learning-based risk prediction scoring system for posttransplantation lymphoproliferative disorder has identified five risk factors: aplastic anemia, partially mismatched related donors, fludarabine use, ATG use, and acute skin graft-versus-host disease. Third, although the incidence of idiopathic pneumonia syndrome was low (1.1%), its mortality rate was high (58.1%). Fourth, difficult-to-treat mantle cell and T-cell lymphomas treated with autologous HSCT during earlier remission had higher survival rates. Fifth, treatment of incurable multiple myeloma with autologous HSCT showed a median progression-free survival and overall survival of 46.5 and 70.4 months, respectively. Sixth, different haploidentical transplantation strategies were compared. Seventh, caution should be taken in administering allogeneic HSCT treatment in older patients with myeloid leukemia with a Charlson Comorbidity Index ≥3 because of a higher risk of nonrelapse mortality.

Low-dose anti-thymocyte globulin plus low-dose post-transplant cyclophosphamide-based regimen for prevention of graft-versus-host disease after haploidentical peripheral blood stem cell transplants: a large sample, long-term follow-up retrospective study

Introduction

The novel low-dose anti-thymocyte (ATG, 5 mg/kg) plus low-dose post-transplant cyclophosphamide (PTCy, 50 mg/kg) (low-dose ATG/PTCy)-based regimen had promising activity for prevention of graft-versus-host disease (GVHD) in haploidentical-peripheral blood stem cell transplantation (haplo-PBSCT), but its impacts on long-term outcomes remain to be defined.

Methods

We performed a large sample, long-term follow-up retrospective study to evaluate its efficacy for GVHD prophylaxis.

Results

The study enrolled 260 patients, including 162 with myeloid malignancies and 98 with lymphoid malignancies. The median follow-up time was 27.0 months. For the entire cohort, the cumulative incidences (CIs) of grade II-IV and III-IV acute GVHD (aGVHD) by 180 days were 13.46% (95% CI, 9.64%-17.92%) and 5.77% (95% CI, 3.37%-9.07%); while total and moderate/severe chronic GVHD (cGVHD) by 2 years were 30.97% (95% CI, 25.43%-36.66%) and 18.08% (95% CI, 13.68%-22.98%), respectively. The 2-year overall survival (OS), relapse-free survival (RFS), GVHD-free, relapse-free survival (GRFS), non-relapse mortality (NRM), and CIs of relapse were 60.7% (95% CI, 54.8%-67.10%), 58.1% (95% CI, 52.2%-64.5%), 50.6% (95% CI, 44.8-57.1%), 23.04% (95% CI, 18.06%-28.40%), and 18.09% (95% CI, 14.33%-23.97%, respectively. The 1-year CIs of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) reactivation were 43.46% (95% CI, 37.39%-49.37%) and 18.08% (95% CI, 13.68%-22.98%), respectively. In multivariate analysis, the disease status at transplantation was associated with inferior survivor outcomes for all patients and myeloid and lymphoid malignancies, while cGVHD had superior outcomes for all patients and myeloid malignancies, but not for lymphoid malignancies.

Discussion

The results demonstrated that the novel regimen could effectively prevent the occurrence of aGVHD in haplo-PBSCT.

[Acute lymphoblastic leukemia in developing countries: Management from the transplant indication (allo/auto) until post-transplant follow-up. Guidelines from the SFGM-TC]

Management of acute lymphoblastic leukemia (ALL) patients in countries with limited resources depends on the means of prognostic stratification, available treatment and logistics. During the 12th annual harmonization workshops of the francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC), a designated working group reviewed the literature in order to elaborate unified guidelines for allogeneic hematopoietic cell transplantation (Allo-HCT) in this disease. Conventional poor prognostic factors can be used to determine the indication of allo-HCT in first remission. Patients lacking a HLA-matched related donor can be allografted with a haploidentical donor allo-HCT if available. Chemotherapy based conditioning regimen can be used if TBI is not available, because the probability to find a radiotherapy department with the capacity for total body irradiation is low. For patients with Philadelphia chromosome positive (Phi+) ALL, post-transplantation tyrosine kinase inhibitors as a systematic maintenance strategy is recommended. Autologous HCT is optional for Phi+ ALL patients with negative minimal residual disease, who not eligible for allo-HCT. Patients with refractory/relapsed disease have a poor prognosis which highlights the importance of acquiring in the future new therapies such as: blinatumumab, inotuzumab, and CAR-T cells.

Posttransplant de novo DSA and NDSA affect GvHD, OS, and DFS after haplo-HSCT in patients without pre-existing HLA antibodies of hematological malignancies

To examine the production time, type, and MFI of post-transplantation de novo HLA antibodies, and their effects on haplo-HSCT outcomes, we retrospectively included 116 patients who were negative for pre-existing HLA antibodies. In total, 322 serum samples from pre-transplantation to post-transplantation were dynamically tested by Luminex and single-antigen bead reagents. Patients were divided into: HLA antibody persistently negative group (group 1), the de novo HLA antibody transiently positive group (group 2), the de novo HLA antibody non-persistently positive group (group 3), and the de novo HLA antibody persistently positive group (group 4). Group 4 included DSA+non-DSA (NDSA) (group 4a) and NDSA (group 4b) groups. The detection rate of de novo HLA antibodies was 75.9% (88/116). The median MFI for de novo HLA antibodies was 2439 (1033-20162). The incidence of II-IV aGvHD was higher in group 2 than in group 1 (52.6% vs 17.9%, P < 0.01); in group 4a than in group 1 (87.5% vs 17.9%, P < 0.001); and in group 4a than in group 4b (87.5% vs 40.0%, P = 0.001). The DFS (37.5% vs 85.7%, P < 0.01) and OS (37.5% vs 85.7%, P < 0.01) of group 4a were lower than those of group 1. The DFS (48.0% vs 85.7%, P < 0.01) and OS (56.0% vs 85.7%, P = 0.03) of group 4b were lower than those of group 1. Multivariate analysis showed that de novo HLA antibody being transiently positive (HR: 5.30; 95% CI: 1.71-16.42, P = 0.01) and persistently positive (HR: 5.67; 95% CI: 2.00-16.08, P < 0.01) were both associated with a higher incidence of II-IV aGvHD. Persistently positive de novo HLA antibodies were a risk factor for reduced DFS (HR: 6.57; 95% CI: 2.08-20.70, P < 0.01) and OS (HR: 5.51; 95% CI: 1.73-17.53, P < 0.01). DSA and NDSA can be detected since 15 days after haplo-HSCT in patients without pre-existing HLA antibodies, and affect aGvHD, DFS, and OS. Haplo-HSCT patients must be monitored for HLA antibodies changes for appropriate preventive clinical management, and we recommend that 1-month post-transplantation is the best test time point.

Lower dose of ATG combined with basiliximab for haploidentical hematopoietic stem cell transplantation is associated with effective control of GVHD and less CMV viremia

Currently, the graft-versus-host disease (GVHD) prophylaxis consists of an immunosuppressive therapy mainly based on antithymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). GVHD remains a major complication and limitation to successful allogeneic haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We modified the ATG-based GVHD prophylaxis with the addition of basiliximab in the setting of haplo-HSCT and attempted to explore the appropriate dosages. We conducted a retrospective analysis of 239 patients with intermediate- or high-risk hematologic malignancies who received haplo-HSCT with unmanipulated peripheral blood stem cells combined or not with bone marrow. All patients received the same GVHD prophylaxis consisting of the combination of methotrexate, cyclosporine or tacrolimus, mycofenolate-mofetil, and basiliximab with different doses of ATG (5-9mg/kg). With a median time of 11 days (range, 7-40 days), the rate of neutrophil engraftment was 96.65%. The 100-day cumulative incidences (CIs) of grade II-IV and III-IV aGVHD were 15.8 ± 2.5% and 5.0 ± 1.5%, while the 2-year CIs of total cGVHD and extensive cGVHD were 9.8 ± 2.2% and 4.1 ± 1.5%, respectively. The 3-year CIs of treatment-related mortality (TRM), relapse, overall survival (OS), and disease-free survival (DFS) were 14.6 ± 2.6%, 28.1 ± 3.4%, 60.9 ± 3.4%, 57.3 ± 3.4%, respectively. Furthermore, the impact of the reduction of the ATG dose to 6 mg/kg or less in combination with basiliximab on GVHD prevention and transplant outcomes among patients was analyzed. Compared to higher dose of ATG(>6mg/kg), lower dose of ATG (≤6mg/kg) was associated with a significant reduced risk of CMV viremia (52.38% vs 79.35%, P<0.001), while the incidences of aGVHD and cGVHD were similar between the two dose levels. No significant effect was found with regard to the risk of relapse, TRM, and OS. ATG combined with basiliximab could prevent GVHD efficiently and safely. The optimal scheme of using this combined regimen of ATG and basiliximab is that administration of lower dose ATG (≤6mg/kg), which seems to be more appropriate for balancing infection control and GVHD prophylaxis.

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

In haploidentical peripheral blood stem cell transplantation (haplo-PBSCT), the combination of anti-thymocyte globulin and post-transplant cyclophosphamide (ATG/PTCy) has a synergistic impact in preventing graft-versus-host disease (GvHD). However, little is known about the long-term consequences of the new combination approach. Our goal is to evaluate the efficacy of ATG/PTCy versus a standard ATG regimen by focusing at long-term outcomes in a more homogeneous group of patients. We retrospectively included 118 adult patients up to 60 years with acute leukemia who underwent haplo-PBSCT at our single institution, following the same myeloablative conditioning regimen. From 2010 to 2020, 78 patients received a modified combination of ATG (2.5 mg/kg/day, on days −3, −2, and −1) and PTCy (40 mg/kg/day on days +3 and +4) compared to 40 patients who had a standard ATG-based regimen (2.5 mg/kg/day from days −4 to −1) from 2008 to 2015. The median follow-up time for all patients was 5.36 years, respectively. The cumulative incidence (CI) of neutrophil and platelet engraftment, as well as CMV reactivation, did not differ statistically between the two groups. The CI of the acute GvHD of grades II–IV and III–IV and extensive chronic GvHD were considerably lower in the ATG/PTCy (34.6%, 8.97%, and 13.63%) than in the ATG cohort (57.5%, 30%, and 38.23%) as validated by multivariable modeling. Additionally, compared to the ATG arm, the ATG/PTCy was a hazard factor associated with a higher risk of relapse (HR = 2.23, p = 0.039). The probability of 5-year overall survival, disease-free survival, and GvHD-free relapse-free survival in the ATG/PTCy group (53.34%, 49.77%, and 36.04%) was comparable with the ATG group (47.5%, 42.5%, and 22.5%), respectively. Our finding suggested that a modified ATG/PTCy combination resulted in a lower risk of acute and chronic GvHD and a higher risk of relapse than the standard ATG-based protocol but had no effect on long-term outcomes. However, certain adjustments in the immunosuppression protocol are warranted to improve the outcome.

[A retrospective comparative study of haplotype hematopoietic stem cell transplantation and human leukocyte antigen-matched sibling donor hematopoietic stem cell transplantation in the treatment of acute B-lymphocyte leukemia]

Objective: To investigate whether haplotype hematopoietic stem cell transplantation (haplo-HSCT) is effective in the treatment of pre transplant minimal residual disease (Pre-MRD) positive acute B lymphoblastic leukemia (B-ALL) compared with HLA- matched sibling donor transplantation (MSDT) . Methods: A total of 998 patients with B-ALL in complete remission pre-HSCT who either received haplo-HSCT (n=788) or underwent MSDT (n=210) were retrospectively analyzed. The pre-transplantation leukemia burden was evaluated according to Pre-MRD determinedusing multiparameter flow cytometry (MFC) . Results: Of these patients, 997 (99.9% ) achieved sustained, full donor chimerism. The 100-day cumulative incidences of neutrophil engraftment, platelet engraftment, and grades Ⅱ-Ⅳ acute graft-versus-host disease (GVHD) were 99.9% (997/998) , 95.3% (951/998) , and 26.6% (95% CI 23.8% -29.4% ) , respectively. The 3-year cumulative incidence of total chronic GVHD was 49.1% (95% CI 45.7% -52.4% ) . The 3-year cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) of the 998 cases were 17.3% (95% CI 15.0% -19.7% ) and 13.8% (95% CI 11.6% -16.0% ) , respectively. The 3-year probabilities of leukemia-free survival (LFS) and overall survival (OS) were 69.1% (95% CI 66.1% -72.1% ) and 73.0% (95% CI 70.2% -75.8% ) , respectively. In the total patient group, cases with positive Pre-MRD (n=282) experienced significantly higher CIR than that of subjects with negative Pre-MRD [n=716, 31.6% (95% CI 25.8% -37.5% ) vs 14.3% (95% CI 11.4% -17.2% ) , P<0.001]. For patients in the positive Pre-MRD subgroup, cases treated with haplo-HSCT (n=219) had a lower 3-year CIR than that of cases who underwent MSDT [n=63, 27.2% (95% CI 21.0% -33.4% ) vs 47.0% (95% CI 33.8% -60.2% ) , P=0.002]. The total 998 cases were classified as five subgroups, including cases with negative Pre-MRD group (n=716) , cases with Pre-MRD<0.01% group (n=46) , cases with Pre-MRD 0.01% -<0.1% group (n=117) , cases with Pre-MRD 0.1% -<1% group (n=87) , and cases with Pre-MRD≥1% group (n=32) . For subjects in the Pre-MRD<0.01% group, haplo-HSCT (n=40) had a lower CIR than that of MSDT [n=6, 10.0% (95% CI 0.4% -19.6% ) vs 32.3% (95% CI 0% -69.9% ) , P=0.017]. For patients in the Pre-MRD 0.01% -<0.1% group, haplo-HSCT (n=81) also had a lower 3-year CIR than that of MSDT [n=36, 20.4% (95% CI 10.4% -30.4% ) vs 47.0% (95% CI 29.2% -64.8% ) , P=0.004]. In the other three subgroups, the 3-year CIR was comparable between patients who underwent haplo-HSCT and those received MSDT. A subgroup analysis of patients with Pre-MRD<0.1% (n=163) was performed, the results showed that cases received haplo-HSCT (n=121) experienced lower 3-year CIR [16.0% (95% CI 9.4% -22.7% ) vs 40.5% (95% CI 25.2% -55.8% ) , P<0.001], better 3-year LFS [78.2% (95% CI 70.6% -85.8% ) vs 47.6% (95% CI 32.2% -63.0% ) , P<0.001] and OS [80.5% (95% CI 73.1% -87.9% ) vs 54.6% (95% CI 39.2% -70.0% ) , P<0.001] than those of MSDT (n=42) , but comparable in 3-year NRM [5.8% (95% CI 1.6% -10.0% ) vs 11.9% (95% CI 2.0% -21.8% ) , P=0.188]. Multivariate analysis showed that haplo-HSCT was associated with lower CIR (HR=0.248, 95% CI 0.131-0.472, P<0.001) , and superior LFS (HR=0.275, 95% CI 0.157-0.483, P<0.001) and OS (HR=0.286, 95% CI 0.159-0.513, P<0.001) . Conclusion: Haplo HSCT has a survival advantage over MSDT in the treatment of B-ALL patients with pre MRD<0.1% .

Outcomes of Different Haploidentical Transplantation Strategies from the Taiwan Blood and Marrow Transplantation Registry

BACKGROUND

The two most noteworthy strategies for haploidentical stem cell transplantation (haplo-HSCT) are posttransplantation cyclophosphamide (PTCy) with or without thymoglobulin (ATG) and granulocyte colony stimulating factor-primed bone marrow plus peripheral blood stem cells (GIAC). We aimed to compare these approaches in patients with hematological malignancies.

METHODS

We enrolled 178 patients undergoing haplo-HSCT, including modified GIAC (mGIAC), PTCy without ATG, and PTCy with ATG.

RESULTS

The patients in the mGIAC group had the most favorable platelet and neutrophil engraftment kinetics. Although the grade III-IV acute graft-versus-host-disease (GvHD) rates were similar, those receiving mGIAC had a significantly higher extensive chronic GvHD rate. The patients receiving mGIAC had a similar cumulative incidence of relapse (CIR) to that in the patients receiving PTCy with ATG, but this was lower than that in the patients receiving PTCy without ATG. The patients receiving mGIAC had the lowest nonrelapse mortality (NRM) and the highest overall survival (OS) rates. The differences in CIR, NRM, and OS remained significant when focusing on patients with low/intermediate-risk diseases before haplo-HSCT. Intriguingly, among patients with high/very-high-risk diseases before haplo-HSCT, no differences were observed in the CIR, NRM, OS, or GvHD/relapse-free survival.

CONCLUSION

the mGIAC approach may yield a better outcome in Taiwanese patients with hematologic malignancies, especially for those with low/intermediate-risk diseases.

Effect of donor characteristics on T cell-replete haploidentical stem cell transplantation over the last 10 years at a single institution

One of the most complex issues with haploidentical stem cell transplantation (haplo-SCT) is donor selection, given that multiple haploidentical donors are often available for a given recipient. To develop evidence-based guidance for donor selection in the setting of anti-thymocyte globulin-based haplo-SCT, we performed a prospective cohort study of 512 patients with haematological malignancies who had haplo-SCT to determine which donor variables were most important in favouring transplant outcomes. Increasing donor age was associated with poorer overall survival (OS) [hazard ratio (HR) 1·08, P = 0·044]. Female donors to male recipients was significantly associated with higher non-relapse mortality (NRM; HR 2·05, P = 0·006). Furthermore, increasing donor age had a higher risk of Grades 3-4 acute graft-versus-host disease (aGVHD; HR 1·17, P = 0·005), female donors to male recipients was associated with a higher risk of Grades 2-4 aGVHD (HR 1·50, P = 0·022). Sibling donors had superior OS, disease-free survival, and NRM than parental donors in patients aged <35 years. However, sibling donors had higher NRM than offspring donors in patients aged ≥35 years. A younger donor, usually a young sibling in younger recipients (aged <35 years) or a young offspring in older patients (aged ≥35 years) and avoiding female donors to male recipients should be preferred when multiple haploidentical donors are available.

Cytokine Release Syndrome in the Immunotherapy of Hematological Malignancies: The Biology behind and Possible Clinical Consequences

Cytokine release syndrome (CRS) is an acute systemic inflammatory syndrome characterized by fever and multiple organ dysfunction associated with (i) chimeric antigen receptor (CAR)-T cell therapy, (ii) therapeutic antibodies, and (iii) haploidentical allogeneic stem cell transplantation (haplo-allo-HSCT). Severe CRS can be life-threatening in some cases and requires prompt management of those toxicities and is still a great challenge for physicians. The pathophysiology of CRS is still not fully understood, which also applies to the identifications of predictive biomarkers that can forecast these features in advance. However, a broad range of cytokines are involved in the dynamics of CRS. Treatment approaches include both broad spectrum of immunosuppressant, such as corticosteroids, as well as more specific inhibition of cytokine release. In the present manuscript we will try to review an update regarding pathophysiology, etiology, diagnostics, and therapeutic options for this serious complication.

Cytokine release syndrome after haploidentical hematopoietic stem cell transplantation with antithymocyte globulin: risk factors analysis and poor impact on outcomes for non-remisssion patients

INTRODUCTION

Cytokine release syndrome (CRS) is a common complication after T-replete HLA haploidentical hematopoietic cell transplantation (haplo-HCT) with PTCy. We aim to assess the incidence, severity, and impact of CRS on clinical outcomes of patients who received haplo-HCT using Beijing Protocol.

METHODS

This was a single-enter retrospective analysis of 286 subjects who received haplo-HCT with Antithymocyte Globulin (ATG).

RESULTS

We identified 147/268 (54.9%) patients who developed CRS, grade 1 CRS (32.5%) and grade ≥2 CRS (22.4%). Eight patients developed severe CRS. The incidence and severity of CRS did not show significant discrimination among patients who received different doses of ATG. By multivariable analysis, age and the disease status at transplantation were significantly associated with the occurrence of CRS (p =.000 and p = .021). In the univariate analysis for the severity of CRS, compared with CRS grade ≥2, patients with CRS grade 0-1 had higher 1-year overall survival (OS) (p = .009). The cumulative incidence of 100-day grades II-IV acute GVHD was 12.4%. The incidence did not show significant differences between patients with CRS or not. The devolvement of CRS is associated with worse OS, inferior disease-free survival, and higher nonrelapse mortality significantly. But the result appeared to be limited to patients in uncomplete remission status before transplantation.

DISCUSSION AND CONCLUSIONS

CRS is less frequent and milder with a protocol based on ATG. CRS can potentially affect the outcomes after haplo-HCT especially for patients in an uncomplete remission. Prospective clinical trials are needed to provide an appropriate scheme for CRS prophylaxis.

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.

[Comparison of prognostic significance between multiparameter flow cytometry and real-time quantitative polymerase chain reaction in the detection of minimal residual disease of Philadelphia chromosome-positive acute B lymphocytic leukemia before allogeneic hematopoietic stem cell transplantation]

目的

探讨多参数流式细胞术（MFC）与实时定量聚合酶链反应技术（RQ-PCR）两种方法检测费城染色体阳性（Ph⁺）急性B淋巴细胞白血病（B-ALL）患者异基因造血干细胞移植（allo-HSCT）前微小残留病（MRD）的预后意义。

方法

回顾性分析2014年7月至2018年2月在北京大学血液病研究所接受allo-HSCT的280例Ph⁺ B-ALL患者，同时用MFC和RQ-PCR法（检测BCR-ABL融合基因表达）检测移植前MRD。

结果

RQ-PCR与MFC检测MRD具有相关性（rs＝0.435，P<0.001）。MFC、RQ-PCR法检测移植前MRD的阳性率分别为25.7％（72/280）、60.7％（170/280）。移植前MFC-MRD阳性组患者移植后白血病3年累积复发率（CIR）明显高于MFC-MRD阴性组（23.6％对8.6％，P<0.001）。RQ-PCR检测BCR/ABL融合基因阳性组（RQ-PCR MRD阳性组）的3年CIR、非复发死亡（NRM）、无白血病生存（LFS）、总生存（OS）与BCR/ABL融合基因阴性组（RQ-PCR MRD阴性组）相比差异均无统计学意义（P>0.05）。移植前RQ-PCR MRD≥1％组比<1％组具有更高的3年CIR（23.1％对11.4％，P＝0.032）、更低的LFS率（53.8％对74.4％，P＝0.015）与OS率（57.7％对79.1％，P＝0.009）。多因素分析显示，移植前MFC-MRD阳性是影响移植后CIR的危险因素（HR＝2.488，95％CI1.216～5.088，P＝0.013），移植前RQ-PCR MRD≥1％是影响LFS（HR＝2.272，95％CI 1.225～4.215，P<0.001）、OS（HR＝2.472，95％ CI 1.289～4.739，P＝0.006）的危险因素。MFC检测MRD预测复发的敏感性、特异性、阳性预测值（PPV）、阴性预测值（NPV）分别为48.50％、77.56％、23.62％、87.16％。以RQ-PCR MRD≥1％预测复发的敏感性、特异性、PPV、NPV分别为23.00％、88.59％、17.15％、91.84％。移植前MFC-MRD阳性或RQ-PCR MRD≥1％二者任一成立为指标预测移植后复发的敏感性、特异性、PPV、NPV分别为54.29％、73.88％、45.70％、91.87％。

结论

MFC和RQ-PCR法检测移植前MRD水平均可预测Ph⁺ B-ALL患者移植预后。移植前MFC-MRD阳性是移植后复发的危险因素。联合使用两种方法（移植前MFC-MRD阳性状态或RQ-PCR MRD≥1％成立）可提高预测移植后复发的敏感性、阳性预测值与阴性预测值，有助于更好筛选出高危患者。

Experience Using Anti-Thymocyte Globulin With Post-Transplantation Cyclophosphamide for Graft-Versus-Host Disease Prophylaxis in Peripheral Blood Haploidentical Stem Cell Transplantation

Haploidentical hematopoietic cell transplantation (HaploHCT) is an alternative treatment option for patients without a suitable 10/10 HLA matched donor. We share an updated experience at our center of using in vivo dual T-cell depletion with anti-thymocyte globulin (ATG) and post-transplantation cyclophosphamide (PTCy) in peripheral blood haploHCT and report the impact of reducing the dose of ATG from 4.5 mg/kg to 2 mg/kg on post-transplantation complications and outcomes. Ninety-five consecutive adults underwent haploHCT at our center between August 2016 and February 2020, all of whom were included in the study. Nine (9.5%) patients received myeloablative conditioning, and 86 (90.5%) patients underwent reduced-intensity haploHCT. All patients received thymoglobulin, PTCy and cyclosporine (CsA) for graft-versus-host disease (GVHD) prophylaxis: Sixty (63.2%) patients received 4.5 mg/kg, and 35 (36.8%) patients received 2 mg/kg of ATG. Clinical information was collected retrospectively and updated in June 2020. The median age was 57 (18-73), and acute myeloid leukemia was the most prevalent diagnosis (58.9%). The day 100 cumulative incidence of grade II-IV and grade III-IV aGVHD, and 1-year moderate/severe cGVHD were 22.3%, 11.1%, and 20.2%, respectively. Those patients who received 2 mg/kg of ATG had higher incidence of grade III-IV aGVHD (23.9% vs 3.5%, P = .006) and comparable moderate/severe cGVHD (1-year 20.6% vs 19.8%, P = .824) than those patients who received 4.5 mg/kg. Overall, the 18-month overall survival (OS), relapse-free survival (RFS), and non-relapse mortality (NRM) were 43.8%, 38.4%, and 40.2%, respectively. The reduction of the ATG dose did not have a significant impact in OS (hazard ratio [HR] 1.06, P = .847), RFS (HR 0.984, P = .955), and in NRM (HR 1.38; P = .348). The reduction of the ATG resulted in a negative impact on aGVHD without conferring any benefit in OS, RFS, and NRM. Consequently, the ATG dose used at our institution in combination with PTCy and CsA for haploHCT continues to be 4.5 mg/kg.

Impaired T- and NK-cell reconstitution after haploidentical HCT with posttransplant cyclophosphamide

Administration of posttransplant cyclophosphamide (PTCy) has significantly expanded the number of patients undergoing HLA-haploidentical hematopoietic cell transplantation (haplo-HCT). To examine immune reconstitution in these patients, we monitored T- and natural killer (NK)-cell recovery in 60 patients receiving bone marrow or peripheral blood stem cell (PBSC) grafts after haplo-HCT with PTCy and 35 patients receiving HLA-matched donor PBSC grafts with standard graft-versus-host disease (GVHD) prophylaxis. Compared with HLA-matched recipients, early T-cell recovery was delayed in haplo-HCT patients and skewed toward effector memory T cells with markedly reduced naive T cells. We found higher regulatory T (Treg)-cell/conventional T (Tcon)-cell ratios early after HCT and increased PD-1 expression on memory T cells. Within the haplo-HCT, patients who did not develop chronic GVHD (cGVHD) had higher PD-1 expression on central and effector memory CD4+ Treg cells at 1 month after transplant. These findings suggest an immunologic milieu that promotes immune tolerance in haplo-HCT patients. NK cells were decreased early after haplo-HCT with preferential expansion of immature CD56brightCD16- NK cells compared with matched donor transplants. One month after transplant, mass cytometry revealed enrichment of immature NK-cell metaclusters with high NKG2A, low CD57, and low killer-cell immunoglobulin-like receptor expression after haplo-HCT, which partially recovered 3 months post-HCT. At 2 months, immature NK cells from both groups were functionally impaired, but interleukin-15 priming corrected these defects in vitro. Increased immature/mature NK-cell ratios were associated with cytomegalovirus reactivation and increased incidence of cGVHD after haplo-HCT. These homeostatic imbalances in T- and NK-cell reconstitution after haplo-HCT reveal opportunities for early immune-based interventions to optimize clinical outcomes.

Haploidentical hematopoietic stem cell transplantation for patients with myeloid sarcoma: a single center retrospective study

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been regarded as a potential strategy for myeloid sarcoma (MS). The previous reports focused mainly on matched sibling donor (MSD) or matched unrelated donor (MUD) transplantation. There are no reports on haploidentical HSCT (haplo-HSCT) in MS. We retrospectively reviewed 14 MS patients who underwent haplo-HSCT. All patients achieved complete donor engraftment. The median time for neutrophil engraftment and platelet engraftment were 10 (12-21) days and 18 (8-31) days. The 100-day cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) and 3-year cumulative incidence of chronic GVHD were 37.7% (95%CI, 23.2-52.1%) and 35.7% (95%CI, 22.2-49.2%). Cytomegalovirus (CMV) reactivation was documented in 86% patients, and only one patient developed CMV pneumonia. Treatment-related mortality occurred in one (7%) patient. The 1- and 3-year cumulative incidence of relapse was 21.4% (95%CI, 11.8-31.1%) and 35.7% (95%CI, 22.4-49.0%). The probability of overall survival at 1 and 3 years was 71.4% (95%CI, 51.3-99.5%) and 64.3% (95%CI, 43.5-95.0%), respectively. The probability of disease-free survival at 1 and 3 years was 71.4% (95%CI, 51.3-99.5%) and 57.1% (95%CI, 36.3-89.9%), respectively. In conclusion, haplo-HSCT is a feasible method for patients with MS who have no MSD or MUD.

Clinical practice recommendation on hematopoietic stem cell transplantation for acute myeloid leukemia patients with FLT3-internal tandem duplication: a position statement from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

The FMS-like tyrosine kinase 3 (FLT3) gene is mutated in 25-30% of patients with acute myeloid leukemia (AML). Because of the poor prognosis associated with FLT3-internal tandem duplication mutated AML, allogeneic hematopoietic stem-cell transplantation (SCT) was commonly performed in first complete remission. Remarkable progress has been made in frontline treatments with the incorporation of FLT3 inhibitors and the development of highly sensitive minimal/measurable residual disease assays. Similarly, recent progress in allogeneic hematopoietic SCT includes improvement of transplant techniques, the use of haploidentical donors in patients lacking an HLA matched donor, and the introduction of FLT3 inhibitors as post-transplant maintenance therapy. Nevertheless, current transplant strategies vary between centers and differ in terms of transplant indications based on the internal tandem duplication allelic ratio and concomitant nucleophos-min-1 mutation, as well as in terms of post-transplant maintenance/consolidation. This review generated by international leukemia or transplant experts, mostly from the European Society for Blood and Marrow Transplantation, attempts to develop a position statement on best approaches for allogeneic hematopoietic SCT for AML with FLT3-internal tandem duplication including indications for and modalities of such transplants and on the potential optimization of post-transplant maintenance with FLT inhibitors.

Impact of Adding Antithymocyte Globulin to Posttransplantation Cyclophosphamide in Haploidentical Stem-Cell Transplantation

BACKGROUND

Graft-versus-host disease (GVHD) is a major cause of mortality after allogeneic stem-cell transplantation. Posttransplantation cyclophosphamide (PT/CY) has become standard prophylaxis of GVHD in T-replete haploidentical transplantation. The question is whether adding antithymocyte globulin (ATG) to PT/CY may further reduce the incidence of GVHD compared to PT/CY only.

PATIENTS AND METHODS

We retrospectively studied 268 patients undergoing myeloablative haploidentical transplantation with thiotepa, busulfan, and fludarabine (TBF) conditioning. Sixty-nine patients (26%) received ATG.

RESULTS

In the ATG group, 3% died due to GVHD versus 8% in the no ATG group. The 100-day and 1-year nonrelapse mortality (NRM) was 0% and 19%, respectively, in the whole cohort. On univariate analysis, the 1-year NRM was 8% versus 23% in patients receiving ATG and no ATG, respectively (P = .005). The no ATG group had a higher incidence of acute GVHD at 12 months compared to the ATG group (22% vs. 12%, respectively, P = .029). The ATG group had better overall survival at 12 months compared to the no ATG group (79% vs. 69%, P = .029). On multivariate analysis, adding ATG to PT/CY had no significant impact on any of the outcomes. A low disease risk index was associated with better overall survival and lower NRM, while Hematopoietic Cell Transplantation-Specific Comorbidity Index (HCT-CI) score ≥ 3 was associated with higher NRM.

CONCLUSION

ATG can be safely used as part of the pretransplantation conditioning and does not increase the incidence of relapse or complications after transplantation.

Key Aspects of the Immunobiology of Haploidentical Hematopoietic Cell Transplantation

Hematopoietic stem cell transplantation from a haploidentical donor is increasingly used and has become a standard donor option for patients lacking an appropriately matched sibling or unrelated donor. Historically, prohibitive immunological barriers resulting from the high degree of HLA-mismatch included graft-vs.-host disease (GVHD) and graft failure. These were overcome with increasingly sophisticated strategies to manipulate the sensitive balance between donor and recipient immune cells. Three different approaches are currently in clinical use: (a) ex vivo T-cell depletion resulting in grafts with defined immune cell content (b) extensive immunosuppression with a T-cell replete graft consisting of G-CSF primed bone marrow and PBSC (GIAC) (c) T-cell replete grafts with post-transplant cyclophosphamide (PTCy). Intriguing studies have recently elucidated the immunologic mechanisms by which PTCy prevents GVHD. Each approach uniquely affects post-transplant immune reconstitution which is critical for the control of post-transplant infections and relapse. NK-cells play a key role in haplo-HCT since they do not mediate GVHD but can successfully mediate a graft-vs.-leukemia effect. This effect is in part regulated by KIR receptors that inhibit NK cell cytotoxic function when binding to the appropriate HLA-class I ligands. In the context of an HLA-class I mismatch in haplo-HCT, lack of inhibition can contribute to NK-cell alloreactivity leading to enhanced anti-leukemic effect. Emerging work reveals immune evasion phenomena such as copy-neutral loss of heterozygosity of the incompatible HLA alleles as one of the major mechanisms of relapse. Relapse and infectious complications remain the leading causes impacting overall survival and are central to scientific advances seeking to improve haplo-HCT. Given that haploidentical donors can typically be readily approached to collect additional stem- or immune cells for the recipient, haplo-HCT represents a unique platform for cell- and immune-based therapies aimed at further reducing relapse and infections. The rapid advancements in our understanding of the immunobiology of haplo-HCT are therefore poised to lead to iterative innovations resulting in further improvement of outcomes with this compelling transplant modality.

Prevalence and risk factors of having antibodies to class I and II human leukocyte antigens in older haploidentical allograft candidates

The effect of donor-specific anti-human leukocyte antigen (HLA) antibodies (DSAs) has been recognized as a factor in graft failure (GF) in patients who underwent umbilical cord blood transplantation (UBT), matched unrelated donor transplantation (MUDT), or haploidentical stem cell transplantation (haplo-SCT). Presently, we know little about the prevalence of and risk factors for having anti-HLA antibodies among older transplant candidates. Therefore, we analyzed 273 older patients with hematologic disease who were waiting for haplo-SCT. Among all patients, 73 (26.7%) patients had a positive panel-reactive antibody (PRA) result for class I, 38 (13.9%) for class II, and 32 (11.7%) for both. Multivariate analysis showed that females were at a higher risk for having a PRA result for class II (P = 0.001) and for having antibodies against HLA-C and HLA-DQ. Prior pregnancy was a risk factor for having a PRA result for class I (P < 0.001) and for having antibodies against HLA-A, HLA-B and HLA-DQ. Platelet transfusions were risk factors for the following: having a positive PRA result for class I (P = 0.014) and class II (P < 0.001); having antibodies against HLA-A, HLA-B, HLA-C, HLA-DP, HLA-DQ, and HLA-DR; and having higher mean fluorescence intensity (MFI) of PRA for class I (P = 0.042). In addition, previous total transfusions were at high risk for having higher numbers of antibodies to specific HLA loci (P = 0.005), and disease course (7.5 months or more) (P = 0.020) were related to higher MFI of PRAs for class I. Our findings indicated that female sex, prior pregnancy, platelet transfusions and disease courses are independent risk factors for older patients with hematologic disease for having anti-HLA antibodies, which could guide anti-HLA antibody monitoring and be helpful for donor selection.

Granulocyte Colony-Stimulating Factor-Primed Unmanipulated Haploidentical Blood and Marrow Transplantation

Granulocyte colony-stimulating factor (G-CSF), a growth factor for neutrophils, has been successfully used for stem cell mobilization and T cell immune tolerance induction. The establishment of G-CSF-primed unmanipulated haploidentical blood and marrow transplantation (The Beijing Protocol) has achieved outcomes for the treatment of acute leukemia, myelodysplastic syndrome, and severe aplastic anemia with haploidentical allografts comparable to those of human leukocyte antigen (HLA)-matched sibling donor transplantation. Currently, G-CSF-mobilized bone marrow and/or peripheral blood stem cell sources have been widely used in unmanipulated haploidentical transplant settings. In this review, we summarize the roles of G-CSF in inducing T cell immune tolerance. We discuss the recent advances in the Beijing Protocol, mainly focusing on strategies that have been used to improve transplant outcomes in cases of poor graft function, virus infections, and relapse. The application of G-CSF-primed allografts in other haploidentical modalities is also discussed.

Two dose levels of rabbit antithymocyte globulin as graft-versus-host disease prophylaxis in haploidentical stem cell transplantation: a multicenter randomized study

BACKGROUND

The optimal dose of rabbit antithymocyte globulin (ATG, ImtixSangstat) minimizing infections without increasing graft-versus-host disease (GVHD) is unknown in T cell-replete, G-CSF-primed haploidentical hematopoietic stem cell transplantation (haplo-HSCT).

METHODS

Four hundred and eight patients were enrolled in this multicenter study to evaluate the effect of 7.5 mg/kg and 10.0 mg/kg rabbit ATG on viral infections and GVHD prophylaxis after haplo-HSCT. The primary endpoint was EBV DNAemia within 1 year posttransplantation.

RESULTS

The 1-year incidence of EBV DNAemia was 20.7% (95% confidence interval, 15.4-26.5) and 40.0% (33.3-46.6) in the 7.5 mg/kg and 10.0 mg/kg groups, respectively (P < 0.001). The 100-day cumulative incidence of grade II to IV aGVHD was 27.1% (21.1-33.4) and 25.4% (19.6-31.5) in the 7.5 mg/kg and 10.0 mg/kg ATG groups, respectively (P = 0.548). The 2-year incidence of chronic GVHD was 34.6% (27.8-41.4) and 36.2% (29.1-43.2) in the 7.5 mg and 10.0 mg groups (P = 0.814). The 1-year incidence of CMV DNAemia was 73.4% (67.2-79.4) and 83.4% (77.5-87.9) in the 7.5 mg/kg and 10.0 mg/kg groups (P = 0.038). The 3-year overall survival posttransplantation was 69.5% (63.2-75.8) and 63.5% (56.2-70.8), and the disease-free survival was 62.2% (55.3-69.1) and 60.3% (53.0-67.6) in the 7.5 mg/kg and 10.0 mg/kg groups, respectively (OS: P = 0.308; DFS: P = 0.660). The counts of EBV- and CMV-specific cytotoxic T cells (CTLs) were higher in the 7.5 mg/kg group than in the 10.0 mg/kg group early posttransplantation.

CONCLUSIONS

Compared with 10.0 mg/kg, 7.5 mg/kg ATG for GVHD prophylaxis was associated with reduced EBV and CMV infections without increased incidence of GVHD in haplo-HSCT, probably by affecting EBV- and CMV-specific CTLs.

TRIAL REGISTRATION

clinicaltrials.gov, NCT01883180 . Registered 14 June 2013.

Minimal residual disease status determined by multiparametric flow cytometry pretransplantation predicts the outcome of patients with ALL receiving unmanipulated haploidentical allografts

This study evaluated the effects of pretransplantation minimal residual disease (pre-MRD) on outcomes of patients with acute lymphoblastic leukemia (ALL) who underwent unmanipulated haploidentical stem cell transplantation (haplo-SCT). A retrospective study including 543 patients with ALL was performed. MRD was determined using multiparametric flow cytometry. Both in the entire cohort of patients and in subgroup cases with T-ALL or B-ALL, patients with positive pre-MRD had a higher incidence of relapse (CIR) than those with negative pre-MRD in MSDT settings (P < 0.01 for all). Landmark analysis at 6 months showed that MRD positivity was significantly and independently associated with inferior rates of relapse (HR, 1.908; P = 0.007), leukemia-free survival (LFS) (HR, 1.559; P = 0.038), and OS (HR, 1.545; P = 0.049). The levels of pre-MRD according to a logarithmic scale were also associated with leukemia relapse, LFS, and OS, except that cases with MRD <0.01% experienced comparable CIR and LFS to those with negative pre-MRD. A risk score for CIR was developed using the variables pre-MRD, disease status, and immunophenotype of ALL. The CIR was 14%, 26%, and 59% for subjects with scores of 0, 1, and 2-3, respectively (P < 0.001). Three-year LFS was 75%, 64%, and 42%, respectively (P < 0.001). Multivariate analysis confirmed the association of the risk score with CIR and LFS. The results indicate that positive pre-MRD, except for low level one (MRD < 0.01%), is associated with poor outcomes in patients with ALL who underwent unmanipulated haplo-SCT.

New Strategy of Acute Graft-vs-Host Disease: Investigation of a Reduced Dose of Antithymocyte Globulin in Haploidentical Hematopoietic Stem Cell Transplantation

Graft-vs-host disease (GVHD) is one of the biggest challenges in haploidentical hematopoietic stem cell transplantation. Antithymocyte globulins (ATGs) are widely used to overcome GVHD, but excessive immunosuppression increases the chances of relapse and infection following transplantation. No defined standard of the appropriate dose of ATG usage is recognized. The study included 11 patients who were treated with a reduced dose of ATG to prevent GVHD in haploidentical hematopoietic stem cell transplantation. A reduced dose of ATG-Thymoglobulin (total dose of 5 mg/kg) was used in the pretreatment protocol for 2 consecutive days. All patients had successful transplantation. The median time of neutrophil engraftment was 12 days. All chimerism tests passed on day 30, 60, and 90 post transplantation. None of the patients had acute GVHD, while only 2 patients had I to II degree chronic GVHD (18.2%). No transplantation-related deaths were observed. The current findings suggest that the reduced dose of ATG can effectively prevent the incidence of acute GVHD in haploidentical hematopoietic stem cell transplantation.

Strategies for Enhancing and Preserving Anti-leukemia Effects Without Aggravating Graft-Versus-Host Disease

Allogeneic stem cell transplantation (allo-SCT) is a curable method for the treatment of hematological malignancies. In the past two decades, the establishment of haploidentical transplant modalities make “everyone has a donor” become a reality. However, graft-versus-host disease (GVHD) and relapse remain the major two causes of death either in the human leukocyte antigen (HLA)-matched transplant or haploidentical transplant settings, both of which restrict the improvement of transplant outcomes. Preclinical mice model showed that both donor-derived T cells and natural killer (NK) cells play important role in the pathogenesis of GVHD and the effects of graft-versus-leukemia (GVL). Hence, understanding the immune mechanisms of GVHD and GVL would provide potential strategies for the control of leukemia relapse without aggravating GVHD. The purpose of the current review is to summarize the biology of GVHD and GVL responses in preclinical models and to discuss potential novel therapeutic strategies to reduce the relapse rate after allo-SCT. We will also review the approaches, including optimal donor selection and, conditioning regimens, donor lymphocyte infusion, BCR/ABL-specific CTL, and chimeric antigen receptor-modified T cells, which have been successfully used in the clinic to enhance and preserve anti-leukemia activity, especially GVL effects, without aggravating GVHD or alleviate GVHD.

Is human leukocyte antigen-matched sibling donor transplant always better than haploidentical allograft?

Currently, haploidentical donor has been an alternative source of stem cell allografts for patients who have no human leukocyte antigen-matched sibling donor or unrelated donors. A number of studies indicated that treating hematological malignancy patients with haploidentical stem cell transplantation (haplo-SCT) could achieve comparable outcomes to those who underwent matched sibling donor transplantation (MSDT). In recent years, more and more evidence support the notion that haploidentical allografts may have a stronger graft-vs-leukemia (GVL) effect than MSDT. In this review, we summarized the transplant outcomes of haplo-SCT and MSDT, mainly focusing on the subgroup of patients who will benefit from the stronger GVL effects of haplo-SCT compared with MSDT. We also offered strategies of how to translate the strong antileukemia activity of haploidentical allograft into superior survival. Future directions of GVL effects in haplo-SCT settings were also discussed.

Haploidentical transplantation outcomes for secondary acute myeloid leukemia: Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT) study

Secondary acute myeloid leukemia (sAML) traditionally has inferior outcomes compared to de novo AML. Allogeneic hematopoietic cell transplantation (HCT) is the sole potentially curative therapy. This study analyzes the outcomes for unmanipulated haploidentical HCT (haploHCT) for sAML using the Acute Leukemia Working Party (ALWP) registry of the European Society for Blood and Marrow Transplantation (EBMT). We identified 154 patients with sAML who underwent haploHCT from 2006 to 2016. Median age at HCT was 60 years with time from diagnosis to HCT 5 months. At transplantation, 69 patients were in first CR and 85 had active disease. Fifty-seven (38.0%) patients underwent myeloablative conditioning and 97 (62.0%) reduced intensity conditioning (RIC) conditioning. Multivariate analysis showed that there was no difference in RI, nonrelapse mortality (NRM), leukemia free survival (LFS), overall survival (OS), or GVHD-free/relapse free survival (GRFS) for conditioning intensity, age, performance status, or graft source. Active disease was associated with higher RI and inferior LFS, OS, and GRFS compared with patients in CR at time of transplant. T-cell depletion with anti-thymoglobulin resulted in higher NRM and inferior LFS, OS, and GRFS compared to post-transplant cyclophosphamide (PTCy) (HR 2.25, 2.01, 2.16, and 1.73, respectively with P values <.05). Our data shows that haploHCT is a feasible alternative for sAML when matched transplantation is unavailable.

Unmanipulated haploidentical in comparison with matched unrelated donor stem cell transplantation in patients 60 years and older with acute myeloid leukemia: a comparative study on behalf of the ALWP of the EBMT

Background

Acute myeloid leukemia (AML) is both more common and with more biologically aggressive phenotype in the elderly. Allogenic stem cell transplantation (allo-SCT) is the best treatment option in fit patients. Either HLA-matched unrelated donor (MUD) or haploidentical (Haplo) donor are possible alternative for patients in need.

Methods

We retrospectively compared non-T-cell-depleted Haplo (n = 250) to 10/10 MUD (n = 2589) in AML patients ≥ 60 years.

Results

Median follow-up was 23 months. Disease status at transplant differs significantly between the two groups (p < 10⁻⁴). Reduced intensity conditioning (RIC) was administrated to 73 and 77% of Haplo and MUD, respectively (p = 0.23). Stem cell source was the bone marrow (BM) in 52% of the Haplo and 6% of MUD (p < 10⁻⁴). Anti-thymocyte globulin (ATG) was most frequently used in MUD (p < 10⁻⁴) while post-Tx cyclophosphamide (PT-Cy) was given in 62% of Haplo. Engraftment was achieved in 90% of the Haplo vs 97% of MUD (p < 10⁻⁴). In multivariate analysis, no significant difference was found between Haplo and MUD for acute (a)graft versus host disease (GVHD) grade II–IV, relapse incidence (RI), non-relapse mortality (NRM), leukemia free survival (LFS), graft-versus-host-free-relapse free survival (GRFS), and overall survival (OS). Extensive chronic (c)GVHD was significantly higher for MUD as compared to Haplo (HR 2, p = 0.01, 95% CI 1.17–3.47). A propensity score analysis confirmed the higher risk of extensive cGVHD for MUD without differences for other outcomes.

Conclusions

Allo-SCT from both Haplo and MUD are valid option for AML patients ≥ 60 years of age with similar results. Transplantation from MUD was associated with higher extensive cGVHD. Our findings suggest that Haplo is a suitable and attractive graft source for patients≥ 60 with AML in need of allo-SCT.

Update on current research into haploidentical hematopoietic stem cell transplantation

INTRODUCTION

Haploidentical stem cell transplantation (Haplo-SCT) is currently a suitable alternative worldwide for patients with hematological diseases, who lack human leukocyte antigen (HLA)-matched siblings or unrelated donors. Areas covered: This review summarizes the advancements in Haplo-SCT in recent years, primarily focusing on the global trends of haploidentical allograft, the comparison of outcomes between Haplo-SCT and other transplantation modalities, strategies for improving clinical outcomes, including donor selection, hematopoietic reconstitution promotion, and graft-versus-host disease, and relapse prevention/management, as well as the expanded indications of Haplo-SCT, such as severe aplastic anemia, myeloma and lymphoma. Expert commentary: Haploidentical allografts, including granulocyte colony-stimulating factor-based protocol and a post-transplant cyclophosphamide-based protocol, have been the mainstream strategy for Haplo-SCT. However, there are many unanswered questions in this field.

Haploidentical allograft is superior to matched sibling donor allograft in eradicating pre-transplantation minimal residual disease of AML patients as determined by multiparameter flow cytometry: a retrospective and prospective analysis

BACKGROUND

This study compared the effects of pre-transplantation minimal residual disease (pre-MRD) on outcomes in AML patients who underwent human leukocyte antigen-matched sibling donor transplantation (MSDT) or who received unmanipulated haploidentical allografts.

METHODS

A retrospective study (n = 339) and a prospective study (n = 340) were performed. MRD was determined using multiparameter flow cytometry.

RESULTS

Either after retrospective or prospective analysis, patients with negative pre-MRD (pre-MRDneg) had a lower incidence of relapse than those with positive pre-MRD (pre-MRDpos) in MSDT settings (P < 0.001 for all), but relapse was comparable in Haplo-SCT settings for patients with pre-MRDneg versus pre-MRDpos (P = 0.866 and 0.161, respectively). In either the retrospective (n = 65) or the prospective study (n = 76), pre-MRDpos subjects receiving Haplo-SCT experienced a lower incidence of relapse than those who underwent MSDT (P < 0.001 and p = 0.017, respectively). Of the patients with pre-MRDpos in either the total (n = 141) or the subgroup excluding cases which received donor lymphocyte infusion (DLI; n = 105), those who underwent MSDT had a higher incidence of relapse than those receiving haplo-SCT (P < 0.01 for all). Multivariate analysis showed that, for pre-MRDpos cases, haplo-SCT was associated with a low incidence of relapse and with better LFS and OS in either retrospective group, prospective group, combination groups, or subgroup not including cases which received DLI.

CONCLUSIONS

The results indicated that, for pre-MRD-positive AML patients, haplo-SCT was associated with lower incidence of relapse and better survival, suggesting a stronger anti-leukemia effect.

Idarubicin-intensified haploidentical HSCT with GvHD prophylaxis of ATG and basiliximab provides comparable results to sibling donors in high-risk acute leukemia

We designed a novel haploidentical hematopoietic stem cell transplantation (haplo-HSCT) system using idarubicin (IDA) intensified conditioning regimens and combination of antithymocyte globulin and basiliximab for GvHD prophylaxis. The outcomes of 110 high-risk acute leukemia patients undergoing haplo-HSCT were compared with 69 contemporaneous high-risk patients receiving HLA-matched sibling transplantation using uniform IDA-intensified regimens. The relapse incidence of haplo-HSCT was 23.4%, and 3-year overall survival (OS) and disease-free survival (DFS) achieved 62.9%, 59.1%, respectively. The cumulative incidences of II-IV and III-IV aGvHD were 28.6 and 14.3%, while limited and extensive cGvHD were 19.4, 13.8%. All these results were equivalent to those of concurrent identical sibling transplantation. Three-year OS and DFS for patients in advance stage reached 48.5, 47.3%. Furthermore, the relapse, 3-year OS of positive minimal residual disease (MRD) patients did not differ from negative MRD patients (18.9% vs 11.5%, 63.6% vs 69.6%), indicating our intensified haplo-HSCT technique could circumvent the dismal prognosis of MRD. These data provide reinforcing evidence that our haplo-HSCT system could dramatically improve the survival of high-risk acute leukemia with low relapse and acceptable transplantation-related mortality, and might be a promising therapeutic option for high-risk patients.

Unmanipulated haploidentical stem cell transplantation in adults with acute lymphoblastic leukemia: a study on behalf of the Acute Leukemia Working Party of the EBMT

Background

Allogenic hematopoietic stem cell transplantation (allo-SCT) is the most effective post-remission treatment for adults with high-risk acute lymphoblastic leukemia (ALL). The aim of the study was to analyze results of unmanipulated haploidentical allo-SCT (haplo-SCT) for adults with ALL and to identify prognostic factors.

Methods

We performed a retrospective analysis on 208 adults transplanted in EBMT centers from 2007 to 2014.

Results

Median age at haplo-SCT was 32 years and median follow-up, 31 months. Forty-four percent of the patients were in first complete remission (CR1). Stem cell source was the bone marrow (BM) for 43% and peripheral blood (PB) for 57% of patients. Myeloablative conditioning (MAC) was used for 66% and reduced intensity regimen (RIC) for 34% of patients. GVHD prophylaxis was based on post-transplant cyclophosphamide (PT-Cy) for 118 (57%) or on anti-thymocyte-globulin (ATG) for 90 (43%) plus standard prophylaxis. One hundred eighty-four (92%) patients achieved engraftment. Cumulative incidence (CI) of grade II–IV acute-graft-versus-host-disease (GVHD) was 31%, grade III–IV 11%, and chronic GVHD 29%. Non-relapse mortality (NRM) and relapse-incidence (RI) were 32 and 37%, respectively. Overall survival (OS), leukemia-free survival (LFS), and GVHD-free, relapse-free-survival (GRFS) at 3 years were 33, 31, and 26%. For patients in CR1, OS, LFS, and GRFS were 52, 47, and 40%, respectively. Disease status was the main factor associated with transplant outcomes. Use of BM was independently associated with improvement in NRM, acute GVHD, GRFS, LFS, and OS.

Conclusions

Unmanipulated haplo-SCT may be considered a valid option for adult patients with high-risk ALL lacking HLA identical donor preferably in early disease status.

Electronic supplementary material

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Lower incidence of acute GVHD is associated with the rapid recovery of CD4+CD25+CD45RA+ regulatory T cells in patients who received haploidentical allografts from NIMA-mismatched donors: A retrospective (development) and prospective (validation) cohort-based study

To investigate the effects of non-inherited maternal antigen (NIMA) on clinical outcomes and immune recovery, especially of regulatory T cells (Tregs), in patients who underwent unmanipulated haploidentical transplantation. A retrospective cohort (n = 57) and a prospective cohort (n = 88) were included. All patients received haploidentical allografts from sibling donors. Reconstitution of immune subsets, including Tregs, was determined using multicolor flow cytometry. In the retrospective cohort, the cumulative incidence of grades II-IV acute GVHD in patients with NIMA-mismatched donors was significantly lower than that of cases with NIPA-mismatched donors (14.8% vs. 43.30%, p = 0.018). Patients with higher percentages of CD4⁺CD25⁺CD45RA⁺ T cells (naive Tregs) within CD4⁺ T cells recovered on day 30 (≥1.55%) experienced a significantly lower incidence of grades II-IV acute GVHD than that of cases with lower percentages of naive Tregs (<1.55%) (13.8% vs. 46.4%, p = 0.010). Multivariate analysis showed that NIMA mismatch and the percentages of naive Tregs were associated with the incidence of grades II-IV acute GVHD [p = 0.050, and 0.031, respectively]. In the prospective cohort, the association of NIMA mismatch [HR = 0.365, 95% CI, 0.169-0.786, p = 0.010] or higher percentages of naive Tregs recovered on day 30 (≥1.55%) [HR = 0.114, 95% CI, 0.027-0.479, p = 0.003] with a lower cumulative incidence of grades II-IV acute GVHD was further demonstrated. No effects of NIMA mismatch on chronic GVHD, transplant-related mortality, relapse, disease-free survival, or overall survival were found. Our results confirmed the role of NIMA mismatch in acute GVHD and provided the first demonstration, based on clinical data, that recovered Tregs may be involved in the effects of NIMA on acute GVHD in a haploidentical transplant setting.