Unmanipulated haploidentical transplants compared with other alternative donors and matched sibling grafts

Characterization of Chronic Graft-versus-host Disease After Haploidentical Stem Cell Transplantation With Posttransplant Cyclophosphamide: A Study on Behalf of GETH-TC

BACKGROUND

Chronic graft-versus-host disease (cGVHD) is a cause of late morbidity and nonrelapse mortality (NRM) after allogenic hematopoietic stem cell transplantation (allo-HSCT). Although studies evaluating haploidentical allo-HSCT (haplo-HSCT) using posttransplant cyclophosphamide (PTCy) demonstrate lower cGVHD rates, comprehensive data describing the clinical profile, risk factors, or outcomes of cGVHD within this platform are scarce.

METHODS

We conducted a retrospective multicenter analysis of 389 consecutive patients who underwent haplo-HSCT PTCy in 7 transplant centers of the Spanish Group Grupo Español de Trasplante Hematopoyético y Terapia Celular (GETH-TC) between 2008 and 2020 describing incidence, clinical profile, risk factors, and cGVHD outcomes.

RESULTS

Ninety-five patients of 389 developed cGVHD. Our data revealed that the incidence and severity of cGVHD are lower than those reported for HLA-identical transplantation with conventional prophylaxis and that the strongest predictor for cGVHD was previous acute GVHD ( P  = 0.031). Also, recipient age ≥60 y ( P  = 0.044) was protective against cGVHD. Moreover, patients with moderate cGVHD had longer event-free survival at 3 y than other patients ( P  = 0.016) and a lower relapse rate at 3 y ( P  = 0.036).

CONCLUSIONS

Our results support the fact that the incidence and severity of cGVHD are lower than those reported for HLA-identical transplantation with conventional prophylaxis. In this series, patients who develop moderate cGVHD after haplo-HSCT PTCy had a higher overall survival and event-free survival, and lower relapse, suggesting higher graft-versus-leukemia effect. Although this is the largest series focused on characterizing cGVHD in haplo-HSCT PTCy, further prospective studies are needed to confirm the findings.

Total Body Irradiation and Fludarabine with Post-Transplantation Cyclophosphamide for Mismatched Related or Unrelated Donor Hematopoietic Cell Transplantation

Allogeneic hematopoietic cell transplantation (HCT) remains the sole curative treatment for most patients with hematologic malignancies. A well-matched donor (related or unrelated) remains the preferred donor for patients undergoing allogeneic HCT; however, a large number of patients rely on alternative donor choices of mismatched related (haploidentical) or unrelated donors to access HCT. In this retrospective study, we investigated outcomes of patients who underwent mismatched donor (related or unrelated) HCT with a radiation-based myeloablative conditioning MAC regimen in combination with fludarabine, and post-transplantation cyclophosphamide (PTCy) as higher-intensity graft-versus-host disease (GVHD) prophylaxis. We retrospectively assessed HCT outcomes in 155 patients who underwent mismatched donor HCT (related/haploidentical versus unrelated [MMUD]) with fractionated-total body irradiation (fTBI) plus fludarabine and PTCy as GVHD prophylaxis at City of Hope from 2015 to 2021. Diagnoses included acute lymphoblastic leukemia (46.5%), acute myelogenous leukemia (36.1%), and myelodysplastic syndrome (6.5%). The median age at HCT was 38 years, and 126 patients (81.3%) were an ethnic minority. The Hematopoietic Stem Cell Transplantation Comorbidity Index was ≥3 in 36.1% of the patients, and 29% had a Disease Risk Index (DRI) of high/very high. The donor type was haploidentical in 67.1% of cases and MMUD in 32.9%. At 2 years post-HCT, disease-free survival (DFS) was 75.4% and overall survival (OS) was 80.6% for all subjects. Donor type did not impact OS (hazard ratio [HR], .72; 95% confidence interval [CI], .35 to 1.49; P = .37) and DFS (HR, .78; 95% CI, .41 to 1.48; P = .44), but younger donors was associated with less grade III-IV acute GVHD (HR, 6.60; 95% CI, 1.80 to 24.19; P = .004) and less moderate or severe chronic GVHD (HR, 3.53; 95% CI, 1.70 to 7.34; P < .001), with a trend toward better survival (P = .099). The use of an MMUD was associated with significantly faster neutrophil recovery (median, 15 days versus 16 days; P = .014) and platelet recovery (median, 18 days versus 24 days; P = .029); however, there was no difference in GVHD outcomes between the haploidentical donor and MMUD groups. Nonrelapse mortality (HR, .86; 95% CI, .34 to 2.20; P = .76) and relapse risk (HR, .78; 95% CI, .33 to 1.85; P = .57) were comparable in the 2 groups. Patient age <40 years and low-intermediate DRI showed a DFS benefit (P = .004 and .029, respectively). High or very high DRI was the only predictor of increased relapse (HR, 2.89; 95% CI, 1.32 to 6.34; P = .008). In conclusion, fludarabine/fTBI with PTCy was well-tolerated in mismatched donor HCT, regardless of donor relationship to the patient, provided promising results, and increased access to HCT for patients without a matched donor, especially patients from ethnic minorities and patients of mixed race.

Comparison of Three Graft-versus-Host Disease Prophylaxis Strategies after T Cell-Replete Haploidentical Hematopoietic Transplantation: Tacrolimus versus Calcineurin Inhibitors + Mycophenolate Mofetil versus Sirolimus + Mycophenolate Mofetil

Since the introduction of post-transplantation cyclophosphamide (PTCy), haploidentical hematopoietic stem cell transplantation (haploSCT) has become a real alternative for patients who lack other eligible donors. The standard graft-versus-host disease (GVHD) prophylaxis after PTCy has been a calcineurin inhibitor (CNI) plus mycophenolate mofetil (MMF) (up to day +35), but promising results with sirolimus (with or without MMF) and single-agent tacrolimus have been published recently. This multicenter retrospective study compared the outcomes of 372 adult haploSCT recipients who received conditioning with thiotepa, busulfan, and fludarabine (TBF), PTCy, and additional GVHD prophylaxis with 1 of 3 strategies: cohort A, single-agent tacrolimus (n = 222); cohort B, CNI + MMF (n = 49); or cohort C, sirolimus + MMF (n = 101). No differences among the 3 cohorts were found in terms of grade II-IV acute GVHD (20% in cohort A, 25% in cohort B, and 30% in cohort C) or grade III-IV acute GVHD (9%, 6%, and 15%, respectively) at 100 days; however, cohort A had the lowest incidence of overall chronic GVHD (24%, 47%, and 52%, respectively; P = .001) and moderate-severe chronic GVHD (13%, 35%, and 33%, respectively; P = .001). There were no differences in 3-year overall survival, progression-free survival, nonrelapse mortality, or relapse among the 3 cohorts. Overall, our study suggests that single-agent tacrolimus, CNI + MMF, and sirolimus + MMF GVHD prophylaxis lead to similar outcomes following haploSCT with TBF and PTCy, with a low incidence of grade III-IV acute GVHD, although possible differences in chronic GVHD require further investigation.

Biologically randomized comparison of haploidentical versus HLA-matched related donor reduced intensity conditioning hematopoietic cell transplantation

BACKGROUND

Using haploidentical donors for allogeneic hematopoietic cell transplantation (HCT) broadens transplant accessibility to a growing number of patients with hematologic disorders. Moreover, haploidentical HCT with post-transplant cyclophosphamide (PTCy) has become widespread practice due to accumulating evidence demonstrating favorable rates of survival and graft-versus-host disease (GvHD). Most studies comparing outcomes by donor sources have been confounded by variability in conditioning regimens, graft type (peripheral blood or bone marrow), and post-transplant GvHD prophylaxis (PTCy or non-PTCy), making it difficult to define the effect of donor source on outcomes. Levine Cancer Institute started a transplant and cellular therapy program in 2014, with both haploidentical and matched related donor (MRD) transplants initially performed using a uniform reduced intensity conditioning (RIC) regimen, peripheral blood grafts, and PTCy-based GvHD prophylaxis.

OBJECTIVE

This retrospective observational study was conducted to compare the clinical outcomes associated with RIC haploidentical HCT and MRD HCT in patients receiving identical conditioning regimens, graft types, and supportive care.

STUDY DESIGN

Our transplant database was queried to evaluate demographic characteristics, clinical features, and outcomes of RIC HCT for consecutive patients with hematologic malignancies who received haploidentical or MRD grafts between March 2014 and December 2017. A MRD was the preferred donor source; when unavailable, a haploidentical donor was used.

RESULTS

Sixty-seven patients underwent haploidentical HCT and 25 MRD HCT. Overall, characteristics of transplant recipients were similar for the haploidentical and MRD groups; however, haploidentical donors were younger than MRDs (median 36 years vs 57 years, P <.0001). Results of univariable analysis showed similar overall survival (OS) for haploidentical and MRD HCT (HR, 1.15; 95% CI, 0.61-2.15; P =.669). One-year, three-year, and five-year OS were 80.2%, 54.7%, and 41.2% for haploidentical HCT and 76.0%, 55.7%, and 51.1% for MRD HCT, respectively. With a median follow-up of 81.90 months, results of multivariable analysis revealed that donor source (haploidentical vs MRD) was not significantly associated with OS (HR, 0.97; 95% CI, 0.51-1.87; P =.933), relapse-free survival (HR, 0.75; 95% CI, 0.42-1.35; P =.337), cumulative incidence of relapse (HR, 0.81; 95% CI, 0.39-1.70; P =.579), or non-relapse mortality (HR, 1.12; 95% CI, 0.40-3.14; P =.827). Cumulative incidences of acute GvHD (aGvHD) and chronic GvHD (cGvHD) were not significantly different for haploidentical and MRD HCT (grades II-IV aGvHD: HR, 1.78; 95% CI, 0.72-4.37; P =.210; grades III-IV aGvHD: HR, 2.84; 95% CI, 0.34-23.63; P =.335; cGvHD: HR, 1.00; 95% CI 0.36-2.76; P =.995).

CONCLUSIONS

With care that was homogenous in terms of conditioning regimens, graft type, GvHD prophylaxis, and supportive care, 92 patients who were biologically randomized to either haploidentical HCT or MRD HCT after RIC with PTCy had comparable outcomes.

Graft-versus-tumor effect of post-transplant cyclophosphamide-based allogeneic hematopoietic cell transplantation

Post-transplant cyclophosphamide (PTCy) is becoming the standard prophylaxis for graft-versus-host disease (GVHD) in HLA-haploidentical allogeneic hematopoietic cell transplantation (allo-HCT) and in HLA-matched allo-HCT. Immune reconstitution in the post-transplant setting may influence the graft-versus-tumor (GVT) effect because PTCy has a profound effect on T cell and natural killer cell functions and their reconstitution after allo-HCT. However, many recent studies have shown that the incidence of relapse after allo-HCT with PTCy is comparable to that after conventional allo-HCT. To further improve the outcomes, it is critical to establish a strategy to maintain or effectively induce the GVT effect when using PTCy as a platform for GVHD prophylaxis. However, there is a paucity of studies focusing on the GVT effect in allo-HCT with PTCy. Therefore, focusing on this issue may lead to the establishment of more appropriate strategies to improve transplantation outcomes without exacerbating GVHD, including novel therapies involving cell modification.

Myeloablative Haploidentical Donor Hematopoietic Transplantation Using Post-Transplantation Cyclophosphamide and Antithymocyte Globulin

Haploidentical donor (haplo-) hematopoietic stem cell transplantation (HSCT) with post-transplantation cyclophosphamide (PTCy) is now performed on a large scale worldwide. Our patient outcomes did not completely reflect the results published by other groups. We herein present the results of 60 patients with hematologic malignancies treated homogeneously on a modified version of the standard protocol by adding ATG as an additional graft-versus-host disease (GVHD) prophylaxis measure. This was a retrospective analysis of 60 haplo-HSCT recipients using a myeloablative conditioning regimen with antithymocyte globulin and PTCy for GVHD prophylaxis. At 5 years, overall survival was 59.2%, relapse-free survival (RFS) was 48.6%, and chronic GVHD (cGVHD) and relapse-free survival was 40%. The median time to neutrophil and platelet engraftment was 16 days and 28.5 days, respectively. The rates of grade II-IV acute GVHD and extensive cGVHD were 46.7% and 23.3%, respectively. The cumulative incidence of relapse was 30%, nonrelapse mortality was 21.6%, and transplantation-related mortality was 11%. Higher Disease Risk Index and 50% HLA match were associated with lower RFS. Female donor to male recipient and older donor age were associated with an elevated risk of cGVHD. The use of PTCy might not yield the same results in different populations. Many remaining questions need to be addressed in randomized trials, including optimal graft source and donor, date of calcineurin inhibitor initiation, personalized or targeted dose of PTCy, immune reconstitution, and others.

Long-term follow-up of haploidentical haematopoietic stem cell transplantation in paediatric patients with high-risk acute myeloid leukaemia: Report from a single centre

Data from 200 children with high-risk acute myeloid leukaemia who underwent their first haploidentical haematopoietic stem cell transplantation (haplo-HSCT) between 2015 and 2021 at our institution were analysed. The 4-year overall survival (OS), event-free survival (EFS) and cumulative incidence of relapse (CIR) were 71.9%, 62.3% and 32.4% respectively. The 100-day cumulative incidences of grade II-IV and III-IV acute graft-versus-host disease (aGVHD) were 41.1% and 9.5% respectively. The 4-year cumulative incidence of chronic GVHD (cGVHD) was 56.1%, and that of moderate-to-severe cGVHD was 27.3%. Minimal residual disease (MRD)-positive (MRD+) status pre-HSCT was significantly associated with lower survival and a higher risk of relapse. The 4-year OS, EFS and CIR differed significantly between patients with MRD+ pre-HSCT (n = 97; 63.4%, 51.4% and 41.0% respectively) and those with MRD-negative (MRD-) pre-HSCT (n = 103; 80.5%, 73.3% and 23.8% respectively). Multivariate analysis also revealed that acute megakaryoblastic leukaemia without Down syndrome (non-DS-AMKL) was associated with extremely poor outcomes (hazard ratios and 95% CIs for OS, EFS and CIR: 3.110 (1.430-6.763), 3.145 (1.628-6.074) and 3.250 (1.529-6.910) respectively; p-values were 0.004, 0.001 and 0.002 respectively). Thus, haplo-HSCT can be a therapy option for these patients, and MRD status pre-HSCT significantly affects the outcomes. As patients with non-DS-AMKL have extremely poor outcomes, even with haplo-HSCT, a combination of novel therapies is urgently needed.

Haploidentical and Matched Sibling Transplantation for Acute Myeloid Leukemia: A Hospital-Based Study

Background

Allogeneic peripheral blood stem cell transplantation (PBSCT) has been increasing for the last years in Latin America. The objective of this study was to describe clinical outcomes in acute myeloid leukemia (AML) receiving allogeneic PBSCT between 2013 and 2019 in a single center of Cali, Colombia.

Methods

A retrospective cohort study was conducted in Fundacion Valle del Lili. Patients diagnosed with AML who received an allogeneic PBSCT between 2013 and 2019 using human leukocyte antigen (HLA)-matched sibling donors (MSDs) or haploidentical related donors (HRDs) with myeloablative conditioning regimen were included. Cases with diagnosis of promyelocytic leukemia, myelodysplastic syndrome-related AML and therapy-related AML were excluded. Data were obtained directly from the hospital PBSCT database and clinical records.

Results

A total of 50 patients were included (HRD, n = 32; MSD, n = 18). Sixty-two percent was in the first complete remission (CR1) at the time of the transplant, of which 26% were MSD and 74% were HRD. The European Group for Blood and Marrow Transplantation (EBMT) risk score was: 44% vs. 50% low, 28% vs. 28% intermediate and 28% vs. 22% high for MSD vs. HRD, respectively. Overall survival at 5 years for MSD was 62% (95% confidence interval (CI): 31-83%) and 43% (95% CI: 25-60%) for HRD. Event-free survival was 56% (95% CI: 26-78%) and 35.6% (95% CI: 18-53%), respectively. Non-relapse mortality at day-100 was 6% (95% CI: 0.8-35%) and 20% (95% CI: 9-39%). Relapse at5 years was 18% (95% CI: 4-58%) and 25% (95% CI: 10-52%). Overall mortality rate was 46%. The grade II-IV, III-IV acute graft-versus-host disease and severe chronic graft-versus-host disease was 44%, 11% and 12% for MSD, and 43%, 9% and 0% for HRD.

Conclusion

These results underline that MSD remains the first donor choice for AML patients in CR1 when available. HRDs are still our next option among alternative donors. It is necessary to find strategies that have a positive impact on those outcomes that markedly affect the quality of allogeneic PBSCT and the prognosis of patients. Comparative, randomized, prospective studies with longer follow-up of haploidentical allogeneic PBSCT with other donor types are required to definitely establish its role among alternative donors.

Combining post-transplant cyclophosphamide with antithymocyte globulin for graft-versus-host disease prophylaxis in hematological malignancies

In search of an ideal partner or alternative to conventional immunosuppressive agents, rabbit anti-thymocyte globulin (ATG) and, more recently, post-transplant cyclophosphamide (PT-Cy) have both emerged as valid and efficient options for preventing graft-versus-host disease (GvHD). To further reduce the risk of GvHD, strategies combining ATG and PT-Cy have recently been investigated. In a haploidentical setting, retrospective studies suggest that combining PT-Cy and ATG may result in a lower incidence of chronic GvHD without increasing the risks of infection or relapse, when compared to PT-Cy without ATG. In haploidentical or unrelated donor settings, adding reduced doses of PT-Cy to ATG may reduce the risk of acute and chronic GvHD and improve survival, particularly GvHD-free, relapse-free survival (GRFS), when compared to ATG without PT-Cy. Overall, the combination of PT-Cy and ATG is a safe and promising approach for patients with hematological malignancies undergoing allogeneic hematopoietic stem cell transplantation (HSCT).

Reduced post-transplant cyclophosphamide dose with antithymocyte globulin in peripheral blood stem cell haploidentical transplantation

Post-transplant cyclophosphamide (PT-Cy) is effective for graft-versus-host disease (GVHD) prophylaxis, but it may cause dose-dependent toxicities, particularly in frail patients. Therefore, we compared the outcomes with a reduced PT-Cy total dose (70 mg/kg) to those with the standard PT-Cy dose (100 mg/kg) in haploidentical hematopoietic cell transplantation (HCT) patients aged ≥ 65 years and those with cardiac comorbidities. All consecutive patients with a hematological malignancy receiving peripheral blood stem cells (PBSCs) after a thiotepa-based conditioning with low-dose antithymocyte globulin were included. Thirty-three patients received PT-Cy at 70 mg/kg and 25 at 100 mg/kg. PT-Cy dose reduction did not increase the risk of GVHD and was associated with faster neutrophil and platelet recovery, and lower cumulative incidences of bacteremia (38% versus 72%, p = 0.004) and cardiac complications (12% versus 44%, p = 0.028). At 2 years, GVHD-free, relapse-free survival (GRFS) was higher with the reduced dose compared to the standard dose (60% versus 33%, p = 0.04). In conclusion, reducing PT-Cy total dose to 70 mg/kg is a safe and valid approach for elderly patients and those with cardiac comorbidities underdoing haploidentical HCT with PBSCs and low-dose antithymocyte globulin. The reduced PT-Cy dose was associated with improved hematological count recovery, lower incidence of toxicities, and higher GRFS.

Unrelated female-to-male bone marrow transplantation would be preferred over cord blood transplantation in male patients

BACKGROUND AIMS

Allogeneic hematopoietic stem cell transplantation from female donors to male recipients (female-to-male allo-HCT) is a well-established risk factor for a greater incidence of non-relapse mortality (NRM) and chronic graft-versus-host disease (GVHD). In contrast, unrelated cord blood transplantation (UCBT) is associated with a lower incidence of chronic GVHD. In this study, survival outcomes were compared between the UCBT and unrelated female-to-male bone marrow transplantation (UFMBMT) groups.

METHODS

We evaluated male allo-HCT recipients who underwent UCBT or UFMBMT between 2012 and 2020 in Japan. There were 2517 cases in the UCBT group, 456 cases in the HLA-matched UFMBMT group and 457 cases in the HLA-mismatched UFMBMT group.

RESULTS

HLA-mismatched UFMBMT was significantly associated with a decreased risk of relapse (hazard ratio [HR] 0.74; 95% confidence interval [CI] 0.57-0.98], P = 0.033) and HLA-matched UFMBMT had the tendency of a decreased risk of relapse (HR 0.78; 95% CI 0.61-1.01, P = 0.059). HLA-matched UFMBMT was also associated with favorable OS (HR 0.82; 95% CI 0.69-0.97, P = 0.021). The relationship between the donor sources and relapse was similarly observed in the lymphoid malignancy cohort.

CONCLUSIONS

The difference of graft-versus leukemia effect by H-Y immunity according to donor sources might contribute to the difference in clinical impact. It might be desirable for patients who could sufficiently wait for donor coordination to select BMT rather than UCBT, even if only unrelated female donors are available for male recipients.

Case Series Using Salvage Haplo-Identical Stem Cells for Secondary Transplantation

In order to expand the donor pool and accessibility of the transplant procedure, it was necessary to introduce haplo-identical stem cell transplants in the Fundeni Clinical Institute from 2015. Even if the Romanian population is an ethnically compact white population, many of the patients referred for bone marrow transplant lack a suitable donor. Hematopoietic stem cell transplant from a haplo-identical donor is an alternative option for those patients without an HLA (Human Leucocyte Antigen)-matched donor (sibling or matched unrelated). This procedure was used also as a salvage option for those who experienced engraftment failure or the rejection of the first stem cell graft. In this case series, we present three such cases, with a haplo-transplant used as a salvage protocol (after an engraftment failure or rejection of the first transplanted cells). The patients we present were diagnosed with AML (acute myeloid leukemia) with MDS (myelodysplastic syndrome), MDS-RAEB 2 (myelodysplastic syndrome-refractory anemia with excess blasts 2), and SAA (severe aplastic anemia). In two of the three cases, the engraftment failure may have been due to the conditioning Fludarabine/Busulfan/Cyclophosphamide (Flu/Bu/CFA) used, combined with marrow grafts. In all three cases, the second transplant was of haplo-identical peripheral blood stem cells using Melphalan/Fludarabine (Mel/Flu) conditioning, the cells engrafted properly and the patients experienced complete chimerism, and two of them are alive with an excellent quality of life.

Effective T-cell replete haploidentical stem cell transplantation for pediatric patients with high-risk hematologic disorders

OBJECTIVES

Patients with high-risk hematologic diseases require intensive modalities, including high-dose chemotherapy and allogeneic hematopoietic stem cell transplantation (allo-HSCT). Haploidentical T-cell-replete transplantation is a logical choice because of the limited availability of matched sibling donors and the prolonged time needed to identify matched unrelated donors in Thailand.

METHODS

The clinical outcomes data of 43 patients undergoing allo-HSCT were reviewed. All patients had high-risk hematologic malignancies, were younger than 20 years, and were in complete cytological remission at the time of allo-HSCT. We used two different conditioning regimens: total body irradiation (TBI) combined with cyclophosphamide, fludarabine, and melphalan (n = 23) and thiotepa combined with fludarabine and busulfan (n = 20). All patients received a graft-versus-host disease prophylaxis regimen consisting of cyclophosphamide, mycophenolate mofetil, and a calcineurin inhibitor or sirolimus.

RESULTS

There was no difference in engraftment between patients receiving either of the regimens. After a median follow-up of 35.8 (range, 0.6-106.2) months, the overall survival (OS) and event-free survival (EFS) rates were 62.4% and 54.7%, respectively. OS and EFS were comparable between the respective regimens.

CONCLUSIONS

We conclude that thiotepa-based conditioning has similar efficacy and tolerability as TBI-based conditioning for haploidentical HSCT with post-transplant cyclophosphamide.

A single-center experience of haploidentical stem cell transplantation in hematological malignancies

BACKGROUND

Since well-designed prospective comparative trials are lacking, haploidentical hematopoietic stem cell transplantations approach should be based on the expertise of a particular center. In this study, we aimed to report the results and outcomes of patients who underwent haploidentical hematopoietic stem cell transplantation.

METHODS

: Thirty-nine patients who underwent transplantation in our clinic between 2015 and 2022 were retrospectively analyzed. Primary end point of this study is to find out the survival rates of the patients.

RESULTS

The overall survival of patients was 29.9 ± 4.9 months. The disease-free survival of the patients was 37.8 ± 5.7 months. The 3-year overall survival rate of the patients was %50 and the 3-year disease-free survival rate of the patients was %53. Nineteen patients were nonsurvivors among a total of 39 patients. Busulfan-fludarabine-thiotepa was the most frequently used conditioning regimen for transplantation. Busulfan-fludarabin-antithymocyte globulin regimen is the second preferred conditioning regimen. Cyclosporine- cyclophosphamide-mycophenolate mofetil was the most widely used graft-versus-host disease prophylaxis regimen. Sixteen patients had graft-versus-host disease, 28% of the patients had acute graft-versus-host disease, and 13% had chronic graft-versus-host disease. Gastrointestinal system consists of the most involved organs in graft-versus-host disease since 15% of the patients had gastrointestinal graft-versus-host disease. First-degree relatives (parent/child) were the most frequent donor source for haploidentical hematopoietic stem cell transplantation. Sepsis was the most frequent reason of death among transplant patients.

DISCUSSION

In our center, we prefer to use high dose posttransplantation cyclophosphamide after haploidentical hematopoietic stem cell transplantation for graft-versus-host disease prophylaxis. With this approach, our center's overall survival and disease-free survival rates are comparable and compatible with the literature findings.

Reduced post-transplant cyclophosphamide doses in haploidentical hematopoietic cell transplantation for elderly patients with hematological malignancies

Although post-transplant cyclophosphamide (PT-Cy) is effective for graft-versus-host disease (GVHD) prophylaxis, it is associated with toxicities, which might be dose-dependent. We compared the outcomes with PT-Cy at 80 mg/kg to those with PT-Cy at 100 mg/kg in elderly patients undergoing haploidentical hematopoietic cell transplantation (HCT). Inclusion criteria included peripheral blood stem cells, hematological malignancy, and age>65 years (or age>60 years if cardiac event history). Thirty-eight patients received PT-Cy at 80 mg/kg and 55 100 mg/kg, divided in two doses. The cumulative incidences (CI) of acute grade II-IV, acute grade III-IV, and moderate/severe chronic GVHD were 32%, 16%, and 13% with PT-Cy at 80 mg/kg compared to 33%, 13%, and 16% with 100 mg/kg, respectively. In multivariable analysis, reducing PT-Cy dose had no significant impact on GVHD. Neutrophil and platelet engraftments were significantly improved, and CI of BK virus-associated hemorrhagic cystitis was reduced with 80 mg/kg of PT-Cy compared to 100 mg/kg. At 2 years, non-relapse mortality was 16% and 31%, progression-free survival 65% and 49%, overall survival 70% and 56%, and GVHD-free, relapse-free survival 52% and 36% with 80 mg/kg and 100 mg/kg, respectively. Reducing PT-Cy dose to 80 mg/kg is safe and associated with improved hematological recovery and lower CI of hemorrhagic cystitis in elderly patients undergoing haploidentical HCT.

Controversies and expectations for the prevention of GVHD: A biological and clinical perspective

Severe acute and chronic graft versus host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. Historically, cord blood and matched sibling transplantation has been associated with the lowest rates of GVHD. Newer methods have modified the lymphocyte components to minimize alloimmunity, including: anti-thymocyte globulin, post-transplant cyclophosphamide, alpha/beta T cell depletion, and abatacept. These agents have shown promise in reducing severe GVHD, however, can be associated with increased risks of relapse, graft failure, infections, and delayed immune reconstitution. Nonetheless, these GVHD prophylaxis strategies have permitted expansion of donor sources, especially critical for those of non-Caucasian decent who previously lacked transplant options. This review will focus on the biologic mechanisms driving GVHD, the method by which each agent impacts these activated pathways, and the clinical consequences of these modern prophylaxis approaches. In addition, emerging novel targeted strategies will be described. These GVHD prophylaxis approaches have revolutionized our ability to increase access to transplant and have provided important insights into the biology of GVHD and immune reconstitution.

Haploidentical Versus Matched Sibling Donor Hematopoietic Stem Cell Transplantation for Adult Patients With Relapsed/Refractory Acute Lymphoblastic Leukemia: A Study From the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

The results of haploidentical stem cell transplantation (haploHCT) for patients with acute lymphoblastic leukemia (ALL) transplanted in active disease remain largely unknown. We retrospectively analyzed adult patients with R/R ALL who underwent haploHCT or matched sibling donor (MSD-HCT) as a first transplantation between 2012 and 2020. The analysis comprised 274 patients, 94 had a haploHCT, and 180 had an MSD-HCT. The median follow-up was 32 months. The median age was 33 (range 18-76) and 37 (18-76) years in the haplo- and MSD-HCT groups, respectively. Post-transplant cyclophosphamide (PTCy) was used in 88% of haploHCT and in 4% of the MSD-HCT group. Graft-versus-host disease grade III-IV was higher in haploHCT than in the MSD-HCT group (18% versus 9%; P = 0.042). The 2-year chronic (c) graft-versus-host disease rates were 17% versus 33% (hazard ratio [HR] = 0.56; P = 0.14), respectively. By multivariate analysis, relapse incidence, and leukemia-free survival were not significatively different between the transplant groups, while nonrelapse mortality (NRM) was significantly higher (25% versus 18% at 2 years; HR = 2.03; P = 0.042) and overall survival (OS) lower (22% versus 38% at 2 years; HR = 1.72; P = 0.009) in the haploHCT group compared with the MSD-HCT group. We conclude that the 2-year OS of R/R ALL patients undergoing MSD transplants is significantly better than in haploHCT with a higher NRM in the latter.

Risk factors for adverse outcomes following haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide: a two-center analysis

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative therapy for several malignant hematologic diseases and alternative donors, including haploidentical, play a significant role in HCT. Despite the increasing use of haplo-HCT with PTCy, some questions remain open. The objective of the present study was to investigate risk factors for adverse outcomes after haplo-HCT with PTCy. This is a retrospective study conducted at two Brazilian centers. A total of 103 patients with hematologic malignancies who underwent first allogeneic, haploidentical HCT with PTCy were included. Risk factors for death were age at transplant (HR = 1.03 for each year; p = 0.002) and high/very high disease risk index (DRI; HR = 2.77; p = 0.0007) and mother as the donor compared with other donors (HR = 3.53; p = 0.005). In multivariate analysis, PFS was significantly poorer for older patients (HR = 1.02; p = 0.006), high/very high DRI (HR = 2.39; p = 0.003), and mother as the donor compared with other donors (HR = 3.18; p = 0.006). Relapse rate was higher for high/very high DRI (HR = 4.01; p = 0.002) and mother as the donor compared with other donors (HR = 2.52; p = 0.05). NRM was higher for older patients (HR = 1.03 for each year; p = 0.03). Tacrolimus was a protective factor for grades II-IV aGVHD (HR = 0.46; p = 0.04) compared with cyclosporine. Peripheral blood (PBSC) was a risk factor for cGVHD (HR = 3.48; p = 0.006), while tacrolimus was protective (HR = 0.30; p = 0.009). Mother as the donor compared with other donors was also a risk factor for poorer OS, PFS, and relapse, suggesting that this combination should be avoided. Tacrolimus was protective for both grades II-IV aGVHD and cGVHD, suggesting that tacrolimus may be more effective than cyclosporine in preventing GVHD. PBSC was a risk factor for cGVHD without any impact on relapse. Prospective studies comparing tacrolimus with cyclosporine are awaited.

Risk factors for late cytomegalovirus infection after completing letermovir prophylaxis

Prophylactic use of letermovir (LMV) markedly reduces the incidence of early clinically significant cytomegalovirus (csCMV) infection within the first 100 days after allogeneic hematopoietic cell transplantation (allo-HCT), which improves transplant outcomes. However, some patients eventually develop late-csCMV infection (beyond day 100) after completing LMV prophylaxis. To assess the incidence of late-csCMV infection as well as its risk factors and impacts on transplant outcome, a total of 81 allo-HCT recipients who had not developed early csCMV infection during LMV prophylaxis were retrospectively analyzed. Among them, 23 (28.4%) patients developed late-csCMV infection (until day 180) at a median time of 131 days after transplantation and 30 days after LMV discontinuation, respectively. Late-csCMV infection was correlated with apparent delayed immune reconstitution: patients transplanted from HLA-mismatched donors (hazard ratio [HR] = 13.0, p = 0.011) or CMV-IgG-negative donors (HR = 2.39, p = 0.043) had a significantly higher risk. In this study, transplant outcomes did not differ between patients with and without late-csCMV infection. This suggests a need to clarify the efficacy of extended administration of LMV for preventing late-csCMV infection in a larger number of allo-HCT recipients, especially those with "high-risk" donors.

Infusion of haploidentical HSCs combined with allogenic MSCs for the treatment of ALL patients

Although haploidentical stem cell transplantation (haplo-HSCT) offers almost all acute lymphoblastic leukaemia (ALL) patients an opportunity for immediate transplantation, it exhibits a higher incidence of graft failure and graft versus host disease (GVHD). Mesenchymal stem cells (MSCs) are characterised by their haematopoiesis-promoting and immunomodulatory capacity. Thus, we designed a combination of haplo-HSCT and MSCs for ALL patients. ALL patients (n = 110) were given haploidentical HSCs combined with allogenic MSCs, and ALL patients without MSC infusion (n = 56) were included as controls. The 100-day cumulative incidences of grade ≥2 acute GVHD (aGVHD) and grade ≥3 aGVHD were 40.00% and 9.09% compared to 42.32% (P = 0.79) and 22.79% (P = 0.03) in patients without MSC infusion, respectively. The 3-year cumulative incidences of chronic GVHD (cGVHD) and extensive cGVHD were 22.27% and 10.27% compared to 32.14% (P = 0.19) and 22.21% (P = 0.04) in patients without MSC infusion, respectively. No significant differences in the 3-year relapse incidence, nonrelapse mortality, leukaemia-free survival or overall survival in groups with and without MSC cotransplantation were observed. Multivariate analysis showed that MSC infusion contributed to a lower risk of developing extensive cGVHD. Our data suggested that haplo-HSCT combined with MSCs may provide an effective and safe treatment for ALL patients.

Optimal Active Anti-Thymocyte Globulin Exposure Associated with Minimum Risk of Virus Reactivation and Comparable Acute Graft-Versus-Host Disease Under Adult Myeloablative Haploidentical Peripheral Blood Stem Cell Transplantation

Anti-thymocyte globulin (ATG) is often included in the conditioning regimen to prevent graft-versus-host disease (GVHD) in allogeneic hematopoietic cell transplantation (allo-HCT). However, the risk of virus reactivation increases significantly. We conducted a single-center prospective study to identify the optimal ATG exposure that ensures engraftment, effectively prevents acute GVHD, and reduces the risk of virus reactivation without increasing relapse of malignant diseases in haploidentical peripheral blood stem cell transplantation (haplo-PBSCT). From September 2018 to June 2020, 106 patients (median age, 32 years) with malignant hematological diseases who received haplo-PBSCT for the first time were enrolled. All patients received 10 mg/kg rabbit ATG (thymoglobulin) divided for 4 days (days -5 to -2). Pre-transplant, post-transplant, and total areas under the concentration-time curve (AUCs) of active ATG were calculated. Total AUC of active ATG was shown to be the best predictor for virus reactivation and acute GVHD of grades II to IV or grades III and IV. The optimal total AUC range of active ATG was 100 to 148.5 UE/mL/day. The median time was 14 versus 13 days (P = .184) for myeloid engraftment and 13 versus 13 days (P = .263) for platelet engraftment in the optimal and non-optimal AUC groups, respectively. The optimal AUC group showed a lower cumulative incidence of cytomegalovirus (CMV) reactivation and persistent CMV viremia than the non-optimal AUC group: 60.6% (95% confidence interval [CI], 48.3%-73.1%) versus 77.1% (95% CI, 64.5%-87.7%; P = .016) and 31.5% (95% CI, 21.2%-45.3%) versus 56.3% (95% CI, 42.9%-70.4%; P = .007), respectively. The cumulative incidence of persistent Epstein-Barr virus (EBV) viremia in the optimal AUC group was significantly lower than the non-optimal total AUC group: 33.1% (95% CI, 22.5%-46.8%) versus 52.6% (95% CI, 39.3%-67.2%; P = .048). However, there was no difference in EBV reactivation (P = .752). Similar outcomes were observed for grade II to IV and grade III and IV acute GVHD between the two groups: 48.6% (95% CI, 36.8%-62.0%) versus 37.0% (95% CI, 24.8%-52.5%; P = .113) and 10.4% (95% CI, 4.8%-21.7%) versus 4.2% (95% CI, 1.0%-15.6%; P = .234, respectively. Relapse, non-relapse mortality, and disease-free survival demonstrated no significant differences between the two groups. But, overall survival at 2 years tended to increase in the optimal AUC group: 75.7% (95% CI, 62.4%-84.8%) versus 57.8% (95% CI, 42.4%-70.4%; P = .061). These data support an optimal active ATG exposure of 110 to 148.5 UE/mL/day in haplo-PBSCT. Individualized dosing of ATG in allo-HCT might reduce the risk of virus reactivation and effectively prevent acute GVHD simultaneously.

Comparison of clinical outcomes between unrelated single umbilical cord blood and "ex-vivo" T-cell depleted haploidentical transplantation in children with hematological malignancies

BACKGROUND

Over the last two decades, umbilical cord blood (UCB) and haploidentical transplantation (HaploHSCT) have emerged as alternative sources of hematopoietic stem cell for allogeneic transplantation. There are few retrospective studies and no prospective studies comparing both types of alternative transplantation in pediatric patients.

RESULTS

We analyzed the data of 134 children with hematological malignancies who received a hematopoietic stem cell transplantation from a single umbilical cord blood (UCB) (n = 42) or an "ex-vivo" T-cell depleted transplant from a haploidentical-related donor (HaploHSCT) (n = 92) between 1996 and 2014. Hematological recovery was faster after HaploHSCT than the UCB transplant group (median times to neutrophil and platelet recovery: 13 vs. 16 days, 10 vs. 57 days, respectively) (P < 0.001). The HaploHSCT group had a significantly early immune reconstitution based on NK and CD8 + T cells compared with the UCB group. However, after the first year post-transplantation, HaploHSCT had a lower number of CD4 + T and B lymphocytes compared with the UCB transplant recipients. The cumulative incidence of TRM was 29±8% in the HaploHSCT group versus 40±5% in the UCB group. Relapse incidence was 21±7% in the HaploHSCT group and 19±8% in the UCB group. Probability of DFS was 58±8% in the HaploHSCT group versus 40±9% in the UCB group (P = 0.051).

CONCLUSIONS

TCD haploidentical transplant is associated with advantages in terms of engraftment and early immune reconstitution kinetics. TCD haploidentical transplant was associated with lower incidence of infectious and non-infectious complications, especially in the early phases of the transplant compared with UCB transplant recipients. However, there are no advantages in transplant outcomes compared with UCB transplant.

Impact of donor types on reduced-intensity conditioning allogeneic stem cell transplant for mature lymphoid malignancies

We retrospectively compared the outcomes of reduced-intensity conditioning (RIC) transplantation from matched related donors (MRD; n = 266), matched unrelated donors (MUD; n = 277), and umbilical cord blood (UCB; n = 513) for mature lymphoid malignancies. The 3-year overall survival rates for the MRD, MUD, and UCB groups were 54%, 59%, and 40%, respectively (P < 0.001). Multivariate analysis showed no differences in survival between the MRD group and the MUD or UCB group. However, survival was significantly affected by the conditioning regimen and graft-versus-host disease (GVHD) prophylaxis in the UCB group, but not in the MRD and MUD groups. Notably, multivariate analysis showed that the risk of overall mortality in the UCB recipients who received the optimal conditioning regimen and GVHD prophylaxis (n = 116) was lower than that in the MRD group (relative risk [RR], 0.69; P = 0.03) and tended to be lower than that in the MUD group (RR, 0.75; P = 0.09). Our results suggest that UCB transplantation performed with the optimal conditioning regimen and GVHD prophylaxis is highly effective. Moreover, UCB is readily available. Thus, UCB transplantation with the optimal conditioning regimen and GVHD prophylaxis is preferable to MUD transplantation when MRD are not available in the setting of RIC transplantation for mature lymphoid malignancies.

Clinical Outcomes of Unrelated Umbilical Cord Blood Graft vs. Haploidentical Donor Transplantation: Critical Issues for an Adequate Comparison

Unrelated umbilical cord blood (UCB) and haploidentical grafts have been used for allogeneic hematopoietic stem and progenitor cell (HSPC) transplantation in patients without a related or non-related human leukocyte antigen (HLA)-matched donor. The less stringent HLA-matching requirement in both sources raises an important possibility for patients in need of urgent transplantation to treat any hematological disease. Selection of the best alternative donor is a difficult task that will depend on donor criteria, center experience, patient disease conditions, and risk, among others. Most comparisons available in scientific publications between both graft sources are obtained from retrospective analysis in wide time windows and a heterogeneous number of patients, types of disease, disease stages, previous treatments, graft source, conditioning regimen, graft vs. host disease (GVHD) approach, and evaluable endpoints. There is also an evident impact of the economic traits since low-income countries must consider less expensive treatments to satisfy the needs of the patients in the most effective possible path. Therefore, haploidentical transplantation could be an appealing option, even though it has not been completely established if any chronic treatment derived from the procedure could become a higher cost. In Colombia, there is a huge experience in UCB transplantation especially in units of pediatric transplantation where benign indications are more common than in adults. Due to the availability of a public UCB bank and HLA high-resolution typing in Colombia, there is a wider inventory of cord blood donors. Unfortunately, we do not have an unrelated bone marrow donor registry, so UCB is an important source along with haploidentical transplantation to consider in decision-making. This minireview focuses on comparing the main issues associated with the use of both HSCP sources and provides tools for physicians who face the difficult decision between these alternative donor sources.

Improved survival for young acute leukemia patients following a new donor hierarchy for allogeneic hematopoietic stem cell transplantation: A phase III randomized controlled study

The aim of our study was to evaluate the most optimal donor for young acute leukemia (AL) patients with multiple donors available for allogeneic hematopoietic stem cell transplantation (allo-HSCT), including HLA-matched sibling donors (MSDs), HLA-matched unrelated donors (URDs), haploidentical parental donors (HPDs), and haploidentical sibling donors (HSDs). From March 2008 to December 2016, 430 AL patients ≤ 35 years of age were included in the discovery, retrospective study. Patients who received transplantation from a MSD or a HSD had better 5-year OS rates compared with patients who received transplantation from a URD or a HPD. A superior graft-versus-leukemia effect was observed for high-risk patients undergoing HSD-HSCT with a lower relapse rate (p = 0.014) and a higher disease-free survival (DFS) rate (p = 0.029) compared with those undergoing MSD-HSCT. Outcomes of high-risk patients receiving an URD or HPD were equivalent. For intermediate/standard-risk patients, either a MSD or HSD may be the front-line donor selection with comparable outcomes. HLA-matched unrelated donors were preferred over HPDs with reduced non-relapse mortality and higher overall survival (OS) and DFS rates. We further conducted an independent prospective randomized study to evaluate the survival advantage with the new donor hierarchy. Two hundred and fifty patients were randomly assigned to follow our new donor hierarchy or the traditional donor hierarchy at a 2:1 ratio. The new donor hierarchy contributed to significantly superior 2-year OS and DFS rates (OS: 76.2% vs. 67.8%, p = 0.046; DFS: 71.8% vs. 64.5%, p = 0.039).

Haploidentical transplantation is feasible and associated with reasonable outcomes despite major infective complications-A single center experience from India

Haploidentical stem cell transplantation (SCT) using post-transplantation cyclophosphamide for graft-versus-host disease (GVHD) prophylaxis is a reasonable therapeutic option for patients who do not have a matched sibling donor. Between 2010 and June 2020, 257 patients underwent 269 Haploidentical transplantations, including 122 children. Indications included both malignant (56.8%) and non-malignant (43.2%) diseases. Conditioning regimens included both myeloablative (57.6%) and nonmyeloablative regimens (42.4%). Peripheral blood stem cells were the predominant graft source (96.2%). Based on the disease risk index, patients were classified into early-, intermediate-, and late-stage disease. Engraftment was seen in 205 patients (76.2%) whereas 39 (14.4%) died before engraftment and 23 (8.6%) had primary graft failure. The cumulative incidence of grade II-IV acute GVHD was 47.8% with a 23.9% incidence of grade III-IV acute GVHD. Chronic GVHD was seen in 41.9% with a 15.4% incidence of extensive chronic GVHD. More than 90% had at least 1 documented infection with a 44% incidence of bacterial, 71% viral, and 38% fungal infection. The 2-year overall survival is 40.5% ± 3.2% with a higher survival among children (48.2% ± 3.4%) compared to adults (34.2% ± 4.1%). Survival was poor with late-stage disease (23.6% ± 4.3%) compared to early- (62.5% ± 7.5%) and intermediate-stage (50.3% ± 4.3%). Factors adversely affecting survival included older age of patient (P = .007), late disease status (P = .000), nonmyeloablative conditioning regimen (P = .003), bone marrow as graft source (P = .006), presence of acute GVHD (P = .069), primary graft failure (P = .000), and presence of a documented bacterial (P = .000) and fungal infection (P = .000). On multivariate analysis, older age (P = .027), presence of acute GVHD (P = .033), documented bacterial infection (P = .000), documented fungal infection (P = .000) and primary graft failure (P = .012) continued to remain significant. Haploidentical SCT offers a reasonable chance of cure for patients with both malignant and nonmalignant hematological diseases. Strategies to reduce aGVHD and infection related mortality needs to be explored further. © 20XX American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

Severe infections and infection-related mortality in a large series of haploidentical hematopoietic stem cell transplantation with post-transplant cyclophosphamide

Severe infections and their attributable mortality are major complications in recipients of allogeneic hematopoietic stem cell transplantation (alloSCT). We herein report 236 adult patients who received haploSCT with PTCy. The median follow-up for survivors was 37 months. The overall incidence of bloodstream infections by gram-positive and gram-negative bacteria at 37 months was 51% and 46%, respectively. The incidence of cytomegalovirus infection was 69%, while Epstein Barr virus infections occurred in 10% of patients and hemorrhagic cystitis in 35% of cases. Invasive fungal infections occurred in 11% at 17 months. The 3-year incidence of infection-related mortality was 19%. The median interval from transplant to IRM was 3 months (range 1-30), 53% of IRM occurred >100 days post-haploSCT. Risk factors for IRM included age >50 years, lymphoid malignancy, and developing grade III-IV acute GvHD. Bacterial infections were the most common causes of IRM (51%), mainly due to gram-negative bacilli BSI. In conclusion, severe infections are the most common causes of NRM after haploSCT with PTCy, with a reemergence of gram-negative bacilli as the most lethal pathogens. More studies focusing on the severe infections after haploSCT with PTCy and differences with other types of alloSCT in adults are clearly warranted.

Bone Marrow versus Peripheral Blood Grafts for Haploidentical Hematopoietic Cell Transplantation with Post-Transplantation Cyclophosphamide

In the coronavirus disease 19 (COVID-19) pandemic era, the number of haploidentical hematopoietic cell transplantations (HCTs) with peripheral blood (PB) grafts increased significantly compared with HCTs with bone marrow (BM) grafts, which may be associated with adverse outcomes. We compared outcomes of HCT in BM graft and PB graft recipients age ≥18 years with hematologic malignancies who underwent T cell- replete haploidentical HCT and received graft-versus-host disease (GVHD) prophylaxis with post-transplantation cyclophosphamide, tacrolimus, and mycophenolate mofetil. Among the 264 patients, 180 (68%) received a BM graft and 84 (32%) received a PB graft. The median patient age was 50 years in both groups. The majority (n = 199; 75%) received reduced-intensity conditioning. The rate of acute leukemia or myelodysplastic syndrome was higher in the BM graft recipients compared with the PB graft recipients (85% [n = 152] versus 55% [n = 46]; P < .01). The median times to neutrophil and platelet engraftment and the incidence of grade II-IV and grade III-IV acute GVHD (aGVHD) were comparable in the 2 groups. Among the patients with grade II-IV aGVHD, the rate of steroid-refractory aGVHD was 9% (95% confidence interval [CI], 5% to 18%) in the BM group versus 32% (95% CI, 19% to 54%) in the PB group (hazard ratio [HR], 3.7, 95% CI, 1.5 to 9.3; P = .006). At 1 year post-HCT, the rate of chronic GVHD (cGVHD) was 8% (95% CI, 4% to 13%) in the BM group versus 22% (95% CI, 14% to 36%) in the PB group (HR, 3.0; 95% CI, 1.4-6.6; P = .005), and the rate of systemic therapy-requiring cGVHD was 2.5% (95% CI, 1% to 7%) versus 14% (95% CI, 7% to 27%), respectively (HR, 5.6; 95% CI, 1.7 to 18; P = .004). The PB group had a significantly higher risk of bacterial and viral infections, with no appreciable advantage in the duration of hospitalization, immune reconstitution, relapse, nonrelapse mortality, or survival. Our data suggest a benefit of the use of BM grafts over PB grafts for haplo-HCT.

American Society for Transplantation and Cellular Therapy Series: #3-Prevention of Cytomegalovirus Infection and Disease After Hematopoietic Cell Transplantation

The Practice Guidelines Committee of the American Society for Transplantation and Cellular Therapy partnered with its Transplant Infectious Disease Special Interest Group to update its 2009 compendium-style infectious diseases guidelines for the care of hematopoietic cell transplant (HCT) recipients. A new approach was taken with the goal of better serving clinical providers by publishing each standalone topic in the infectious disease series as a concise format of frequently asked questions (FAQ), tables, and figures. Adult and pediatric infectious disease and HCT content experts developed and answered FAQs. Topics were finalized with harmonized recommendations that were made by assigning an A through E strength of recommendation paired with a level of supporting evidence graded I through III. The third topic in the series focuses on the prevention of cytomegalovirus infection and disease in HCT recipients by reviewing prophylaxis and preemptive therapy approaches; key definitions, relevant risk factors, and diagnostic monitoring considerations are also reviewed.

Salvage HLA-haploidentical hematopoietic stem cell transplantation with post-transplant cyclophosphamide for graft failure in non-malignant disorders

Graft failure requires urgent salvage HSCT, but there is no universally accepted approach for this situation. We investigated T-cell replete haploidentical HSCT with post-transplantation cyclophosphamide following serotherapy-based, radiation-free, reduced intensity conditioning in children with non-malignant disorders who had rejected their primary graft. Twelve patients with primary or secondary graft failure received T-cell replete bone marrow grafts from haploidentical donors and post-transplantation cyclophosphamide. The recommended conditioning regimen comprised rituximab 375 mg/m2, alemtuzumab 0.4 mg/kg, fludarabine 150 mg/m2, treosulfan 20-24 g/m2 and cyclophosphamide 29 mg/kg. After a median follow-up of 26 months (7-95), eleven of twelve patients (92%) are alive and well with complete donor chimerism in ten. Neutrophil and platelet engraftment were observed in all patients after a median of 18 days (15-61) and 39 days (15-191), respectively. Acute GVHD grade I was observed in 1/12 patients (8%) and mild chronic GVHD in 1/12 patients (8%). Viral reactivations and disease were frequent complications at 75% and 42%, respectively, but no death from infectious causes occurred. In summary, this retrospective analysis demonstrates that a post-transplantation cyclophosphamide-based HLA-haploidentical salvage HSCT after irradiation-free conditioning results in excellent engraftment and overall survival in children with non-malignant diseases.

Real-world experience: Introduction of T cell replete haploidentical transplantations in a single center

Objectives

The aim of this study was to describe real-world data on outcomes of T cell replete haploidentical hematopoietic stem cell transplantation (HSCT) after the introduction of this modality in a single center and to compare them with different donor types.

Method

Outcomes of 30 consecutive patients with hematological malignancies that received T cell replete haploidentical HSCT with posttransplantation cyclophosphamide (PTCY) from 2016 to 2018 in our center were analyzed and compared to the outcome of human leukocyte antigen (HLA)-related and unrelated matched donor HSCT (n = 97) and to a historical cohort of T cell depleted haploidentical HSCT (n = 11).

Results

One year graft-versus-host-free, relapse-free survival in haploidentical HSCT was comparable with other donor types (haplo 40%, matched related donor [MRD] 33%, matched unrelated donor [MUD] 25%, p = 0.55). Non relapse mortality was high in haploidentical HSCT (50%), mostly due to infectious complications. However, relapse rates were only 3%, and OS and progression-free survival after 1 year were 47% and thereby also similar to HLA-matched HSCT in our center (MRD 53%, MUD 48%).

Conclusion

Our data show that T cell replete haploidentical HSCT has similar outcomes to HLA identical HSCT after introduction in our center. More strict adaptation on infection prevention was a crucial aspect of our learning curve. Overall, this type of transplantation is a feasible option when lacking an HLA-identical donor. This option has advantages over an unrelated donor as it brings less logistical challenges than MUD transplantations.

Pre-transplant minimal residual disease assessment and transplant-related factors predict the outcome of acute myeloid leukemia patients undergoing allogeneic stem cell transplantation

We studied pretransplant minimal residual disease (MRD) in 224 patients (median age 44 years; range 17-65) with acute myeloid leukemia (AML) undergoing allogeneic stem cell transplant (HSCT) in complete remission. MRD was evaluated on marrow samples using multicolor flow cytometry and assessment of WT1 gene expression. Both methods showed a strong prognostic value and their combination allowed the identification of three groups of patients with different risk of relapse. In multivariate analysis, combined MRD was the only predictor of cumulative incidence of relapse, regardless of donor type, conditioning regimen, first or second CR at HSCT, HSCT year, and ELN risk group. Multivariate regression model showed that only negative combined MRD status (P < .001) and myeloablative conditioning (P = .004) were independently associated with better OS. Among MRD-positive patients, a reduced incidence of relapse was observed in patients receiving haplo transplant (P < .05) and in patients who showed grade II-IV aGVHD (P < .03). In patients with negative combined MRD, the intensity of conditioning regimen did not affect the overall favorable outcome. We suggest that pretransplant MRD evaluation combined with transplant-related factors can identify AML patients at higher risk for relapse and might help in defining the overall transplant strategy.

Early Cardiac Toxicity Associated With Post-Transplant Cyclophosphamide in Allogeneic Stem Cell Transplantation

Background

Post-transplant cyclophosphamide (PT-Cy) has become a standard of care in haploidentical hematopoietic stem cell transplantation (HSCT) to reduce the risk of graft-versus-host disease. However, data on cardiac events associated with PT-Cy are scarce.

Objectives

This study sought to assess the incidence and clinical features of cardiac events associated with PT-Cy.

Methods

The study compared clinical outcomes between patients who received PT-Cy (n = 136) and patients who did not (n = 195), with a focus on early cardiac events (ECE) occurring within the first 100 days after HSCT. All patients had the same systematic cardiac monitoring.

Results

The cumulative incidence of ECE was 19% in the PT-Cy group and 6% in the no–PT-Cy group (p < 0.001). The main ECE occurring after PT-Cy were left ventricular systolic dysfunction (13%), acute pulmonary edema (7%), pericarditis (4%), arrhythmia (3%), and acute coronary syndrome (2%). Cardiovascular risk factors were not associated with ECE. In multivariable analysis, the use of PT-Cy was associated with ECE (hazard ratio: 2.7; 95% confidence interval: 1.4 to 4.9; p = 0.002]. Older age, sequential conditioning regimen, and Cy exposure before HSCT were also associated with a higher incidence of ECE. Finally, a history of cardiac events before HSCT and ECE had a detrimental impact on overall survival.

Conclusions

PT-Cy is associated with a higher incidence of ECE occurring within the first 100 days after HSCT. Patients who have a cardiac event after HSCT have lower overall survival. These results may help to improve the selection of patients who are eligible to undergo HSCT with PT-Cy, especially older adult patients and patients with previous exposure to Cy.

GVHD Prophylaxis 2020

Graft-vs. host disease (GVHD), both acute and chronic are among the chief non-relapse complications of allogeneic transplantation which still cause substantial morbidity and mortality despite significant advances in supportive care over the last few decades. The prevention of GVHD therefore remains critical to the success of allogeneic transplantation. In this review we briefly discuss the pathophysiology and immunobiology of GVHD and the current standards in the field which remain centered around calcineurin inhibitors. We then discuss important translational advances in GVHD prophylaxis, approaching these various platforms from a mechanistic standpoint based on the pathophysiology of GVHD including in-vivo and ex-vivo T-cell depletion alongwith methods of selective T-cell depletion, modulation of T-cell co-stimulatory pathways (checkpoints), enhancing regulatory T-cells (Tregs), targeting T-cell trafficking as well as cytokine pathways. Finally we highlight exciting novel pre-clinical research that has the potential to translate to the clinic successfully. We approach these methods from a pathophysiology based perspective as well and touch upon strategies targeting the interaction between tissue damage induced antigens and T-cells, regimen related endothelial toxicity, T-cell co-stimulatory pathways and other T-cell modulatory approaches, T-cell trafficking, and cytokine pathways. We end this review with a critical discussion of existing data and novel therapies that may be transformative in the field in the near future as a comprehensive picture of GVHD prophylaxis in 2020. While calcineurin inhibitors remain the standard, post-transplant eparinsphamide originally developed to facilitate haploidentical transplantation is becoming an attractive alternative to traditional calcinuerin inhibitor based prophylaxis due to its ability to reduce severe forms of acute and chronic GVHD without compromising other outcomes, even in the HLA-matched setting. In addition T-cell modulation, particularly targeting some important T-cell co-stimulatory pathways have resulted in promising outcomes and may be a part of GVHD prophylaxis in the future. Novel approaches including targeting early events in GVHD pathogenesis such as interactions bvetween tissue damage associated antigens and T-cells, endothelial toxicity, and T-cell trafficking are also promising and discussed in this review. GVHD prophylaxis in 2020 continues to evolve with novel exicitng therapies on the horizon based on a more sophisticated understanding of the immunobiology of GVHD.

Combining Three Different Pretransplantation Scores Improves Predictive Value in Patients after Haploidentical Stem Cell Transplantation with Thiotepa, Busulfan, and Fludarabine Conditioning and Post-Transplantation Cyclophosphamide

One hundred and sixty-one patients underwent haploidentical stem cell transplantation (haploSCT) with thiotepa, busulfan, and fludarabine conditioning followed by post-transplantation cyclophosphamide (PTCy) (on days +3 and +4) and tacrolimus as graft-versus-host disease prophylaxis. Forty-two percent of patients had a high or very high revised Disease Risk Index (rDRI), 55% had an European Society for Blood and Marrow Transplantation risk score (EBMT-RS) ≥4, and 36% had an age-adjusted Hematopoietic Cell Transplant Comorbidity Index (HCT-CI-age) score ≥3. Each of these was considered an unfavorable score. Using the pretransplantation unfavorable scores that had an independent impact on each transplantation outcome studied in multivariate analysis allowed for better stratification of patient outcomes. Thus, the 3-year overall survival (OS) in patients with 0, 1, 2, and 3 unfavorable scores was 86%, 56%, 36%, and 24%, respectively. Nonrelapse mortality (NRM) was negatively impacted by the EBMT-RS and the HCT-CI-age score (3-year NRM in patients with 0, 1, and 2 unfavorable scores was 12%, 33%, and 43%, respectively), whereas the EBMT-RS and the rDRI had an impact on the 3-year relapse incidence (8%, 18%, and 41% in patients with 0, 1, and 2 unfavorable scores, respectively). In conclusion, our study shows that combining 2 or 3 of these well-defined pretransplantation scores improves the ability to predict transplantation outcomes in the setting of haploSCT with PTCy.

EBV-PTLD in a patient after haploidentical stem-cell transplantation with post-transplant cyclophosphamide

Here, we describe the case of a male patient with Epstein-Barr virus post-transplantation lymphoproliferative disorder (EBV-PTLD), which developed 18 months after a haploidentical hematopoietic stem cell transplantation (haplo-HSCT) and the administration of post-transplant cyclophosphamide (PTCy). Of note, no anti-thymoglobulin was used in the entire clinical course. Prior to the onset of EBV-PTLD, the patient had pulmonary chronic graft-versus-host disease and was treated with prednisolone and tacrolimus. After stopping immunosuppressive therapy, he was diagnosed with EBV-positive infectious mononucleosis PTLD, and EBV-associated hemophagocytic syndrome; therefore, dexamethasone and rituximab monotherapies were administered. After four courses of rituximab, EBV-DNA was no longer detected in the peripheral blood, and the patient's laboratory data improved. Overall, this study highlights the need to predict the risk factors associated with the development of EBV-PTLD in transplanted patients after haplo-HSCT with PTCy.

Augmented immunosuppression and PTCY-based haploidentical hematopoietic stem cell transplantation for thalassemia major

Alternate donor HSCT for thalassemia major from a matched unrelated donor or haploidentical family donor is a feasible therapeutic option in children with no matched family donor. Aggressive pretransplant immunosuppression, reduced toxicity conditioning, and PTCY result in excellent thalassemia-free survival. We describe here our experience in this cohort. We performed a retrospective analysis of the data on children who underwent a haploidentical HSCT for thalassemia major with PTCY at our center from August 2017 to August 2019. All children received pretransplant immune suppression for 6 weeks with fludarabine and dexamethasone, hypertransfusion and chelation with intravenous desferrioxamine. Conditioning included thiotepa, fludarabine, rabbit ATG, and cyclophosphamide, and GvHD prophylaxis included PTCY with tacrolimus. Twenty children were included and nineteen children engrafted. Acute hypertension occurred in five children, bacterial infection in eight children and viral respiratory infection in three children. Three children suffered from graft rejection. Reactivation of viruses namely CMV, adenovirus, and BK virus was seen in 60% of children. Grades 1-2 acute GvHD of the skin in four children (20%) and limited chronic GvHD of the skin in four children (20%). Immune cytopenia was documented in three children (15%). Haploidentical HSCT offers a therapeutic option for children with thalassemia major with no suitably matched family or unrelated donors. Our reduced toxicity regimen with PTCY offers a DFS of 75% and OS of 95% with low transplant-related mortality of 5%.

Haploidentical Stem Cell Transplantation With a Novel Conditioning Regimen in Older Patients: A Prospective Single-Arm Phase 2 Study

Objective: Haploidentical stem cell transplantation (haplo-SCT) has demonstrated encouraging results in younger patients. There is also an increasing need for haplo-SCT in older patients. However, the high risk of treatment-related mortality (TRM) in older patients is still a major concern. We aimed to investigate a novel conditioning regimen (Bu/Flu/Cy/ATG) followed by haplo-SCT in older patients.

Method: This prospective, single-arm clinical trial was performed at Peking University Institute of Hematology, China. Patients were enrolled if they were (1) diagnosed with acute leukemia or MDS; (2) without MSD and MUD, and with HID available; and (3) age ≥55 years. The Bu/Flu/Cy/ATG regimen consisted of the following agents: Ara-C (2 g/m²/day, injected i.v.) on days-10 and−9; BU (9.6 mg/kg, injected i.v. in 12 doses) on days-8,−7, and−6; Flu (30 mg/m²/day, injected i.v.) from day−6 to day−2; Cy (1 g/m²/day, injected i.v.) on days−5 and−4; semustine (250 mg/m², orally) on day-3 and antithymocyte globulin (ATG) [2.5 mg/kg/day, rabbit, SangStat (Lyon, France)] on days−5,−4,−3, and−2. The primary endpoint was 1-year TRM.

Results: From April 1, 2018 to April 10, 2020, a total of 50 patients were enrolled. All patients achieved neutrophil engraftment with complete donor chimerism. The cumulative incidence of grade 2-4 aGVHD at day-100 was 22.0%. The cumulative incidences of CMV viremia and EBV viremia on day 100 were 68.0 and 20.0%, respectively. The cumulative incidence of TRM at 1-year was 23.3%. and the cumulative incidence of relapse (CIR) at 1 year after transplantation was 16.5%. The overall survival (OS) and leukemia-free survival (LFS) at 1 year were 63.5 and 60.2%, respectively. The outcomes were also comparable with patients who received Bu/Cy/ATG regimen using a propensity score matching method.

Conclusions: In conclusion, this study suggested that a novel conditioning regimen followed by haploidentical HSCT might be a promising option for older patients. The study was registered as a clinical trial.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT03412409.

Haploidentical Hematopoietic Stem Cell Transplantation with Post-Transplantation Cyclophosphamide in Children with High-Risk Leukemia Using a Reduced-Intensity Conditioning Regimen and Peripheral Blood as the Stem Cell Source

The use of haploidentical donor hematopoietic stem cell transplantation with post-transplantation cyclophosphamide (Haplo-PTCy) in children is increasing; however, it is still not clear which preparative regimen is best in this setting. We present the long-term results of 42 patients age <18 years with high-risk leukemia who underwent this procedure using a reduced-intensity conditioning regimen (RIC) and peripheral blood as the stem cell source. Twenty-six patients had acute lymphoblastic leukemia, 13 had acute myelogenous leukemia, 2 had juvenile myelomonocytic leukemia, and 1 had blast crisis of chronic myelogenous leukemia. One-third of the patients were in first remission, 50% were in second remission, 14% were in third remission, and 3% had refractory disease. Neutrophil recovery occurred in 100% of the 40 patients alive at day +30, and transplantation-related mortality at 1 year was 14%. The incidence of acute graft-versus-disease (GVHD) grade III-IV was 17%, and the cumulative incidence of moderate to severe chronic GVHD at 1 year was 29%. The median duration of follow-up for surviving patients was 45 months; overall survival and event-free survival at 36 months were 56% and 46%, respectively. Long-term results of this series show that the use of an RIC regimen with peripheral blood stem cells as the cell source, in children with high-risk leukemia who underwent haplo-PTCy has tolerable toxicity, universal engraftment, and good survival rates.

Haploidentical stem cell transplantation vs matched unrelated donor transplantation in adults with hematologic malignancies: a systematic review and meta-analysis

OBJECTIVES

Haploidentical hematopoietic stem cell transplantation (Haplo-SCT) and matched unrelated donor transplantation (MUD-SCT) are two important options when a matched sibling donor (MSD) is unavailable. Several studies comparing Haplo-SCT and MUD-SCT have reported inconsistent clinical outcomes. Therefore, it is necessary to synthesize the existing evidence regarding outcomes of stem cell transplantations comparing Haplo-SCT with MUD-SCT.

METHODS

We searched for titles of articles in MEDLINE (PubMed), Cochrane library, EMBASE database that compared transplantation with Haplo-SCT versus MUD-SCT. To compare clinical outcomes between Haplo-SCT and MUD-SCT, we performed a meta-analysis of 17 studies and reported the pooled odd ratios (OR) of 6 endpoints including overall survival (OS), progression free survival (PFS), non-relapse mortality (NRM), relapse rate (RR), acute graft-versus-host disease (aGVHD) and chronic graft- versus-host disease (cGVHD).

RESULTS

We found that Haplo-SCT was associated with a comparable OS (pooled OR of 0.99, 95% Confidence Interval (CI) 0.86-1.14), PFS (OR 1.00, 95% CI 0.88-1.15), NRM (OR 0.83, 95% CI 0.65-1.04) and RR (OR 1.08, 95% CI 0.95-1.22) compared to MUD-SCT. We also found a significantly decreased risk of aGVHD (OR 0.74, 95% CI 0.62-0.88) and cGVHD (OR 0.50, 95% CI 0.38-0.66) in Haplo-SCT group.

CONCLUSION

Results of this meta-analysis demonstrates that Haplo-SCT achieves comparable clinical outcomes compared to MUD-SCT in terms of OS, PFS, TRM and RR, but is better than MUD-SCT in terms of decreased aGVHD and cGVHD risk. Haplo-SCT is a valid option for patient needing urgent transplantation.

Immune Reconstitution after Haploidentical Donor and Umbilical Cord Blood Allogeneic Hematopoietic Cell Transplantation

Allogeneic hematopoietic cell transplantation (HCT) is the only potentially curative therapy for a variety of hematologic diseases. However, this therapeutic platform is limited by an initial period when patients are profoundly immunocompromised. There is gradual immune recovery over time, that varies by transplant platform. Here, we review immune reconstitution after allogeneic HCT with a specific focus on two alternative donor platforms that have dramatically improved access to allogeneic HCT for patients who lack an HLA-matched related or unrelated donor: haploidentical and umbilical cord blood HCT. Despite challenges, interventions are available to mitigate the risks during the immunocompromised period including antimicrobial prophylaxis, modified immune suppression strategies, graft manipulation, and emerging adoptive cell therapies. Such interventions can improve the potential for long-term overall survival after allogeneic HCT.

Single Cord Blood Transplantation Versus Unmanipulated Haploidentical Transplantation for Adults with Acute Myeloid Leukemia in Complete Remission

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative post-remission therapy for adult patients with acute myeloid leukemia (AML) in complete remission (CR). The availability of alternative human leukocyte antigen (HLA)-mismatched donors, such as cord blood and haploidentical related donors, could allow patients to receive allogeneic HCT who are without an HLA-matched sibling or unrelated donor. The use of these alternative donors is preferable for patients with advanced disease due to the rapid availability. However, comparative data for cord blood transplantation (CBT) and haploidentical related donor transplantation (haplo-HCT) are limited for adult patients with AML in CR. We sought to compare overall survival (OS); leukemia-free survival (LFS); graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS); and chronic GVHD-free, relapse-free survival (CRFS) between single-unit CBT (SCBT) and haplo-HCT recipients for adult patients with intermediate- or poor-risk AML in CR. We retrospectively analyzed and compared the results of allogeneic hematopoietic cell transplantation in 1313 adult patients with intermediate- or poor-risk AML in CR who received either SCBT (n = 1102) or unmanipulated haplo-HCT (n = 211) between 2007 and 2018 in Japan. Among the whole cohort, the cumulative incidences of neutrophil and platelet recovery were significantly lower in SCBT recipients compared with those in haplo-HCT recipients (P < .001 for neutrophil, P < .001 for platelet). SCBT was significantly associated with a higher incidence of grade II to IV acute GVHD and lower incidence of extensive chronic GVHD compared to haplo-HCT (P = .013 for grades II to IV acute GVHD; P = .006 for extensive chronic GVHD). Haplo-HCT recipients developed a higher incidence of cytomegalovirus (CMV) antigenemia compared to SCBT recipients (P = .004). In the multivariate analysis, there were no significant differences for grades III or IV acute GVHD (hazard ratio [HR], 1.17; 95% confidence interval [CI], .88 to 1.57; P = .26), relapse incidence (HR, 1.09; 95% CI, .76 to 1.58; P = .61), non-relapse mortality (HR, .83; 95% CI, .58 to 1.18; P = .32), OS (HR, .92; 95% CI, .70 to 1.20; P = .56), LFS (HR, .94; 95% CI, .73 to 1.21; P = .67), GRFS (HR, 1.12; 95% CI, .90 to 1.40; P = .27), or CRFS (HR, 1.15; 95% CI, .92 to 1.44; P = .19) between the two donor types. In the propensity score matching analysis, which identified 180 patients in each cohort, there were no significant differences in transplant outcomes between the two donor types, except for delayed neutrophil (P < .001) and platelet recovery (P < .001) and a higher incidence of grades II to IV acute GVHD (P = .052) in SCBT. SCBT and unmanipulated haplo-HCT had similar survival outcomes for adult patients with AML in CR despite the lower hematopoietic recovery and higher grade II to IV acute GVHD in SCBT recipients and the higher CMV antigenemia in haplo-HCT recipients.

Phase II Trial of Costimulation Blockade With Abatacept for Prevention of Acute GVHD

PURPOSE

Severe (grade 3-4) acute graft-versus-host disease (AGVHD) is a major cause of death after unrelated-donor (URD) hematopoietic cell transplant (HCT), resulting in particularly high mortality after HLA-mismatched transplantation. There are no approved agents for AGVHD prevention, underscoring the critical unmet need for novel therapeutics. ABA2 was a phase II trial to rigorously assess safety, efficacy, and immunologic effects of adding T-cell costimulation blockade with abatacept to calcineurin inhibitor (CNI)/methotrexate (MTX)-based GVHD prophylaxis, to test whether abatacept could decrease AGVHD.

METHODS

ABA2 enrolled adults and children with hematologic malignancies under two strata: a randomized, double-blind, placebo-controlled stratum (8/8-HLA-matched URD), comparing CNI/MTX plus abatacept with CNI/MTX plus placebo, and a single-arm stratum (7/8-HLA-mismatched URD) comparing CNI/MTX plus abatacept versus CNI/MTX CIBMTR controls. The primary end point was day +100 grade 3-4 AGVHD, with day +180 severe-AGVHD-free-survival (SGFS) a key secondary end point. Sample sizes were calculated using a higher type-1 error (0.2) as recommended for phase II trials, and were based on predicting that abatacept would reduce grade 3-4 AGVHD from 20% to 10% (8/8s) and 30% to 10% (7/8s). ABA2 enrolled 142 recipients (8/8s, median follow-up = 716 days) and 43 recipients (7/8s, median follow-up = 708 days).

RESULTS

In 8/8s, grade 3-4 AGVHD was 6.8% (abatacept) versus 14.8% (placebo) (P = .13, hazard ratio = 0.45). SGFS was 93.2% (CNI/MTX plus abatacept) versus 82% (CNI/MTX plus placebo, P = .05). In the smaller 7/8 cohort, grade 3-4 AGVHD was 2.3% (CNI/MTX plus abatacept, intention-to-treat population), which compared favorably with a nonrandomized matched cohort of CNI/MTX (30.2%, P < .001), and the SGFS was better (97.7% v 58.7%, P < .001). Immunologic analysis revealed control of T-cell activation in abatacept-treated patients.

CONCLUSION

Adding abatacept to URD HCT was safe, reduced AGVHD, and improved SGFS. These results suggest that abatacept may substantially improve AGVHD-related transplant outcomes, with a particularly beneficial impact on HLA-mismatched HCT.

Allogeneic hematopoietic stem cell transplantation for intermediate-risk acute myeloid leukemia in the first remission: outcomes using haploidentical donors are similar to those using matched siblings

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective and curative treatment for acute myeloid leukemia (AML). We explored the outcome of haploidentical donor (HID) transplantation for intermediate-risk AML and compared to that of matched sibling donor (MSD) transplants. One hundred twenty-seven consecutive patients with intermediate-risk AML in the first complete remission (CR1) who underwent allo-HSCT between January 1, 2015, and August 1, 2016, were enrolled. Thirty-seven patients received MSD grafts, and 90 received HID grafts. The 2-year leukemia-free survival (LFS) of the HID group was comparable to that of the MSD group: 82.0% ± 4.1% versus 82.7% ± 6.4%, P = 0.457. The 2-year cumulative incidences of relapse and transplantation-related mortality (TRM) were comparable between the HID and MSD groups (relapse, 4.5% ± 0.1%, versus 11.5% ± 0.3%, P = 0.550; TRM, 13.4% ± 0.1% vs. 5.8% ± 0.2%, P = 0.154). The HID recipients had a trend of a lower 2-year cumulative incidence of positive posttransplant flow cytometry (FCM+) and relapse than the MSD recipients (5.6% ± 0.1% vs. 19.9% ± 0.5%, P = 0.092). These results suggest that the outcomes of allo-HSCT with HIDs are comparable to those with MSDs in terms of LFS, TRM, and relapse for intermediate-risk AML in CR1. HIDs could be an alternative to MSDs for intermediate-risk AML.

Selection of Suitable Alternative Donor in the Absence of Matched Sibling Donor: A Retrospective Single-Center Study to Compare between Haploidentical, 10/10 and 9/10 Unrelated Donor Transplantation

Background: Finding a suitable donor at the optimal time is one of the most challenging issues in many transplant centers. We evaluated the clinical outcomes of 248 patients with acute leukemia and without matched sibling donors (MSD) who underwent alternative transplantation, including haploidentical (n=118), 10/10 matched unrelated (MUD, n=91), 9/10 mismatched unrelated (MMUD, n=21), and 9/10 mismatched related (MMRD, n=18) between January 2010 and November 2019 in our center. Materials and Methods: The myeloablative conditioning regimen was used in most of the patients. Both post-transplant cyclophosphamide (40mg/kg at +3, +4) and pre-transplant ATG were used in most of haploidentical transplantations. Patients with unrelated donors received ATG as a part of the conditioning regimen. Results: The median follow-up was 31.83 months. No significant difference in probability of 3-year leukemia- free survival (LFS) and overall survival (OS) as well as 3-year relapse incidence (RI) was noted among donor sources. A significant difference was found in the 3-year cumulative incidence (CI) of non-relapse mortality (NRM) among the donor sources: 37.89%, 24.20%, 24.30%, and 11.48%, for haplo, 9/10 MMUD, 10/10 MUD, and 9/10 MMRD (p=0.02). Using the multivariable Cox model, the advanced age of patients and Major-ABO mismatched were two risk factors independently associated with lower OS and DFS as well as higher NRM, whereas male donor and AML disease compared to ALL were associated with a better OS and DFS. Conclusion: No significant differences were observed in the overall outcome of haplo with other alternative transplantations, suggesting that haploidentical transplantation is a suitable, accessible, and inexpensive option.

T-Cell-Replete Versus ex vivo T-Cell-Depleted Haploidentical Haematopoietic Stem Cell Transplantation in Children With Acute Lymphoblastic Leukaemia and Other Haematological Malignancies

Allogeneic haematopoietic stem cell transplantation (HSCT) represents a potentially curative option for children with high-risk or refractory/relapsed leukaemias. Traditional donor hierarchy favours a human leukocyte antigen (HLA)-matched sibling donor (MSD) over an HLA-matched unrelated donor (MUD), followed by alternative donors such as haploidentical donors or unrelated cord blood. However, haploidentical HSCT (hHSCT) may be entailed with significant advantages: besides a potentially increased graft-vs.-leukaemia effect, the immediate availability of a relative as well as the possibility of a second donation for additional cellular therapies may impact on outcome. The key question in hHSCT is how, and how deeply, to deplete donor T-cells. More T cells in the graft confer faster immune reconstitution with consecutively lower infection rates, however, greater numbers of T-cells might be associated with higher rates of graft-vs.-host disease (GvHD). Two different methods for reduction of alloreactivity have been established: in vivo T-cell suppression and ex vivo T-cell depletion (TCD). Ex vivo TCD of the graft uses either positive selection or negative depletion of graft cells before infusion. In contrast, T-cell-repleted grafts consisting of non-manipulated bone marrow or peripheral blood grafts require intense in vivo GvHD prophylaxis. There are two major T-cell replete protocols: one is based on post-transplantation cyclophosphamide (PTCy), while the other is based on anti-thymocyte globulin (ATG; Beijing protocol). Published data do not show an unequivocal benefit for one of these three platforms in terms of overall survival, non-relapse mortality or disease recurrence. In this review, we discuss the pros and cons of these three different approaches to hHSCT with an emphasis on the significance of the existing data for children with acute lymphoblastic leukaemia.

How to Combine the Two Landmark Treatment Methods-Allogeneic Hematopoietic Stem Cell Transplantation and Chimeric Antigen Receptor T Cell Therapy Together to Cure High-Risk B Cell Acute Lymphoblastic Leukemia?

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has made tremendous progress in the last few decades and is increasingly being used worldwide. The success of haploidentical HSCT has made it possible to have "a donor for everyone". Patients who received transplantation in remission may have a favorable outcome, while those who were transplanted in advanced stages of disease have a poor prognosis. Although chimeric antigen receptor T (CAR-T) cell therapy is currently a milestone in the immunotherapy of relapsed or refractory (R/R) B cell acute lymphoblastic leukemia (B-ALL) and has demonstrated high remission rates in patients previously treated in multiple lines, the relatively high relapse rate remains a barrier to CAR-T cell therapy becoming an excellent cure option. Therefore, combining these two approaches (allo-HSCT and CAR-T cell therapy) is an attractive area of research to further improve the prognosis of R/R B-ALL. In this review, we will discuss the current clinical practices of combining allo-HSCT with CAR-T cell therapy based on available data, including CAR-T cells as a bridge to allo-HSCT for R/R B-ALL and CAR-T cell infusion for post-transplant relapse. We will further explore not only other possible ways to combine the two approaches, including CAR-T cell therapy to clear minimal residual disease peri-transplantation and incorporation of CAR technology to treat graft-versus-host disease, but also the potential of CAR-T cells as a part of allo-HSCT.