Dual T-cell depletion with ATG and PTCy for peripheral blood reduced intensity conditioning allo-HSCT results in very low rates of GVHD

Post-transplant cyclophosphamide compared to sirolimus/tacrolimus in reduced intensity conditioning transplants for patients with lymphoid malignancies

Despite novel cellular and immunomodulatory therapies, allogeneic hematopoietic stem cell transplantation (HSCT) remains a treatment option for lymphoid malignancies. Post-transplant cyclophosphamide (PTCY) is increasingly employed for graft vs. host disease (GVHD) prophylaxis. This study aims to evaluate the safety and efficacy of PTCY in reduce intensity (RIC) HSCT for patients with lymphoid neoplasms compared to sirolimus with tacrolimus (SIR/TAC). The primary endpoint was to compare grade III-IV acute GVHD, severe chronic GVHD, and relapse-free survival (GRFS) between the two GVHD prophylaxis strategies. This study, conducted from January 2012 to December 2020, included 171 consecutive patients (82 in the PTCY and 89 in the SIR/TAC group). Results revealed a significantly decreased incidence of moderate and severe forms of chronic GVHD in PTCY cohort (5.8% [95% CI, 1.8 to 13.1]) versus the SIR/TAC cohort (39.6% [95% CI, 29.3 to 49.7] (p < 0.001)). Other outcomes, including GRFS (PTCY [45.9% (95% CI, 35.8-58.7)] and SIR/TAC groups [36.8% (95% CI, 28-48.4)], (p = 0.72)), non-relapse mortality (NRM), relapse and overall survival (OS) were similar in both groups. Interestingly, the failure to achieve GRFS was mainly attributed to GVHD in the SIR/TAC group, while disease relapse was the primary reason in the PTCY cohort.

The prophylactic application of low-dose rabbit antithymocyte globulin in matched siblings HSCT with high-risk factors for graft-versus-host disease

Relapse and graft-versus-host disease (GVHD) are currently the predominant causes of mortality post allogeneic hematopoietic stem cell transplantation (allo-HSCT). The contentious use of antithymocyte globulin (ATG) for preventing GVHD in matched sibling HSCT scenarios has been a topic of significant debate. A retrospective analysis was conducted on matched sibling HSCT cases with high-risk factors for GVHD in our center from January 2018 to June 2023. Our assessment revealed that the group administered with ATG exhibited a 30 % incidence of acute GVHD (aGVHD), in contrast to 81.8 % in the non-ATG cohort (P = 0.037) among matched sibling HSCT cases with high GVHD risk factors. Furthermore, chronic GVHD (cGVHD) occurred in 20 % of the ATG group and 72.7 % of the non-ATG group (P = 0.03). Notably, the administration of ATG did not significantly impact disease relapse (p = 0.149), infection rates (p = 0.64), granulocyte recovery time (p = 0.15), platelet recovery time (p = 0.12), overall survival (p = 0.889), or disease-free survival time (p = 0.787). The use of rabbit antithymocyte globulin (r-ATG) at a 5 mg/kg dosage demonstrated a notable reduction in aGVHD and cGVHD incidences within sibling matched HSCT cases with high-risk factors for GVHD, without increasing rates of disease recurrence or infections. These findings highlight the potential benefit of using low-dose r-ATG in high-risk of GVHD sibling matched allogeneic HSCTs, although further validation with a larger cohort is necessary.

Real-World Impact of Routine Addition of Antithymocyte Globulin to Standard GVHD Prophylaxis in Myeloablative Unrelated Donor Transplants: Important Gains in Graft-versus-Host Disease Prevention though No Difference in Overall Survival

INTRODUCTION

Antithymocyte globulin (ATG) has been demonstrated to reduce the incidence of graft-versus-host disease (GVHD); however, it remains controversial whether these gains are offset by an increase in relapse.

METHODS

We conducted a retrospective historical control study consisting of patients (n = 210) who underwent myeloablative allogeneic hematopoietic stem-cell transplantation (HSCT) from 2014 to 2020.

RESULTS

The incidence of acute GVHD was lower in the ATG group (51.4%) than the non-ATG group (control) (70.0%, p = 0.010). The incidence of chronic GVHD was also lower in the ATG group at 1-year (36.4% vs. 62.9%, p < 0.001) and 2-year (40.0% vs. 65.7%, p < 0.001) post-HSCT. The mortality due to GVHD was higher in the control (18.5%) than the ATG group (4.3%; p = 0.024). The severe GVHD-relapse-free survival was higher in the ATG group (36.4%) than the control (12.9%; p < 0.001). Nevertheless, the 2-year overall survival was similar.

CONCLUSION

Our results confirm the effectiveness of ATG in prevention of GVHD in the real-world setting and enhanced GVHD-free survival. An important result is the equalization of overall survival between the ATG and control groups at 1- and 2-year post-HSCT and implies that earlier GVHD-associated mortality may be offset by later relapse mortality producing similar overall survival over time.

Reduced-toxicity conditioning regimen with low dose post-transplantation cyclophosphamide and low-dose anti-thymocyte globulin as graft-versus-host disease prophylaxis for haploidentical stem cell transplantation in older patients

Reduced-toxicity conditioning (RIC) regimens are used for allogeneic hematopoietic stem cell transplantation in older patients. However, successful outcomes are hindered by graft-versus-host disease (GVHD), treatment-related mortality, and relapse, particularly after haploidentical donor hematopoietic stem cell transplantation (HID-HSCT). The aim of this study was to evaluate the effectiveness of an RIC conditioning regimen that included a combination of cyclosporin A, methotrexate (on day + 1), mycophenolate, lower doses of post-transplantation PTCy (40 mg/kg on day + 3), and ATG (7.5 mg/kg) as GVHD prophylaxis prior to haplo-stem cell transplantation (haplo-SCT) in older patients.

METHODS

We retrospectively analyzed outcomes in 55 patients ≥ 55 years of age with hematologic malignancies treated with fludarabine, cytarabine, busulfan, and low-dose cyclophosphamide as the conditioning regimen between January 1, 2019, and November 30, 2023.

RESULTS

Neutrophil engraftment was successful in all patients within 28 days, with 54 patients (98.2%) achieving complete donor chimerism. The cumulative incidence of non-relapse mortality was 0% at 30 days, 7.5% at 100 days, and 19% at 1 year. The cumulative incidence of grade II-IV acute graft-versus-host disease (aGVHD) was 25% (95%CI, 15-38%), whereas that of grade III-IV aGVHD was 9.1% (95% CI, 3.3-19%). The cumulative incidence of extensive chronic graft-versus-host disease at 1 year was 3.6% (95%CI, 0.66-11%). The cumulative incidences of relapse, overall survival, and GVHD-free/relapse-free survival at 1 year were 9.0%, 71.6%, and 67.1%, respectively.

CONCLUSIONS

An RIC conditioning regimen, including a combination of lower PTCy/ATG as GVHD prophylaxis, followed by haplo-SCT, might be a promising option for appropriately selected older patients.

Allogeneic hematopoietic stem cell transplant for familial hemophagocytic lymphohistiocytosis: a case report and literature review

Objectives

This study aims to discuss the clinical manifestations and treatment of Familial hemophagocytic lymphohistiocytosis (FHL) caused by a mutation in the UNC13D gene.

Methods

A 6-year-old female child presented with unexplained febricity, splenomegaly, pancytopenia, hemophagocytic lymphohistiocytosis in bone marrow, decreased NK cell activity, soluble CD25 levels > 44000ng/ml. Genetic sequencing revealed a mutation in the UNC13D gene. Additionally, the patient experienced intermittent fever with seizures characterized by involuntary twitching of the left upper limb. Head magnetic resonance imaging (MRI) showed white matter lesions.

Results

According to the HLH-2004 diagnostic criteria revised by the International Society of Histiocytosis the patient was diagnosed with FHL. Despite receiving HLH-2004 treatment, the disease relapsed. However, after a salvage allogeneic Hematopoietic Stem Cell Transplant (HSCT), febricity, abnormal blood cells, and neurological symptoms significantly improved.

Conclusions

Prompt performance of allogeneic HSCT is crucial upon diagnosis of FHL, especially when neurological involvement is present.

Outcomes of Antithymocyte Globulin-Post-Transplantation Cyclophosphamide-Cyclosporine-Based versus Antithymocyte Globulin-Based Prophylaxis for 10/10 HLA-Matched Unrelated Donor Allogeneic Hematopoietic Cell Transplantation

In 2015, dual T cell depletion with antithymocyte globulin (ATG) and post-transplantation cyclophosphamide (PTCy) combined with cyclosporine A (CsA) replaced our prior institutional graft-versus-host disease (GVHD) prophylaxis regimen of 4.5 mg/kg ATG, CsA, and mycophenolate mofetil (MMF) (ATG-based) in 10/10 HLA-matched unrelated donor (MUD) peripheral blood allogeneic hematopoietic stem cell transplantation (allo-HCT). The initial ATG dose of 4.5 mg/kg [ATG(4.5)/PTCy] was reduced to 2 mg/kg [ATG(2)/PTCy] in 2018. This study compares the results obtained from 444 adults undergoing MUD allo-HCT at our institution who received ATG(4.5)/PTCy (n = 127) or ATG(2)/PTCy (n = 223) with those who received ATG-based prophylaxis without PTCy (n = 84). The rates of grade II-IV and grade III-IV acute GVHD (aGVHD) at day +100 and moderate/severe chronic GVHD (cGVHD) at 1 year were 35.7%, 21.6%, and 14.7%, respectively, in patients receiving ATG-based prophylaxis without PTCy; 16.5%, 4.9%, and 4.3% in patients receiving ATG(4.5)/PTCy; and 23.3% (P = .004), 8.0% (P < .001), and 14.1% (P =.006) in patients receiving ATG(2)/PTCy. One-year overall survival (OS), nonrelapse mortality (NRM), and GVHD-free relapse-free survival (GRFS) were 69.8%, 25.3%, and 52.0%, respectively, for patients receiving ATG-based prophylaxis without PTCy; 82.7%, 17.3%, and 59.8% for patients receiving ATG(4.5)/PTCy; and 78.3% (P = .446), 14.7% (P = 101), and 56.2% (P = .448) for patients receiving ATG(2)/PTCy. On univariate analyses, the use of ATG(2)/PTCy was associated with a lower risk of NRM (hazard ratio, .54; P = .023) compared with the use of ATG-based prophylaxis without PTCy. ATG(2)/PTCy prophylaxis effectively prevents GVHD and is associated with comparable relapse risk, OS, and GRFS as seen with ATG(4.5)/PTCy and ATG-based prophylaxis without PTCy.

Pretransplant Blinatumomab Improves Outcomes in B Cell Acute Lymphoblastic Leukemia Patients Who Undergo Allogeneic Hematopoietic Cell Transplantation

BACKGROUND

Blinatumomab, a bispecific monoclonal antibody, effectively controls refractory B cell acute lymphoblastic leukemia (ALL) and promotes measurable residual disease (MRD) negativity. This study investigated the impact of pretransplant blinatumomab on allogeneic hematopoietic cell transplantation (HCT) outcomes in B cell ALL patients.

METHODS

We analyzed the effect of pretransplant blinatumomab on transplant outcomes of 117 adults undergoing allogeneic HCT for B cell ALL at Princess Margaret Hospital, Toronto, between 2010 and 2021. Outcomes assessed included overall survival (OS), graft-versus-host disease and relapse-free survival (GRFS), cumulative incidences of relapse (CIR), and nonrelapse mortality (NRM).

RESULTS

The median follow-up was 36 months. Thirty-one participants (26.5%) received blinatumomab. Blinatumomab group had higher proportions of individuals with high disease risk index, primary induction failure and was more likely to receive dual T cell depletion with antithymocyte globulin and post-transplant cyclophosphamide. Two-year OS, GRFS, NRM, and CIR in the blinatumomab and nonblinatumomab groups were, respectively: 65.4% versus 45.6% (P = .05), 42.2% versus 17.3% (P = .01), 3.2% versus 43.0% (P = .007) and 34.4% versus 14.4% (P = .02). Blinatumomab was associated with a lower incidence of day-100 grade 2 to 4 and grade 3 to 4 acute graft-versus-host disease (aGVHD): 27.5% versus 56.7% (P = .009), and 10.9% versus 34.7% (P = .04), respectively. Multivariate analysis confirmed the association between pretransplant blinatumomab and improved OS and NRM.

CONCLUSIONS

Pretransplant blinatumomab is associated with improved OS and lower risk of NRM in B cell ALL patients undergoing allogeneic HCT, likely reflecting lower burden of treatment-related toxicity in this population. Larger prospective trials are warranted to validate our findings.

Novel approaches to acute graft-versus-host disease prevention

The field of graft-versus-host disease (GvHD) has experienced significant growth, with increased number of clinical trials and the approval of several agents by the US Food and Drug Administration for both acute and chronic GvHD treatment. In addition, the development of prognostic biomarker algorithms has enabled risk stratification in acute GvHD. However, prevention remains the cornerstone of GvHD management. Notable recent changes include the expansion of donor options with the increased use of haploidentical donor and unrelated donor transplantation, the development of ex vivo selective T-cell depletion strategies, recent approval by the Food and Drug Administration of abatacept for GvHD prevention, and the application of posttransplant cyclophosphamide in matched and mismatched donor settings. In this article, we review the results of recent clinical trials in GvHD prophylaxis and discuss the changes in clinical practice and promising emerging strategies driving the field forward.

Choosing Between Older Matched Sibling Donor and Younger Matched Unrelated Donor in Allogeneic Hematopoietic Cell Transplantation: Comparison of Clinical Outcomes in Acute Myeloid Leukemia and Myelodysplastic Syndrome

The choice between an older matched sibling donor (MSD) and a younger matched unrelated donor (MUD) in allogeneic hematopoietic cell transplantation (HCT) remains a subject of ongoing debate. In this single-center retrospective study of 377 patients who received peripheral blood stem cell (PBSC) transplants for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS), we compared outcomes of 85 patients who received grafts from MSDs age >60 years and 292 patients who received grafts from MUDs age <30 years. Compared to recipients of MSD transplants, recipients of MUD transplants were younger and more likely to receive dual T cell depletion (TCD), a higher CD34+ cell dose, and a fresh graft. Recipients of MSD transplants were maintained on immunosuppressive therapy longer than those who received MUD grafts. We found no differences in overall survival, relapse-free survival, graft-versus-host disease (GVHD)-free and relapse-free survival, nonrelapse mortality, relapse, engraftment, graft failure, and acute GVHD between recipients of MSD grafts and recipients of MUD grafts. We report a higher 30-day incidence, but not 1-year incidence, of bloodstream infections among recipients of MUD transplants compared to subjects who received their grafts from a MSD. The incidence of moderate-severe chronic GVHD was higher in MSD graft recipients compared with MUD graft recipients in univariate analysis, but not in multivariate analysis. Although this difference could reflect the greater use of dual TCD, known to be associated with very low rates of chronic GVHD in MUD transplant recipients, the incidence of moderate-severe chronic GVHD was no different between MSD and MUD transplant recipients following propensity score matching, suggesting that other variables could be responsible. Taken together, our data suggest that in patients with AML or MDS who receive PBSC transplants, such factors as convenience, ease of access, and costs should be considered when selecting an older MSD over a younger MUD.

Post-transplantation cyclophosphamide as GVHD prophylaxis in allogenic hematopoietic stem cell transplantation: Recent advances and modification

Allogenic hematopoietic stem cell transplantation (allo-HSCT) is the most important therapeutic option for hematological disorders, although graft-versus-host disease (GVHD) remains the main cause of mortality. Post-transplantation cyclophosphamide (PTCY) induces immune tolerance and is associated with a low incidence of GVHD and non-relapse mortality. Therefore, PTCY has emerged as a safe and effective GVHD prophylaxis in haploidentical transplantation and has been expanded to matched related or unrelated donor and mismatched unrelated donor HSCT. On the basis of current understanding of the mechanisms of PTCY and antithymocyte globulin (ATG) in the prevention of GVHD, growing evidence suggests that the combination of ATG and PTCY could improve allo-HSCT clinical outcomes. Further research will focus on optimizing PTCY regimens by modifying the timing of administration or adding other immunosuppressive agents.

Interaction Between High-Dose Intravenous Busulfan and Post-Transplantation Cyclophosphamide on Hemorrhagic Cystitis After Allogeneic Hematopoietic Cell Transplantation

This study investigates the incidence and predictors of hemorrhagic cystitis (HC) in 960 adults undergoing allo- hematopoietic stem cell transplantation. Two hundred fifty-two (26.5%) patients received myeloablative conditioning regimens, and 81.4% received high-dose intravenous busulfan (HD Bu). Six hundred ninety-five (72.4%) patients received post-transplantation cyclophosphamide (PTCY)-based prophylaxis, and 91.4% additionally received anti-thymocyte globulin (ATG) and Cyclosporine A (CsA) (PTCY-ATG-CsA). Two hundred twenty-eight (23.8%) patients developed HC. The day 100 cumulative incidences of grades 2-4 and 3-4 HC were 11.1% and 4.9%. BK virus was isolated in 58.3% of urinary samples. Using HD BU myeloablative regimens increased the risk for grade 2-4 HC (hazard ratio [HR] = 1.97, P = .035), and HD BU combined with ATG-PTCY-CsA increased this 4 times (HR = 4.06, P < .001) for grade 2-4 HC compared to patients who received neither of these drugs. A significant correlation was documented between grade II-IV acute graft-versus-host disease and grade 2-4 HC (HR = 2.10, P < .001). Moreover, patients with BK-POS grade 2-4 HC had lower 1-year overall survival (HR = 1.51, P = .009) and higher non-relapse mortality (HR = 2.31, P < .001), and patients with BK-NEG grade 2-4 HC had comparable post-transplantation outcomes. In conclusion, intravenous HD Bu was identified as a predictor for grade 2-4 HC. Moreover, when HD Bu was combined with PTCY-ATG-CsA, the risk increased 4-fold. Based on the results provided by this study, preventing the onset of HC, especially in high-risk patients, is mandatory because its presence significantly increases the risk for mortality.

Reduced-dose post-transplant cyclophosphamide plus low-dose post-transplant anti-thymocyte globulin as graft-versus-host disease prophylaxis with fludarabine-busulfan-cytarabine conditioning in haploidentical peripheral blood stem cell transplantation: A multicentre, randomized controlled clinical trial

Anti-thymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy)-based regimens are widely used for graft-versus-host disease (GVHD) prophylaxis in haploidentical haematopoietic stem cell transplantation (haplo-HSCT). To improve the effectiveness of GVHD prophylaxis in haploidentical peripheral blood stem cell transplantation (haplo-PBSCT), we conducted a multicentre, randomized clinical trial to determine the efficacy of reduced-dose PTCy (40 mg/kg/d on days 3 and 4) combined with low-dose post-transplant ATG (2.5 mg/kg on day 8)-based GVHD prophylaxis (reduced-dose PTCy/ATG) with fludarabine-busulfan-cytarabine (FBA) conditioning for patients with haematological malignancies. From 2018 to 2022, 122 patients from four institutions were randomly assigned 1:1 to either a reduced-dose PTCy/ATG or a standard-dose ATG group ('Beijing Protocol', ATG: 10 mg/kg). All patients achieved myeloid engraftment. Cumulative incidences of grade II-IV (11.5% vs 39.3%, p = 0.001) and grade III-IV (6.6% vs 24.6%, p = 0.014) acute GVHD at day 100 were significantly reduced in the reduced-dose PTCy/ATG group. Furthermore, two-year overall survival, disease-free survival and GVHD-free/relapse-free survival were significantly improved in the reduced-dose PTCy/ATG group (75.4% vs 54.1%, p = 0.021; 72.7% vs 55.0%, p = 0.044; 61.3% vs 42.3%, p = 0.022 respectively). Our results demonstrate that the addition of low-dose ATG to reduced-dose PTCy with FBA conditioning is a promising strategy in haplo-PBSCT.

Bacterial Bloodstream Infections in Patients Undergoing Allogeneic Hematopoietic Cell Transplantation With Post-Transplantation Cyclophosphamide

This study investigates the incidence and predictors for bacterial bloodstream infection (BSI) in 330 adults undergoing allo-HCT, and explores the effect of post-transplantation cyclophosphamide (PTCY) on the probability of presenting this complication. All patients received levofloxacin during the aplastic phase. Only the first episode of BSI was counted as an event. Patients were classified into 2 groups: PTCY-based (n = 200) versus other prophylaxis (n = 130). One hundred twenty-four patients were diagnosed with a first episode of BSI, most of them during the first 30 days (70.2%). Proportions of BSIs caused by Gram-positive bacteria were comparable to those caused by Gram-negative bacteria (48.3% versus 45.9%). The cumulative incidence of BSI was higher in patients receiving PTCY than in those receiving other prophylaxis (days 30 and 100: 35.0% and 37.0% versus 13.1% and 18.5%, P < .001). At day 30, the likelihood of BSI was 2.41 (P = .012) times higher in the PTCY group than in the non-PTCY group. The 30-day mortality rate in all patients with BSI was 8.0%, lower (P = .002) in the PTCY group (2.3%) than in the non-PTCY group (21.6%). Finally, the overall survival of patients receiving PTCY and diagnosed with BSI was similar to that of patients without presenting this complication. © 2023 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

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.

Low-dose post-transplant cyclophosphamide with low-dose antithymocyte globulin for prevention of graft-versus-host disease in first complete remission undergoing 10/10 HLA-matched unrelated donor peripheral blood stem cell transplants: a multicentre, randomized controlled trial

The most widely used regimens of graft-versus-host disease (GVHD) prophylaxis in HLA-matched unrelated donor peripheral blood stem cell transplantation (MUD-PBSCT) are based on anti-thymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). To improve the efficiency of GVHD prophylaxis, a novel regimen, composed of low-dose PTCy (20 mg/kg on day +3 and +4) and low-dose ATG (6 mg/kg), was evaluted in patients with hematological malignancies ungoing 10/10 HLA MUD-PBSCT in first remission (CR1). In our prospective, multicenter study, 104 patients were randomly assigned one-to-one to low-dose PTCy-ATG (n = 53) or standard-dose ATG (10 mg/kg, n = 51). Both the cumulative incidences (CIs) of grade II-IV acute GVHD (aGVHD) and chronic GVHD (cGVHD) at 2 years in low-dose PTCy-ATG cohort were significantly reduced (24.5% vs. 47.1%; P = 0.017; 14.1% vs. 33.3%; P = 0.013). The CI of non-relapse-mortality (NRM) was much lower (13.2% vs. 34.5%; P = 0.049) and GVHD-free, relapse-free survival (GRFS) was significantly improved at 2 years in low-dose PTCy-ATG arm (67.3% vs 42.3%; P = 0.032). The low-dose PTCy-ATG based GVHD prophylaxis is a promising strategy for patients in CR1 after 10/10 HLA MUD-PBSCT.

Outcomes of haploidentical peripheral stem cell transplantation with combination of post-transplant cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG) compared to unrelated donor transplantation in acute myeloid leukemia: A retrospective 10-year experience

In the evolution of haploidentical hematopoietic stem cell transplantation (haplo-HSCT), In vivo T-cell modulation with concomitant use of anti-thymocyte globulin (ATG) and high-dose post-transplant cyclophosphamide (PTCy) provides a novel promising method on transplant outcomes; however, the long-term effects of this therapy are mostly unknown. We retrospectively compared the long-term outcomes of adult acute myeloid leukemia (AML) patients undergoing a haplo-HSCT (n = 92) with a new modified combination of ATG and PTCy in the context of peripheral blood stem cell (PBSC) and myeloablative conditioning (MAC) with an otherwise similar group of AML patients who received an unrelated donor (URD) HSCT (n = 57) with ATG protocol from February 2010 to December 2020 at our single-center (HORCSCT). Median follow-up was 3.73 and 4.28 years for haploidentical and URD-HSCT, respectively. In haplo-HSCT, the cumulative incidence of grades II-IV and III-IV acute graft versus host disease (aGvHD) and extensive chronic GvHD (cGvHD) was much lower than in URD (27% versus 56% for grades II-IV, 8.7% versus 24.5% for grades III-IV, and 15.4% versus 34.7% for extensive cGvHD, respectively). Five-year overall survival (OS) was 54.03% for haplo and 54.48% for URD (p = 0.927); GvHD-free relapse-free survival (GRFS) was 44.1% and 29.86% (p = 0.149); relapse incidence was 15.79% and 26.95% (p = 0.72); and non-relapse mortality (NRM) was 29.48% and 26.32% (p = 0.73), respectively. Using multivariable analyses, when compared to Haplo, URD was a significant predictor of relapse (HR=1.80, p = 0.039); however, no difference in OS, GRFS, and NRM was noted between haplo and URD. Therefore, given the favorable results with haplo-HSCT and considering donor availability promptly with low cost, it conservatively suggested that haplo-HSCT with the introduced protocol could be viewed as the first alternative for patients with AML in the absence of matched sibling donors.

Acute kidney injury within 100 days post allogeneic hematopoietic cell transplantation is associated with increased risk of post-transplant complications and poor transplant outcomes

Allogeneic hematopoietic cell transplantation (HCT) offers cure for some patients with hematological diseases but is associated with significant risk of morbidity and mortality. We investigated the incidence of AKI and its impact on transplant outcomes among 408 patients transplanted at Princess Margaret Hospital Cancer Centre, Toronto, Canada. The overall incidence of AKI at 100 days was 64.2%. Compared to those with no AKI, patients who developed AKI had inferior 2-y overall survival (OS), 44.7% vs. 62.4% (P = 0.0004), higher 2-y transplant related mortality (TRM) 36.8% vs. 18.7% (P = 0.0003), lower 2-y graft-vs-host disease (GVHD)- and relapse-free survival (GRFS), 21.0% vs. 39.8% (P = 0.0002), and higher 100-day grade 3-4 acute GVHD (aGVHD), 12.4% vs. 6.3% (P = 0.01). There was no difference in 2-y incidence of relapse between the AKI and non-AKI groups, 24.2% vs. 24.3% (P = 0.84), 100-day grade 2-4 aGVHD, 27.7% vs. 25.7 (P = 0.41) or 2-y moderate-severe chronic GVHD, 24.0% vs. 21.6% (P = 0.79). Patients who develop AKI within 100 days of HCT have inferior OS and GRFS with higher rates of TRM and grade 3-4 aGVHD. These results highlight the importance of close monitoring of renal function, multidisciplinary collaboration, and implementation of protective strategies throughout HCT to optimize transplant and kidney outcomes.

PTCY and Tacrolimus for GVHD Prevention for Older Adults Undergoing HLA-Matched Sibling and Unrelated Donor AlloHCT

INTRODUCTION

The use of PTCY for graft-versus-host disease (GHVD) prevention is becoming prevalent in the transplant community when HLA-identical sibling (MSD) and 10/10 HLA-matched (MUD) and 9/10 mismatched (MMUD) unrelated donors are selected for alloHSCT. However, reported evidence on outcomes from elderly receiving PTCY-containing GVHD prophylaxis remains limited.

OBJECTIVES

This study aims to compare the outcomes of PTCY-TK prophylaxis and conventional GVHD prophylaxis in patients aged >50 years undergoing peripheral blood alloHSCT from a single institution.

STUDY DESIGN

A total of 161 consecutive patients aged >50 years undergoing alloHSCT between Jan-2014 and Feb-2021 were included. Data was collected retrospectively and updated in December 2021. Patients received grafts from HLA-identical sibling (MSD), and from 10/10 and 9/10 HLA matched and mismatched unrelated donors (UD).

RESULTS

Overall, median age was 60 years and 91 (54.8%) received PTCY-TK for GVHD prevention. Time to neutrophil and platelet engraftment was longer in the PTCY-TK group (20 vs. 16 days and 19 vs. 11 days, P< 0.001). The cumulative incidences of grade II-IV and III-IV aGVHD at day +100 and moderate/severe cGVHD at 2 years were 18.2%, 5.7% and 9.5% for patients receiving PTCY-TK, and 26.0%, 9.6% and 39.5% for those that did not. The multivariate analysis showed that PTCY-TK reduced the probability of grade II-IV aGVHD (HR 0.41, p=0.035), of cGVHD [any grade: HR 0.43 (p=0.014), and of moderate/severe cGVHD (HR 0.15 (p<0.001)]. At 2-years, the overall survival (65.4% vs. 65.6%, p=0.472), non-relapse mortality (17.4% vs. 13.7%, p=0.967), and cumulative incidence of relapse rates (24.2% vs. 27.5%, p=0.712) were comparable between both cohorts; GVHD-Free/Relapse-free survival (GRFS) was higher in the PTCY-TK group (2-years: 50.2% vs. 21.8%; HR 0.42, p=0.001). In patients aged ≥50 years, Conclusion: PTCY-TK was safe and a more effective drug combination than non-PTCY containing GVHD prophylaxis, even with the use of matched and mismatched UD, and resulted in comparable relapse rates and better GRFS.

Addition of a Single Low Dose of Anti T-Lymphocyte Globulin to Post-Transplant Cyclophosphamide after Allogeneic Hematopoietic Stem Cell Transplant: A Pilot Study

Correlation between risk of graft-versus-host disease (GvHD) and CD3⁺ counts within the peripheral blood stem cell graft has recently been reported in the setting of post-transplant cyclophosphamide (PT-Cy). We aimed to investigate the benefit of the addition of a single dose of anti-T lymphocyte globulin (ATLG 5 mg/kg) to PT-Cy in this setting. Starting in 2019, all patients receiving PBSC transplant containing CD3⁺ counts above 300 × 10⁶/kg (study group) received a post-transplant dose of ATLG in addition to standard PT-Cy. The study was designed as a real-life analysis and included all consecutive Hematopoietic Stem Cell Transplantation (HSCT) recipients according to the above-mentioned inclusion criterion (n = 21), excluding cord blood and bone marrow donors. Using a 1:2 matched-pair analysis, we compared the outcomes with a historical population who received PT-Cy only (control group). We found a delayed platelet engraftment (29% vs. 45% at 30 days, p = 0.03) and a non-significant trend toward higher risk of poor graft function (29% vs. 19%, p = 0.52). The addition of ATLG impacted long-term immune reconstitution on the CD4⁺ subsets, but this did not translate into higher rate of relapse or viral infection. Acute GvHD was not significantly impacted, but 1-year cumulative incidence of chronic GvHD was significantly lower in the study group (15% vs. 41%, p = 0.04). Survival outcomes were comparable. In conclusion PT-Cy and ATLG was overall safe and translated into a low rate of chronic GvHD incidence.

Anti-thymocyte Globulin and Post-Transplant Cyclophosphamide do not abrogate the inferior outcome risk conferred by human leukocyte antigen-A and -B mismatched donors

In donor selection for allogeneic stem cell transplant, several factors are considered for potential impact on transplant outcome. Previous publications suggested single HLA-mismatched unrelated donors (MMUD) may be equivalent to 10/10 matched unrelated donors (MUDs). We retrospectively examined factors affecting outcome in a single-center study using ATG followed by post-transplant cyclophosphamide, termed ATG-PTCy, GvHD prophylaxis. Fifty-two patients who received grafts from MMUD and 188 patients transplanted from MUD between January 2015 and December 2019, at Princess Margaret Cancer Centre, Canada, were enrolled. All patients received reduced-intensity conditioning. Overall survival for 9/10 recipients at 2 years was significantly worse, 37.2% versus 68.5% for 10/10 MUDs, p < .001, as were NRM at 1 year 39.5% versus 11.7%, p < .001, and GRFS at 2 years 29.8% versus 58.8%, p < .001, respectively, potentially due to higher incidence of infections including CMV. By multivariable analysis, factors correlating with survival negatively were DRI, and MMUD, whereas for NRM MMUD and increasing age were unfavorable. For GRFS significant unfavorable factors included donor age ≤32 years, female donor to male recipient, DRI high-very high and MMUD. These data suggest that MMUD, primarily HLA-A and HLA-B MMUD, confer significantly inferior outcome despite use of ATG-PTCy. Further development of novel conditioning regimens and GvHD prophylaxis is needed to mitigate these risks.

Sequential Transplantation of Haploidentical Stem Cell and Unrelated Cord Blood With Using ATG/PTCY Increases Survival of Relapsed/Refractory Hematologic Malignancies

Allogeneic haploidentical HSCT (haplo-HSCT) and unrelated umbilical cord blood transplantation(UCBT)are used in patients lacking HLA-identical sibling or unrelated donors. With myeloablative condition and GVHD prophylaxis of using low-dose ATG and post-transplantation cyclophosphamide (PTCY), we conducted a prospective clinical trial. Of eligible 122 patients from February 2015 to December 2019 in the study, 113 patients were involved. Forty-eight patients were in the group of sequential haplo-cord transplantation (haplo-cord HSCT), and 65 patients were in the group of single UCBT. The primary endpoint of 2-year disease-free survival (DFS) was no statistical difference between groups (64.1 vs. 56.5%), p>0.05. The analysis of subgroup patients with relapsed/refractory showed haplo-cord HSCT was associated with better OS (HR 0.348, 95% CI, 0.175–0.691; p=0.0025), DFS (HR 0.402, 95% CI, 0.208–0.779; p=0.0069), and GRFS (HR 0.235, 95% CI, 0.120–0.457, p<0.0001) compared to the single cord group. The 2-year’s probability in OS, DFS, and GRFS was 64.9 vs. 31.6%, 64.5 vs. 31.6%, and 60.8 vs. 15.0% in the haplo-cord group and single cord group, respectively. III-IV acute GVHD 8.3 vs. 6.2%, chronic GVHD 25.8 vs. 13.7%, and extensive chronic GVHD 5.3 vs. 1.8% were shown in corresponding group, p>0.05. The patients engrafted persistently with UCB showed better survival outcomes. Our sequential Haplo-cord HSCT with ATG/PTCY improved the survival of patients and might be an alternative transplantation approach for patients with relapsed/refractory hematologic malignancies.

CMV Infection and CMV-Specific Immune Reconstitution Following Haploidentical Stem Cell Transplantation: An Update

Haploidentical stem cell transplantation (haploSCT) has advanced to a common procedure for treating patients with hematological malignancies and immunodeficiency diseases. However, cure is seriously hampered by cytomegalovirus (CMV) infections and delayed immune reconstitution for the majority of haploidentical transplant recipients compared to HLA-matched stem cell transplantation. Three major approaches, including in vivo T-cell depletion (TCD) using antithymocyte globulin for haploSCT (in vivo TCD-haploSCT), ex vivo TCD using CD34 + positive selection for haploSCT (ex vivo TCD-haploSCT), and T-cell replete haploSCT using posttransplant cyclophosphamide (PTCy-haploSCT), are currently used worldwide. We provide an update on CMV infection and CMV-specific immune recovery in this fast-evolving field. The progress made in cellular immunotherapy of CMV infection after haploSCT is also addressed. Groundwork has been prepared for the creation of personalized avenues to enhance immune reconstitution and decrease the incidence of CMV infection after haploSCT.

Bloodstream Infections and Outcomes Following Allogeneic Hematopoietic Cell Transplantation: A Single-Center Study

This study investigated the single-center incidence and risk factors for bloodstream infections (BSIs) in 651 adults who underwent allogeneic hematopoietic cell transplantation (alloHCT) between 2015 and 2019 and explored the impact of these BSIs on post-transplantation outcomes. Antibiotic prophylaxis with ciprofloxacin was given during the aplastic phase. Overall, the median patient age was 57 years, 79.7% of patients received an alternative donor graft, and 68.7% received post-transplantation cyclophosphamide (PTCy) as part of their graft-versus-host disease (GVHD) prophylaxis. Of the 651 patients, 358 (55.0%) had at least 1 episode of BSI, and the overall mortality rate secondary to this complication was 7.5% (12.6% among those diagnosed with at least 1 episode of BSI). BSI was more often diagnosed during the first 30 days (58.7%), and gram-positive bacteria were the most prevalent microorganisms isolated during the entire post-transplantation follow-up (62%). A high Disease Risk Index (hazard ratio [HR], 1.47; P < .029) and receipt of PTCy-based GVHD prophylaxis (HR, 3.33; P < .001) were identified as risk factors for BSI. Additionally, univariate analysis showed that patients diagnosed with a BSI during post-transplantation follow-up had worse overall survival (HR, 2.48; P < .001) and higher nonrelapse mortality (HR, 2.68; P < .001) than those without BSI. In conclusion, alloHCT recipients with a BSI had a higher risk of mortality compared with those who did not develop BSI. The inclusion of PTCy as part of GVHD prophylaxis was identified as an independent risk factor for BSI during early post-transplantation follow-up. Single-center analyses focused on reporting the incidence and risk factors for BSI highlight the need for active implementation of preemptive strategies to decrease BSI incidence in the alloHCT setting. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Anti-thymocyte globulin and post-transplant cyclophosphamide predisposes to inferior outcome when using cryopreserved stem cell grafts

During 2020, the concurrent novel COVID-19 pandemic lead to widespread cryopreservation of allogeneic hematopoietic cell transplant grafts based on National Marrow Donor Program and European Society of Blood and Marrow Transplantation recommendations, in order to secure grafts before the start of conditioning chemotherapy. We sought to examine the impact of this change in practice on patient outcomes. We analyzed the outcomes of 483 patients who received hematopoietic stem cell transplantation (HSCT) between August 2017 and August 2020, at Princess Margaret Cancer Centre, Canada, in the retrospective study, comparing the outcomes between those who received cryopreserved or fresh peripheral blood stem cell grafts. Overall compared with those who received fresh grafts (n = 348), patients who received cryopreserved grafts (n = 135) had reduced survival and GRFS, reduced incidence of chronic graft-versus-host disease (GvHD), delay in neutrophil engraftment, and higher graft failure (GF), with no significant difference in relapse incidence or acute GvHD. However, recipients of cryopreserved matched-related donor HSCT showed significantly worse OS, NRM, GRFS compared with fresh grafts. Multivariable analysis of the entire cohort showed significant impact of cryopreservation on OS, relapse, cGvHD, GF, and GRFS. We conclude that cryopreservation was associated with inferior outcomes post-HSCT, possibly due to the combination of ATG and post-transplant cyclophosphamide impacting differential tolerance to cryopreservation on components of the stem cell graft; further studies are warranted to elucidate mechanisms for this observation.

Allogeneic Hematopoietic Stem Cell Transplantation in Therapy Related Acute Leukemia

Therapy related acute leukemia consists of a unique subset of acute leukemia with an increased frequency of high risk cytogenetic and molecular abnormalities, dismal response to therapy, higher relapse rates and poor overall survival. Therapy related acute myeloid leukemia (t-AML) is a better defined disease entity than therapy related acute lymphoid leukemia (t-ALL). However, in recent times, t-ALL is also being increasingly recognized and extensively studied. Therapy related acute myeloid leukemia is usually classified together with therapy related myelodysplastic syndrome. However, the management of these two diseases maybe different regarding needs of induction chemotherapy and eligibility for upfront allogeneic hematopoietic stem cell transplantation (Allo HSCT). There is also evidence regarding differences in prognosis and outcomes between these two entities. Allo HSCT offers a potential for cure in t-AML and t-ALL. However, existing literature on the same is confounded by inclusion of t-MDS and secondary acute leukemias. Here we review the current evidence on the outcomes and predictors of outcomes of Allo HSCT in the management of therapy related acute leukemias. We also shed light into the under-representation of therapy related leukemias in clinical trials. This stresses the need for prospective trials incorporating measurable residual disease monitoring and sequential next generation sequencing based genomic data for accurate prognostication and management of therapy related acute leukemia.

Lower dose of ATG combined with post-transplant cyclophosphamide for HLA matched RIC alloHCT is associated with effective control of GVHD and less viral infections

This study compares the outcomes before and after reducing the ATG dose from 4.5 to 2 mg/kg, in a combination of PTCy and CsA for GVHD prevention, in 250 patients treated with HLA matched RIC PB-alloHCT (70% received 4.5 mg/kg and 30% received 2 mg/kg). The incidences of grade II-IV and III-IV aGVHD at day +100, and moderate/severe cGVHD at 1-year were 12.6% vs. 20% (p = 0.431), 3.6% vs. 4.5% (p = 0.935), and 10.9% vs. 26.1% (p = 0.480), respectively. PTLD (9.1% vs. 1.3%, p = 0.026) and viral infections (30.3% vs. 12%; p = 0.001) were lower for those treated with 2 mg/kg of ATG. The reduction of the ATG dose resulted in a comparable OS (2-year: 64.7% vs. 64.7%), GRFS (2-year: 48.0% vs. 44.5%), RFS (2-year: 57.0% vs. 62.0%), and NRM (2-year: 17.8 vs. 14.9). The use of (2 mg/kg) ATG-PTCy-CsA for HLA matched RIC alloHCT results in lower viral infections, and incomparable GVHD preventive effect and survival rates.

Allogeneic hematopoietic cell transplantation with cord blood versus mismatched unrelated donor with post-transplant cyclophosphamide in acute myeloid leukemia

BACKGROUND

Allogeneic hematopoietic cell transplantation (allo-HCT) using a mismatched unrelated donor (MMUD) and cord blood transplantation (CBT) are valid alternatives for patients without a fully human leukocyte antigen (HLA)-matched donor. Here, we compared the allo-HCT outcomes of CBT versus single-allele-mismatched MMUD allo-HCT with post-transplant cyclophosphamide (PTCy) in acute myeloid leukemia.

METHODS

Patients who underwent a first CBT without PTCy (N = 902) or allo-HCT from a (HLA 9/10) MMUD with PTCy (N = 280) were included in the study. A multivariate regression analysis was performed for the whole population. A matched-pair analysis was carried out by propensity score-based 1:1 matching of patients (177 pairs) with known cytogenetic risk.

RESULTS

The incidence of grade II-IV and grade III-IV acute graft-versus-host disease (GVHD) at 6 months was 36% versus 32% (p = 0.07) and 15% versus 11% (p = 0.16) for CBT and MMUD cohorts, respectively. CBT was associated with a higher incidence of graft failure (11% vs. 4%, p < 0.01) and higher 2-year non-relapse mortality (NRM) (30% vs. 16%, p < 0.01) compared to MMUD. In the multivariate analysis, CBT was associated with a higher risk of, NRM (HR = 2.09, 95% CI 1.46-2.99, p < 0.0001), and relapse (HR = 1.35, 95% CI 1-1.83, p = 0.05), which resulted in worse leukemia-free survival (LFS) (HR = 1.68, 95% CI 1.34-2.12, p < 0.0001), overall survival (OS) (HR = 1.7, 95% CI 1.33-2.17, p < 0.0001), and GVHD-free, relapse-free survival (GRFS) (HR = 1.49, 95% CI 1.21-1.83, p < 0.0001) compared to MMUD. The risk of grade II-IV acute GVHD (p = 0.052) and chronic GVHD (p = 0.69) did not differ significantly between the cohorts. These results were confirmed in a matched-pair analysis.

CONCLUSIONS

CBT was associated with lower LFS, OS, and GRFS due to higher NRM, compared to MMUD allo-HCT with PTCy. In the absence of a fully matched donor, 9/10 MMUD with PTCy may be preferred over CBT.

Inferior outcomes with reduced intensity conditioning followed by allogeneic hematopoietic cell transplantation in fit individuals with acute lymphoblastic leukemia: a Canadian single-center study and a comparison to registry data

Allogeneic hematopoietic cell transplantation (HCT) can offer cure to some patients with acute lymphoblastic leukemia (ALL). It remains unclear how conditioning intensity affects transplant outcomes in ALL. In this retrospective study, we compared outcomes between 27 patients <60 who received reduced intensity conditioning (RIC) at Princess Margaret Hospital Cancer Center (PMCC) and 226 Cell Therapy Transplant Canada (CTTC) age-matched controls who received myeloablative conditioning (MAC) between 2007 and 2018. Compared to CTTC patients, PMCC patients had an inferior 2-y OS: 0.29 (95% CI: 0.11-0.49) vs 0.63 (0.56-0.70), HR = 2.10 (1.23-3.55), p = 0.006, higher TRM: 0.41 (0.22-0.60) vs 0.24 (0.18-0.30), HR = 2.00 (1.05-3.81), p = 0.04 and a trend toward increased risk of relapse: 0.36 (0.17-0.56) versus 0.17 (0.12-0.22), HR = 1.72 (0.82-3.62), p = 0.15. In multivariate analysis, RIC and the use of T-cell depletion (TCD) were associated with inferior OS. In ALL patients <60, the use of RIC with TCD is associated with inferior allogeneic HCT outcomes.

Grade 2 acute GVHD is a factor of good prognosis in patients receiving peripheral blood stem cells haplo-transplant with post-transplant cyclophosphamide

BACKGROUND

The impact of acute graft versus host disease (GVHD) on survivals for patients receiving a haploidentical allogeneic stem-cell transplant (Allo-SCT) with peripheral blood stem-cells (PBSC) complemented by post-transplant cyclophosphamide (PTCY) is ill-known.

MATERIAL AND METHODS

This retrospective study included 131 patients who received a PBSC haplograft in order to precise the impact of acute GVHD on outcomes. There were 78 males and 53 females and the median age for the whole cohort was 59 years (range: 20-71). Thirty-five patients were allografted for a lymphoid disease and 96 for a myeloid malignancy, including 67 patients with acute myeloid leukemia (AML).

RESULTS

The cumulative incidence (CI) of day 100 grade 2-4 and 3-4 acute GVHD was 43.4 + 4.6% and 16.7 + 3.4%, respectively. The 2-year CI of moderate/severe chronic GVHD was 10.1 + 2.8%. The only factor affecting the occurrence of GVHD was GVHD prophylaxis. Indeed, CI of day 100 grade 2-4 (but not grade 3-4) acute GVHD was significantly reduced when adding anti-thymoglobulin (ATG) to PTCY. However, in multivariate analysis, grade 2 acute GVHD was significantly associated with better disease-free (HR: 0.36; 95%CI: 0.19-0.69, p = .002) and overall (HR: 0.35; 95%CI: 0.1-0.70, p = .003) survivals. The same results were observed when considering only AML patients.

CONCLUSION

Acute grade 2 GVHD is a factor of good prognosis after PBSC haplotransplant with PTCY. Further and larger studies are needed to clarify the complex question of GVHD prophylaxis in the setting of haplo-transplant, especially that of combining ATG and PTCY.

Predictors of outcomes of therapy-related acute myeloid leukemia after allogeneic hematopoietic stem cell transplantation

BACKGROUND/OBJECTIVE

Existing literature on allogeneic hematopoietic stem cell transplantation (allo-HSCT) in therapy-related acute myeloid leukemia (t-AML) is confounded by the inclusion of patients with secondary AML and t-MDS. We aim to report our 20-year experience of HSCT in t-AML.

METHODS

We retrospectively reviewed patients with t-AML who underwent HSCT. Patients were analyzed for prior malignancy, therapy, time to diagnosis of t-AML, transplant details, relapse-free survival (RFS), overall survival (OS), and predictors of outcomes.

RESULTS

In total, 68 patients (59.9% female; median age, 56.5 years) underwent HSCT. Acute and chronic graft-versus-host disease (GVHD) occurred in 39 (57.4%) and 23 (33.8%) patients, respectively. Cumulative incidence of relapse, nonrelapse mortality, RFS, and OS at 2 years were 17.9%, 34.5%, 47.6%, and 49.3%, respectively. Significant predictors of reduced OS were presence of 11q23 rearrangement (hazard ratio [HR], 3.24), using induction regimens other than FLAG-Ida or 7 + 3 (HR, 3.65), haploidentical donors (HR, 3.48), Eastern Cooperative Oncology Group performance status 2 or higher (HR, 5.83), and using cyclosporine A-methotrexate as GVHD prophylaxis (HR, 2.41). A significant decrement in survival was seen with an increasing number of any of these prognostic factors.

CONCLUSION

Outcomes of t-AML are satisfactory after allo-HSCT. Patients with t-AML with good-risk karyotypes, good performance status, having HLA-matched donors, and receiving intensive induction regimens have better outcomes after HSCT.

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.

Comparison of alemtuzumab, anti-thymocyte globulin, and post-transplant cyclophosphamide for graft-versus-host disease and graft-versus-leukemia in murine models

Graft-versus-host disease is a major complication after allogeneic hematopoietic stem cell transplantation for hematological malignancies. Immunosuppressive drugs, such as anti-thymocyte globulin, alemtuzumab, and post-transplant cyclophosphamide, have been used to prevent graft-versus-host disease in HLA-mismatched haploidentical hematopoietic stem cell transplantation. Here, we investigated whether these drugs could ameliorate graft-versus-host disease without diminishing the graft-versus-leukemia effect by using a xenogeneic transplanted graft-versus-host disease/graft-versus-leukemia model. Anti-thymocyte globulin treatment diminished graft-versus-host disease symptoms, completely depleted the infiltration of inflammatory cells in the liver and intestine, and led to prolonged survival. By contrast, improvement after post-transplant cyclophosphamide treatment remained minimal. Alemtuzumab treatment modestly prolonged survival despite an apparent decrease of Tregs. In the graft-versus-leukemia model, 1.5 to 2.0 mg/kg of anti-thymocyte globulin and 0.6 to 0.9 mg/kg of alemtuzumab reduced graft-versus-host disease with minimal loss of graft-versus-leukemia effect. Mice treated with 400 mg/kg of post-transplant cyclophosphamide did not develop graft-versus-host disease or leukemia, but it was difficult to evaluate the graft-versus-leukemia effect due to the sensitivity of A20 cells to cyclophosphamide. Although the current settings provide narrow optimal therapeutic windows, further studies are warranted to maximize the benefits of each immunosuppressant.

Feasibility of reduced-dose posttransplant cyclophosphamide and cotransplantation of peripheral blood stem cells and umbilical cord-derived mesenchymal stem cells for SAA

Posttransplant cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis is an effective strategie for patients receiving matched sibling donor hematopoietic stem cell transplantation (MSD-HSCT) and haploidentical HSCT (haplo-HSCT). We evaluated the effectiveness and safety of reduced-dose cyclophosphamide, 20 mg/kg for 13 patients in MSD-HSCT cohort and 25 mg/kg for 22 patients in haplo-HSCT cohort, on days + 3, + 4 combined with cotransplantation of peripheral blood stem cells (PBSCs) and human umbilical cord-derived mesenchymal stem cells (UC-MSCs) for severe aplastic anemia (SAA). In MSD-PTCy cohort, the times to neutrophil and platelet engraftment were significantly shorter than those in the MSD-control cohort (P < 0.05). The cumulative incidence of acute GVHD (aGVHD) at day + 100 (15.4%) was lower than that in the MSD-control cohort (P = 0.050). No patient developed chronic GVHD (cGVHD). The 1-year overall survival (OS) and event-free survival (EFS) rates were 100% and 92.3%. In haplo-PTCy cohort, the times to neutrophil and platelet engraftment were significantly shorter than those in the haplo-control cohort (P < 0.05). The cumulative incidences of aGVHD at day + 100 and 1-year cGVHD were 31.8% and 18.2%, and the 1-year OS and EFS rates were 81.8% and 66.9%. Reduced-dose PTCy and cotransplantation of PBSCs and UC-MSCs is an acceptable alternative to patients with SAA.

Comparison of Haploidentical Bone Marrow versus Matched Unrelated Donor Peripheral Blood Stem Cell Transplantation with Posttransplant Cyclophosphamide in Patients with Acute Leukemia

PURPOSE

Posttransplant cyclophosphamide (PTCy) is increasingly being utilized as a principle GvHD prophylaxis strategy in allogeneic hematopoietic cell transplantation (allo-HCT). A haploidentical (haplo) or matched unrelated donor (UD) is a valid option in the absence of a matched related donor.

EXPERIMENTAL DESIGN

We compared the outcomes of patients with acute leukemia who underwent haplo bone marrow (haplo-BM, N = 401) versus UD mobilized peripheral blood stem cells (UD-PB, N = 192) transplantation in the setting of PTCy.

RESULTS

The median follow-up duration was 36 months in the haplo-BM group and 16.6 months in the UD-PB group, respectively (P < 0.01). Myeloablative conditioning was used in 64.6% and 42.7% of haplo-BM and UD-PB patients, respectively (P < 0.01). Cumulative incidence of neutrophil engraftment at day 30 was 87% in haplo-BM versus 94% in UD-PB, respectively (P = 0.21). In the multivariate analysis, the risk of grade 2-4 acute GvHD (HR = 0.53, P = 0.01) and chronic GvHD (HR = 0.50, P = 0.02) was significantly lower in the haplo-BM group compared with the UD-PB group. There was no significant difference between the study groups with respect to relapse incidence, nonrelapse mortality, leukemia-fee survival, overall survival, or GvHD-free and relapse-free survival.

CONCLUSIONS

The use of a haplo donor with a BM graft resulted in a lower incidence of GvHD compared with a UD-PB stem cell graft in the setting of PTCy for patients with acute leukemia. However, differences in GvHD did not translate into a difference in survival outcomes. Based upon these data, UD-PB or haplo-BM should be considered equally acceptable sources for allo-HCT.