Nonmyeloablative HLA-haploidentical bone marrow transplantation with high-dose posttransplantation cyclophosphamide: effect of HLA disparity on outcome

Post-transplantation cyclophosphamide and cyclosporine A versus methotrexate and cyclosporine A for graft-versus-host disease prophylaxis after allogeneic peripheral stem cell transplantation in adult acute myeloid leukemia patients

BACKGROUND

Different prophylactic protocols are available for preventing graft-versus-host disease (GVHD) after matched sibling donor (MSD) allogeneic hematopoietic cell transplantation (allo-HCT). This study aimed to compare the effectiveness of post-transplantation cyclophosphamide plus cyclosporine A (PT-CY/CSA) versus methotrexate plus CSA (MTX/CSA) as GVHD prophylaxis protocols in adult acute myeloid leukemia (AML) patients who received peripheral blood stem cells (PBSC) from fully matched donors.

METHODS

The 1-year outcomes of 89 patients treated with PT-CY/CSA and 90 patients treated with MTX/CSA who had MSD allo-HCT for AML using unmanipulated mobilized PBSC were examined and compared.

RESULTS

The cumulative incidence of acute GVHD at 100 days was considerably lower in the PT-CY/CSA group (4% vs 19.3%, p = 0.002), however there were no statistically significant difference in the cumulative incidence of chronic GVHD at 1-year (19.6% vs 37.4%, p = 0.053). Significant delays in neutrophil and platelet engraftments were reported in the PT-CY/CSA group (17 vs 12 days) and (13 vs 12 days), respectively (p < 0.001). The cumulative incidences of relapse (19.1% vs 13.7%, p = 0.470), overall survival (79.1% vs 77.3%, p = 0.986), non-relapse mortality (16.5% vs 16.8%, p = 0.837), and the GVHD and relapse-free survival (GRFS) (53.7% vs 46.6%, p = 0.478) did not differ statistically at 1-year.

CONCLUSION

PT-CY/CSA demonstrated a significant decrease in the rate of acute GVHD. However, it was associated with engraftment delay.

Comparable relapse incidence after unrelated allogeneic stem cell transplantation with post-transplant cyclophosphamide versus conventional anti-graft versus host disease prophylaxis in patients with acute myeloid leukemia: A study on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

We compared relapse incidence (RI) post-unrelated transplantation with post-transplant cyclophosphamide (PTCy) versus no PTCy graft-versus-host disease (GVHD) prophylaxis, in 7049 acute myeloid leukemia (AML) patients in remission, 707 with PTCy, and 6342 without (No PTCy). The patients in the PTCy group were younger, 52.7 versus 56.6 years (p < .001). There were more 9/10 donors in the PTCy group, 33.8% versus 16.4% (p < .001), and more received myeloablative conditioning, 61.7% versus 50.2% (p < .001). In the No PTCy group, 87.7% of patients received in vivo T-cell depletion. Neutrophil and platelet engraftment were lower in the PTCy versus No PTCy group, 93.8% and 80.9% versus 97.6% and 92.6% (p < .001). RI was not significantly different in the PTCy versus the No PTCy group, hazard ratio (HR) of 1.11 (95% confidence interval [CI] 0.9-1.37) (p = .31). Acute GVHD grades II-IV and III-IV, were significantly lower in the PTCy versus the No PTCy group, HR of 0.74 (95% CI 0.59-0.92, p = .007) and HR = 0.56 (95% CI 0.38-0.83, p = .004), as were total and extensive chronic GVHD, HRs of 0.5 (95% CI 0.41-0.62, p < .001) and HR = 0.31 (95% CI 0.22-0.42, p < .001). Non-relapse mortality (NRM) was significantly lower with PTCy versus the No PTCy group, HR of 0.67 (95% CI 0.5-0.91, p = .007). GVHD-free, relapse-free survival (GRFS) was higher in the PTCy versus the No PTCy group, HR of 0.69 (95% CI 0.59-0.81, p = .001). Leukemia-free survival (LFS) and overall survival (OS) did not differ between the groups. In summary, we observed comparable RI, OS, and LFS, significantly lower incidences of GVHD and NRM, and significantly higher GRFS in AML patients undergoing unrelated donor-hematopoietic stem cell transplantation with PTCy versus No PTCy GVHD prophylaxis.

Incidence, risk factors and therapy response of acute graft-versus-host disease after myeloablative hematopoietic stem cell transplantation with posttransplant cyclophosphamide

Posttransplant cyclophosphamide, sirolimus and mycophenolate mofetil (PTCy/siro/MMF) constitutes an innovative and well-tolerated acute graft-versus-host disease (aGVHD) prophylaxis after allogeneic stem cell transplantation (allo-HSCT), but risk factors for aGVHD incidence and therapy failure in this setting are scarce. This study prospectively registered all consecutive adult patients with hematologic malignancies who received a myeloablative allo-HSCT using PTCy/siro/MMF prophylaxis at our institution between 2017 and 2023. A total of 385 patients were included, of whom 44%, 34% and 22% were transplanted from matched sibiling, matched unrelated and haploidentical donors, respectively. The 180-day cumulative incidence of aGVHD was 21% (95% confidence interval [CI] 17-25%) for grade II-IV and 11% (95% CI 8-14%) grade III-IV aGVHD. The use of haploidentical donors was associated with an increased risk of severe aGVHD. Among 75 patients receiving first-line systemic corticosteroids, 49% achieved a sustained complete response, while 23% and 24% developed steroid-dependent (SD-aGVHD) and steroid-refractory aGVHD (SR-aGVHD), respectively. SR-aGVHD was associated with worse salvage treatment response and overall survival compared to SD-aGVHD. The 1-year cumulative incidence of aGVHD-related mortality was 5.4% (95% CI, 3.3-8.1). Risk factors for aGVHD-related mortality included haploidentical donors, older donors, diagnosis of myeldysplastic neoplasms, and grade IV aGVHD. This study confirms a low incidence aGVHD with PTCy/siro/MMF prophylaxis. SR-aGVHD showed poorer response to salvage therapies and worse survival, while haploidentical donors and older donor age were negative predictors for aGVHD-related deaths.

Human leukocyte antigen evolutionary divergence as a novel risk factor for donor selection in acute lymphoblastic leukemia patients undergoing haploidentical hematopoietic stem cell transplantation

Introduction

The human leukocyte antigen (HLA) evolutionary divergence (HED) reflects immunopeptidome diversity and has been shown to predict the response of tumors to immunotherapy. Its impact on allogeneic hematopoietic stem cell transplantation (HSCT) is controversial in different studies.

Methods

In this study, we retrospectively analyzed the clinical impact of class I and II HED in 225 acute lymphoblastic leukemia patients undergoing HSCT from related haploidentical donors. The HED for recipient, donor, and donor-recipient pair was calculated based on Grantham distance, which accounts for variations in the composition, polarity, and volume of each amino acid within the peptide-binding groove of two HLA alleles. The median value of HED scores was used as a cut-off to stratify patients with high or low HED.

Results

The class I HED for recipient (R_HEDclass I) showed the strongest association with cumulative incidence of relapse (12.2 vs. 25.0%, P = 0.00814) but not with acute graft-versus-host disease. The patients with high class II HED for donor-recipient (D/R_HEDclass II) showed a significantly higher cumulative incidence of severe aGVHD than those with low D/R_HEDclass II (24.0% vs. 6.1%, P = 0.0027). Multivariate analysis indicated that a high D/R_HEDclass II was an independent risk factor for the development of severe aGVHD (P = 0.007), and a high R_HEDclass I had a more than two-fold reduced risk of relapse (P = 0.028). However, there was no discernible difference in overall survival (OS) or disease-free survival (DFS) for patients with high or low HED, which was inconsistent with the previous investigation.

Discussion

While the observation are limited by the presented single center retrospective cohort, the results show that HED has poor prognostic value in OS or DFS, as well as the associations with relapse and aGVHD. In haploidentical setting, class II HED for donor-recipient pair (D/R_HEDclass II) is an independent and novel risk factor for finding the best haploidentical donor, which could potentially influence clinical practice if verified in larger cohorts.

Surrogates of Endothelial Injury Predict Survival After Post-transplant Cyclophosphamide

Post-transplant cyclophosphamide (PT-Cy) is becoming the standard of care for preventing graft-versus-host disease (GVHD) following allogeneic hematopoietic stem cell transplant (alloHCT). Cyclophosphamide is associated with endothelial injury. We hypothesized that the endothelial activation and stress index (EASIX) score, being a marker of endothelial dysfunction, will predict non-relapse mortality (NRM) in alloHCT patients receiving PT-Cy for GVHD prophylaxis. We evaluate the prognostic ability of the hematopoietic cell transplantation-specific comorbidity index (HCT-CI) and EASIX scores, and report other factors influencing survival, in patients with hematologic malignancies undergoing alloHCT and receiving PT-Cy-based GVHD prophylaxis. Adult patients with hematologic malignancies who underwent alloHCT and received PT-Cy for GVHD prophylaxis at the three Mayo Clinic locations were included in this study. We retrospectively reviewed the Mayo Clinic database and the available electronic medical records to determine the patient, disease, and transplant characteristics. An HCT-CI score of ≥3 was considered high. The EASIX score was calculated from labs available between day -28 (of alloHCT) to the day of starting conditioning and analyzed on log2 transformed values. A log2-EASIX score ≥2.32 was considered high. The cumulative incidence of NRM was determined using competing risk analysis, with relapse considered as competing risk. Overall survival (OS) from transplant was determined using Kaplan-Meier and log-rank methods. Cox-proportional hazard method was used to evaluate factors impacting survival. A total of 199 patients were evaluated. Patients with a high log2-EASIX score had a significantly higher cumulative incidence of NRM at 1 year after alloHCT (34.5% versus 12.3%, P = .003). Competing risk analysis showed that a high log2-EASIX score (HR 2.92, 95% CI 1.38 to 6.17, P = .005) and pre-alloHCT hypertension (HR 2.15, 95% CI 1.06 to 4.36, P = .034) were independently predictive of 1 year-NRM. Accordingly, we combined the two factors to develop a composite risk model stratifying patients in low, intermediate, and high-risk groups: 111 (55.8%) patients were considered low-risk, 76 (38.2%) were intermediate and 12 (6%) were high-risk. Compared to patients in the low-risk group, the intermediate (HR 2.38, 95% CI 1.31 to 4.33, P = .005) and high-risk (HR 5.77, 95% CI 2.31 to 14.39, P < .001) groups were associated with a significantly inferior 1-year OS. Multiorgan failure (MOF) was among the common causes of NRM (14/32, 43.8%) particularly among patients with prior pulmonary comorbidities [7 (50%) patients]. Our study shows that EASIX score is predictive of survival after PT-Cy. The novel EASIX-HTN composite risk model may stratify patients prior to transplant. MOF is a common cause of NRM in patients receiving PT-Cy, particularly among patients with pulmonary comorbidities.

PTCy vs CNI-based GVHD prophylaxis in HLA-matched transplants for Hodgkin lymphoma: a study of the LWP of the EBMT

ABSTRACT

Studies comparing the efficacy of posttransplant cyclophosphamide (PTCy) to conventional calcineurin inhibitor (CNI)-based graft-versus-host disease (GVHD) prophylaxis regimens in patients with Hodgkin lymphoma (HL) are scarce. This study aimed to compare the outcomes of patients with HL undergoing hematopoietic stem cell transplantation (HSCT) from HLA-matched donors who received GVHD prophylaxis with either PTCy- or conventional CNI-based regimens, using data reported in the European Society for Blood and Marrow Transplantation database between January 2015 and December 2022. Among the cohort, 270 recipients received conventional CNI-based prophylaxis and 176 received PTCy prophylaxis. Notably, PTCy prophylaxis was associated with delayed hematopoietic recovery but also with a lower risk of chronic (25% vs 43%; P < .001) and extensive chronic GVHD (13% vs 28%; P = .003) compared with the CNI-based cohort. The 2-year cumulative incidence of nonrelapse mortality and relapse was 11% vs 17% (P = .12) and 17% vs 30% (P = .007) for PTCy- and CNI-based, respectively. Moreover, the 2-year overall survival (OS), progression-free survival (PFS), and GVHD-free, relapse-free survival (GRFS) were all significantly better in the PTCy group compared with the CNI-based group: 85% vs 72% (P = .005), 72% vs 53% (P < .001), and 59% vs 31% (P < .001), respectively. In multivariable analysis, PTCy was associated with a lower risk of chronic and extensive chronic GVHD, reduced relapse, and better OS, PFS, and GRFS than the CNI-based platform. Our findings suggest that PTCy as GVHD prophylaxis offers more favorable outcomes than conventional CNI-based prophylaxis in adult patients with HL undergoing HSCT from HLA-matched donors.

Donor's age influences outcome in haploidentical hematopoietic stem cell transplantation with post-transplant cyclophosphamide - a single center experience

Haploidentical stem cell transplantation (haplo-SCT) using post-transplantation cyclophosphamide (post-Cy) is considered a reasonable therapeutic option for patients who lack matched donor or who urgently need transplant procedure due to high risk disease. We analyzed the results of haplo-SCT performed in years 2018-2023. Eighty one patients (46 males) at median age of 52 years underwent haplo-SCT using peripheral blood as a stem cell source in most cases. Indications included hematological malignancies (acute leukemias in 88% of cases). In 25 cases (31%) transplantation was performed in relapsed/refractory disease. Majority of patients (61%) presented with very high and high disease risk index (DRI). Conditioning regimens were as follows: nonmyeloablative - 46 cases (57%), myeloablative - in 18 (22%) and reduced intensity - 17(20%). 90% of patients engrafted. All patients received unified immunosuppressive treatment (post-Cy/TAC/MMF). Median follow-up time was 12 months The cumulative incidence of acute and chronic GVHD was 37.5% and 37.6%, respectively. Estimated 2-year overall survival (OS) was 43.1% and donor's age was the only factor influencing survival. The 2-year progression-free survival (PFS) was 42.5%, whereas relapse incidence (RI) - 35%. The cumulative incidence of non-relapse mortality (NRM) was 44% and was mostly due to infections. Haplo-SCT is a feasible treatment option for hematological patients. Younger donor improves post-transplant survival. Strategies to reduce infection-related mortality and relapse rate remain a challenge.

Post-transplant-cyclophosphamide and short-term Everolimus as graft-versus-host-prophylaxis in patients with relapsed/refractory lymphoma and myeloma-Final results of the phase II OCTET-EVER trial

BACKGROUND

Conditioning regimens and the choice of immunosuppression have substantial impact on immune reconstitution after allogeneic hematopoietic stem cell transplantation (aHSCT). The pivotal mechanism to maintain remission is the induction of the graft-versus-tumor effect. Relapse as well as graft versus host disease remain common. Classic immunosuppressive strategies implementing calcineurin inhibitors (CNI) have significant toxicities, hamper the immune recovery, and reduce the anti-cancer immune response.

METHODS

We designed a phase II clinical trial for patients with relapsed and refractory lymphoid malignancies undergoing aHSCT using a CNI-free approach consisting of post-transplant cyclophosphamide (PTCy) and short-term Everolimus after reduced-intensity conditioning and matched peripheral blood stem cell transplantation. The results of the 19 planned patients are presented. Primary endpoint is the cumulative incidence and severity of acute GvHD.

RESULTS

Overall incidence of acute GvHD was 53% with no grade III or IV. Cumulative incidence of NRM at 1, 2, and 4 years was 11%, 11%, and 16%, respectively, with a median follow-up of 43 months. Cumulative incidence of relapse was 32%, 32%, and 42% at 1, 2, and 4 years after transplant, respectively. Four out of six early relapses were multiple myeloma patients. Overall survival was 79%, 74%, and 62% at 1, 2, and 4 years. GvHD-relapse-free-survival was 47% after 3 years.

CONCLUSIONS

Using PTCy and short-term Everolimus is safe with low rates of aGvHD and no severe aGvHD or cGvHD translating into a low rate of non-relapse mortality. Our results in this difficult to treat patient population are encouraging and warrant further studies.

Early Tapering of Cyclosporine Is Feasible in Haploidentical Stem Cell Transplantation: A Single Center Experience

INTRODUCTION

Cyclosporine-A (CsA) and post transplantation cyclophosphamide (PTCy) are common agents used for graft versus host disease (GVHD) prophylaxis in Haploidentical hematopoietic cell transplantation (haplo-HCT). However, the impact of CsA cessation timing in the posttransplant setting on clinical outcomes is uncertain. We aimed to investigate the impact of a novel approach that integrated early CsA cessation with PTCy utilization.

PATIENTS AND METHODS

This study was a single arm retrospective study carried out at a tertiary referral hospital hematology and bone marrow transplantation center between 2009 and 2022. The patients who received haplo-HCT with ATG, PTCy and CsA as GVHD prophylaxis were included. CsA was planned for cessation starting at day 45 to day 60. Acute and chronic GVHD were evaluated and graded. CsA blood concentrations and its impact on acute and chronic GVHD was evaluated.

RESULTS

Thirty-one patients composed of 19 (61.3%) male and 12 (38.7%) female patients with a median age of 31 years (20-58). Busulfan and TBI based conditioning regimens were the most utilized regimens. The majority of donors were first degree relatives. Stem cell origin was peripheral blood for all patients. GVHD prophylaxis consisted of ATG, CsA and PTCy. Acute GVHD was observed in 9 (29%) cases, whereas chronic GVHD was seen in 3 (9.7%) cases, with 2 of them having overlapping GVHD. Age, gender, number of chemotherapy lines, transplant characteristics, infused CD34 cell count, and engraftment durations were similar among patients with and without GVHD. Patients with GVHD had similar 1st, 2nd, 3rd and 4th week CsA concentrations compared to patients without GVHD (p > 0.05). The presence of GVHD was not associated with worse progression free survival and overall survival (p = 0.6, p = 0.5, respectively). CMV reactivation was more common in the GVHD group.

CONCLUSION

In the current study, we did not find an impact of CsA concentration on GVHD and post-transplant outcomes in Haplo-HCT setting. Therefore, together with the use of PTCy, early CsA cessation can be an option; further studies are needed to understand all aspects of this approach.

HLA-Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplantation Cyclophosphamide versus HLA-Matched Unrelated Donor Transplantation for Myelodysplastic Syndrome

Allogeneic hematopoietic cell transplantation (allo-HCT) is the sole curative therapy for myelodysplastic syndrome (MDS). In the absence of an HLA-matched sibling donor, an HLA-matched unrelated donor (MUD) is considered the leading candidate. However, in recent decades, the alternative donor pool has been extended to HLA-haploidentical donors, especially with the development of graft-versus-host disease (GVHD) prophylaxis using post-transplantation cyclophosphamide (PTCy). Comparative data for haploidentical and MUD allo-HCT in patients with MDS are scarce. We retrospectively analyzed 697 adult patients with MDS who underwent HLA-haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) with PTCy (n = 136), MUD bone marrow transplantation (MUD-BMT) (n = 465), or MUD peripheral blood stem cell transplantation (MUD-PBSCT) (n = 96) as their first allo-HCT between 2014 and 2020 using Japanese registry data. Multivariable analyses demonstrated faster neutrophil engraftment (hazard ratio [HR], 2.19; 95% confidence interval [CI], 1.65 to 2.90; P < .001) and platelet engraftment (HR, 2.31; 95% CI, 1.72 to 3.10; P < 0001) in the MUD-PBSCT cohort compared with the haplo-PBSCT cohort. MUD-BMT was associated with a higher incidence of grade II-IV acute GVHD than haplo-PBSCT (HR, 1.52; 95% CI, 1.00 to 2.29; P = .048). Among patients without in vivo T cell depletion using antithymocyte globulin (ATG) (haplo-PBSCT, n = 136; MUD-BMT, n = 446; MUD-PBSCT, n = 65), MUD-PBSCT recipients experienced faster hematopoietic recovery, MUD-BMT recipients (HR, 1.54; 95% CI, 1.02 to 2.32; P = .042) or MUD-PBSCT recipients (HR, 1.83; 95% CI, 1.06 to 3.18; P = .03) had a higher incidence of grade II-IV acute GVHD, and MUD-PBSCT recipients developed chronic GVHD more frequently than haplo-PBSCT recipients (HR, 1.74; 95% CI, 1.04 to 2.89; P = .034). There were no significant differences in overall survival, disease-free survival, GVHD-free relapse-free survival, relapse, or nonrelapse mortality in the haplo-PBSCT cohort versus the MUD-BMT or MUD-PBSCT cohorts. In conclusion, despite differences in the incidences of hematopoietic engraftment and GVHD depending on graft type and ATG use in MUD transplant recipients, major transplantation outcomes were comparable between recipients of haplo-PBSCT using PTCy and recipients of MUD-BMT or MUD-PBSCT.

Post-Transplantation Cyclophosphamide-Based Graft-versus-Host Disease Prophylaxis in HLA-Matched and Haploidentical Donor Transplantation for Patients with Hodgkin Lymphoma: A Comparative Study of the Lymphoma Working Party of the European Society for Blood and Marrow Transplantation

Post-transplantation cyclophosphamide (PTCy) has emerged as a promising approach for preventing graft-versus-host disease (GVHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, there is a lack of studies examining the impact of this GVHD prophylaxis when different donor types are used in patients with Hodgkin lymphoma (HL). This study compared the outcomes of patients with HL undergoing HSCT from HLA-matched donors, including matched sibling donors (MSDs) and matched unrelated donors (MUDs), and haploidentical donors, using PTCy as the GVHD prophylaxis approach in all cohorts. We retrospectively compared outcomes of allo-HSCT from 166 HLA-matched donors (96 sibling and 70 unrelated donors) and 694 haploidentical donors using PTCy-based GVHD prophylaxis in patients with HL registered in the European Society for Blood and Marrow Transplantation database from 2010 to 2020. Compared to HLA-matched HSCT, haploidentical donor HSCT was associated with a significantly lower rate of platelet engraftment (86% versus 94%; P < .001) and a higher rate of grade II-IV acute GVHD (34% versus 24%; P = .01). The 2-year cumulative incidence of nonrelapse mortality (NRM) was significantly lower in the HLA-matched cohort compared to the haploidentical cohort (10% versus 18%; P = .02), resulting in a higher overall survival (OS) rate (82% versus 70%; P = .002). There were no significant differences between the 2 cohorts in terms of relapse, progression-free survival, or GVHD-free relapse-free survival. In multivariable analysis, haploidentical HSCT was associated with an increased risk of grade II-IV acute GVHD and NRM and worse OS compared to HLA-matched HSCT. Our findings suggest that in the context of PTCy-based GVHD prophylaxis, transplantation from HLA-matched donors appears to be a more favorable option compared to haploidentical HSCT.

Graft-versus-host disease after an outpatient peripheral blood hematopoietic cell transplant using reduced-intensity conditioning: a single-center LATAM experience

BACKGROUND

HLA compatibility predicts allogeneic hematopoietic cell transplant (allo-HCT) and graft-versus-host disease (GvHD) outcomes. There is insufficient information regarding GvHD outcomes for outpatient HLA-identical and haploidentical-HCT employing reduced-intensity conditioning (RIC).

RESEARCH DESIGN AND METHODS

We compare GvHD outcomes between donor types and report risk factors associated with GvHD. Stem cell source was T-cell replete peripheral blood. GvHD prophylaxis was post-transplant cyclophosphamide (PT-CY), mycophenolic acid, and calcineurin inhibitors for haploidentical (n = 107) and oral cyclosporine (CsA) plus methotrexate i.v. for HLA-identical (n = 89) recipients.

RESULTS

One hundred and ninety-six HCT transplant patients were included. aGvHD and cGvHD frequency were similar between HCT types. aGvHD severity was comparable, but severe cGvHD was less frequent in the haploidentical group (p = .011). One-hundred-day cumulative incidence (CI) of aGvHD for haploidentical and HLA-identical was 31% and 33% (p = .84); 2-year CI of cGvHD was 32% and 38% (p = .6), respectively. Haploidentical recipients had less steroid-refractory cGvHD (p = .043). Patients with cGvHD had less 2-year relapse (p = .003); both aGvHD and cGvHD conferred higher OS (p = .010 and p = .001), respectively. Male sex was protective for steroid-refractory cGvHD (p = .028).

CONCLUSIONS

Acute and chronic GvHD rates were comparable between HLA-identical and haploidentical transplant groups. cGvHD severity was lower in the haploidentical group.

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.

Relapse after allogeneic transplantation with post-transplant cyclophosphamide: Shattering myths and evolving insight

Early studies in allogeneic blood or marrow transplantation (alloBMT) demonstrated that HLA-mismatching was protective again relapse. However, benefits in relapse reduction were outweighed by a high risk of graft-versus-host disease (GVHD) when using conventional pharmacological immunosuppression. Post-transplant cyclophosphamide(PTCy)-based platforms abated the risk of GVHD thereby overcoming the negative effects of HLA-mismatching on survival. However, since its inception, PTCy has been shadowed by a reputation for a greater risk of relapse when compared with traditional GVHD prophylaxis. Specifically, whether PTCy reduces the anti-tumor efficacy of HLA-mismatched alloBMT by killing alloreactive T cells has been the subject of debate since the early 2000's. Here we review the many studies demonstrating the potent graft-versus-malignancy (GVM) properties of alloBMT with PTCy. We discuss the laboratory data from PTCy platforms supporting that T regulatory cells may be a major mechanism of prevention of GVHD and that natural killer (NK) cells may be early effectors of GVM. Finally, we propose potential paths to optimize GVM through selecting for class II mismatching and augmenting NK cell activity.

Graft versus Leukemia in 2023

Allogeneic hematopoietic stem cell transplantation (HSCT) is commonly utilized in the management of leukemia across multiple subtypes. Graft versus leukemia (GVL) is a critical component of successful transplantation and involves donor cells eradicating residual leukemia within the recipient. Graft versus host disease (GVHD) by contrast is a common complication of the transplantation process in which donor cells identify the recipient's various organ systems as foreign, thereby leading to a multitude of organ toxicities that can be described as autoimmune in nature. As both GVL and GVHD are mediated by a similar mechanism, these processes are felt to occur in tandem with one another. Here, we review the allogeneic HCT process in the context of GVL.

Impact of donor age and relationship on outcomes of peripheral blood haploidentical hematopoietic cell transplantation

Here we describe a retrospective analysis of outcomes in 299 patients who underwent peripheral blood haplo-HCT with PTCy from July 2009 through May 2021 and their association with donor characteristics. Patients had mostly acute leukemias and high or very high DRI. Multivariate analyses were conducted examining OS, NRM, relapse, cytokine release syndrome, acute and chronic GVHD. Donor characteristics included age, sex, relationship, ABO status, CMV status, and HLA match grade. Our analysis revealed increasing donor age was associated with higher NRM (compared to age <30; age 30-44 HR, 1.65; P = 0.110, age >44 HR, 1.80; P = 0.056) but lower relapse risk (compared to age <30; age 30-44 HR, 0.61; P = 0.034, age > 44 HR, 0.71; P = 0.132). There were no differences in CRS, aGVHD or cGVHD. We found no difference in outcomes based on the donor-recipient relationship. No differences were found based on HLA match grade or DRB1 match status. Increasing donor age was associated with lower relapse risk but higher NRM, resulting in no difference in OS based on donor age. Other donor factors including relationship (parent/sibling/child/ maternal), CMV status, donor sex, HLA match grade, and DRB1 status were not associated with outcomes.

The delicate balance of graft versus leukemia and graft versus host disease after allogeneic hematopoietic stem cell transplantation

INTRODUCTION

The curative basis of allogeneic hematopoietic stem cell transplantation (HSCT) relies in part upon the graft versus leukemia (GvL) effect, whereby donor immune cells recognize and eliminate recipient malignant cells. However, alloreactivity of donor cells against recipient tissues may also be deleterious. Chronic graft versus host disease (cGvHD) is an immunologic phenomenon wherein alloreactive donor T cells aberrantly react against host tissues, leading to damaging inflammatory symptoms.

AREAS COVERED

Here, we discuss biological insights into GvL and cGvHD and strategies to balance the prevention of GvHD with maintenance of GvL in modern HSCT.

EXPERT OPINION/COMMENTARY

Relapse remains the leading cause of mortality after HSCT with rates as high as 40% for some diseases. GvHD is a major cause of morbidity after HSCT, occurring in up to half of patients and responsible for 15-20% of deaths after HSCT. Intriguingly, the development of chronic GvHD may be linked to lower relapse rates after HSCT, suggesting that GvL and GvHD may be complementary sides of the immunologic foundation of HSCT. The ability to fine tune the balance of GvL and GvHD will lead to improvements in survival, relapse rates, and quality of life for patients undergoing HSCT.

Significance of Degree of HLA Disparity Using T-cell Replete Peripheral Blood Stem Cells From Haploidentical Donors With Posttransplantation Cyclophosphamide in AML in First Complete Hematologic Remission: A Study of the Acute Leukemia Working Party of the EBMT

Availability of haploidentical donors has broadened utilization of allogeneic hematopoietic cell transplantation (allo-HCT). Peripheral blood stem cells (PBSC) are being used with increased frequency in haploidentical allo-HCT. We evaluated extent of HLA disparity (2-3/8 versus 4/8 HLA antigen mismatches) on post-allograft outcomes when using T-cell replete PBSC from haploidentical donors for acute myeloid leukemia in first complete remission. Primary objectives entailed assessing cumulative incidence of grade 2-4 acute graft-versus-host disease (GVHD) and chronic GVHD (any grade). A total of 645 patients received a haploidentical allo-HCT from a donor with either 2-3 of 8 HLA antigen mismatches (n = 180) or with 4 of 8 HLA antigen mismatches (n = 465). Presence of 2-3 of 8 versus 4 of 8 HLA mismatches did not affect the incidence of acute GVHD (grade 2-4) and chronic GVHD (any grade). Overall survival (OS), leukemia-free survival (LFS) relapse incidence (RI), nonrelapse mortality and the composite endpoint of GVHD-free relapse-free survival were also similar among the groups. Pertaining to HLA-B leader matching effect, our analysis did not discern any difference in aforementioned post-allograft outcomes for this variable. However, in univariate analysis, absence of an antigen mismatch in HLA-DPB1 showed a trend for better OS. Notwithstanding inherent limitations associated with registry data, our results did not show an advantage of selecting a haploidentical donor with 2-3 of 8 HLA antigen mismatches over one with 4 of 8 HLA antigen mismatches when using PBSC as the cell source. Adverse cytogenetics remains a major adverse determinant of inferior OS and LFS and a higher RI. Using reduced-intensity conditioning yielded worse OS and LFS.

Investigation of KIR/HLA relationship and other clinical variables after T-cell-replete haploidentical bone marrow transplantation in patients with acute myeloid leukemia (AML)

BACKGROUND

KIR/HLA mismatch in hematopoietic stem cell transplantation (HSCT), particularly in patients with acute myeloid leukemia (AML), was related to decreased recurrence rates, improved engraftment, and a reduction in graft-versus-host disease, according to recent research (GVHD). Uncertainty exists about the impact of KIR/HLA mismatch on haploidentical-HSCTs treated with post-transplant cyclophosphamide (PTCy). We attempted to analyze the effects of KIR/HLA mismatch on clinical outcomes on transplant outcomes using the cohort of 54 AML patients who received a haplo-HSCT with PTCy.

RESULTS

In contrast to KIR/HLA match, our findings showed that donor KIR/HLA mismatch was substantially associated with superior OS (HR, 2.92; (P = 0.04)). Moreover, donor KIR/HLA mismatch (KIR2DS1_D/C2⁺ _R and KIR2DS2_D/C1⁺ _R mismatch versus KIR2DL1_D/C2^- _R mm, KIR2DL2/3_D/C1^- _R mm and KIR3DL1_D/Bw4^- mm) was correlated with the improvements in OS (HR, 0.74; P = 0.085) and activating. KIR/HLA mismatch versus KIR/HLA match was significantly correlated with improvements in OS (HR, .46; P = 0.03) and inhibitory. KIR/HLA mismatch versus KIR/HLA match was enhancement in the OS (HR, .93; P = 0.06). Despite a higher rate of aGvHD (grade I-IV) in the patients with KIR/HLA mismatch compared to KIR/HLA matched (57% vs. 33% (p = 0.04). However, the KIR/HLA mismatch group saw a decreased relapse rate (3.2% vs. 23%, p = 0.04).

CONCLUSION

This analysis shows the significance of KIR/HLA Incompatibility, other clinical variables like CMV, the relationship between donor/recipient and donor age, and the relationship between donor/recipient and donor age in the haplo-donor selection process. It also suggests that KIR and HLA mismatching between donor and recipient could be routinely performed for haplo-donor selection and may improve clinical outcomes after haplo-HSCTs with PTCy.

Three-Year Outcomes in Recipients of Mismatched Unrelated Bone Marrow Donor Transplants Using Post-Transplantation Cyclophosphamide: Follow-Up from a National Marrow Donor Program-Sponsored Prospective Clinical Trial

The use of post-transplantation cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis has resulted in reductions in GVHD and improved outcomes in allogeneic hematopoietic cell transplantation (HCT) using HLA-mismatched related donors. We report the 3-year outcomes of the first multicenter prospective clinical trial using PTCy in the setting of mismatched unrelated donor (MMUD) bone marrow HCT. The study enrolled 80 patients, treated with either myeloablative conditioning (MAC; n = 40) or reduced-intensity conditioning (RIC; n = 40), with the primary endpoint of 1-year overall survival (OS). The median follow-up for this study was 34 months (range, 12 to 46 months) in the RIC group and 36 months (range, 18 to 49 months) in the MAC group. Three-year OS and nonrelapse mortality were 70% and 15%, respectively, in the RIC group and 62% and 10% in the MAC group. No GVHD was reported after 1 year. The incidence of relapse was 29% in the RIC group and 51% in the MAC group. OS did not differ based on HLA match grade (63% in the 7/8 strata and 71% in the 4 to 6/8 strata). These encouraging outcomes, which were sustained for 3 years post-HCT, support the continued exploration of MMUD HCT using a PTCy platform. Important future areas to address include relapse reduction and furthering our understanding of optimal donor selection based on HLA and non-HLA factors.

Allogeneic stem cell transplantation for patients with acute myeloid leukemia (AML) in second complete remission (CR2) transplanted from unrelated donors with post-transplant cyclophosphamide (PTCy). A study on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Post-transplant cyclophosphamide (PTCy) is being increasingly used as graft-versus-host disease (GVHD) prophylaxis post allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with acute myeloid leukemia (AML) transplanted in first complete remission (CR1). However, results may differ in patients transplanted in CR2. We retrospectively evaluated transplant outcomes of adult AML patients transplanted between 2010-2019 from 9-10/10 human leukocyte antigen (HLA)-matched unrelated donor (UD) in CR2. In total, 127 patients were included (median age 45.5 years, 54% male). Median follow-up was 19.2 months. Conditioning was myeloablative (MAC) in 50.4% and the graft source was peripheral blood in 93.7% of the transplants. Incidence of acute (a)GVHD II-IV and III-IV was 26.2% and 9.2%. Two-year total and extensive chronic (c)GVHD were 34.3% and 13.8 %, respectively. Two-year non-relapse mortality (NRM), relapse incidence (RI), leukemia-free survival (LFS), overall survival (OS), and GVHD-free, relapse-free survival (GRFS) were 17.2%, 21.1%, 61.7, %, 65.2%, and 49.3%, respectively. Time from diagnosis to transplant (>18 months) was a favorable prognostic factor for RI, LFS, OS, and GRFS while favorable risk cytogenetics was a positive prognostic factor for OS. The patient's age was a poor prognostic factor for NRM and cGVHD. Finally, the female-to-male combination and reduced intensity conditioning (RIC) were poor and favorable prognostic factors for cGVHD, respectively. We conclude that PTCy is an effective method for GVHD prophylaxis in AML patients undergoing allo-HCT in CR2 from UD.

The Impact of Graft CD3+ T-Cell Dose on the Outcome of T-Cell Replete Human Leukocyte Antigen-Mismatched Allogeneic Hematopoietic Peripheral Blood Stem Cells Transplantation

Background

Data on whether the graft CD3-positive (CD3⁺) T-cell dose in T-cell-replete human leukocyte antigen (HLA)-mismatched allogeneic hematopoietic peripheral blood stem cells transplantation (PBSCT) influences post-transplant outcomes are controversial.

Methods

Using King Hussein Cancer Center (KHCC) Blood and Marrow Transplantation (BMT) Registry database, 52 adult subjects, receiving the first T-cell-replete HLA-mismatched allogeneic hematopoietic PBSCT for acute leukemias or myelodysplastic syndrome, were identified, from January 2017 to December 2020. The cutoff value of graft CD3⁺ T-cell dose was identified using the receiver operating characteristic (ROC) formula and Youden's analysis. Subjects were divided into two cohorts: cohort 1 with low CD3⁺ T-cell dose (n = 34) and cohort 2 with high CD3⁺ T-cell dose (n = 18). Correlative analyses were performed between CD3⁺ T-cell dose and the risk of graft-versus-host disease (GvHD), relapse, relapse-free survival (RFS), and overall survival (OS). P-values were two-sided and considered significant when P < 0.05.

Results

Subject covariates were displayed. Subject's characteristics were comparable, except for higher nucleated cells and more female donors in the high CD3⁺ T-cell cohort. The 100-day cumulative incidence of acute GvHD (aGvHD) was 45±7% and 3-year cumulative incidence of chronic GvHD (cGvHD) was 28±6.7%. There was no statistically significant difference between the two cohorts in aGvHD (50% vs. 39%, P = 0.4) or cGvHD (29% vs. 22%, P = 0.7). The 2-year cumulative incidence of relapse (CIR) was 67.5±16.3% for low compared with 14.3±6.8% for high CD3⁺ T-cell cohort (P = 0.018). Fifteen subjects relapsed and 24 have died, 13 due to disease relapse. There was an improvement in 2-year RFS (94% vs. 83%; P = 0.0022) and 2-year OS (91% vs. 89%; P = 0.025) in low CD3⁺ T-cell cohort compared with high CD3⁺ T-cell cohort. Graft CD3⁺ T-cell dose is the only significant risk factor for relapse (P = 002), and OS (P = 0.030) in univariate analysis which was maintained in multivariate for relapse (P = 0.003), but not for OS (P = 0.050).

Conclusions

Our data suggest that high graft CD3⁺ T-cell dose is associated with lower risk of relapse, and might improve long-term survival, but has no influence on the risk of developing aGvHD or cGvHD.

How I prevent GVHD in high-risk patients: posttransplant cyclophosphamide and beyond

Advances in conditioning, graft-versus-host disease (GVHD) prophylaxis and antimicrobial prophylaxis have improved the safety of allogeneic hematopoietic cell transplantation (HCT), leading to a substantial increase in the number of patients transplanted each year. This influx of patients along with progress in remission-inducing and posttransplant maintenance strategies for hematologic malignancies has led to new GVHD risk factors and high-risk groups: HLA-mismatched related (haplo) and unrelated (MMUD) donors; older recipient age; posttransplant maintenance; prior checkpoint inhibitor and autologous HCT exposure; and patients with benign hematologic disorders. Along with the changing transplant population, the field of HCT has dramatically shifted in the past decade because of the widespread adoption of posttransplantation cyclophosphamide (PTCy), which has increased the use of HLA-mismatched related donors to levels comparable to HLA-matched related donors. Its success has led investigators to explore PTCy's utility for HLA-matched HCT, where we predict it will be embraced as well. Additionally, combinations of promising new agents for GVHD prophylaxis such as abatacept and JAK inhibitors with PTCy inspire hope for an even safer transplant platform. Using 3 illustrative cases, we review our current approach to transplantation of patients at high risk of GVHD using our modern armamentarium.

How to improve the outcomes of elderly acute myeloid leukemia patients through allogeneic hematopoietic stem cell transplantation

In recent years, with the gradual advancement of haploidentical transplantation technology, the availability of donors has increased significantly, along with the widespread use of reduced-intensity conditioning and the improvement of nursing techniques, giving more elderly acute myeloid leukemia (AML) patients the chance to receive allogeneic hematopoietic stem cell transplantation. We have summarized the classic and recently proposed pre-transplant assessment methods and assessed the various sources of donors, conditioning regimens, and post-transplant complication management based on the outcomes of large-scale clinical studies for elderly AML patients.

Post-transplant cyclophosphamide versus anti-thymocyte globulin in allogeneic hematopoietic stem cell transplantation from unrelated donors: A systematic review and meta-analysis

Background

Post-transplant cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG) are both common graft-versus-host disease (GVHD) prophylaxis strategies in allo-HSCT from unrelated donors. However, no consensus has reached on which regimen is optimal. Although several studies concerning this topic exist, the outcomes of different studies still conflict with each other. Therefore, an overall comparison of the two regimens is urgently needed to help make informed clinical decisions.

Methods

Studies comparing PTCy and ATG regimens in unrelated donor (UD) allo-HSCT were searched in four critical medical databases from inception to April 17, 2022. The primary outcome was grade II-IV aGVHD, grade III-IV aGVHD and chronic GVHD (cGVHD), and the secondary outcomes included overall survival (OS), relapse incidence (RI), non-relapse mortality (NRM), and several severe infectious complications. The quality of articles was assessed by the Newcastle-Ottawa scale (NOS), and data were extracted by two independent investigators and then analyzed by RevMan 5.4.

Results

Six out of 1091 articles were eligible for this meta-analysis. Compared with the ATG regimen, prophylaxis based on PTCy achieved a lower incidence of grade II-IV aGVHD incidence (RR=0.68, 95% CI 0.50-0.93, P=0.010, I ^{2 =} 67%), grade III-IV aGVHD (RR=0.32, 95% CI 0.14-0.76, P=0.001, I ^{2 =} 75%), NRM (RR=0.67, 95% CI 0.53-0.84, P=0.17, I ^{2 =} 36%), EBV-related PTLD (RR=0.23, 95% CI 0.09-0.58, P=0.85, I ^{2 =} 0%) and better OS (RR=1.29, 95% CI 1.03-1.62, P=0.0001, I ^{2 =} 80%). The cGVHD, RI, CMV reactivation and BKV-related HC showed no significant difference between the two groups (RR=0.66, 95% CI 0.35-1.26, P<0.00001, I ^{2 =} 86%; RR=0.95, 95% CI 0.78-1.16, P=0.37, I ^{2 =} 7%; RR=0.89, 95% CI 0.63-1.24, P=0.07, I ^{2 =} 57%; RR=0.88, 95% CI 0.76-1.03, P=0.44, I ^{2 =} 0%).

Conclusion

In the setting of unrelated donor allo-HSCT, prophylaxis based on PTCy can lower the incidence of grade II-IV aGVHD, grade III-IV aGVHD, NRM and EBV-related complication, achieve better OS compared to ATG-based regimen. And cGVHD, RI, CMV reactivation and BKV-related HC were comparable in the two groups.

[The impact of donor-to-recipient gender compatibility on outcomes of haploid hematopoietic stem cell transplantation in patients with hematological malignancies]

Objective: To investigate how gender differences between the donor and the recipient affect the effectiveness of antithymocyte globulin (ATG) and pure peripheral blood stem cell (PBSC) hematopoietic stem cell transplantation (haplo-HSCT) in the treatment of malignant hematological diseases. Methods: From February 2015 to September 2020, 648 hematological malignancies patients underwent myeloablative condition regimen haplo-HSCT treatment at the Bone Marrow Transplant Center of the First Affiliated Hospital of Zhejiang University. The median age was 32 (14-62) years, with 363 males (56.0% ) and 285 females (44.0% ) present. 242 cases of acute lymphoblastic leukemia (ALL) (37.3% ) , 293 cases of acute myeloid leukemia (AML) (45.2% ) , 56 cases of myelodysplastic syndrome (MDS) (8.7% ) , 27 cases of non-Hodgkin's lymphoma (NHL) (4.2% ) , and 30 cases of other hematological malignancies (4.6% ) . Results: ① The 3-year overall survival (OS) , DFS, the incidence of Ⅱ-Ⅳ grade acute graft-versus-host disease (aGVHD) , the incidence of Ⅲ-Ⅳ grade aGVHD, the 3-year incidence of moderate & severe chronic GVHD (cGVHD) , severe cGVHD, the 3-year incidence of relapse, and NRM of the whole group were (73.10±1.90) % , (70.80±1.90) % , (33.96±1.87) % , (13.08±1.33) % , (35.10±2.14) % , (10.66±1.38) % , (19.43±1.67) % , and (9.80±1.24) % , respectively. ②There was no statistically significant difference between the donor-recipient gender match and donor-recipient gender mismatch groups in the 28-day cumulative neutrophil engraftment rate, 28-day cumulative platelet engraftment rate, the incidence of Ⅱ-Ⅳ grade aGVHD, the incidence of Ⅲ-Ⅳ grade aGVHD, 3-year OS, 3-year DFS, the cumulative incidence of relapse, NRM, and incidence of moderate & severe cGVHD, severe cGVHD. ③The 28-day cumulative neutrophil engraftment rate did not differ statistically between the male-female, female-female, male-male, and female-male groups (P=0.148) . The incidence of Ⅱ-Ⅳ grade aGVHD, the incidence of Ⅲ-Ⅳ grade aGVHD, 3-year OS, 3-year DFS, cumulative relapse rate, and NRM, and the incidence of cGVHD were not statistically different among the four groups (P>0.05) . The 28-day cumulative platelet engraftment rate of the female-male group was significantly lower than male-female group, and the female-female group [ (91.45±2.63) % vs. (94.77±1.75) % , P=0.004; (91.45±2.63) % vs. (95.54±2.05) % , P=0.005]. No significant difference existed in the 28-day cumulative platelet engraftment rate between the female-male group and the male-male group [ (91.45±2.63) % vs. (95.08±1.41) % , P=0.284]. ④Among patients ≤35 years old, the 3-year incidence of severe cGVHD patients receiving sister donors and sibling donors were (26.71±5.90) % and (10.33±4.43) % , respectively (P=0.054) . Patients accepting daughter donors and son donors had a 3-year incidence of moderate and severe cGVHD that was 40.07% vs. 27.41% , respectively, among those over 35 (40.07±6.65) % vs. (27.41±4.54) % (P=0.084) . ⑤Female donors to male recipients had a significantly lower 28-day cumulative platelet engraftment rate compared to the other groups [ (91.45±2.63) % vs. (95.08±0.95) % , P=0.037]. ⑥ Female donors to male recipients had a significantly lower 28-day cumulative platelet engraftment rate than the other groups in the ATG-Fresenius (ATG-F) 10 mg/kg group [ (89.29±4.29) % vs. (94.49±1.45) % , P=0.037]. But when compared to the other groups in the Rabbit Antihuman Thymocyte Immunoglobulin (rATG-T) 6 mg/kg group, the 28-day cumulative platelet implantation rate between female donors and male recipients was not significantly different [ (93.44±3.38) % vs. (95.62±1.26) % , P=0.404]. Conclusion: The main clinical outcomes of patients with malignant blood diseases following transplantation are unaffected by the gender combination of the donor and patient in the haplo-HSCT mode based on ATG and PBSC sources. Female donors to male recipients have a lower 28-day cumulative platelet engraftment rate and longer platelet engraftment times.

Post-transplant cyclophosphamide for GVHD prophylaxis in pediatrics with chronic active Epstein-Barr virus infection after haplo-HSCT

BACKGROUND

Chronic active Epstein-Barr virus infection (CAEBV) is a rare but life-threatening progressive disease. Human leukocyte antigen (HLA)-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is the best choice as sometimes HLA-matched donor is not accessible. However, graft-versus-host-disease (GVHD) following transplantation remains a major cause of treatment failure and elevated mortality. Post-transplant cyclophosphamide (PTCy) has recently emerged for effective GVHD prophylaxis in a haploidentical setting in many hematologic malignancies. Here, we report the performance of PTCy for GVHD prophylaxis in a series of CEABV patients treated with haplo-HSCT.

METHODS

Consecutive pediatric CAEBV patients who were treated with haplo-HSCT and give PTCy for GVHD prophylaxis were analyzed. 1-year GVHD and relapse-free survival (GRFS), overall survival (OS) and cumulative incidence of moderate-to-severe chronic GVHD (cGVHD) were estimated.

RESULTS

A total of 8 patients ranging from 2 to 15 years old were included. Among them, 4 patients had early complications after haplo-HSCT. Counts of T-cell subsets increased within 6 months post transplantation, indicating an immune reconstitution. Only 1 patient developed grade II acute GVHD, and 2 patients had moderate cGVHD. One patient died from diffuse alveolar hemorrhage within the first year after transplantation. The 1-year GRFS rate, OS rate and cumulative incidence of moderate-to-severe cGVHD were 62.5%, 87.5% and 25.0%, respectively.

CONCLUSION

Our findings suggest that, among CAEBV patients treated with haplo-HSCT, PTCy may be an alternative choice for the prevention of GVHD.

Characteristics of Graft-Versus-Host Disease (GvHD) After Post-Transplantation Cyclophosphamide Versus Conventional GvHD Prophylaxis

Post-transplantation cyclophosphamide (PTCy) has been shown to effectively control graft-versus-host disease (GvHD) in haploidentical (Haplo) transplantations. In this retrospective registry study, we compared GvHD organ distribution, severity, and outcomes in patients with GvHD occurring after Haplo transplantation with PTCy GvHD prophylaxis (Haplo/PTCy) versus HLA-matched unrelated donor transplantation with conventional prophylaxis (MUD/conventional). We evaluated 2 cohorts: patients with grade 2 to 4 acute GvHD (aGvHD) including 264 and 1163 recipients of Haplo and MUD transplants; and patients with any chronic GvHD (cGvHD) including 206 and 1018 recipients of Haplo and MUD transplants, respectively. In comparison with MUD/conventional transplantation ± antithymocyte globulin (ATG), grade 3-4 aGvHD (28% versus 39%, P = .001), stage 3-4 lower gastrointestinal (GI) tract aGvHD (14% versus 21%, P = .01), and chronic GI GvHD (21% versus 31%, P = .006) were less common after Haplo/PTCy transplantation. In patients with grade 2-4 aGvHD, cGvHD rate after Haplo/PTCY was also lower (hazard ratio [HR] = .4, P < .001) in comparison with MUD/conventional transplantation without ATG in the nonmyeloablative conditioning setting. Irrespective of the use of ATG, non-relapse mortality rate was lower (HR = .6, P = .01) after Haplo/PTCy transplantation, except for transplants that were from a female donor into a male recipient. In patients with cGvHD, irrespective of ATG use, Haplo/PTCy transplantation had lower non-relapse mortality rates (HR = .6, P = .04). Mortality rate was higher (HR = 1.6, P = .03) during, but not after (HR = .9, P = .6) the first 6 months after cGvHD diagnosis. Our results suggest that PTCy-based GvHD prophylaxis mitigates the development of GI GvHD and may translate into lower GvHD-related non-relapse mortality rate.

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

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

Impact of donor kinship on non-T-cell depleted haploidentical stem cell transplantation with post transplantation cyclophosphamide for acute leukemia: From the ALWP of the EBMT

Non-T-cell depleted haploidentical hematopoietic cell transplantation (Haplo-HCT) is a unique transplantation setting in which several donors are available. We assessed the impact of donor kinship on outcome of Haplo-HCT with post-transplantation cyclophosphamide in a cohort of 717 acute leukemia patients. We compared sibling with parent donors in patients ≤45 years, and child with sibling donors in patients >45 years. Donor kinship was not associated with worse outcomes in multivariate analysis. For patients ≤45 years, the hazard ratio (HR) for leukemia-free survival (LFS), overall survival (OS), relapse incidence (RI), and chronic graft-versus-host disease (cGVHD) was 0.87 (p = 0.75), 1.19 (p = 0.7), 0.52 (p = 0.19), and 0.99 (p = 0.97) for parents versus siblings, respectively, and for patients >45 years the HR was 0.93 (p = 0.8), 0.98 (p = 0.94), 1.3 (p = 0.53), and 0.98 (p = 0.95) for children versus siblings, respectively. Univariate incidence of acute GVHD grade II-IV was significantly higher in patients transplanted from siblings versus children (p = 0.002). Factors associated with inferior outcome were advanced disease and earlier transplant. In patients ≤45 years, acute lymphocytic leukemia and peripheral blood stem cell graft were additional prognostic factors for OS. We did not find a significant impact of donor kinship on transplantation outcome when analyzing by age group (≤45 and >45 years).

HLA informs risk predictions after haploidentical stem cell transplantation with posttransplantation cyclophosphamide

Hematopoietic cell transplantation from HLA-haploidentical related donors is increasingly used to treat hematologic cancers; however, characteristics of the optimal haploidentical donor have not been established. We studied the role of donor HLA mismatching in graft-versus-host disease (GVHD), disease recurrence, and survival after haploidentical donor transplantation with posttransplantation cyclophosphamide (PTCy) for 1434 acute leukemia or myelodysplastic syndrome patients reported to the Center for International Blood and Marrow Transplant Research. The impact of mismatching in the graft-versus-host vector for HLA-A, -B, -C, -DRB1, and -DQB1 alleles, the HLA-B leader, and HLA-DPB1 T-cell epitope (TCE) were studied using multivariable regression methods. Outcome was associated with HLA (mis)matches at individual loci rather than the total number of HLA mismatches. HLA-DRB1 mismatches were associated with lower risk of disease recurrence. HLA-DRB1 mismatching with HLA-DQB1 matching correlated with improved disease-free survival. HLA-B leader matching and HLA-DPB1 TCE-nonpermissive mismatching were each associated with improved overall survival. HLA-C matching lowered chronic GVHD risk, and the level of HLA-C expression correlated with transplant-related mortality. Matching status at the HLA-B leader and HLA-DRB1, -DQB1, and -DPB1 predicted disease-free survival, as did patient and donor cytomegalovirus serostatus, patient age, and comorbidity index. A web-based tool was developed to facilitate selection of the best haploidentical-related donor by calculating disease-free survival based on these characteristics. In conclusion, HLA factors influence the success of haploidentical transplantation with PTCy. HLA-DRB1 and -DPB1 mismatching and HLA-C, -B leader, and -DQB1 matching are favorable. Consideration of HLA factors may help to optimize the selection of haploidentical related donors.

Number of HLA-Mismatched Eplets Is Not Associated with Major Outcomes in Haploidentical Transplantation with Post-Transplantation Cyclophosphamide: A Center for International Blood and Marrow Transplant Research Study

The number of haploidentical hematopoietic stem cell transplantations (haplo-HSCT) performed has increased substantially in recent years. Previous single-center studies using in silico algorithms to quantitively measure HLA disparity have shown an association of the number of HLA molecular mismatches with relapse protection and/or increased risk of acute graft-versus-host disease (GVHD) in haplo-HSCT. However, inconsistent results from small studies have made it difficult to understand the full clinical impact of molecular mismatch in haplo-HSCT. In this study, we investigated the potential of the HLA class I and II mismatched eplet (ME) score measured by HLAMatchmaker, as well as ME load at a specific locus to predict outcomes in a registry-based cohort of haplo-HSCT recipients. We analyzed data from 1287 patients who underwent their first haplo-HSCT for acute lymphoblastic leukemia, acute myelogenous leukemia, or myelodysplastic syndrome between 2013 and 2017, as entered in the Center for International Blood and Marrow Transplant Research database. ME load at each HLA locus and total class I and II were scored using the HLAMatchmaker module incorporated in HLA Fusion software v4.3, which identifies predicted eplets based on the crystalized HLA molecule models and identifies ME by comparing donor and recipient eplets. In the study cohort, ME scores derived from total HLA class I or class II loci or individual HLA loci were not associated with overall survival, disease-free survival, nonrelapse mortality, relapse, acute GVHD, or chronic GVHD (P < .01). An unexpected strong association was identified between total class II ME load in the GVH direction and slower neutrophil engraftment (hazard ratio [HR], 0.82; 95% confidence interval [CI], 0.75 to 0.91; P < .0001) and platelet engraftment (HR, 0.80; 95% CI, 0.72 to 0.88; P < .0001). This was likely attributable to ME load at the HLA-DRB1 locus, which was similarly associated with slower neutrophil engraftment (HR, 0.82; 95% CI, 0.73 to 0.92; P = .001) and slower platelet engraftment (HR, 0.76; 95% CI, 0.70 to 0.84; P < .0001). Additional analyses suggested that this effect is attributable to a match versus a mismatch in the graft-versus-host direction and not to ME load, as a dose effect was not identified. These findings contradict those of previous relatively small studies reporting an association between ME load, as quantified by HLAMatchmaker, and haplo-HSCT outcomes. This study failed to demonstrate the predictive value of ME from HLA molecules for major clinical outcomes, and other molecular mismatch algorithms in haplo-HSCT settings should be tested.

Risk Factors for early CMV reactivation and Impact of early CMV reactivation on Clinical Outcomes after T Cell-replete Haploidentical Transplantation with Post-transplant Cyclophosphamide

BACKGROUND

Risk factors for cytomegalovirus (CMV) reactivation and the impact of CMV reactivation on patients' outcomes have been extensively investigated after matched related or unrelated donor transplants, but little is known in the setting of haploidentical stem cell transplant (Haplo-SCT) with post-transplant cyclophosphamide (PT-Cy), where recipients are supposed to be more severely immune-compromised.

METHODS

We retrospectively analyzed a cohort of 554 consecutive patients undergoing Haplo-SCT with PT-Cy at 3 different centers.

RESULTS

Early CMV reactivation, taking place within the first 120 days after transplant, occurred in 242 patients for an estimated cumulative incidence of 44%. Out of those patients, 74 (30%) had recurrent CMV and 20 (8%) CMV disease. By multivariable analysis, positive recipient CMV serostatus (Hazard ratio [HR] > 2.5, p<0.001), disease histology (lymphoid vs myeloid: HR 0.66, p=0.003) and increasing recipient age (HR 1.01, p=0.015) were independent predictors of CMV reactivation. At four months landmark analysis, CMV reactivation was associated with higher 1-year and 5-year cumulative incidence of non-relapse mortality (NRM) relative to patients without reactivation: 13% vs 5% and 22% vs 9%, respectively (p<0.001). By multivariable analysis, CMV reactivation was an independent negative predictor of non-relapse mortality (NRM) (HR 2.69, p<0.001) and was close to statistical significance for overall survival (OS) (HR: 1.38, p=0.062).

CONCLUSIONS

Our results suggest that CMV reactivation plays an important role at determining NRM. Because patient CMV serostatus is the main predictor of CMV reactivation, it should be considered when evaluating strategies for preventing CMV reactivation.

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

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

Tacrolimus initial steady state level in post-transplant cyclophosphamide-based GvHD prophylaxis regimens

Post-transplant cyclophosphamide (PTCy) combined with tacrolimus (TAC) as graft-versus-host disease (GvHD) prophylaxis post-hematopoietic cell transplantation (HCT) is safe and effective. Optimal serum levels of TAC in this combination remain undetermined. We hypothesized that TAC at initial steady state (TISS) of <10 ng/mL could promote optimal transplant outcomes and prevent TAC-associated toxicities. We retrospectively analyzed a consecutive case series of 210 patients who received PTCy/TAC-based prophylaxis post-HCT from 1/2013–6/2018. Patients received HCT from haploidentical (n=172) or mismatched donors (n=38), and flat dose (FD) or weight-based dose (WBD) TAC. Twenty-four-month overall survival (OS), disease free survival (DFS), and relapse rate (RR) were 61%, 56%, and 22%, respectively, in TISS <10 ng/mL cohort (n=176), and 50%, 43%, and 35%, respectively, in TISS ≥10 ng/mL cohort (n=34) (OS, P=0.71; DFS, P=0.097; RR, P=0.031). OS, DFS, RR, non-relapse mortality, acute GvHD grade II-IV, grade III-IV or chronic GvHD by TISS were similar in multivariable analysis. TISS ≥10 ng/mL conferred increased risk of viral infection (P=0.003). More patients receiving FD vs. WBD had TISS <10 ng/mL (P=0.001). Overall, TISS <10 ng/mL early post HCT conferred similar survival outcomes and lowered risk of viral infection and toxicities compared to TISS ≥10 ng/mL.

Effective Immunosurveillance After Allogeneic Hematopoietic Stem Cell Transplantation in Acute Myeloid Leukemia

The number of patients receiving allogeneic hematopoietic stem cell transplantation (alloHCT) has increased constantly over the last years due to advances in transplant technology development, supportive care, transplant safety, and donor availability. Currently, acute myeloid leukemia (AML) is the most frequent indication for alloHCT. However, disease relapse remains the main cause of therapy failure. Therefore, concepts of maintaining and, if necessary, reinforcing a strong graft-versus-leukemia (GvL) effect is crucial for the prognosis and long-term survival of the patients. Over the last decades, it has become evident that effective immunosurveillance after alloHCT is an entangled complex of donor-specific characteristics, leukemia-associated geno- and phenotypes, and acquired resistance mechanisms. Furthermore, adoption of effector cells such as natural killer (NK) cells, alloreactive and regulatory T-cells with their accompanying receptor repertoire, and cell–cell interactions driven by messenger molecules within the stem cell and the bone marrow niche have important impact. In this review of pre- and posttransplant elements and mechanisms of immunosurveillance, we highlight the most important mechanisms after alloHCT.

Impact of mother donor, peripheral blood stem cells and measurable residual disease on outcomes after haploidentical hematopoietic cell transplantation with post-transplant cyclophosphamide in children with acute leukaemia

Haploidentical hematopoietic-cell transplantation using post-transplant cyclophosphamide(Haplo-PTCy) is a feasible procedure in children with haematologic malignancies. However, data of a large series of children with acute leukaemia(AL) in this setting is missing. We analysed 144 AL Haplo-PTCy paediatric recipients; median age was 10 years. Patients had acute lymphoblastic(ALL; n = 86) or myeloblastic leukaemia(AML; n = 58) and were transplanted in remission(CR1: n = 40; CR2: n = 57; CR3+: n = 27) or relapse (n = 20). Bone marrow was the graft source in 57%; donors were father (54%), mother (35%), or sibling (11%). Myeloablative conditioning was used in 87%. Median follow-up was 31 months. At day +100, cumulative incidence (CI) of neutrophil recovery and acute GVHD (II-IV) were 94% and 40%, respectively. At 2-years, CI of chronic GVHD and relapse, were 31%, 40%, and estimated 2-year overall survival (OS), leukaemia-free survival (LFS) and graft-versus-host-relapse-free survival (GRFS) were 52%, 44% and 34% respectively. For patients transplanted in remission, positive measurable residual disease (MRD) prior to transplant was associated with decreased LFS (p = 0.05) and GRFS (p = 0.003) and increased risk of relapse (p = 0.02). Mother donor was associated with increased risk of chronic GVHD (p = 0.001), decreased OS (p = 0.03) and GRFS (p = 0.004). Use of PBSC was associated with increased risk of chronic GVHD (p = 0.04). In conclusion, achieving MRD negativity pre-transplant, avoiding use of mother donors and PBSC as graft source may improve outcomes of Haplo-PTCy in children with AL.

Successful engraftment of haploidentical stem cell transplant with post-transplantation cyclophosphamide in a patient with adenosine deaminase deficiency

BACKGROUND

SCID are characterized by an imbalance in cellular and humoral immunity. Enzyme ADA deficiency represents from 10% to 15% of the SCID. This generates diminished maturation of the cell precursors. Treatments include enzyme replacement therapy, allogenic, or autologous HSCT with gene therapy, with HSCT being of choice when an identical HLA donor exists.

CASE REPORT

Male patient, without relevant family antecedents or consanguinity. The patient had multiple infections during the first months of life, evidencing low immunoglobulin levels, with absence of T and B lymphocytes, and natural killer cells. Severe combined immunodeficiencies are considered due to ADA deficiency; management was begun and is derived to our hospital. Admission at 8 months of life, with chronic malnutrition and psychomotor retardation. The HLA studies were conducted without finding an identical donor, taken to HSCT with haploidentical donor. Conditioning regimen with cyclophosphamide, fludarabine, melphalan, and thymoglobulin. This patient received prophylaxis for graft-versus-host disease with cyclophosphamide, cyclosporine, and methotrexate. A 22 months post-transplant, the patient was without immunosuppressants or immunoglobulin, without evidence of graft-versus-host disease or new infections.

CONCLUSIONS

The ADA deficiency is an infrequent pathology that can be potentially fatal if adequate treatment is not started. Haploidentical HSCT, using post-transplantation cyclophosphamide, emerges as a viable option with which good results can be achieved and improve the quality of life in patients with no other therapeutic alternatives.

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.

ABO Mismatch in Allogeneic Hematopoietic Stem Cell Transplant: Effect on Short- and Long-term Outcomes

Supplemental Digital Content is available in the text.

Background.

The impact of ABO incompatibility (ABO-I) on hematopoietic stem cell transplant outcomes is still debated.

Methods.

We retrospectively investigated 432 consecutive transplants performed at our center (2012–2020). All patients but 6 were affected by hematologic malignancies. The effect of different ABO match combinations on engraftment rate, transfusion support, acute and chronic graft-versus-host disease incidences, nonrelapse mortality (NRM), disease-free survival, and overall survival was assessed in univariate and multivariate analysis. Significance was set at P < 0.05.

Results.

ABO match distribution among transplants was as follows: 223 ABO-compatible, 94 major ABO-I, 82 minor ABO-I, and 33 bidirectional ABO-I. At univariate analysis, major ABO-I delayed the engraftment of neutrophils, platelets, and erythroid cells. At multivariate analysis, major ABO-I transplants displayed delayed erythroid engraftment (odds ratio [OR], 0.51; 95% confidence intervals [CIs], 0.38-0.70; P < 0.0001) and hindered transfusion independence for both red blood cells (OR, 0.52; 95% CI, 0.37-0.72; P = 0.0001) and platelets (0.60; 95% CI, 0.45-0.86; P = 0.0048). Moreover, major ABO-I transplants received greater amounts of blood products (P < 0.0001 for red blood cells and P = 0.0447 for platelets). In comparison with other ABO matches, major ABO-I was associated with an increased NRM (OR, 1.67; 95% CI, 1.01-2.75; P = 0.0427). No effects of ABO-mismatch were found on graft-versus-host disease, disease-free survival, and overall survival.

Conclusions.

Major ABO mismatch delays multilineage engraftment hinders transfusion independence and increases NRM. The prognostic impact of transfusion burden in hematopoietic stem cell transplantation deserves to be explored.

Incidence and impact of community respiratory viral infections in post-transplant cyclophosphamide-based graft-versus-host disease prophylaxis and haploidentical stem cell transplantation

Community respiratory viral infections (CRVIs) are associated with pulmonary function impairment, alloimmune lung syndromes and inferior survival in human leucocyte antigen (HLA)-matched allogeneic haematopoietic stem cell transplant (HCT) recipients. Although the incidence of viral infections in HLA-haploidentical HCT recipients who receive post-transplant cyclophosphamide (PTCy)-based graft-versus-host disease (GVHD) prophylaxis is reportedly increased, there are insufficient data describing the incidence of CRVIs and the impact of donor source and PTCy on transplant outcomes. Analysing patients receiving their first HCT between 2012 and 2017 for acute myeloid leukaemia, acute lymphoblastic leukaemia and myelodysplastic syndromes, we describe comparative outcomes between matched sibling transplants receiving either calcineurin-based GVHD prophylaxis (SibCNI, N = 1605) or PTCy (SibCy, N = 403), and related haploidentical transplants receiving PTCy (HaploCy, N = 757). The incidence of CRVIs was higher for patients receiving PTCy, regardless of donor type. Patients in the HaploCy cohort who developed a CRVI by day +180 had both a higher risk of treatment-related mortality [hazard ratio (HR) 2⋅14, 99% confidence interval (CI) 1⋅13-4⋅07; P = 0⋅002] and inferior 2-year overall survival (HR 1⋅65, 99% CI 1⋅11-2⋅43; P = 0⋅001) compared to SibCNI with no CRVI. This finding justifies further research into long-term antiviral immune recovery, as well as development of preventive and treatment strategies to improve long-term outcomes in such patients.

Relationship of donor age and relationship to outcomes of haploidentical transplantation with posttransplant cyclophosphamide

Allogeneic blood or marrow transplantation (BMT) physicians seek to optimize all possible variables to improve outcomes. Selectable factors include conditioning, graft-versus-host disease (GVHD) prophylaxis, graft source, and donor. Many patients, especially those with eligible haploidentical (haplo) donors, will have multiple donor options. We seek to identify factors to optimize the choice of haplo donors when using posttransplantation cyclophosphamide (PTCy) GVHD prophylaxis. We evaluated the effect of modifiable donor characteristics (donor age and relationship) on outcomes following haplo BMT with a uniform nonmyeloablative conditioning and PTCy. From 2002 to 2017, 889 consecutive adult patients underwent nonmyeloablative haplo BMT with PTCy. Median follow-up among survivors was 2.5 years after BMT. Median recipient age was 59 (range: 18 to 76) years and median donor age was 40 (range: 13 to 79) years. Multivariable analyses demonstrated that increasing donor age by decade was associated with poorer overall survival (hazard ratio [HR], 1.13 [1.05, 1.22; P = .0015]), worse progression-free survival (HR, 1.09 [1.02, 1.16; P = .015]), and a higher risk for grade 2 to 4 and grade 3 to 4 GVHD (1.3 [1.06, 1.61; P = .013]), but not for chronic GVHD (HR, 1.06 [0.94, 1.2]; P = .37). These less-favorable results with older donors were attributable to worse nonrelapse mortality (HR, 1.19 [1.05, 1.34]; P = .006), not relapse. Parents were associated with inferior outcomes compared with sibling donors, whereas no significant differences were observed between parental donors. These data suggest that the youngest, adult-sized donors should be preferred when multiple haplo donors are available.

Impact of donor age and kinship on clinical outcomes after T-cell-replete haploidentical transplantation with PT-Cy

Donor selection contributes to improve clinical outcomes of T-cell-replete haploidentical stem cell transplantation (haplo-SCT) with posttransplant cyclophosphamide (PT-Cy). The impact of donor age and other non-HLA donor characteristics remains a matter of debate. We performed a multicenter retrospective analysis on 990 haplo-SCTs with PT-Cy. By multivariable analysis, after adjusting for donor/recipient kinship, increasing donor age and peripheral blood stem cell graft were associated with a higher risk of grade 2 to 4 acute graft-versus-host-disease (aGVHD), whereas 2-year cumulative incidence of moderate-to-severe chronic GVHD was higher for transplants from female donors into male recipients and after myeloablative conditioning. Increasing donor age was associated with a trend for higher nonrelapse mortality (NRM) (hazard ratio [HR], 1.05; P = .057) but with a significant reduced risk of disease relapse (HR, 0.92; P = .001) and improved progression-free survival (PFS) (HR, 0.97; P = .036). Increasing recipient age was a predictor of worse overall survival (OS). Risk of relapse was higher (HR, 1.39; P < .001) in patients aged ≤40 years receiving a transplant from a parent as compared with a sibling. Moreover, OS and PFS were lower when the donor was the mother rather than the father. Pretransplant active disease status was an invariably independent predictor of worse clinical outcomes, while recipient positive cytomegalovirus serostatus and hematopoietic cell transplant comorbidity index >3 were associated with worse OS and PFS. Our results suggest that younger donors may reduce the incidence of aGVHD and NRM, though at higher risk of relapse. A parent donor, particularly the mother, is not recommended in recipients ≤40 years.

Myeloablative haploidentical BMT with posttransplant cyclophosphamide for hematologic malignancies in children and adults

Promising results have been reported for patients with high-risk hematologic malignancies undergoing HLA-haploidentical bone marrow transplantation (haploBMT) with posttransplantation cyclophosphamide (PTCy), but there are few data on outcomes with myeloablative conditioning in this context. We report the results of a single-institution, prospective phase 2 trial of myeloablative haploBMT using busulfan-based or total body irradiation-based conditioning in 96 children or adults (median age, 42 years; range, 1-65 years) with high-risk hematologic malignancies. Recovery of neutrophils and platelets occurred at a median of 24 and 29 days. Engraftment of donor cells with chimerism >95% was achieved in 91%. The cumulative incidence of acute graft-versus-host disease (GVHD) grades II to IV and grades III to IV at day 100 was 11% and 4%, and of chronic GVHD at 6 and 12 months was 4% and 15%, with 6% moderate to severe. The cumulative incidence of nonrelapse mortality was 6% at 100 days and 11% at 1 year (19% in those aged >55 years). The cumulative incidence of relapse at 1 year was 35%; at 3 years, it was 43%. In multivariable analysis, relapse was associated with increased age (P = .02 for age 20-55 years and P = .02 for age >55 years) and with minimal residual disease before transplantation (P = .05). The overall survival at 1 and 3 years is 73% and 54%, and event-free survival at 1 and 3 years is 57% and 49%. We show that haploBMT with PTCy after myeloablative conditioning is safe and efficacious for adult and pediatric patients with hematologic malignancies. Careful consideration must be given to using myeloablative conditioning in patients age >55 years. This trial was registered at www.clinicaltrials.gov as #NCT00796562.

Molecular disparity in human leukocyte antigens is associated with outcomes in haploidentical stem cell transplantation

Haploidentical donors are increasingly used for patients requiring hematopoietic stem cell transplantation (HSCT). Although several factors have been associated with transplant outcomes, the impact of HLA disparity in haploidentical HSCT (haplo-HSCT) remains unclear. We investigated the impact of HLA disparity quantified by mismatched eplets (ME) load of each HLA locus on the clinical outcome of 278 consecutive haploidentical transplants. Here, we demonstrated that the degree of HLA molecular mismatches, at individual HLA loci, may be relevant to clinical outcome in the haplo-HSCT. A significantly better overall survival was associated with higher ME load from HLA-A (hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.95-0.99; P = .003) and class I loci (HR, 0.99; 95% CI, 0.97-0.99; P = .045) in the host-versus-graft direction. The apparent survival advantage of HLA-A ME was primarily attributed to reduced risk in relapse associated with an increase in HLA-A ME load (subdistribution HR, 0.95; 95% CI, 0.92-0.98; P = .004). Furthermore, we have identified an association between the risk of grade 3-4 acute graft-versus-host disease (GVHD) and a higher ME load at HLA-B and class I loci in graft-versus-host (GVH) direction. Additionally, GVH nonpermissive HLA-DPB1 mismatch defined by T-cell epitope grouping was significantly associated with relapse protection (subdistribution HR, 0.19; 95% CI, 0.06-0.59; P = .004) without a concurrent increase in GVHD. These findings indicate that alloreactivity generated by HLA disparity at certain HLA loci is associated with transplant outcomes, and ME analysis of individual HLA loci might assist donor selection and risk stratification in haplo-HSCT.

Analysis of HLA haplotype and clinical factors during hematopoietic stem cell transplantation

BACKGROUND

The human leukocyte antigen (HLA) haplotype of the recipient in hematopoietic stem cell transplantation (HSCT) is a key factor in its success or failure. We analyzed the relationship between HLA haplotype frequency and associated clinical factors in HSCT patients.

METHODS

Patients who underwent allogeneic HSCT between 2000 and 2019 at our institution were enrolled in this study. The HSCT composition was 77 bone marrow transplantations (BMT), 38 peripheral blood stem cell transplantations (PBSCT), and 36 cord blood transplantations (CBT). Patients were classified into three groups according to their donor HLA haplotype frequency in the Japan Population: group A, top 1-10 haplotypes; group B, top 11-100 haplotypes; and group C, haplotype 101-. We then compared various items including clinical biomarkers with the HLA haplotype frequency.

RESULTS

A significant negative correlation was identified between older persons and length of survival. There are also significant correlations between survival and levels of immunoglobulin G, D-dimer, and C-reactive protein, as well as the platelet-large cell ratio before transplantation. A total of 96, 30, and 25 patients were classified into groups A, B, and C, respectively. The HSCT match rate was significantly higher in group A patients than in those of groups B and C. In contrast, the death rate, D-dimer level, and length of time for engraftment were significantly higher in group B and C patients than in those of group A.

CONCLUSION

An assessment of transplant-related complications is important in improving the performance of HSCT. The present data suggest that a special therapeutic strategy is necessary for HSCT using low-frequency HLA haplotypes.

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.

HLA-Haploidentical Family Donors: The New Promise for Childhood Acute Lymphoblastic Leukaemia?

Allogeneic haematopoietic stem cell transplantation (HSCT) is indicated in children with high-risk, relapsed or refractory acute lymphoblastic leukaemia (ALL). HLA-matched grafts from cord blood and stem cell repositories have allowed patients without suitable sibling donors to undergo HSCT. However, challenges in procuring matched unrelated donor (MUD) grafts due to high cost, ethnic disparity and time constraints have led to the exponential rise in the use of stem cells from human leukocyte antigen (HLA)-haploidentical family donors. Whilst HLA-haploidentical HSCT (hHSCT) performed in adult patients with acute leukaemia has produced outcomes similar to MUD transplants, experience in children is limited. Over the last 5 years, more data have emerged on hHSCT in the childhood ALL setting, allowing comparisons with matched donor transplants. The feasibility of hHSCT using adult family donors in childhood ALL may also address the ethical issues related to selection of minor siblings in matched sibling donor transplants. Here, we review hHSCT in paediatric recipients with ALL and highlight the emergence of hHSCT as a promising therapeutic option for patients lacking a suitable matched donor. Recent issues related to conditioning regimens, donor selection and graft-vs.-host disease prophylaxis are discussed. We also identify areas for future research to address transplant-related complications and improve post-transplant disease-free survival.