Superior Graft-versus-Leukemia Effect Associated with Transplantation of Haploidentical Compared with HLA-Identical Sibling Donor Grafts for High-Risk Acute Leukemia: An Historic Comparison

Current status of conditioning regimens in haploidentical hematopoietic cell transplantation

The development of effective prophylaxis strategies against graft-versus-host disease (GVHD) has contributed to the widespread use of haploidentical related hematopoietic cell transplantation (Haplo-HCT). Currently, GVHD prophylaxis containing posttransplant cyclophosphamide (PTCY) is considered the standard of care in Haplo-HCT, and recent studies have shown comparable results for PTCY-based Haplo-HCT and HCT from other donor sources. The conditioning regimen plays an important role in eradicating tumor cells to prevent disease relapse and suppressing the recipient's immune system to facilitate engraftment. PTCY-based Haplo-HCT was initially developed using a nonmyeloablative conditioning regimen consisting of fludarabine, cyclophosphamide and low-dose total body irradiation, but high relapse rates reinforced the need to intensify the conditioning regimen. In this respect, various myeloablative and reduced-intensity conditioning regimens have been investigated. However, the optimal conditioning regimens for PTCY-based Haplo-HCT have not yet been established, and this issue needs to be addressed based on data from patients undergoing the procedure. In this article, we review the existing literature on conditioning regimens for PTCY-based Haplo-HCT and discuss future perspectives.

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.

The clinical outcomes of haploidentical stem cell transplantation (haplo-HSCT) for patients with therapy-related myelodysplastic syndrome: comparable to de novo myelodysplastic syndrome

Therapy-related myelodysplastic syndrome (t-MDS) is defined as a complication in patients with cancer following exposure to chemotherapy and/or radiotherapy and has an inferior outcome compared with de novo myelodysplastic syndrome (de novo MDS). This study aimed to estimate and compare the clinical outcomes of haploidentical stem cell transplantation (haplo-HSCT) for t-MDS and de novo MDS. We retrospectively analyzed 96 patients with MDS who received haplo-HSCT between January 2015 and December 2021. Eleven patients with t-MDS and 85 patients with de novo MDS were matched using the case-pair method in a 1:8 ratio with the following pairing criteria: (1) sex, (2) age (± 5 years), (3) year of haplo-HSCT (± 2 years), and (4) blast cell counts (≥ 5% or not). The 3-year overall survival and disease-free survival after haplo-HSCT for t-MDS versus de novo MDS patients were 72.7% versus 75.1% (P = 0.99) and 54.5% versus 67.0% (P = 0.50), respectively. The 3-year cumulative incidence of relapse was 36.4% versus 15.5% (P = 0.08), respectively. In multivariate analysis, there was no difference in relapse between t-MDS and de novo MDS. The 3-year cumulative non-relapse mortality rates were 9.1% versus 17.6% (P = 0.45), respectively. This study confirmed the comparable clinical outcomes of haplo-HSCT on the prognosis of t-MDS and de novo MDS.

Harnessing allogeneic CD4+ T cells to reinvigorate host endogenous antitumor immunity

Immune checkpoint blockade (ICB) therapies developed over the past decade have been among the most promising approaches for the treatment of patients with advanced cancers. However, the overall objective response rate of ICB therapy for various cancers remains insufficient. Hence, novel strategies are required to improve the efficacy of immunotherapy for advanced cancers. The graft-versus-tumor (GVT) effect, which reflects strong antitumor immunity, is known to occur after allogeneic hematopoietic stem cell transplantation (HSCT). The GVT effect is mainly caused by transplanted donor lymphocytes that recognize and react to distinct alloantigens on tumor cells. In contrast, transplanted allogeneic cells can, in some instances, induce endogenous antitumor immunity in recipients if the graft has been rejected. Because of this ability, allogeneic cells have also been used to induce endogenous antitumor immunity without HSCT, and their beneficial immune response is referred to as the "allogenic effect." Here, we review the usefulness of allogeneic cells, particularly allogeneic CD4+ T cells, in cancer immunotherapy by highlighting their unique potential to induce host endogenous antitumor immunity.

Donor lymphocyte infusion in Acute Myeloid Leukemia

Donor lymphocyte infusion (DLI) is an important treatment modality in the management of relapsed hematological malignancies after allogeneic hematopoietic cell transplantation (allo-HCT). Donor T lymphocytes can be used in a therapeutic, pre-emptive or prophylactic manner in an attempt to stimulate a graft versus leukemia (GVL) effect and eradicate residual disease or even prevent relapse in a high-risk setting. DLIs are not without complications, however, graft versus host disease (GVHD) in particular. Data to date is limited to retrospective and small prospective studies. This review summarizes the available literature on approaches to managing relapse, dosing and timing of DLI, complications and potential future therapies.

Matched related versus unrelated versus haploidentical donors for allogeneic transplantation in AML patients achieving first complete remission after two induction courses: a study from the ALWP/EBMT

We compared transplants (HSCT) from matched related siblings (MSD) with those from matched 10/10 and mismatched 9/10 unrelated (UD) and T-replete haploidentical (Haplo) donors in acute myeloid leukemia (AML) in first complete remission (CR1) achieved after two inductions, a known poor prognostic factor. One thousand two hundred and ninety-five patients were included: MSD (n = 428), UD 10/10 (n = 554), UD 9/10 (n = 135), and Haplo (n = 178). Acute GVHD II-IV was higher in all groups compared to MSD. Extensive chronic (c) GVHD was significantly higher in UD 9/10 (HR = 2.52; 95% CI 1.55-4.11, p = 0.0002) and UD 10/10 (HR = 1.48; 95% CI 1.03-2.13, p = 0.036) and cGVHD all grades were higher in UD 9/10 vs MSD (HR = 1.77; 95% CI 1.26-2.49, p = 0.0009). Non-relapse mortality was higher in all groups compared to MSD. Relapse incidence, leukemia-free, and overall survival did not differ significantly between donor types. Finally, GVHD-free relapse-free survival was lower in HSCT from UD 9/10 (HR = 1.56, 95% CI 1.20-2.03, p = 0.0009) but not in those from UD 10/10 (HR = 1.13, p = 0.22) and Haplo donors (HR = 1.12, p = 0.43) compared to MSD. In conclusion, in AML patients undergoing HSCT in CR1 achieved after two induction courses 10/10 UD and Haplo but not 9/10 UD donors are comparable alternatives to MSD.

Non-T-depleted haploidentical transplantation with post-transplant cyclophosphamide in patients with secondary versus de novo AML in first complete remission: a study from the ALWP/EBMT

We compared outcomes of adult patients with secondary acute myeloid leukemia (sAML) versus de novo AML after non-T-depleted haploidentical stem cell transplant (HaploSCT) with post-transplant cyclophosphamide (PTCy). Seventeen hundred and eleven AML patients (sAML-231, de novo-1480) in first complete remission transplanted from 2010 to 2021, were included. Patients with de novo AML were younger, median age 55.8 versus 60.8 years, p < 0.0001, had better transplantation comorbidity index (HCT-CI) ≥ 3 21.3% versus 40.8%, p < 0.0001 and Karnofsky performance status (KPS) with KPS ≥ 90 in 78% versus 68.5%, respectively, p = 0.002. The two patient groups did not differ with respect to gender, cytomegalovirus serostatus, and cell source. Median time from diagnosis to HaploSCT was 5.2 versus 4.9 months, respectively, p = 0.005. Fewer sAML patients received myeloablative conditioning 35.1% versus 50.1%, p < 0.0001. Two hundred and eleven sAML and 410 de novo AML patients were included in the matched-pair analysis matching two de novo AML with each sAML. No significant difference was observed in any transplantation outcome parameter between the sAML versus de novo AML groups. Two-year non-relapse mortality and relapse incidence did not differ with HaploSCT for de novo versus sAML; 21.4% versus 21%, hazard ratio (HR) = 0.98, p = 0.9 and 23.4% versus 20.6%, HR = 0.92, p = 0.67, respectively. Two-year leukemia-free survival, overall survival, and graft-versus-host disease (GVHD)-free, relapse-free survival were also not different between the de novo AML and sAML groups 55.2% versus 58.4%, HR = 0.95, p = 0.67; 61.4% versus 66.4%, HR = 0.91, p = 0.51 and 46.3% versus 48.2%, HR = 0.92, p = 0.48, respectively. Similarly, the incidence of engraftment as well as acute and chronic GVHD was similar between the 2 cohorts. In conclusion, HaploSCT with PTCy may be able to overcome the bad prognosis of sAML as results are not significantly different to those of HaploSCT in de novo AML.

Total body irradiation-free haploidentical peripheral blood stem cell transplantation compared to related and unrelated donor transplantation in pediatrics with acute lymphoblastic leukemia

BACKGROUND

Acute lymphoblastic leukemia (ALL) is the most prevalent childhood cancer under the age of 15 years. Despite the recent advances in therapeutic regimens, relapse occurs in 15%-20% of pediatric patients after chemotherapy, and hematopoietic stem cell transplantation (HSCT) is the best treatment option. However, donor availability is one of the major challenges. Over the last decade, haploidentical donor (HID) transplantation has evolved as an alternative option. Herein, we aimed to compare the transplant outcomes in pediatric patients receiving total body irradiation (TBI)-free myeloablative regimens, between non-HID and HID transplant.

PATIENTS AND METHODS

The study included 60 pediatric ALL patients who had undergone HSCT from October 2016 until September 2020. Forty-three patients received non-HID HSCT, while 17 patients received HID. The sources of stem cells (SC) were peripheral blood stem cells (PBSC) for all the patients. The conditioning regimen was based on busulfan and cyclophosphamide. For graft-versus-host disease (GvHD) prophylaxis, patients received cyclosporine and methotrexate in the setting of non-HID transplantation, where HIDs received post-transplant cyclosporine and cyclophosphamide.

RESULTS

The cumulative incidences of 3-year overall survival (OS) were 73.1%, 66.6%, and 69.5%, for matched sibling donor-matched related donor (MSD-MRD), matched unrelated donor-mismatched unrelated donor (MUD-MMUD), and HID groups, respectively (p = .85). The cumulative incidences of grade II-IV acute GvHD for the MRD, MUD-MMUD, and HID groups were 29%, 41%, and 49%, respectively (p = .47). Furthermore, the 3-year cumulative incidence of chronic GvHD was MSD-MRD: 70% versus MUD-MMUD: 42% versus HID: 45% (p = .64). The 3-year cumulative incidence of relapse post transplantation was 45%, 18%, and 45%, respectively, for the MSD-MRD, MUD-MMUD, and HID groups, and the differences were not statistically significant (p = .55). There was a higher risk for cytomegalovirus (CMV) infection in patients receiving HID transplants compared to those of non-HIDs (p < .01).

CONCLUSION

Our results indicate that PBSC-HID transplant outcomes in the setting of non-TBI conditioning are comparable to those of non-HIDs in pediatric ALL patients.

Mutation of the TP53 gene in acute lymphoblastic leukemia does not affect survival outcomes after haploidentical hematopoietic stem cell transplantation

Previous studies have demonstrated that TP53 mutation is correlated with insufficient therapy response and unfavorable prognosis in acute lymphoblastic leukemia (ALL). Few studies have investigated the impact of TP53 mutation in ALL patients after haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We completed a retrospective study of 65 ALL patients with available TP53 status who underwent haplo-HSCT. They were divided into a TP53 mutation group (TP53^mut ) and a TP53 wild-type (TP53^wt ) group. TP53^mut showed comparable 2-year cumulative incidence of relapse (CIR) rates (13.1% vs 12.5%, P = .96) and 2-year leukemia-free survival (LFS) (74.2% vs 77.4%, P = .80) with TP53^wt . No significant differences in 2-year overall survival (OS) rates (82.9% vs 87.3%, P = .61) or 2-year NRM rates (12.7% vs 10.2%, P = .69) were observed in TP53^mut and TP53^wt patients. Multivariate analysis suggested that white blood cell (WBC) count at initial diagnosis (>50 × 10⁹ /L: hazard ratio [HR] = 3.860, P = .016) and age (>40 years old: HR = 4.120, P = .012) are independent risk factors for 2-year LFS. Our study showed that TP53 mutations may not be related to the unfavorable impact on survival in ALL patients after treatment with haplo-HSCT. The present results suggested that haplo-HSCT may eliminate the poor prognosis effect of TP53 mutation in ALL.

Comparison of clinical outcomes between peripheral blood stem cells and peripheral blood stem cells plus bone marrow in myelodysplastic syndrome patients with haploidentical transplantation

The comparison of haploidentical G-CSF-mobilized peripheral blood and bone marrow transplantation (HBMT) for patients with myelodysplastic syndrome (MDS) and haploidentical G-CSF-primed peripheral blood stem cell transplantation (HPBSCT) remains unclear. We performed a retrospective analysis using a propensity score method on 140 MDS patients who received HPBSCT (n = 46) or HBMT (n = 94) with BU/CY as a conditioning regimen prior to transplantation at our center between June 2016 and June 2021. HBMT recipients were associated with a reduced incidence of grade III-IV acute GVHD (17.22% vs. 30.57%, p = 0.019) within 100 days, reduced 2-year transplant-related mortality (TRM) (14.29% vs. 28.94%, p = 0.045) and superior 2-year overall survival (OS) (81.6% vs. 66.0%, p = 0.027), progression-free survival (PFS) (80.9% vs. 61.2%, p = 0.015), and GVHD relapse-free survival (GRFS) (64.6% vs. 53.3%, p = 0.062) compared with HPBSCT, but 2-year relapse incidence (RI) (5.96% vs. 9.39%, p = 0.445) was not affected. Multivariate analysis revealed that a GPB/GBM mixture was the independent factor for a reduced incidence of grade III-IV acute GVHD (p = 0.018) and TRM (p = 0.048), improved OS (p = 0.029), PFS (p = 0.019) and GRFS (p = 0.072). Collectively, the use of a GPB/GBM mixture as stem cell grafts for haplo-HSCT in patients with MDS appears to be an optimal choice.

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

BACKGROUND

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

METHODS

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

RESULTS

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

DISCUSSION

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

Haploidentical haematopoietic stem cell transplantation for TP53-mutated acute myeloid leukaemia

Acute myeloid leukaemia (AML) patients with tumour protein p53 (TP53) mutations are often resistant to chemotherapy and have worse clinical outcomes than patients without TP53 mutations. In this study, we compared clinical outcomes of patients with AML with and without TP53 mutations who underwent haploidentical haematopoietic stem cell transplantation (haplo-HSCT). For the TP53-mutation group and TP53 wild-type group, the 2-year cumulative incidence of relapse (CIR) was (39.0% vs. 21.2% respectively, p = 0.088), the 2-year non-relapse mortality (NRM) rate was (3.2% vs. 8.4% respectively, p = 0.370), the 2-year leukaemia-free survival (LFS) was (57.7% vs. 71.3% respectively, p = 0.205), the 2-year overall survival (OS) rate was (69.9% vs. 81.3% respectively, p = 0.317), the 100-day cumulative incidence of Grade II-IV acute graft-versus-host disease (GvHD) was (6.5% vs. 20.7% respectively, p = 0.074), the 2-year cumulative incidence of chronic GvHD was (52.3% vs. 53.1% respectively, p = 0.493) and the 2-year GvHD-free/relapse-free survival (GRFS) was (57.7% vs. 69.6% respectively, p = 0.347). Our data showed that there were no significant differences in 2-year clinical outcomes between the two groups. Multivariable analysis showed TP53 mutations had no significant impact on CIR, NRM, OS, GvHD, LFS or GRFS. Our findings suggest that patients with AML with TP53 mutations may at least partially benefit from haplo-HSCT. Haplo-HSCT might be the recommended treatment for such patients.

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 strategies to improve relapse-free survival in childhood leukemia: Whole blood donor lymphocyte infusions and lenalidomide for inducing graft-versus-leukemia effect

INTRODUCTION

Post-transplant graft-versus-leukemia (GVL) effect has been shown to be an important determinant of a successful outcome following hematopoietic stem cell transplantation (HSCT) in children with acute leukemia. PATIENTS AND METHODS: We performed a retrospective analysis of the children up to 18 years of age with acute leukemia who underwent HSCT between November 2002 and November 2018. GVL induction strategies included whole blood donor lymphocyte infusions (DLI) and/or lenalidomide.

RESULTS

A total of 134 children were included with engraftment in 125 children (93%). Acute graft-versus-host disease (GVHD) was documented in 85 (63%) children without any induction strategies. GVL induction strategies were employed in 19 children (14%); DLI (n = 12), Lenalidomide (n = 2), DLI + lenalidomide (n = 5). Among the 19, 12 children (63%) are alive without relapse; 6 children died of relapse (31%). Among the 6 who died of relapse despite induction strategies, 5/6 had ALL and one child had AML. GVL induction was effective in preventing relapse in 7/12 (58%) children with ALL and 5/6 (83%) children with AML. Relapse-free survival in the cohort is 73/134 (55%) with a median follow-up of 32 months. GVHD of any grade was significantly associated with a lower risk of relapse (p = .008). Median survival time was 160.3 days (range 132-187) in those with chronic GVHD versus 88.3 days (range 68-107) in those without (p value = .004).

CONCLUSION

Pre-emptive whole blood DLIs in graded aliquots, and lenalidomide are important tools for post HSCT GVL induction, which significantly impacts relapse-free survival in childhood leukemia.

Comparison of Outcomes of Haploidentical Peripheral Blood Stem Cell Transplantation Supported by Third-Party Cord Blood Versus Human Leukocyte Antigen-Matched Sibling Peripheral Blood Stem Cell Transplantation in Hematologic Malignancy Patients

Recent studies have shown that haploidentical hematopoietic stem cell transplantation supported by third-party cord blood (haplo-cord-HSCT) results in rapid hematopoietic recovery, low incidences of graft-versus-host disease (GVHD), and relapse of hematologic malignancies. However, few reports on haploidentical peripheral blood stem cell transplantation supported by third-party cord blood (haplo-cord-PBSCT) have been published. To evaluate the outcomes of patients who underwent haplo-cord-PBSCT or human leukocyte antigen (HLA)-matched sibling donor peripheral blood stem cell transplantation (MSD-PBSCT), we retrospectively reviewed the clinical data of patients with hematologic malignancies who underwent haplo-cord-PBSCT (n = 93) or MSD-PBSCT (n = 72) in our hospital from March 2017 to December 2020. In the haplo-cord-PBSCT and MSD-PBSCT groups, the median time for neutrophil and platelet engraftment was 13 vs. 12 days (p = 0.07) and 16 vs. 13 days (p = 0.06), respectively. The 30-day cumulative incidences of neutrophil engraftment were 100.0% and 98.6% (p = 0.12). The 100-day cumulative incidences of platelet engraftment were 96.8% and 98.6% (p = 0.01). The 100-day cumulative incidences of grade II–IV and grade III–IV acute GVHD were 29.1% vs. 23.6% (p = 0.42) and 9.7% vs. 4.2% (p = 0.18). The cumulative incidences of total and moderate/severe chronic GVHD at 1 year were 26.5% vs. 17.4% and 8.1% vs. 4.5%, respectively, and at 3 years were 34.7% vs. 34.3% (p = 0.60) and 13.6% vs. 10.6% (p = 0.49), respectively. The cumulative incidences of relapse at 1 year were 9.3% and 7.2% and at 3 years were 17.0% and 17.0% (p = 0.98). Non-relapse mortality (NRM) at 1 year was 14.6% and 8.6% and at 3 years was 17.4% and 8.6% (p = 0.13) in two groups. The probabilities of overall survival (OS), disease-free survival (DFS), and GVHD-free/relapse-free survival (GRFS) at 1 year were 81.7% vs. 88.6%, 76.1% vs. 84.2%, and 71.7% vs. 79.7%, respectively, and at 3 years were 78.7% vs. 79.0%, 65.6% vs. 74.4%, and 55.5% vs. 63.6%, respectively, in the corresponding group, p > 0.05. In conclusion, for patients with acute myeloid leukemia/myelodysplastic syndrome (AML/MDS) and acute lymphoid leukemia (ALL), haplo-cord-PBSCT results in similar outcomes compared with MSD-PBSCT, and it may be a valid alternative transplantation method.

Association Between Cytomegalovirus and Epstein-Barr Virus Co-Reactivation and Hematopoietic Stem Cell Transplantation

The co-reactivation of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in patients undergoing hematopoietic stem cell transplantation (HSCT) has been found. Research has shown that the reactivation of CMV or EBV is closely related to poor HSCT outcomes. In this study, we describe the clinical characteristics of HSCT patients with co-reactivation of CMV and EBV. We retrospectively reviewed the medical records of 327 patients who underwent HSCT at the Peking University People’s Hospital Institute of Hematology. Co-reactivation of CMV and EBV was observed in a total of 75 patients (22.9%) who also had a higher incidence of hemorrhagic cystitis (P=0.000). HSCT patients with CMV and co-reactivation of CMV and EBV had a significantly lower 1-year overall survival (OS; P=0.050). Further, COX regression analysis showed that viral infection was a risk factor for 1-year OS (HR, 12.625 for co-reactivation vs. no reactivation, p=0.021, and HR 13.580 for CMV reactivation vs. no reactivation, P=0.013). In conclusion, the patients with CMV reactivation had poorer outcome after HSCT regardless of EBV reactivation.

A Prospective Trial Comparing Haploidentical Donor Transplantation With Cord Blood Versus HLA-Matched Sibling Donor Transplantation for Hematologic Malignancy Patients

Although haploidentical donor (HID) hematopoietic stem cell transplantation (HSCT) has achieved similar survival to HLA-identical sibling donor (ISD) transplantation, the delayed hematopoietic engraftment as well as higher incidence of graft-versus-host-disease (GVHD), results in prolonged hospitalization, higher costs, and increased morbidity. In this study, a prospective, non-randomized clinical study was designed to evaluate the outcomes of patients who underwent HID HSCT supported by cord blood or ISD HSCT. Between May 2017 and November 2020, 113 patients were enrolled to undergo HID HSCT supported by cord blood (n=88) or ISD HSCT (n=25). The cumulative incidence of neutrophil and platelet engraftment at 30days was comparable in these two groups. Importantly, there was no significant difference in the cumulative incidence of grade II-IV aGVHD at 100days (20.5% [95% confidence interval [CI]: 12.2%–28.8%] versus 12.0% [95% CI: 0.2%–23.8%], P = 0.32) and cGVHD at 1 year (19.5% [95% CI: 11.2%–27.8%] versus 16.6% [[95% CI: 1.3%–31.9%] P = 0.70) between the two groups. Among the HID and ISD groups, the 2-year disease free survival was 76.8 and 80.0% (P = 0.83), the 2-year overall survival was 82.4 and 88.0% (P = 0.66), the 2-year GVHD-free, relapse-free survival was 68.9 and 75.3% (P = 0.62), respectively. Our results indicate that HID transplantation supported by cord blood may offer a good alternative to ISD HSCT for patients with hematopoietic malignancies.

Optimization of Donor Lymphocyte Infusion for AML Relapse After Allo-HCT in the Era of New Drugs and Cell Engineering

Donor lymphocyte infusion (DLI) is a key strategy for the treatment of AML relapse after allogeneic hematopoietic cell transplantation (allo-HCT) and has been used for either prophylactic, pre-emptive, or therapeutic purposes. However, the prognosis of these patients remains dismal even after DLI infusion (2-year overall survival, ~25%), and the efficacy is achieved at the cost of toxicities such as graft-versus-host (GVH) disease. Attempts to optimize DLI efficacy and safety, such as dose/timing modification and the use of cytoreduction, before DLI have been performed previously. Recently, a great number of novel targeted and immunomodulatory agents have emerged. Some of them, such as hypomethylating agents, FLT3 and Bcl-2 inhibitors, have been used in combination with DLI, aiming to enhance the graft-versus-leukemia effect. Moreover, manipulation of the DLI graft through cell selection (e.g., donor NK cells) or cell engineering (donor CAR-T cells) has shown potentially superior anti-tumor effects but less GVH effect than conventional DLI in clinical trials. This review summarizes the recent advances on the use of DLI for the prophylaxis/treatment of AML relapse and discusses future strategies which may further improve the treatment efficacy.

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

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

Alloantigen-activated (AAA) CD4+ T cells reinvigorate host endogenous T cell immunity to eliminate pre-established tumors in mice

BACKGROUND

Cancer vaccines that induce endogenous antitumor immunity represent an ideal strategy to overcome intractable cancers. However, doing this against a pre-established cancer using autologous immune cells has proven to be challenging. "Allogeneic effects" refers to the induction of an endogenous immune response upon adoptive transfer of allogeneic lymphocytes without utilizing hematopoietic stem cell transplantation. While allogeneic lymphocytes have a potent ability to activate host immunity as a cell adjuvant, novel strategies that can activate endogenous antitumor activity in cancer patients remain an unmet need. In this study, we established a new method to destroy pre-developed tumors and confer potent antitumor immunity in mice using alloantigen-activated CD4⁺ (named AAA-CD4⁺) T cells.

METHODS

AAA-CD4⁺ T cells were generated from CD4⁺ T cells isolated from BALB/c mice in cultures with dendritic cells (DCs) induced from C57BL/6 (B6) mice. In this culture, allogeneic CD4⁺ T cells that recognize and react to B6 mouse-derived alloantigens are preferentially activated. These AAA-CD4⁺ T cells were directly injected into the pre-established melanoma in B6 mice to assess their ability to elicit antitumor immunity in vivo.

RESULTS

Upon intratumoral injection, these AAA-CD4⁺ T cells underwent a dramatic expansion in the tumor and secreted high levels of IFN-γ and IL-2. This was accompanied by markedly increased infiltration of host-derived CD8⁺ T cells, CD4⁺ T cells, natural killer (NK) cells, DCs, and type-1 like macrophages. Selective depletion of host CD8⁺ T cells, rather than NK cells, abrogated this therapeutic effect. Thus, intratumoral administration of AAA-CD4⁺ T cells results in a robust endogenous CD8⁺ T cell response that destroys pre-established melanoma. This locally induced antitumor immunity elicited systemic protection to eliminate tumors at distal sites, persisted over 6 months in vivo, and protected the animals from tumor re-challenge. Notably, the injected AAA-CD4⁺ T cells disappeared within 7 days and caused no adverse reactions.

CONCLUSIONS

Our findings indicate that AAA-CD4⁺ T cells reinvigorate endogenous cytotoxic T cells to eradicate pre-established melanoma and induce long-term protective antitumor immunity. This approach can be immediately applied to patients with advanced melanoma and may have broad implications in the treatment of other types of solid tumors.

Dynamic immune profiling identifies the stronger graft-versus-leukemia (GVL) effects with haploidentical allografts compared to HLA-matched stem cell transplantation

Haploidentical stem cell transplantation (haplo-SCT) achieves superior or at least comparable clinical outcomes to HLA-matched sibling donor transplantation (MSDT) in treating hematological malignancies. To define the underlying regulatory dynamics, we analyzed time courses of leukemia burden and immune abundance of haplo-SCT or MSDT from multiple dimension. First, we employed two nonirradiated leukemia mouse models which carried human AML-ETO or MLL-AF9 fusion gene to establish haplo-identical and major histocompatibility (MHC)-matched transplantation models and investigated the immune cell dynamic response during leukemia development in vivo. We found that haplo-matching the MHCs of leukemia cells with recipient mouse T cells prolonged leukemic mice survival and reduced leukemia burden. The stronger graft-versus-leukemia activity in haplo-SCT group mainly induced by decreased apoptosis and increased cytotoxic cytokine secretion including tumor necrosis factor-α, interferon-γ, pore-forming proteins and CD107a secreted by T cells or natural killer cells. Furthermore, we conducted a prospective clinical trial which enrolled 135 patients with t(8;21) acute myeloid leukemia that displayed minimal residual disease before transplantation and underwent either haplo-SCT or MSDT. The results showed that the haplo-SCT slowed the kinetics of the leukemia burden in vivo and reduced the cumulative incidence of relapse compared with MSDT. Ex vivo experiments showed that, 1 year after transplantation, cytotoxic T lymphocytes from the haplo-SCT group had higher cytotoxicity than those from the MSDT group during the same period. Our results unraveled the role of immune cells in superior antileukemia effects of haplo-SCT compared with MSDT.

Myeloablative Haploidentical Transplant as an Alternative to Matched Sibling Transplant for Peripheral T-Cell Lymphomas

The number of HLA-haploidentical allogeneic hematopoietic stem-cell transplantation (Haplo-HSCT) is increasing. Comparative studies about Haplo-HSCT versus allo-HSCT with HLA-matched sibling donors (MSD-HSCT) have been tried in leukemias and B-cell lymphomas. Few studies were reported in Peripheral T-cell lymphomas (PTCLs). We performed a multicenter retrospective study about 52 patients with PTCLs undergoing Haplo-HSCT (n = 20) or MSD-HSCT (n = 32). All Haplo-HSCT recipients received antithymocyte globulin (ATG) based graft versus host disease (GVHD) prophylaxis. The median follow-up for all survivors was 38 months. The 100-day cumulative incidence of grade II to IV acute GVHD was similar (19% in the MSD-HSCT group versus 28% in the Haplo-HSCT group, P = 0.52). The 2-year cumulative incidence of chronic GVHD (limited and extensive) after Haplo-HSCT (30%) was also similar with that in the MSD-HSCT group (50%, P = 0.15). The 3-year relapse rates (33% vs 27%, P = 0.84) and non-relapse mortality (21% vs 22%, P = 0.78) did not differ between these two groups. There were also no differences in 3-year overall survival (OS) (48% vs 50%, P = 0.78) and progression-free survival (47% vs 51%, P = 0.95) between these two groups. On multivariate analysis, prognostic index for T-cell lymphoma (PIT) score (higher than 1: hazard ratio [HR], 4.0; P = 0.003) and disease status (stable or progression disease before HSCT: HR, 2.8; P = 0.03) were independent variables associated with worse OS. We concluded that ATG-based haplo-HSCT platform could work as an alternative to MSD-HSCT for patients with PTCLs.

Comparison of Two Strategies for Prophylactic Donor Lymphocyte Infusion in Patients With Refractory/Relapsed Acute Leukemia

Prophylactic donor lymphocyte infusion (pDLI) could reduce relapse in patients with refractory/relapsed acute leukemia (RRAL) undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT), but optimal timing of pDLI remains uncertain. We compared the outcomes of two strategies for pDLI based on time from transplant and minimal residual disease (MRD) status in patients with RRAL. For patients without grade II–IV acute graft-versus-host disease (aGVHD) on day +60, pDLI was given on day +60 regardless of MRD in cohort 1, and was given on day +90 unless MRD was positive on day +60 in cohort 2. A total of 161 patients with RRAL were enrolled, including 83 in cohort 1 and 78 in cohort 2. The extensive chronic GVHD (cGVHD) incidence in cohort 2 was lower than that in cohort 1 (10.3% vs. 27.9%, P = 0.006) and GVHD-free/relapse-free survival (GRFS) in cohort 2 was superior to that in cohort 1 (55.1% vs. 41.0%, P = 0.042). The 2-year relapse rate, overall and leukemia-free survival were comparable between the two cohorts (29.0% vs. 28.2%, P = 0.986; 63.9% vs. 64.1%, P = 0.863; 57.8% vs. 61.5%, P = 0.666). Delaying pDLI to day +90 based on MRD for patients with RRAL undergoing allo-HSCT could lower extensive cGVHD incidence and improve GRFS without increasing incidence of leukemia relapse compared with pDLI on day +60.

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

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

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

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

Comparable outcomes among unmanipulated haploidentical, matched unrelated, and matched sibling donors in BU-based myeloablative hematopoietic stem cell transplantation for intermediate and adverse risk acute myeloid leukemia in complete remission: a single-center study

There are a limited number of studies comparing outcomes of busulfan (BU)-based myeloablative hematopoietic stem cell transplantation using unmanipulated haploidentical donors (HIDs), HLA-matched unrelated donors (MUDs), and HLA-matched sibling related donors (MSDs) in acute myeloid leukemia (AML) patients with complete remission (CR) status. With this background, we compared outcomes among 377 cases of CR following consecutive HID-HSCT for AML (CR) to 86 MUD and 92 MSD-HSCT cases. All patients received BU-based myeloablative conditioning and an unmanipulated graft within the same period. The median patient age was 23 years (range 1.1 to 65 years), and 230 patients (41.4%) were under age18. Among the 555 patients, 432 (77.8%) were of intermediate cytogenetic risk and 123 (22.2%) were of adverse risk. A total of 113 patients (20.5%) had FLT3-ITD+ AML, 425 patients (76.6%) were in first complete remission (CR1) post-transplant, and 130 (23.4%) patients were in second CR (CR2). GVHD prophylaxis included mycophenolate mofetil (MMF), cyclosporine-A (CSA) with short-term methotrexate (MTX) for HID, and MUD-HSCT. MMF is not used for MSD-HSCT. The median survival follow-up time was 42 months (range 18-91 months). The 3-year leukemia-free survival (LFS) among the HID, MUD, and MSD cohorts was 73.8% ± 4.8%, 66.4% ± 8.5%, 74.5% ± 2.4%, respectively (P = 0.637). Three-year overall survival (OS) was 74.9% ± 2.4%, 81.8% ± 4.3%, and 77.5% ± 4.5% among the HID, MUD, and MSD cohorts, respectively (P = 0.322). There were no difference among the relapse rate among the HID, MUD, and MSD donor cohorts (14.3% ± 4.0% vs 20.3% ± 6.4% vs 14.5% ± 2.2, respectively; P = 0.851) or the non-relapse mortality (NRM) (12.3% ± 3.5% vs 9.5% ± 3.2% vs 14.0% ± 1.8%, respectively; P = 0.441). Multivariate analyses showed that MRD-positive pre-HSCT was the only risk factor associated with a lower OS and LFS and higher risk of relapse among all 555 patients. Compared with the use of a MUD or MSD, an HID for HSCT had similar outcomes among AML patients with CR states who underwent an allo-HSCT with BU-based myeloablative conditioning. MFC-MRD-positive pre-HSCT was an independent negative factor impact on outcomes for AML patients in CR. We conclude that for AML patients who do not have a MSD or if an urgent transplant is required, HSCT from an HID is a valid option.

Unmanipulated haploidentical hematopoietic stem cell transplantation for children with myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal disorders and is rare in children. Allogeneic hematopoietic stem cell transplantation (HSCT) is commonly used in children with MDS with excess blasts and in patients with refractory cytopenia of childhood (RCC) associated with monosomy 7, complex karyotype, severe neutropenia, or transfusion dependence. We recruited 27 children with MDS who received haploidentical hematopoietic stem cell transplantation (haplo-HSCT). At transplantation, 10 patients had RCC, 12 patients had advanced MDS (RAEB and RAEB-T), and 5 patients had myelodysplasia-related acute myeloid leukemia (MDR-AML). All patients received granulocyte colony-stimulating factor (G-CSF)-mobilized bone marrow cells and peripheral blood stem cells. At a median follow-up of 24.1 months (range: 2.0-74.5 months) after HSCT, the estimated probabilities of 3-year disease-free survival (DFS) and overall survival (OS) were both 81.9% (95% CI, 66.8-100.0%). The estimated 3-year incidences of relapse (CIR) and non-relapse mortality (NRM) were both 7.4% (95% CI, 1.2%-21.4%). The 100-day cumulative incidence of grade II-IV aGVHD was 52.6% (95% CI, 42.9-62.3%), while that of grade III-IV aGVHD was 11.1% (95% CI, 5.1-17.1%). The 3-year cumulative incidences of overall and extensive cGVHD were 42.3% (95% CI, 19.8%-57.5%) and 21.1% (95% CI, 2.5%-63.2%), respectively. Univariate analysis showed that chronic GVHD significantly affected OS and DFS. Haploidentical HSCT may be an effective treatment option with easier donor availability for pediatric patients with MDS.

Haploidentical related donor vs matched sibling donor allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia and myelodysplastic syndrome aged over 50 years: A single-center retrospective study

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative therapeutic option for patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Increasing data suggest that haploidentical donor (HID) transplantation achieve comparable outcomes with HLA-matched sibling donor (MSD) in adult AML/MDS. This retrospective study compared the outcomes of AML or MDS patients age ≥50 years underwent HID and MSD transplantation. One hundred and fifty-six patients were enrolled in this study, including 75 HID and 81 MSD transplantation. The 100-day cumulative incidence of II-IV° acute graft-versus-host disease (GVHD) was 33.3 ± 5.4% vs 22.2 ± 4.6%, respectively, in HID and MSD groups (P = .066), and III-IV° acute GVHD was not significantly different between two groups (5.3%±2.6% vs 6.2%±2.7%, respectively, P = .823). The 2-year cumulative incidence of limited and extensive chronic GVHD was not statistically different in HID and MSD groups (20.9 ± 5.5% vs 18.9 ± 4.8% and 13.0 ± 4.7% vs 19.7 ± 5.0%, P = .889 and P = .269, respectively). The 2-year cumulative incidences of relapse (27.0 ± 5.6% vs 22.7 ± 5.1%, P = .509), 2-year overall survival (63.0 ± 5.8% vs 66.7 ± 5.4%, P = .454), 2-year transplant-related mortality (17.2 ± 4.6% vs 17.4 ± 4.4%, P = .847), 2-year progression-free survival (59.3 ± 5.8% vs 64.5 ± 5.4%, P = .437), 2-year GVHD-free relapse-free survival (42.6 ± 5.9% vs 40.9 ± 5.6%, P = .964) were not significantly different in the two groups. The present data showed equivalent outcomes in AML or MDS patients age ≥50 years underwent HID and MSD transplantation.

The effect of donor type on outcomes in adults with acute myeloid leukemia after reduced-intensity hematopoietic peripheral blood cell transplant - a retrospective study

We retrospectively analyzed outcomes in patients with acute myeloid leukemia (AML) receiving reduced-intensity conditioning (RIC) hematopoietic stem cell transplants (HCT) from a peripheral blood (PB) source. We identified 46 haploidentical HCT (haplo), 59 matched unrelated donor HCT (MUD), and 40 matched related donor HCT (SIB) patients at a single institution. Haplo had improved overall survival (OS) when compared to MUD, HR 2.03 (P = 0.01) but not SIB, HR 1.17 (P = 0.61). There were no differences in relapse rates or treatment-related mortality (TRM). Haplo had higher rates of acute graft-versus-host disease (GVHD) grade II-IV at day 180 than MUD (44% vs. 25%, P = 0.03) and SIB (44% vs. 13% P < 0.01). Rates of acute GVHD III-IV and chronic GVHD were similar among the groups. Haplo had slower engraftment rates compared to MUD with neutrophil engraftment at 87% vs. 93%, (P < 0.01) and platelet engraftment at 59% vs. 86%, (P < 0.01) at 28 days. Although patients receiving haplo had higher acute GVHD II-IV and slower engraftment, they did not have increased TRM. These data may suggest that patients receiving haplo have improved OS compared to MUD for AML patients receiving RIC transplants. This should be confirmed using a larger cohort.

Comparison of central nervous system relapse outcomes following haploidentical vs identical-sibling transplant for acute lymphoblastic leukemia

To explore the incidence, risk factors, and outcomes of central nervous system (CNS) relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute lymphoblastic leukemia (ALL) and to compare the differences in CNS relapse between haploidentical donor HSCT (HID-HSCT) and HLA-identical sibling donor HSCT (ISD-HSCT). We performed a retrospective nested case-control study on patients with CNS relapse after allo-HSCT. The cumulative incidence of CNS relapse was 4.06% after allo-HSCT in ALL, with a significantly poor prognosis. The incidence was 3.91% and 5.36% in HID-HSCT and ISD-HSCT, respectively (p = .227). Among the patients with CNS relapse, the overall survival (OS) at 3 years was 56.2 ± 6.8% in the HID-HSCT subgroup and 76.9 ± 10.2% in the ISD-HSCT subgroup (p = .176). The 3-year cumulative incidence of systemic relapse was also comparable between the two subgroups (HID-HSCT, 40.6 ± 7.4%; ISD-HSCT, 13.3 ± 8.7%, respectively, p = .085). Younger age (p = .045), T-ALL (p = .035), hyperleukocytosis at diagnosis (p < .001), advanced disease stage at transplant (p < .001), pre-HSCT CNS involvement (p < .001), and absence of chronic graft vs host disease (cGVHD) (p < .001) were independent risk factors for CNS relapse after allo-HSCT. In conclusion, CNS relapse was a significant complication after allo-HSCT in ALL and was associated with poor prognosis. The incidences and outcomes were comparable between HID-HSCT and ISD-HSCT.

Haploidentical donor is preferred over matched sibling donor for pre-transplantation MRD positive ALL: a phase 3 genetically randomized study

Background

Previous reports suggest a benefit associated with haploidentical donor transplantation (HIDT) compared to matched sibling donor transplantation (MSDT) in certain contexts, and the choice of optimal candidates warrants further investigation.

Methods

We designed a prospective genetically randomized study to evaluate donor options between acute lymphoblastic leukemia (ALL) patients positive for measurable residual disease (MRD) pre-transplantation who underwent HIDT (n = 169) or MSDT (n = 39).

Results

The cumulative incidence of positive MRD post-transplantation was 26% (95% CI, 19–33%) and 44% (95% CI, 28–60%) for HIDT and MSDT, respectively (P = 0.043). Compared to the HIDT cohort, the MSDT cohort had a higher 3-year cumulative incidence of relapse (CIR; 47%, 95% CI, 31–63% vs. 23%, 95% CI, 17–29%; P = 0.006) and lower 3-year probability of leukemia-free survival (LFS; 43%, 95% CI, 27–59% vs. 65%, 95% CI, 58–72%; P = 0.023) and overall survival (OS; 46%, 95% CI, 30–62% vs. 68%, 95% CI, 61–75%; P = 0.039), without a difference in non-relapse-mortality (10%, 95% CI, 1–19% vs. 11%, 95% CI, 6–16%; P = 0.845). Multivariate analysis showed that HIDT is associated with a low CIR (HR = 0.364; 95% CI, 0.202–0.655; P = 0.001) and better LFS (HR = 0.414; 95% CI, 0.246–0.695; P = 0.001) and OS (HR = 0.380; 95% CI, 0.220–0.656; P = 0.001).

Conclusions

HIDT is better than MSDT in view of favorable anti-leukemia activity for patients with pre-transplantation MRD positive ALL. The current study paves the way to determine that haploidentical donors are the preferred choice regardless of available matched sibling donors in a subgroup population.

Trial registration

ClinicalTrials.gov Identifier: NCT02185261. Registered July 9, 2014. https://clinicaltrials.gov/ct2/show/NCT02185261?term=NCT02185261&draw=2&rank=1.

Haploidentical versus HLA-matched sibling transplantation for refractory acute leukemia undergoing sequential intensified conditioning followed by DLI: an analysis from two prospective data

BACKGROUND

Compared with HLA-matched sibling donor (MSD) transplant, the outcomes of haploidentical donor (HID) transplant for refractory acute leukemia need to be further explored. In this study, we compared the outcomes of HID with MSD for refractory acute leukemia.

PATIENTS AND METHODS

This study population came from two prospective multicenter trials (NCT01883180, NCT02673008). Two hundred and seventy-eight patients with refractory acute leukemia were enrolled in this study, including 119 in HID group and 132 in MSD group. Sequential intensified conditioning was employed in all patients, and donor lymphocyte infusion (DLI) was administered in patients in the absence of active GVHD and according to minimal residual disease (MRD) from day + 60 post-transplantation for preventing relapse.

RESULTS

The complete remission of leukemia by day + 30 post-transplant were 94% and 93%, respectively, in HID and MSD groups (p = .802). The 1-year incidence of grades II-IV acute GVHD was 62% and 54% (p = .025), and 3-year incidence of chronic GVHD was 55% and 55% (p = .789), respectively, in two groups. HID transplant had lower incidence of first episode of MRD positivity and relapse than MSD transplant (28% vs 45%, p = .006; 26% vs 38%, p = .034). There was higher infection-related mortality in HID than MSD (8% vs 2%, p = .049) within the first 100 days' post-transplant. The 5-year overall survival was 46% and 42% (p = .832), respectively; the 5-year disease-free survival was 43% and 39% (p = .665), in HID and MSD groups, respectively.

CONCLUSIONS

HID transplant has lower relapse, but higher infection-related mortality and similar survival rates in refractory acute leukemia by the strategy of sequential intensified conditioning followed by DLI compared with MSD transplant.

Impact of prophylactic/preemptive donor lymphocyte infusion and intensified conditioning for relapsed/refractory leukemia: a real-world study

Prophylactic/preemptive donor lymphocyte infusion (p/pDLI) and intensified conditioning have shown promising results in experimental studies of refractory/relapsed acute leukemia (RRAL), but real-world data remain scarce. We conducted a multicenter, population-based analysis of 932 consecutive patients. The three-year leukemia-free survival (LFS) rates were 56% for patients receiving both p/pDLI and intensified myeloablative conditioning (MAC) (intenseMAC) and 30% for those who received neither therapy per landmark analysis. Multivariable analyses were run separately for acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL), and p/pDLI treatment was linked to significantly higher LFS than non-DLI for both AML and ALL patients without increasing the nonrelapse mortality. IntenseMAC was associated with significantly lower relapse and higher LFS than nonintensified MAC despite higher nonrelapse mortality rates in ALL, while there was no impact of intenseMAC observed in AML. p/pDLI achieved superior outcomes in both matched-sibling donor (MSD) and haploidentical donor transplantation, while intenseMAC only influenced MSD outcomes. Data suggest that RRAL patients receiving "total therapy" by way of p/pDLI and intensified conditioning treatment have an improved chance for LFS, with p/pDLI being safer with a more extensive impact relative to intenseMAC. Patients with RRAL can tolerate both interventions and achieve a reasonable outcome.

Matched-Pair Analysis of Transplant from Haploidentical, Unmanipulated Bone Marrow Donor versus HLA Identical Sibling for Patients with Hematologic Malignancies

A matched-pair analysis of transplant-related outcomes was carried out in 116 of 255 consecutive patients who received transplants from an HLA identical sibling (n = 58) or haploidentical related donor (n = 58). The 2 patient series were matched with 9 variables: period of transplant, patient and donor age, sex, diagnosis, disease phase, conditioning regimen, donor-recipient sex, and cytomegalovirus (CMV) status combinations. As graft-versus-host disease (GVHD) prophylaxis, all patients received the standard cyclosporine and methotrexate association with the addition of anti-thymocyte globulins, mycophenolate mofetil, and basiliximab in haploidentical, unmanipulated bone marrow recipients. Anti-infectious management, transfusion policy, and supportive care were identical for all patients. By comparing the 2 patient series, no statistically significant difference was observed for the cumulative incidence of advanced acute and extensive chronic GVHD, transplant-related mortality, and relapse. With a median follow-up of 3.5 years, the 5-year disease-free survival was 37% ± 6% and 36% ± 6% for HLA identical sibling and haploidentical recipients, respectively. The results of transplant from HLA identical siblings and haploidentical donors are comparable. Regardless of the HLA matching, other factors known to affect the transplant outcomes, such as donor-recipient age, sex, and CMV status combinations, might drive the search for the best donor.

Current Status and Future Directions in Graft-Versus-Host Disease Prevention Following Allogeneic Blood and Marrow Transplantation in Adults

Graft-versus-host disease (GvHD) in its acute and chronic forms continues to represent a significant barrier to the success and wide-applicability of blood and marrow transplantation as a potentially curative treatment modality for a number of benign and malignant blood conditions. Presently, calcineurin inhibitor (CNI)-based regimens remain the most commonly used prevention strategy, although post-transplant cyclophosphamide is emerging as an alternative approach, and is providing a backbone for innovative CNI-free combinations. In this paper, we review the current strategies used for the prevention of GvHD, and highlight some of the developing and promising combinations.

Clinical applications of donor lymphocyte infusion from an HLA-haploidentical donor: consensus recommendations from the Acute Leukemia Working Party of the EBMT

Donor lymphocyte infusion has been used in the management of relapsed hematologic malignancies after allogeneic hematopoietic cell transplantation. It can eradicate minimal residual disease or be used to rescue a hematologic relapse, being able to induce durable remissions in a subset of patients. With the increased use of haploidentical hematopoietic cell transplantation, there is renewed interest in the use of donor lymphocytes to either treat or prevent disease relapse post transplant. Published retrospective and small prospective studies have shown encouraging results with therapeutic donor lymphocyte infusion in different haploidentical transplantation platforms. In this consensus paper, finalized on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we summarize the available evidence on the use of donor lymphocyte infusion from haploidentical donor, and provide recommendations on its therapeutic, pre-emptive and prophylactic use in clinical practice.

Haploidentical transplantation might have superior graft-versus-leukemia effect than HLA-matched sibling transplantation for high-risk acute myeloid leukemia in first complete remission: a prospective multicentre cohort study

This study aimed to investigate graft-versus-leukemia (GVL) of haploidentical donor (HID) compared with HLA-matched sibling donor (MSD) for high-risk acute myeloid leukemia (H-AML) in first complete remission (CR1). One hundred and eighty-nine patients with H-AML in CR1 were enrolled in this multicentre prospective cohort study. Patients were assigned to groups transplanted with HID (n = 83) or MSD (n = 106) based on donor availability (biological randomization). The primary endpoint was the incidence of MRD positivity posttransplantation (post-MRD+). All post-MRD+ patients received preemptive interventions. The cumulative incidences of post-MRD+ were 18 and 42% in HID and MSD groups, respectively, (p < 0.001). Fifty-two patients received preemptive DLI, including 13 (16%) in HID and 39 cases (37%) in MSD groups (p = 0.001). Among HID and MSD groups, the 3-year cumulative incidence of relapse were 14 and 24% (p = 0.101); the 3-year cumulative incidence of treatment-related mortality were 15 and 10% (p = 0.368); the 3-year overall survival rates were 72 and 68% (p = 0.687); the 3-year disease-free-survival were 71 and 66% (p = 0.579); the 3-year graft-versus-host disease and relapse free survival were 63 and 43% (p = 0.035), respectively. HID might have a stronger GVL than MSD in H-AML patients. HID transplantation as postremission therapy should be recommended as one of the optimal choices for H-AML patients in CR1.

Haploidentical transplantation for acute myeloid leukemia patients with minimal/measurable residual disease at transplantation

There have been conflicting results regarding the impact of minimal/measurable disease at transplant on acute myeloid leukemia (AML) outcomes after haploidentical transplantation (haplo-SCT). We assessed the impact of pre-transplant disease status on post-transplant outcomes of 143 patients treated with haplo-SCT using fludarabine-melphalan (FM) conditioning and post-transplant cyclophosphamide (PTCy). With a median follow-up of 29 months, the two-year PFS for all patients was 41%. Compared to patients in complete remission (CR) at transplant, those with active disease (n = 29) and CR with incomplete count recovery (CRi) (n = 39) had worse PFS. They had hazard ratios (HR) of 3.5 (95% CI: 2.05-6.1; P < .001) and 2.3 (95% CI: 1.3-3.9; P = .002), respectively. Among patients who were in CR at transplant, there were no differences in PFS between those who had minimal residual disease (MRD) positive (n = 24), and MRD negative (n = 41) (HR 1.85, 95%CI: 0.9-4.0; P = .1). In multivariable analysis for patients in CR, only age was predictive for outcomes, while MRD status at transplant did not influence the treatment outcomes. Our findings suggest that haplo-SCT with FM conditioning regimen and PTCy-based GVHD prophylaxis has a protective effect, and may potentially abrogate the inferior outcomes of MRD positivity for patients with AML. Patients with positive MRD may benefit from proceeding urgently to a haplo-SCT, as this does not appear to negatively impact transplant outcomes.

[Clinical observation of 12 patients with refractory/relapsed acute myeloid leukemia treated with allogeneic hematopoietic stem cell transplantation containing cladribine regimen]

Objective: To investigate the safety and efficacy of allogeneic hematopoietic stem cell transplantation (allo-HSCT) containing cladribine sequential busulfan regimen for refractory/relapsed acute myeloid leukemia (AML) . Methods: The clinical data of 12 refractory/relapsed AML patients received allo-HSCT with cladribine sequential busulfan regimen. Results: ① Of the 12 patients, 9 were males and 3 females, with a median age of 36 (27-50) years. The donors were identical sibling (3) , matched unrelated (1) and haploidentical family member (9) respectively. Nine patients reached partial remission and other remained no remission after chemotherapy before allo-HSCT. The median previous chemotherapy courses before allo-HSCT were 6 (2-13) . ② Conditioning regimen: Smostine 250 mg·m(-2)·d(-1), d-7; Cladribine 5 mg·m(-2)·d(-1), d-6 to d-2; Cytarabine Arabinoside 2 g·m(-2)·d(-1), d-6 to d-2; Busulfan 3.2 mg·m(-2)·d(-1), d-6 to d-3; Rabbit anti-human thymocyte immunoglobulin (ATG) 1.5 mg·m(-2)·d(-1) (unrelated donor transplantation) or 2.0-2.5 mg·m(-2)·d(-1) (haplo-HSCT) , d-4 to d-1. ③ Of the 12 patients, 11 patients attained complete haploidentical engraftment, one case occurred primary graft failure. The median durations for neutrophils and platelet implantations were 15 (15-21) and 19 (17-30) days respectively. ④After conditioning, no hepatic veno-occlusive diseases were observed, hemorrhagic cystitis occurred in 2 patients, 8 patients had fever, 3 cases experienced acute GVHD grade II, localized chronic GVHD occurred in 8 patients. ⑤The median follow-up was 8 (4-12) months. Leukemia relapse occurred in 2 patients at time of 6, 12 months after allo-HSCT. The estimated 1-year OS and DFS were (71.1±1.8) % and (62.2±1.8) %, respectively. Conclusions: allo-HSCT with cladribine sequential busulfan regimen was a feasible choice with favorable outcome for refractory/relapsed AML.

Conditioning Regimen of 5-Day Decitabine Administration for Allogeneic Stem Cell Transplantation in Patients with Myelodysplastic Syndrome and Myeloproliferative Neoplasms

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment for patients with myelodysplastic syndromes (MDS) and myelodysplastic/myeloproliferative neoplasms (MDS/MPN). However, post-HSCT relapse remains a major cause of treatment failure. Here we assessed the efficacy of a new conditioning regimen comprising decitabine (Dec), busulfan (Bu), cyclophosphamide (Cy), fludarabine (Flu), and cytarabine (Ara-c) for allo-HSCT in patients with MDS and MDS/MPN. A total of 48 patients were enrolled, including 44 with MDS and 4 with chronic myelomonocytic leukemia (CMML). Patients received Dec 20 mg/m²/day on days -9 to -5, combined with a Bu/Cy/Flu/Ara-c-modified preparative regimen. At a median follow-up of 522 days (range, 15 to 1313 days), the overall survival (OS) was 86%, relapse incidence was 12%, and nonrelapse mortality was 12%. The incidence of severe acute (grade III-IV) graft-versus-host disease (GVHD) was 23% and that of chronic GVHD was 15%. At 2 years, OS was 74% and 86%, respectively for high-risk and very-high-risk patients with MDS. Survival was promising in patients with poor-risk gene mutations, such as TP53 and ASXL1 (88%), and in those with ≥3 gene mutations (79%). Results of immunomonitoring studies revealed that proper natural killer cells made essential contributions to these favorable clinical outcomes. Overall, this new regimen was associated with a low relapse rate, low incidence and severity of GVHD, and satisfactory survival in allo-HSCT recipients with MDS and MDS/MPN.

Increased risk of 100-day and 1-year infection-related mortality and complications in haploidentical stem cell transplantation

Background: While haploidentical transplantation has led to the near-universal availability of donors, several challenges for this form of transplant still exist. This study sought to investigate the rates of infection-related mortality and other complications following haploidentical vs nonhaploidentical transplant. Methods: We conducted a retrospective cohort study in adults with various malignant and benign hematological conditions who underwent allogeneic hematopoietic stem cell transplantation from 2011 to 2018. One hundred-day and 1-year overall survival were defined as survival from the time of transplant until 100 days or 1 year later. Results: A total of 187 patients were included in this study, with 45 (24.1%) receiving transplants from haploidentical donors and 142 (75.9%) from nonhaploidentical donors. There were similar rates of acute graft-versus-host disease (GVHD) (40% vs 38% in haploidentical vs nonhaploidentical recipients, P=0.86) and chronic GVHD (44.4% vs 43.7%, P=1). Rates of 100-day and 1-year infection-related mortality were significantly higher in the haploidentical group compared to the nonhaploidentical group (8.9% vs 1.4% at 100 days, P=0.03, and 15.9% vs 3.8% at 1 year, P=0.01). There were also higher rates of cytomegalovirus infections (59.1% vs 23.8%, P<0.01), BK virus-associated hemorrhagic cystitis (40.9% vs 8.4%, P<0.01), and BK viremia (15.9% vs 0.8%, P<0.01) in haploidentical recipients. Conclusions: Despite the use of identical antimicrobial prophylactic and treatment agents, haploidentical recipients were found to have significantly increased rates of 100-day and 1-year infection-related mortality as well as several other infectious complications.

The consensus on the monitoring, treatment, and prevention of leukemia relapse after allogeneic hematopoietic stem cell transplantation in China

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an important curative therapy for patients with leukemia. However, relapse remains the leading cause of death after transplantation. In recent years, substantial progress has been made by Chinese physicians in the field of establishment of novel transplant modality, patient selection, minimal residual disease (MRD) monitoring, and immunological therapies, such as modified donor lymphocyte infusion (DLI) and chimeric antigen receptor T (CART) cells, as well as MRD-directed intervention for relapse. Most of these unique systems are distinct from those in the Western world. In this consensus, we reviewed the efficacy of post-HSCT relapse management practice from available Chinese studies on behalf of the HSCT workgroup of the Chinese Society of Hematology, Chinese Medical Association, and compared these studies withthe consensus or guidelines outside China. We summarized the consensus on routine practices of post-HSCT relapse management in China and focused on the recommendations of MRD monitoring, risk stratification directed strategies, and modified DLI system. This consensus will likely contribute to the standardization of post-HSCT relapse management in China and become an inspiration for further international cooperation to refine global practices.

Efficacy and Safety of Unmanipulated Haploidentical Related Donor Allogeneic Peripheral Blood Stem Cell Transplantation in Patients with Relapsed/Refractory Acute Myeloid Leukemia

Background:

Studies of haploidentical-related donor (HRD) stem cell transplantation using a combination of peripheral blood stem cells (PBSCs) and bone marrow as the graft have reported encouraging results for patients with hematological diseases. However, few studies specifically reported transplantation of only PBSCs from HRDs among patients with relapsed or refractory acute myeloid leukemia (AML). Here, the long-term outcomes and side effects of unmanipulated HRD PBSC transplantation (HRD-PBSCT) for relapsed/refractory AML were analyzed.

Methods:

We performed a retrospective analysis of the outcomes in relapsed/refractory AML patients who underwent PBSCT from HRDs (n = 36).

Results:

Thirty-one (86.1%) patients in the HRD-PBSCT group achieved platelet recovery. The cumulative incidence of acute graft-versus-host disease (aGVHD) in the HRD-PBSCT group was 40.00%, and the cumulative incidence of grades 2–4 aGVHD in this group was 13.33%. A total of 13 patients in the HRD-PBSCT group had recurrent disease at a median of 183 days after transplantation (range: 10–1700 days), reaching cumulative incidences of relapse of 50.28% at 5 years. On multivariate analysis, donor age and patient age >40 years were independent risk factors for inferior disease-free survival or overall survival (P < 0.05). The results of the present study demonstrate rapid and complete neutrophil engraftment, a low incidence of grade 2–4 aGVHD, and promising survival rates in patients after HRD-PBSCT. Thus, granulocyte colony-stimulating factor–primed PBSCs may be a reliable graft source in unmanipulated HRD-HSCT under myeloablative conditioning when no matched sibling donor is available.

Conclusions:

Our results support the feasibility, effectiveness, and tolerability of PBSCs as a graft source in unmanipulated HRD transplantation under myeloablative conditioning in patients with leukemia.