Haploidentical Peripheral Blood Stem Cell Research Articles

Outcomes of haploidentical peripheral blood stem cell transplantation following myeloablative conditioning using two types of rabbit ATG: a propensity score-matched analysis.

During hematopoietic stem cell transplantation (HSCT), ATG depletes T cells in-vivo to improve engraftment and prevent graft-versus-host disease (GVHD). Here, we compared the clinical efficacy of two different types of ATGs: thymoglobulin and anti-human T-lymphocyte immunoglobulin (Grafalon). A total of 469 patients who received haploidentical transplantation were enrolled in this retrospective study. We applied a propensity score (PS)-matched analysis and 209 patients were assigned to each group. Clinical outcomes were compared between two groups and primary outcome was overall survival (OS). There was no significant difference in OS between two groups. Within the first 180days after HSCT, Grafalon was associated with lower incidences of Epstein-Barr virus (EBV) viremia (31.6 vs. 54.5%, P < 0.0001) and cytomegalovirus viremia (CMV) viremia (54.5 vs. 67.9%, P = 0.005) compared to thymoglobulin. Patients receiving Grafalon had a higher rate of moderate/severe chronic GVHD (26.3 vs. 18.2%, P = 0.046). However, the incidences of engraftment failure, grade II-IV acute GVHD, relapse, non-relapse mortality (NRM), and GVHD-free relapse-free survival (GRFS) did not differ greatly between groups. In the subgroup analysis, Grafalon improved the OS of lymphoid malignancies with young ages (< 40years old) (HR, 0.55; P = 0.04) or with a high/very high disease risk index (HR, 0.36; P = 0.04). In the myeloid cohort, Grafalon reduced NRM in the patients who received non-female for male transplantation grafts (HR, 0.17; P = 0.02). Our results suggest the two types of ATG may differentially influence transplant outcomes and it may optimize ATG selection according to the condition of patients.

Establishment of acute graft-versus-host disease model after non-myeloablative haploidentical peripheral blood stem cell transplantation in aged mice

Objective: To establish an acute graft-versus-host disease (aGVHD) model in aged mice after non-myeloablative haploidentical peripheral blood stem cell transplantation (haplo-PSCT). Methods: C57BL/6 (H-2b) male mice aged 6-8 weeks were used as donor mice, and CB6F1 (H-2b×d) female mice aged 14-16 months were used as recipient mice. The donor mice were injected subcutaneously with rehuman granulocyte-colony stimulating factor (rhG-CSF) 5 days before transplantation for hematopoietic stem cell mobilization.The recipient mice were divided into control group (CG), spleen cell low-dose group (SL), spleen cell medium-dose group (SM) and spleen cell high-dose group (SH) according to random number table method, with 16 rats in each group, all of which received total linear accelerator X-ray irradiation (TBI) with a total dose of 6 Gy. Peripheral blood mononuclear cells (PBMC) and spleen cells of different doses (0.5×107/each, 1.0×107/each and 2.0×107/each in SL group, SM group and SH group, respectively) were transfused through the tail vein within 4 hours after TBI, and only the same amount of normal saline was transfused in CG group. After transplantation, the survival and weight changes of mice in each group were observed for 30 days, and the changes of blood routine were monitored regularly. Mice peripheral blood was collected 21 days after transplantation to detect the chimerism rate of the donor. Hematoxylin-eosin staining was performed on the skin, liver and colon of mice 21 days after transplantation to analyze the histopathological changes of aGVHD target organs. Results: All the mice in each group were successfully transplanted. After TBI, the weight and activity of mice in all groups decreased, and the phenomenon of bone marrow suppression appeared. During the observation period, all mice in CG group and SL group survived, 3 mice in SM group died with survival time of (26.0±5.8) days, and 6 mice in SH group died with survival time of (20.9±7.3) days. The body weight of mice in SH group was lower than that in CG group, SL group and SM group 21days after transplantation [(25.0±0.7), (25.5±0.4), (25.0±1.4) vs (20.8±0.8) g, all P<0.05]. Compared with CG group, SL group and SM group, the levels of leukocyte, erythrocyte, hemoglobin and platelet in SH group decreased 21 days after transplantation (all P<0.05). There was no significant difference in donor chimerism rate among SL group, SM group and SH group [(95.8%±0.8%), (95.5%±1.4%) and (95.1%±1.3%), respectively, all P>0.05]. Compared with CG group, SL group and SM group, the tissue structure of aGVHD target organs in SH group was severely damaged, with a large number of inflammatory cells infiltratedand higher histopathological scores than SL group and SM group (all P<0.05). Conclusion: For aging CB6F1 mice, after 6 Gy TBI pretreatment with linear accelerator X-ray, PBMC (1×107/each) and spleen cells (2.0×107/each) were injected to successfully induce aGVHD model after non-myelablative haplo-PSCT.

Graft CD8 T-cell-based risk system predicts survival in antithymocyte globulin-based myeloablative haploidentical peripheral blood stem cell transplantation.

This study investigated the cellular composition of peripheral blood grafts for anti-thymocyte globulin (ATG)-based myeloablative haploidentical haematopoietic stem cell transplantation (haplo-HSCT). Clinical characteristics were retrospectively evaluated in a training cohort with ATG-based myeloablative haplo-HSCT between January 2016 and February 2020 and confirmed in a validation cohort between March 2020 and June 2021. A higher dose of graft CD8+ T cells (≥ 0.85 × 108 kg-1) was significantly improved overall survival (OS;hazard ratio [HR], 1.750; P = 0.002) and disease-free survival (DFS; HR, 1.751; P < 0.001) in the training cohort, according to multivariate Cox regression analysis. Higher doses of mononuclear cells (MNCs) demonstrated better OS (HR, 1.517; P = 0.038) and DFS (HR, 1.532; P = 0.027). Older patient age (> 46 years), older donor age (≥ 50 years) and a higher refined disease risk index (rDRI) were also related to OS. A graft CD8+ T-cell risk system based on graft CD8+ T-cell dose, donor age and rDRI was constructed using a nomogram model after LASSO Cox regression analysis. It showed acceptable discrimination, with a C-index of 0.62 and 0.63, respectively. Graft CD8+ T-cell dose was negatively correlated with donor age (P < 0.001) and positively correlated with a higher lymphocyte percentage in the peripheral blood before mobilisation (P < 0.001). A higher CD8+ T-cell dose in peripheral blood-derived grafts improves patients' survival with ATG-based myeloablative haplo-HSCT. Younger donors with higher lymphocyte percentages improved patients' survival with an intermediate rDRI risk.

Impact of CD34 positive cell dose in donor graft on the outcomes after haploidentical peripheral blood stem cell transplantation with post-transplant cyclophosphamide – A retrospective single-center study with a Japanese cohort

BackgroundHaploidentical peripheral blood stem cell transplantation (haplo-PBSCT) with post-transplant cyclophosphamide (PTCy) is an important therapeutic option for patients lacking an HLA-matched donor. However, the significance of CD34+ cell dose in grafts has not been fully elucidated. ObjectiveWe aimed to explore the impact of CD34+ cell dose on outcomes after haplo-PBSCT with PTCy. Study DesignWe retrospectively investigated 111 consecutive patients who underwent haplo-PBSCT with PTCy or HLA-matched PBSCT from related donors. ResultsThere were no statistically significant differences in 3-year overall survival (p = 0.559) or progression-free survival (p = 0.974) between haplo-PBSCT and matched PBSCT. Delayed neutrophil engraftment and a lower incidence of graft-versus-host disease were observed in haplo-PBSCT. The median dose of CD34+ cells was 4.9 × 106 /kg in 57 haplo-PBSCT and 4.5 × 106 /kg in 54 matched PBSCTs. Importantly, patients who underwent haplo-PBSCT with the administration of CD34+ cell at a dose of ≥4.0 × 106 /kg significantly had improved OS (p = 0.015) and decreased incidence of disease relapse (p = 0.001) without increasing incidence of GVHD. ConclusionOur data suggest that a higher dose of CD34+ cells in haplo-PBSCT with PTCy positively impacts the outcomes without an increase of GVHD.

ABO Incompatibility Haploidentical Peripheral Blood Stem Cell Transplantation Combined with a Single Cord Blood Unit for Severe Aplastic Anemia Patients

Background: For young severe aplastic anemia (SAA) patients without HLA matched donors, haploidentical hematopoietic stem cell transplantation can be used as an alternative selection. The grafts of classic Beijing protocol in China is a combination of bone marrow and peripheral blood stem cell. For patients with major or minor blood type incompatibility, bone marrow stem cells need to undergo red blood cell or plasma removal treatment. There was rare reports about haploidentical peripheral blood stem cell combined with a single unrelated cord blood unit for ABO incompatibility haploidentical stem cell transplantation in SAA patients. Objective: To observe the efficacy of ABO incompatibility haploidentcial peripheral blood hematopoietic stem cell transplantation combined with a single unrelated cord blood unit for SAA patients. Method s : Fifty-five SAA patients underwent stem cell transplantation from August 2018 to February 2022 in the First Affiliated Hospital of Xi'an Jiaotong Univeristy were divided into two groups based on donor-recipient ABO compatibility, the donor-recipient ABO matched group（BM+PB group）using haploidentical bone marrow and peripheral blood stem cell as grafts, and donor-recipient ABO mismatched group（CB+PB group）, using unrelated cord blood and haploidentical peripheral blood stem cell as grafts. The differences of hematopoietic reconstitution, acute and chronic GVHD, CMV and EB virus infection, PFS, and OS between the two groups were compared. Result s : There were 30 cases in CB+PB group and 27 cases in the BM+PB group. Except for differences in donor-recipient ABO compatibility, the other characteristics of the two groups of patients were comparable((P&amp;gt;0.05). One patient in the BM+PB group had primary graft failure, while the rest of the patients were successfully implanted. There were no significant statistical differences in neutrophil,platelet and red blood cells recovery rates, the incidence of acute and chronic GVHD, CMV, EB virus infection, and PTLD between the two groups of patients(P&amp;gt;0.05). There was no significant statistical difference in OS between the two groups of patients(P&amp;gt;0.05)(Figure 1). Conclusion: For SAA patients with donor-recipient ABO incompatibility could use haploidentical peripheral blood cell combined with unrelated cord blood for transplantation which had compared outcome with haploidentcal bone marrow and peripheral blood cell transplantation.

T-Cell Depletion with Both Reduced Dose Anti-Thymocyte Globulin and Reduced Dose Post-Transplant Cyclophosphamide in Haploidentical Peripheral Blood Stem Cell Transplantation for Acute Leukemia and Myelodysplatic Syndrome

Graft-versus-host disease (GVHD) prophylaxis in allogeneic hematopoietic stem cell transplantation from HLA haplo-identical familial donor (haplo-HSCT) is based on in vivo T-cell depletion with either anti-thymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). ATG has made significant contributions to enabling haplo-HSCT. However, the benefit of ATG may be often mitigated by higher risk of viral reactivation, including cytomegalovirus (CMV) and Epstein-Barr virus (EBV) due to a slower immune reconstitution. PTCy revolutionized HLA-mismatched HSCT and rapidly became the standard-of-care. However, it also has problems due to a cytokine release syndrome (CRS) -like symptoms and excessive cytotoxicity leading to the risk of acute cardiotoxicity and the possibility of alleviated graft-versus-leukemia effect. Considering a demand for more optimal in vivo T-cell depletion, we tried to combine both ‘lower-dose’ ATG and ‘lower-dose’ PTCy before and after stem cell infusion, respectively, hoping they can mitigate their individual limitations while maintaining the effectiveness of in vivo T-cell depletion. We retrospectively included 60 adults with acute leukemia or myelodysplastic syndrome who underwent haplo-HSCT following busulfan (3.2 mg/kg/day for 4 days as myeloablative and for 2 days as reduced intensity conditioning) and fludarabine (a total of 160 mg/m 2) between January 2019 and June 2023. Among them, 32 received a novel combination of ATG (a total of 3.0, 3.5, or 4.0 mg/kg depending on the absolute lymphocyte count level on days -3) and PTCy (50mg/kg on day +3 and 30mg/kg on day +4) compared to 28 patients who received ATG only (2.5 mg/kg/day from days -3 to -1, a total of 7.5 mg/kg) as in vivo T-cell depletion. Most patients received cyclosporine and mycophenolate mofetil as GVHD prophylaxis. The median follow-up duration for all patients was 8 months (median 9 months in the ATG/PTCy group and 7.5 months in the ATG group, respectively; P = 0.744). Baseline characteristics including age, sex, disease status, modified EBMT score, and the intensity of conditioning, were well-balanced except slightly higher infused CD34+ cells in the ATG/PTCy group (median 5.2 vs. 4.7 x 10 6/kg, P = 0.042). The cumulative incidence of acute GVHD at day +100 and moderate to severe chronic GVHD at 1 year were significantly lower in the ATG/PTCy group compared to the ATG group, respectively [grades II-IV acute GVHD: 20.4% (95% confidence interval [CI], 4.3-33.8%) vs. 48.4% (95% CI, 25.2-64.4%), P = 0.014; grades III-IV acute GVHD: 7.5% (95% CI, 0-17.1%) vs 31.1% (95% CI, 10.5-46.9%), P = 0.019; and moderate to severe chronic GVHD: 9.5% (95% CI, 0-21.2%) vs. 60% (95% CI, 23.3-79.1%), P = 0.007]. The ATG/PTCy group had a tendency of less incidence and severity of the haplo-fever. Multivariate analysis showed a significantly higher GRFS (hazard ratio 0.35, P = 0.002) and OS (hazard ratio 0.4, P = 0.014) for an ATG/PTCy group. The use of dual T-cell depletion with the reduced dose ATG in combination with the reduced dose PTCy showed a significantly superior early transplant outcome over with ATG of 7.5 mg/kg in terms of both GVHD and survival outcomes.

A Novel Post-Transplant Regimen for Selectively Promoting Unrelated Cord Blood Engraftment in Haploidentical-Cord Transplantation in Childhood Leukemia: A Single-Arm, Dual-Center Trial

Background Our previous studies indicated that complementary transplantation that was combined with a haploidentical peripheral blood stem cell (PBSC) transplant (haplo-SCT) and unrelated cord blood (UCB) transplant using a post-transplant cyclophosphamide (PTCy) regimen was applicable in children with acute leukemia. A better leukemia-free survival (LFS) was found in the UCB engraftment group, however, the engraftment of PBSC or UCB was unpredictable in the setting of complementary transplantation. Here, we conducted a prospective single-arm dual-center trial to investigate the effect of post-transplant cyclophosphamide plus fludarabine regimen for selectively promoting UCB engraftment in haploidentical-cord transplant. Methods This updated conditioning regimen was performed in two hospitals in China, including a total of eligible 78 pediatric patients who were enrolled from September 2019 to October 2022. The median follow-up was 24 months. This study is in progress. Meanwhile, 55 historically consecutive patients from December 2012 to June 2019 were included for comparison. The updated conditioning regimen (PT-Cy/Flu group) consisted of fludarabine (40mg/m 2, d-5 to d-3 and d+3, d+4), busulfan (100mg/m 2, d-6 to d-3), haplo-PBSC (d0), PTCy (50mg/kg, d+3, d+4) and UCB (d+6). The fludarabine was applied at d-6 to d-2 in the original conditioning regimen (PT-Cy group). In addition to PTCy, tacrolimus or cyclosporine and mycophenolate mofetil were administered as prophylaxis of GVHD. The primary aim was the UCB engraftment rate. In addition, the 2-year mid-term inspection included overall survival (OS), LFS, non-relapse mortality (NRM), graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS), and cumulative incidence of acute and chronic GVHD. Results The characteristic of patients were shown in Table 1. In brief, 47 (60.3%) acute myeloid leukemia and 27 (34.6%) acute lymphoblastic leukemia pediatric patients were included. 64 (82.1%) patients achieved first complete remission (CR1) before SCT. The median of PBSC mononuclear cells was 20.0×10 8/kg and CD34 + cells was 12.1×10 6/kg, while the median of CB total nuclear cells was 5.0×10 7/kg and CD34 + cells was 1.8×10 5/kg. Eventually, 73 (93.6%) patients in the PT-Cy/Flu group achieved full UCB engraftment by short tandem repeat (STR) detection, while the UCB engraftment rate was 24 (43.6%) in the PT-Cy group (p&amp;lt;0.001). The OS of the PT-Cy/Flu group was 88.6% ± 4.0% (95%CI 81.2% - 96.7%), which was significantly higher than the PT-Cy group [60.0% ± 6.6% (95%CI 48.4% - 74.5%), p&amp;lt;0.001] (Figure 1A). Of note, the LFS was markedly higher in the PT-Cy/Flu group compared to PT-Cy group [83.2% ± 4.3% (95%CI 75.2% - 92.0%) vs. 54.2% ± 6.8% (95%CI 42.4% - 69.2%), p&amp;lt;0.001] (Figure 1B). However, there was no statistical difference in NRM between the PT-Cy/Flu and PT-Cy groups (7.7% ± 0.1% vs 12.7% ± 0.2%, p=0.326). Moreover, similar cumulative incidence of III-IV acute GVHD and severe chronic GVHD were found between groups (Figure 1C, D). Finally, the GRFS of the PT-Cy/Flu was obviously better than the PT-Cy group [70.1% ± 5.9% (95%CI 59.5% - 82.5%) vs 39.4% ± 7.6% (95%CI 27.0% - 57.5%), p=0.025] (Figure 1E). Conclusion These results suggested that the novel post-transplant cyclophosphamide plus fludarabine regimen can be considered as a strategy for selectively facilitating UCB engraftment and improving LFS in haploidentical-cord transplant in children with acute leukemia.

Haploidentical Hematopoietic Stem Cell Transplantation with Post-Transplant Cyclophosphamide in the Chilean National Health System. a Single Center Study

Haploidentical peripheral blood stem cell transplantation with post-transplant cyclophosphamide (Haplo-PTCy) is the most common transplantation modality in low-and-middle-income countries (LMIC). Registry data has shown comparable outcomes when using haploidentical donors versus Matched Unrelated Donors (MUD) in patients with acute leukemias. In the Chilean Public Health System Haplo-PTCy was incorporated in 2016 for adults up to 60 years old. We analyzed all adult patients who received an Haplo-PTCy at Hospital del Salvador, in a prospective registry study between 2016 and 2021. The primary outcome was overall survival (OS). Secondary outcomes were event-free survival (EFS), cumulative incidence of relapse, and incidence of grade II-IV acute graft-versus-host disease (aGVHD) at day +100. Overall survival and EFS were estimated using the Kaplan-Meier method. The cumulative incidence of relapse was calculated using relapse as the primary event and death without relapse as a competing event. Acute GVHD is shown as absolute incidence at day +100. All statistical analyses were performed with R. This study was done in compliance with the Helsinki Declaration and was approved by the Institutional Review Board. Eighty-five Haplo-PTCy were performed in 82 patients (Table 1). Three-second Haplo-PTCy were excluded from this analysis. The median age was 25 years (range, 15-51), and 65% were male. Ninety-four percent of patients had a neoplastic disease (77/82), and the most common diagnosis was acute lymphoblastic leukemia (57%). Forty-seven percent proceeded to transplant in the first complete response. Most of the patients (76%) presented a low hematopoietic cell transplantation (HCT)-specific comorbidity index. Conditioning was mostly myeloablative (96%). The median dose of CD34+ cells infused was 8.1 x 106/kg (range, 2.4-10.0). No patient needed a desensitization regimen. Cytokine release syndrome (CRS) was common (86%) but no grade 3 CRS was observed. Primary graft failure was observed in one patient (1.2%). Poor graft function was observed in 11 patients (13%). Five patients (6.1%) died before engraftment. The incidence of grade II-IV aGVHD at day +100 was 29% (grade IV was not observed). With a median follow-up of 33 months (range 0-84), the estimated 3-year OS and EFS were 68.3% (95% CI 59-79%) and 64.6% (95% CI 55-76%), respectively (Figure 1). In patients with neoplastic disease (n=77), the 3-year cumulative incidence of relapse was 23% (95% CI 15-33%). Haplo-PTCy is feasible in LMIC. This cohort of cases, mostly young patients with neoplastic disease, shows encouraging survival with an acceptable aGVHD and relapse incidence.

UM171 Expanded Cord Blood Transplantation Outcomes Compare Favorably to All Different Stem Cell Sources: An EBMT Registry Case-Control Analysis

Background: Cord blood (CB) transplantation (CBT) has several advantages compared with other graft sources, such as permissive human leucocyte antigen (HLA) mismatches, and low risk of chronic graft-versus-host disease (GVHD) and relapse. However, CBT has fallen into disfavor because of its high risk of non-relapse mortality (NRM) and prolonged hospitalization due to its low cell dose. Furthermore, the need for the rare large cord bloods (CBs) leads to selection of poorly HLA-matched CBs, known to further increase NRM. UM171 is a small molecule that expands hematopoietic stem cells. A phase I-II study of a single UM171-expanded, myeloablative and reduced intensity CBT for patients with high-risk hematologic malignancies who lacked a donor, demonstrated prompt neutrophil engraftment, the ability to use smaller, better HLA-matched CBs, and a low NRM of 5% (Cohen S et al. Lancet Haematol 2020). The aim of the current analysis was to compare outcomes after a UM171 CBT to real-world cohorts of 6 other stem cell sources identified in the European Society for Blood and Marrow Transplantation (EBMT) registry. Methods: This is a retrospective study comparing 22 adults who received a single UM171-expanded CBT in the phase I-II study between 2016-2018, to 6 cohorts of patients allografted from different stem cell sources and reported to the EBMT registry. Control patients were eligible if they had received a myeloablative or reduced intensity allogeneic transplant for a hematologic malignancy in Europe during 2010-2021, were between the ages of 18-65 years, and had a Karnofsky performance status (KPS) score ≥70. The different donor control cohorts were: 1) CB, single or double units, with a calcineurin inhibitor (CNI) and mycophenolate mofetil (MMF) for GVHD prophylaxis, 2) 10/10 HLA-matched unrelated donor (MUD) peripheral blood stem cells (PBSC) with a CNI and MMF or methotrexate (MTX), 3) 10/10 MUD bone marrow (BM) with a CNI and MMF or MTX, 4) 9/10 HLA-MUD BM or PBSC (9/10 UD), 5) T cell replete haploidentical donor (haplo) BM or PBSC, and 6) matched sibling donor (MSD) BM or PBSC. Exclusion criteria included in vitro manipulated grafts and CBT recipients who received anti-thymocyte globulin or alemtuzumab. Patients were directly matched for disease and status at transplant and propensity score matching was used for prior allograft, age, KPS, and conditioning regimen. Endpoints included engraftment, GVHD, NRM, relapse, progression-free survival (PFS), overall survival (OS), and GVHD-free relapse-free survival (GRFS). The EBMT attempted to identify 3 controls for each patient. If no control was identified for a UM171 patient, the latter was excluded from the analysis. Results: Between 17 and 21 UM171 CB patients were compared to 36 to 62 controls depending on the donor group as 1-3 controls could not be identified for each patient (Table 1). Median follow-up for the UM171 group was 36 months and generally longer for the controls. Neutrophil engraftment with UM171 CB was similar to all donor groups except slower for CB and MUD BM. Platelet engraftment was consistently slower for UM171 CB except when compared to conventional CB. The incidence of severe acute GVHD was similar across all donor groups. As there was no severe chronic GVHD in the UM171 group, the latter was associated with less extensive/severe chronic GVHD compared to MUD (PBSC and BM) and MSD. There was a trend towards lower NRM for UM171 CB compared to haplo and 9/10 UD but it did not reach statistical significance. PFS, OS and GRFS were all better with UM171 CB compared to haplo. Finally, GRFS was improved with UM171 CB when compared to MUD PBSC (Figue 1), 9/10 UD, and MSD. Conclusions: This registry matched case-control analysis demonstrated real-word evidence suggesting UM171-expanded CBT recipients have improved outcomes compared to other donor types. More specifically and due to the absence of severe chronic GVHD with UM171 CB, GRFS was better with UM171 CB when compared to other graft sources except for CB and MUD BM. Also, OS and PFS were superior with UM171 CB compared to haplo donors. Limitations of this study included the small number of UM171 patients, the inability to identify controls for each case, and certain missing data for the controls. UM171 expansion of CB appeared to achieve the desired outcome of maintaining benefits of CB while removing its disadvantages. Thus, prospective randomized studies are warranted to confirm these results.

Incidence, Risk Factors, Characteristics, and Outcome of Chronic Graft Versus Host Disease in Children Undergoing Haploidentical Peripheral Blood Stem Cell Transplant With Post-transplant Cyclophosphamide.

Chronic graft versus host disease (cGVHD) is a major cause of morbidity postallogeneic peripheral blood stem cell transplant (PBSCT). There is paucity of literature describing incidence, risk factors, characteristics, and outcome of cGVHD in children undergoing haploidentical PBSCT with post-transplant cyclophosphamide (PTCy). Here, we describe our experience from our center regarding the same. All children who underwent haploidentical PBSCT with PTCy between January 2016 and December 2021 at our center and survived beyond day+100 post-transplant were included in this retrospective study. Conditioning regimens used were: Thiotepa-Fludarabine-Cyclophosphamide with 2Gy single fraction total body irradiation, Thiotepa-Busulfan-Fludarabine, Fludarabine-total body irradiation and Fludarabine-Melphalan. Peripheral blood was used as stem cell source in all patients. GVHD prophylaxis was PTCy 50mg/kg on day +3 and +4, Mycophenolate mofetil and Calcineurin inhibitors. Clinical and laboratory data was electronically retrieved and analyzed based on National Institute of Health Consensus Criteria-2014 at regular intervals. Impact of various patient, donor, and transplant-related factors on development of cGVHD were analyzed. Incidence of relapse, event free survival (EFS) and overall survival (OS) were calculated and compared between cGVHD and no cGVHD groups. Patients with rejection were excluded from risk factor analysis for cGVHD but were considered for survival analysis. Fifty-one children included in this study. Median age of transplant of our cohort was 7.5 years with male:female=1.6:1. Eight patients had rejection with autologous recovery. History of acute GVHD (aGVHD) was present in 15/51 (Grade III to IV in 7/51). cGVHD developed in 19/51 patients (mild-9/51, moderate-6/51, and severe-4/51). Skin was the most common organ involved (100%) followed by gastrointestinal tract (47.4%), liver (36.8%), eyes (21%), lungs (21%), mouth (15.7%), and joints (5.2%). Advanced donor age (>30y) and previous aGVHD were found to be significantly associated with increased risk of developing cGVHD. At last follow-up, complete response and partial response of cGVHD was seen in 6/19 and 4/19 patients, respectively. Overall mortality was 15/51 (cause of mortality was relapse of cancer 8/15, cGVHD-3/15, other 4/15). EFS and OS of full cohort was 55% and 70.6%, respectively. Compared with patients without cGVHD, patients with cGVHD demonstrated a lower relapse (18.2% vs. 40%, P =0.2333), higher EFS (68.4% vs. 53.1%, P =0.283), and higher OS (73.7% vs. 68.8%, P =0.708). Incidence of cGVHD was high in children undergoing haploidentical PBSCT with PTCy. Other than PBSC graft source; donor age and previous aGVHD were the risks factors for development of cGVHD. Patients with cGVHD had lower incidence of relapse translating into better survival but this difference was not statistically significant.

Sirolimus Is an Acceptable Alternative to Tacrolimus for Graft-versus-Host Disease Prophylaxis after Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplantation Cyclophosphamide

Graft-versus-host disease (GVHD) prophylaxis with post-transplantation cyclophosphamide (PTCy), tacrolimus (Tac), and mycophenolate mofetil (MMF) for allogeneic haploidentical donor (haplo) hematopoietic cell transplantation (HCT) results in comparable outcomes to matched unrelated donor HCT. A phase II study from the Moffitt Cancer Center substituting sirolimus (Siro) for Tac in this prophylactic regimen reported comparable rates of grade II-IV acute GVHD (aGVHD). Many centers have substituted Siro for Tac in this setting based on a preferable side effect profile, although comparative data are limited. In this study, we retrospectively compared outcomes in haplo-HCT with PTCy/Siro/MMF versus haplo-HCT with PTCy/Tac/MMF. The study cohort included all consecutive patients receiving haploidentical donor T cell-replete peripheral blood stem cell (PBSC) HCT for hematologic malignancies at Moffitt Cancer Center or the City of Hope National Medical Center between 2014 and 2019. A total of 423 patients were included, of whom 84 (20%) received PTCy/Siro/MMF and 339 (80%) received PTCy/Tac/MMF. The median age for the entire cohort was 54 years (range, 18 to 78 years), and the median follow-up was 30 months. The Siro group had a higher proportion of patients age ≥60 years (58% versus 34%; P < .01), and the groups also differed in diagnosis type, conditioning regimen, and cytomegalovirus serostatus. There were no significant differences in the rates of grade II-IV aGVHD (45% versus 47%; P = .6) at day +100 or chronic GVHD (cGVHD) (47% versus 54%; P = .79) at 2 years post-HCT. In multivariate analysis, neutrophil engraftment at day +30 was significantly better in the Tac group (odds ratio, .30; 95% confidence interval, .1 to .83; P = .02), with a median time to engraftment of 17 days versus 18 days in the Siro group, but platelet engraftment was similar in the 2 groups. Otherwise, in multivariate analysis, GVHD prophylaxis type had no significant influence on aGVHD or cGVHD, nonrelapse mortality, relapse, GVHD-free relapse-free survival, disease-free survival, or overall survival after PBSC haplo-HCT. These findings suggest that Siro is a comparable alternative to Tac in combination with PTCy/MMF for GVHD prophylaxis, with overall similar clinical outcomes despite delayed engraftment after peripheral blood stem cell haplo-HCT. Although Tac remains the standard of care, Siro may be substituted based on the side effect profile of these medications, with consideration of patient medical comorbidities at HCT.

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

The novel low-dose anti-thymocyte (ATG, 5 mg/kg) plus low-dose post-transplant cyclophosphamide (PTCy, 50 mg/kg) (low-dose ATG/PTCy)-based regimen had promising activity for prevention of graft-versus-host disease (GVHD) in haploidentical-peripheral blood stem cell transplantation (haplo-PBSCT), but its impacts on long-term outcomes remain to be defined. We performed a large sample, long-term follow-up retrospective study to evaluate its efficacy for GVHD prophylaxis. The study enrolled 260 patients, including 162 with myeloid malignancies and 98 with lymphoid malignancies. The median follow-up time was 27.0 months. For the entire cohort, the cumulative incidences (CIs) of grade II-IV and III-IV acute GVHD (aGVHD) by 180 days were 13.46% (95% CI, 9.64%-17.92%) and 5.77% (95% CI, 3.37%-9.07%); while total and moderate/severe chronic GVHD (cGVHD) by 2 years were 30.97% (95% CI, 25.43%-36.66%) and 18.08% (95% CI, 13.68%-22.98%), respectively. The 2-year overall survival (OS), relapse-free survival (RFS), GVHD-free, relapse-free survival (GRFS), non-relapse mortality (NRM), and CIs of relapse were 60.7% (95% CI, 54.8%-67.10%), 58.1% (95% CI, 52.2%-64.5%), 50.6% (95% CI, 44.8-57.1%), 23.04% (95% CI, 18.06%-28.40%), and 18.09% (95% CI, 14.33%-23.97%, respectively. The 1-year CIs of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) reactivation were 43.46% (95% CI, 37.39%-49.37%) and 18.08% (95% CI, 13.68%-22.98%), respectively. In multivariate analysis, the disease status at transplantation was associated with inferior survivor outcomes for all patients and myeloid and lymphoid malignancies, while cGVHD had superior outcomes for all patients and myeloid malignancies, but not for lymphoid malignancies. The results demonstrated that the novel regimen could effectively prevent the occurrence of aGVHD in haplo-PBSCT.

Targeted dosing of anti-thymocyte globulin in adult unmanipulated haploidentical peripheral blood stem cell transplantation: A single-arm, phase 2 trial.

Anti-thymocyte globulin (ATG) is widely used in allogeneic hematopoietic stem cell transplantation to prevent severe graft-versus-host disease (GVHD) and graft failure. However, overexposure to ATG may increase cytomegalovirus (CMV), Epstein-Barr virus (EBV) reactivation, non-relapse mortality, and disease recurrence. To investigate the optimal dosing of ATG, we established a targeted dosing strategy based on ATG concentration monitoring for haploidentical peripheral blood stem cell transplantation (haplo-PBSCT). The aim of this phase 2 trial is to evaluate the safety and efficacy of the ATG-targeted dosing strategy in adult unmanipulated haplo-PBSCT. ATG was administered for 4 days (-5 days to -2 days) during conditioning. The ATG doses on -3 days and -2 days were adjusted by our dosing strategy to achieve the optimal ATG exposure. The primary endpoint was CMV reactivation on +180 days. Between December 2020 and January 2022, 66 haplo-PBSCT patients were enrolled and 63 of them were evaluable with a median follow-up of 632 days. The cumulative incidence of CMV reactivation was 36.7% and that of EBV was 58.7%. The 1-year disease-free survival was 82.5%, overall survival was 92.1%, and CD4+ T-cell reconstruction on +100 days was 76.8%. The most common severe regimen-associated toxicities (> grade 3) were infections (51.5%) and gastrointestinal toxicity (25.5%). A total of 102 haplo-PBSCT patients who received the conventional fixed ATG dose (cumulative 10 mg/kg) comprised historical control. The outcomes in historical control were inferior to those of phase 2 trial cohort (CMV reactivation: 70.8%, p < .001; EBV reactivation: 76.0%, p = .024; CD4 + T-cell reconstruction: 54.1%, p = .040). In conclusion, ATG-targeted dosing strategy reduced CMV/EBV reactivation and improved survival without increasing GVHD after haplo-PBSCT. These advantages may be associated with accelerated immune reconstitution.

Prophylactic donor lymphocyte infusion after haploidentical hematopoietic cell transplantation and post-transplant cyclophosphamide for treatment of high-risk myeloid neoplasms in children: A retrospective study.

Post-transplant cyclophosphamide (PTCy) has been recommended for prevention of graft-versus-host disease (GvHD) following haploidentical hematopoietic cell transplantation (haplo-HCT) for treatment of malignant blood diseases, but disease relapse remains a problem. Although donor lymphocyte infusion (DLI) is reported to be effective for treating post-transplantation relapse, the efficacy and safety of prophylactic-DLI (pro-DLI) post haplo-HCT, and PTCy in pediatric patients with hematological malignancies is unknown. We retrospectively analyzed the outcomes of 54 pediatric patients with high-risk myeloid neoplasms who received a PTCy regimen for GvHD prophylaxis and pro-DLI after haploidentical peripheral blood stem cell transplantation. The high-risk myeloid neoplasms in this cohort included acute myeloid leukemia (n=46) and myelodysplastic syndromes (n=8). Median follow-up was for 19.7 (range: 3.4-46.6) months. The cumulative incidences of grade II-IV and III-IV acute GvHD were 37.0% (95% CI: 22.7%-48.7%) and 16.7% (95% CI: 6.1%-26.0%), respectively. There were no graft-failure events, and the 2-year rate of moderate/severe chronic GvHD was 8.1% (95% CI: 0%-16.7%). The 2-year non-relapse mortality, relapse, disease-free survival, GvHD-free relapse-free survival, and overall survival rates were 5.1% (95% CI: 0%-11.7%), 16.6% (95% CI: 5.3%-26.6%), 78.9% (95% CI: 68.0%-91.6%), 62.2% (95% CI: 49.4%-78.3%), and 87.3% (95% CI: 78.3%-97.4%), respectively. Prophylactic donor lymphocyte infusion in the setting of haploidentical hematopoietic cell transplantation with post-transplant cyclophosphamide appears to be effective and safe in pediatric patients with high-risk myeloid neoplasms.

High levels of NK Cells in graft are associated with reduced febrile neutropenia after haploidentical peripheral blood stem cell transplantation.

To investigate the impact of natural killer (NK) cells in the graft on the outcome following haploidentical peripheral blood stem cell transplantation (haplo-PBSCT). We retrospectively collected data from patients who had undergone haplo-PBSCT at our centre from January 2019 to November 2021. The percentage of NK cells in stem cell grafts was detected by flow cytometry. Based on the median (range) count of NK cells (1.8 [0.4-6.0] × 108/kg), patients were separated into high and low NK cell count groups. Data from 96 patients were analysed. Patients were evenly distributed (48 in each group) into high and low NK cell count groups. There was no significant difference in neutrophil and platelet recovery between the two groups. However, the rates of febrile neutropenia, bacterial infection, and invasive fungal disease (IFD) were significantly reduced in the high compared with the low NK cell count group. There was no significant difference in rates of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections between groups. There was no significant difference between groups in grades II and above acute graft versus host disease (GVHD), progression-free survival (PFS), or overall survival (OS). A high number of NK cells in the graft may reduce febrile neutropenia, IFD and bacterial infection following haplo-PBSCT but it has no significant effect on aGVHD, PFS, or OS.

Successful treatment of DOCK8 deficiency by allogeneic hematopoietic cell transplantation from alternative donors.

Dedicator of cytokinesis 8 (DOCK8) deficiency is a rare autosomal recessive inborn error of immunity (IEI) characterized by eczematous dermatitis, elevated serum IgE, and recurrent infections, comprising a seemingly hyper-IgE syndrome (HIES). DOCK8 deficiency is only curable with allogeneic hematopoietic cell transplantation (HCT), but the outcome of HCT from alternative donors is not fully understood. Here, we describe the cases of two Japanese patients with DOCK8 deficiency who were successfully treated by allogeneic HCT from alternative donors. Patient 1 underwent cord blood transplantation at the age of 16years, and Patient 2 underwent haploidentical peripheral blood stem cell transplantation with post-transplant cyclophosphamide at the age of 22years. Each patient received a fludarabine-based conditioning regimen. Their clinical manifestations, including refractory molluscum contagiosum, promptly improved post-HCT. They achieved successful engraftment and immune reconstitution without serious complications. Alternative donor sources such as cord blood and haploidentical donors can be options for allogeneic HCT for DOCK8 deficiency.

Efficacy and safety of allogeneic hematopoietic cell transplantation in acute myeloid leukemia patients aged &gt; 65 years with unfavorable cytogenetics

Unrelated donor bone marrow transplantation (UR-BMT), unrelated donor cord blood stem cell transplantation (UR-CBT), and haploidentical peripheral blood stem cell transplantation (Haplo-PBSCT) are the main alternative stem cell sources for allogeneic hematopoietic cell transplantation (HCT) in Japan. The present study aimed to identify factors associated with the outcomes of UR-BMT, UR-CBT, and Haplo-PBSCT in older patients with acute myeloid leukemia (AML) and intermediate- or poor-risk cytogenetics to improve the clinical efficacy and safety of allogeneic HCT. We retrospectively analyzed data for 448 AML patients aged > 65 years who received UR-BMT (n = 102), UR-CBT (n = 250), or Haplo-PBSCT (n = 96) between 2014 and 2020. Overall survival (OS) in the UR-BMT group was superior (P = 0.033) to that in the other groups. However, all patients without complete remission (non-CR) who had Karnofsky performance status (KPS) < 80 at HCT and poor-risk cytogenetics died within 1 year after HCT. Multivariate Cox regression analysis identified KPS <80 at HCT and poor-risk cytogenetics as independent predictors of worse OS in non-CR patients. KPS < 80 may be an alternative indicator for non-CR AML patients with poor-risk cytogenetics during the selection of HCT, alternative treatments, or best supportive therapy, and the optimal KPS is important for the success of HCT.

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

Acute lymphoblastic leukemia (ALL) is the most prevalent childhood cancer under the age of 15years. 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. 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. 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). 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.

Unique Reduced-Intensity Conditioning Haploidentical Peripheral Blood Stem Cell Transplantation Protocol for Patients with Hematologic Malignancy

Reduced-intensity conditioning (RIC) haploidentical (haplo-) hematopoietic stem cell transplantation (HSCT) requires more hematopoietic progenitor and stem cells (HPSCs) to promote engraftment and immune reconstitution and needs a stronger graft-versus-leukemia effect. Peripheral blood stem cells (PBSCs) offer advantages over bone marrow; however, the use of higher-dose non-T cell-depleted (non-TCD) in vitro PBSCs may increase the occurrence of severe graft-versus-host disease (GVHD). This prospective, single-arm clinical study was performed to investigate using high-dose non-TCD in vitro PBSCs as the graft source, using fludarabine/Ara-C/busulfan (FAB) as the conditioning regimen, using rabbit antithymocyte globulin to remove T cells in vivo, and enhancing GVHD prophylaxis with an IL-2 receptor antagonist in RIC-haplo-HSCT in patients with hematologic malignancies age 50 to 70 years or <50 years with comorbidities (Hematopoietic Cell Transplantation Comorbidity Index score ≥2) classified as intermediate to high risk. The primary endpoint was day 100 acute GVHD (aGVHD). A total of 47 patients were enrolled; the median age was 52 years (range, 30 to 68 years), the median duration of follow-up was 34 months (range, 2 to 99 months), and the medium-infused doses of mononuclear cells, CD34+ cells, and CD3+ cells were 15.93×108/kg, 8.68×106/kg, and 5.57×108/kg, respectively. The cumulative incidence of grade II-IV aGVHD at day 100 was 30.3% (95% confidence interval [CI], 15.9% to 44.8%), and that of grade III-IV aGVHD was 10.2% (95% CI, .6% to 19.8%). The 2-year cumulative incidence of chronic GVHD (cGVHD) was 34.9% (95% CI, 19.0% to 50.8%). The 2-year cumulative incidences of localized and extensive cGVHD were 26.1% (95% CI, 11.80% to 40.40%) and 8.7% (95% CI, 3.26% to 20.65%), respectively. The 2-year cumulative incidence of relapse was 17.3% (95% CI, 5.1% to 29.5%), the 2-year overall survival rate was 71.2% (95% CI, 57.9% to 84.5%), and the 2-year disease-free survival rate was 66.2% (95% CI, 52.1% to 80.3%). The incidence of aGVHD was not high, and the overall efficacy was good. This study demonstrates that this unique RIC-haplo-PBSC transplantation protocol was effective in treating hematologic malignancies. Nonetheless, larger prospective multicenter clinical trials and experimental studies should be performed to further confirm our findings.

Therapeutic effect of haploidentical peripheral blood stem cell treatment on relapsed/refractory ovarian cancer

The traditional immunotherapy is limited on relapsed/refractory metastatic ovarian cancer because tumors cause immunosuppression. Since new therapeutic strategies to improve clinical outcomes for patients with relapsed/refractory metastatic ovarian carcinoma are needed, the aim of this study was to evaluate the therapeutic effect of haploidentical peripheral blood stem cells (haplo-PBSCs) adoptive treatment on relapsed/refractory ovarian cancer. Thirteen patients with advanced stage of ovarian cancer and refractory history after surgery and chemotherapy were treated with interleukin-2 activated haplo-PBSCs donated by their parents or children. Clinical outcomes including therapeutic response by measuring tumor size changes using CT scanning, CA-125 levels and survival times were evaluated. T and NK cell population in patients before and after treatment was detected by flow cytometry analysis. The median follow-up time after haplo-PBSCs adoptive treatment was 14months. At the time of the last follow-up, the median overall survival after haplo-PBSCs adoptive treatment was 9.1months. Ten patients (76.9%) achieved a relief of symptoms, including abdominal distention, ache, fatigue, and poor appetite. During the first 2months after treatment, CA125 levels decreased in 10 patients (76.9%). Five patients (38.5%) had a stable disease and 1 patient (8%) had partial response. T cell population (CD3+CD4+ and CD3+CD8+) and CD3-CD16+CD56+ NK cells were increased in patients after haplo-PBSCs adoptive treatment. Our study reveals that haplo-PBSCs adoptive treatment is associated with an anti-tumor effect and increasing immune responses in patients with relapsed/refractory ovarian cancer.