Haploidentical Peripheral Blood Stem Cell Transplantation Research Articles

Adoptive transfer of CMV-specific TCR-T cells for the treatment of CMV infection after haploidentical hematopoietic stem cell transplantation

BackgroundCytomegalovirus (CMV) reactivation after unmanipulated haploidentical stem cell transplantation (SCT) frequently occurs, causing life-threatening morbidities and transplantation failure. Pre-emptive therapy upon the detection of CMV viremia using antiviral agents is...

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

Allogeneic peripheral blood stem cell transplantation (PBSCT) has been increasing for the last years in Latin America. The objective of this study was to describe clinical outcomes in acute myeloid leukemia (AML) receiving allogeneic PBSCT between 2013 and 2019 in a single center of Cali, Colombia. A retrospective cohort study was conducted in Fundacion Valle del Lili. Patients diagnosed with AML who received an allogeneic PBSCT between 2013 and 2019 using human leukocyte antigen (HLA)-matched sibling donors (MSDs) or haploidentical related donors (HRDs) with myeloablative conditioning regimen were included. Cases with diagnosis of promyelocytic leukemia, myelodysplastic syndrome-related AML and therapy-related AML were excluded. Data were obtained directly from the hospital PBSCT database and clinical records. A total of 50 patients were included (HRD, n = 32; MSD, n = 18). Sixty-two percent was in the first complete remission (CR1) at the time of the transplant, of which 26% were MSD and 74% were HRD. The European Group for Blood and Marrow Transplantation (EBMT) risk score was: 44% vs. 50% low, 28% vs. 28% intermediate and 28% vs. 22% high for MSD vs. HRD, respectively. Overall survival at 5 years for MSD was 62% (95% confidence interval (CI): 31-83%) and 43% (95% CI: 25-60%) for HRD. Event-free survival was 56% (95% CI: 26-78%) and 35.6% (95% CI: 18-53%), respectively. Non-relapse mortality at day-100 was 6% (95% CI: 0.8-35%) and 20% (95% CI: 9-39%). Relapse at5 years was 18% (95% CI: 4-58%) and 25% (95% CI: 10-52%). Overall mortality rate was 46%. The grade II-IV, III-IV acute graft-versus-host disease and severe chronic graft-versus-host disease was 44%, 11% and 12% for MSD, and 43%, 9% and 0% for HRD. These results underline that MSD remains the first donor choice for AML patients in CR1 when available. HRDs are still our next option among alternative donors. It is necessary to find strategies that have a positive impact on those outcomes that markedly affect the quality of allogeneic PBSCT and the prognosis of patients. Comparative, randomized, prospective studies with longer follow-up of haploidentical allogeneic PBSCT with other donor types are required to definitely establish its role among alternative donors.

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.

Efficacy and safety of allogeneic hematopoietic cell transplantation in acute myeloid leukemia patients aged > 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.

Haploidentical Peripheral Blood Stem Cell Transplantation (Haplo-PBSCT) with Cyclophosphamide Pos Transplant (CyPost) in High-Risk Hematologic Malignancies. Results of 5 Years in Transplant Center in Northeast of Mexico

Introduction: Haploidentical peripheral blood stem cell transplantation ( Haplo-PBSCT) is a curative option in patient with hematology malignancy. In Mexico is very difficult to find an identical HLA donor , for this reason Haplo PBSCT it is an option in our public Health institution.Materials and methods: we aimed a retrospective study since (2017 -2021) in our Hospital Unidad Médica de alta Especialidad 25, Instituto Mexicano del Seguro Social (IMSS UMAE 25) Monterrey, Mexico. We include patients over 15 years of age who were undergo Haplo PBSCT with hematolgy malignancies . We performed Analysis of Overall and Relapse-free survival with kaplan meier curves and incidence of acute and chronic graft versus host disease (GVHD) and percentage of Transplant-Related Mortality (TRM).Results: we analized a 38 patients, the median age was 35 years (range 15-64). Of the total , 25 were male (65%) and 13 famale (34%). The rest of baseline data is described in table 1.The median time of neutrophil engrafment was days 17 ( 11-26 ) and platelets was 19.5 days ( 12-38 ). The Incidence of Primary Graft failure was 18 % ( seven patients). Patients with graft had 99-100% chimerism at day 100. The Incidence of aGVHD was 26 % and the cGVHD was 16%. DLI was used in four patients to treat passenger lymphocyte syndrome (2 patients) and ( 2 patients) with severe graft rejection.The principal cause of death was sepsis in eleven patients (29%). Two patients with acute leukemia (AML and ALL) died after development of post transplant lymphoproliferative disease. The TRM was 28.2%. There were no relapse-related deaths during follow-up after Haplo-PBSCT.The median of survival was 4.5 months ( range 1-44) with Overall Survival (OS) of 42 % at 3 years ( figure 1).Conclusion: Our analysis shows results that were comparable with those published in first world international transplant centers . Relapse remains the major cause of transplant failure, in our population the antigenic disparity between donor and recipient can strengthen the immune response versus disease. Haplo-PBSCT is a feasible transplantation method in patients with hematological malignancies in developing countries with limited resources. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Nonmyeloablative, HLA-Mismatched Unrelated Peripheral Blood Transplantation with High-Dose Post-Transplantation Cyclophosphamide

High-dose post-transplantation cyclophosphamide (PTCy) is an effective platform for prevention of severe graft-versus-host disease (GVHD) after allogeneic bone marrow (BM) transplantation with mismatched unrelated donors (mMUDs). Previous studies evaluating PTCy with mMUDs favored BM allografts over peripheral blood stem cell transplantation (PBSCT) due to concerns that PBSCT may be associated with an increased risk of acute and chronic GVHD. In addition, haploidentical PBSCT is associated with high rates of cytokine release syndrome (CRS), which is another concern with mMUD PBSCT. This study was conducted to determine the feasibility and safety of using mMUD PBSCT with PTCy as GVHD prophylaxis. Patients who received mMUD PBSCT using a PTCy-based GVHD prophylaxis at Johns Hopkins Hospital as part of a prospective clinical trial of mMUD and non-first-degree relative haploidentical transplantation with PTCy (ClinicalTrials.gov identifier NCT01203722) were included. All patients underwent T cell-replete PBSCT between November 2012 and August 2020. Statistical analyses were performed using the Kaplan-Meier method and proportional subdistribution hazard regression model for competing risks. The 29 patients in the study had a median age of 54 years, with 10 patients (34%) age ≥60 years. Nineteen grafts (66%) were matched for 9/10 HLA loci, 6 (21%) were match for 8/10, and 4 (14%) were matched for 7/10. No primary or secondary graft failure occurred. The median time to neutrophil recovery (≥500/µL) was 17 days, and that to platelet recovery (≥20,000/µL) was 28 days. Full donor chimerism was achieved in all patients by day +60. The cumulative incidence (CuI) of grade II-IV acute GVHD at 180 days was 15% (90% confidence interval [CI], 3% to 26%). There were no cases of severe chronic GVHD, 3 cases of mild chronic GVHD, and 1 case of moderate chronic GVHD. The CuI of nonrelapse mortality (NRM) was 7% (90% CI, NA to 18%) at 1 year. Eighteen patients (62%) experienced mild CRS (grade 1-2), and 1 patient (3%) experienced severe CRS (grade 3-5). At 1 year, the CuI of relapse was 29% (90% CI, 8% to 50%), overall survival was 93% (90% CI, 85% to 100%), progression-free survival was 64% (90% CI, 46% to 88%), GVHD-free relapse-free survival was 41% (90% CI, 23% to 73%), and chronic GVHD-free relapse-free survival was 64% (90% CI, 46% to 88%). Our data indicate that mMUD PBSCT using PTCy-based GVHD prophylaxis is safe and feasible. All patients engrafted, and rates of NRM (7%) and acute GVHD (15%) at 1 year were low. There was only 1 case (3%) of severe CRS. Compared with previously published outcomes, mMUD PBSCT using PTCy-based GVHD prophylaxis has a safety and efficacy profile that may not be different from that of PBSCT from matched donors. These results further solidify that all patients who require blood or BM transplantation should be able to find an acceptable donor.

Risk factors and associations with clinical outcomes of cytomegalovirus reactivation after haploidentical versus matched-sibling unmanipulated PBSCT in patients with hematologic malignancies.

In allogeneic hematopoietic stem cell transplantation recipients, cytomegalovirus (CMV) infection can cause overt CMV-associated disease, which is a main cause of transplantation-associated mortality. CMV infection correlates closely with donor's type. We therefore examined whether risk factors of CMV reactivation and clinical endpoints in patients with hematologic malignancies after allogeneic peripheral blood stem cell transplantation (PBSCT) differed between using matched-sibling donors (MSD-SCT) and haploidentical donors (HID-SCT). In this retrospective cohort study, we enrolled in 200 consecutive patients received an unmanipulated G-CSF-mobilized allogeneic PBSCT. Ninety (45%) patients received MSD-SCT and 110 (55%) received HID-SCT. Quantitative PCR was used for monitoring of CMV reactivation after transplantation. One-year cumulative incidence of CMV DNAemia was 55.0%, ranging from 23.5% in MSD-SCT group to 81.0% in HID-SCT group (p < 0.001). Although univariate analyses showed that non-myeloid malignancies, disease in complete remission status at transplantation, pretreatment with antithymocyte globulin, HLA-haploidentical donors, male donors, previous Epstein-Barr virus DNAemia, and absolute lymphocyte count on day 30 < 0.6 × 109/L were respectively associated with CMV reactivation after transplantation in total cohort of recipients (all p < 0.05), haploidentical donors were found to be the only independent predictor in multivariate analyses (Hazard ratio = 6.4, p < 0.001). Furthermore, univariate analyses revealed that non-myeloid malignancies and previous Epstein-Barr virus DNAemia were respectively associated with CMV reactivation in MSD-SCT recipients, and female was associated with CMV reactivation in HID-SCT recipients (all p < 0.05). In HID-SCT recipients, but not MSD-SCT recipients, previous CMV DNAemia was associated with a lower cumulative incidence of acute graft-versus-host disease (49.2% vs. 72.6%, p <0.001). CMV DNAemia did not play a role in the relapse rate, but it was strongly associated with an increased risk of non-relapse mortality either in total cohort of recipients (30.5% vs. 13.7%; p =0.003) or in the HID-SCT subgroup (36.0% vs. 16.7%; p =0.030). Relapse-free survival and overall survival in total cohort of recipients with CMV DNAemia were both inferior to those without CMV DNAemia (45.3% vs. 57.6% and 54.8% vs. 65.8%, respectively; both p < 0.05). However, in subgroup analysis according to donor's type, neither relapse-free survival nor overall survival was impacted by CMV status (both p >0.05). This study addressed differences in incidence, risk factors, and associations with clinical outcomes of CMV reactivation after haploidentical versus matched-sibling PBSCT.

High proportions of CD3+ T cells in grafts delayed lymphocyte recovery and reduced overall survival in haploidentical peripheral blood stem cell transplantation.

T cells in grafts serve an important role in the pathogenesis of graft versus host disease (GVHD) and immune recovery during HLA matched allogeneic stem cell transplantation. However, the role of T cells in the haploidentical peripheral blood stem cell transplantation (Haplo-PBSCT) is yet to be determined. In the present study, the role of CD3+ T cells in grafts and impact on hematopoietic and immune recovery, cytomegalovirus (CMV) reactivation, GVHD, relapse, progress free survival and overall survival (OS) were evaluated and analyzed. A total of 30 patients who underwent haplo-PBSCT were included in the present study. CD3+ T cells accounted for a median of 23.1% (range 8-47.4%) with a median dose of 299.7x106/kg (range 104-623.4). Patients were divided into two groups according to the CD3+ T cell count: Above the median (high T cell group) and below the median CD3+ T cell (low T cell group). No significant difference was identified between neutrophil and platelet recovery time between two groups (P>0.05). The mean lymphocyte recovery time of high T cell group and low T cell group were 107.07 days (95% CI 79.88-134.25), and 50.4 days (95% CI 41.42-59.38), respectively. The lymphocyte recovery time of high T cell group was higher that of low T cell group (P<0.05). No significant difference between CMV reactivation, chronic GVHD and primary disease relapse rates was observed between two groups (P>0.05). The cumulative incidence of grade II or above acute GVHD was higher in the high T groups compared with low T groups (P<0.05). The overall survival and progress free survival rates were higher in the low T cell group compared with the high T cell group (P<0.05). In conclusion, high levels of CD3+ T cells in the grafts were associated with delayed lymphocyte recovery and an increased risk of acute GVHD and decreased overall survival.

Haploidentical CD34-Selected Peripheral Blood Stem Cell Transplantation (PBSCT) from Related Donors in Pediatric Patients with Malignant and Non-Malignant Disorders

Background Hematopoietic stem cell transplantation (HSCT) from HLA-haploidentical related donors is increasingly considered for transplant candidates who lack a histocompatible related or unrelated donor. Since October 2015, we have been performing haploidentical PBSCT, utilizing a two-step approach first described by Grosso et al. (Biol Blood Marrow Transplant 21:646, 2015), in which the lymphoid and CD34+ cell populations are administered separately. Selective depletion of alloreactive T-cell clones is accomplished by administering high-dose cyclophosphamide (CY) after the donor lymphocyte infusion but prior to infusion of the CD34-selected peripheral blood stem cell product. Methods As of June 2019, 15 pts have undergone haploidentical PBSCT from related donors for treatment of AML (n=1), ALL (n=8), MDS (n=3), CML (n=1) JMML (n=1) and HLH (n=1). Median age at transplant was 11 years (range, 0.7-23.5 years). Twelve pts were conditioned with TBI 1200 cGy and CY 60 mg/kg IV x 2, while 3 pts received fludarabine 35 mg/m2 IV x 4, busulfan 0.8-1 mg/kg IV q6h x 16 doses, and CY 60 mg/kg IV x 2. The mother served as the donor for 8 pts, the father for 6 pts and an adult sister for 1 pt. Donor lymphocytes containing 2 × 108 CD3+ cells/kg were infused after completion of TBI or busulfan, depending on the conditioning regimen utilized, followed 66 hours later by administration of CY 60 mg/kg daily x 2. CD34+ selected peripheral blood stem cells were infused 48 hours after the second dose of CY. GvHD prophylaxis consisted of tacrolimus and mycophenolate, both begun on Day -1. In the absence of GvHD, mycophenolate was discontinued at Day +30 and tacrolimus was tapered over 1 month, beginning on Day +60. Results Median CD34+ cell dose was 7.9 × 106/kg (range, 4.1-12.3). Neutrophil and platelet (>20,000/microliter) engraftment occurred at a median of 9 days (range, 8-10 days) and 9.5 days (range, 8-20 days), respectively. All pts achieved full donor chimerism, with no secondary graft failure. Pts were discharged a median of 22 days post-transplant (range, 15-77 days). Grade II-III acute GvHD (mostly transient skin involvement) was observed in 5 pts and 1 pt developed Stage IV acute liver GvHD. Chronic skin GvHD (1 mild, 1 extensive) was observed in 2 pts. Two pts have died, one from progressive disease and one from multiorgan failure in the setting of severe acute liver GvHD. Six pts (1 JMML, 1 AML, 1 MDS, 3 ALL) have suffered disease relapse, 68-446 days post-transplant. All 3 ALL pts subsequently received CAR T-cell therapy. Eight pts remain relapse-free survivors a median of 2.4 years (range, 0.3-3.8 years) post-transplant. Conclusion Haploidentical HSCT using this two-step methodology is a safe and effective approach for pts lacking a suitably compatible donor. Relapse of disease remains the most frequent obstacle to successful treatment.

Characterization of Immune Cells Producing Regulatory Cytokines That Mediate Engraftment in Sickle Cell Disease Patients after Haploidentical Peripheral Blood Stem Cell Transplantation

Sickle cell disease (SCD) is an inherited blood disorder in which red blood cells are sickle-shaped as a result of an amino acid alteration from glutamate to valine at the sixth position of the β-globin chain. Hematopoietic stem cell transplant (HSCT) is a curative option for SCD, with both HLA-matched and haploidentical transplant being viable approaches. Stable mixed chimerism and tolerance induction are sufficient to reverse the sickle phenotype. Graft rejection and graft versus host disease may occur following nonmyeloablative haploidentical peripheral blood stem cell transplantation (PBSCT). Various regulatory cytokines have been identified as biomarkers of engraftment in graft transplantation. Previously, we observed that TGF-β, interleukin (IL)-7, and IL-10 cytokines were elevated in engrafted SCD patients as compared to those who rejected their grafts following haploidentical PBSCT. Now, we aim to identify the immune cell populations responsible for producing the above cytokines in both engrafted and rejected patients. The plasma samples of 21 SCD patients who underwent nonmyeloablative haploidentical PBSCT at the National Institutes of Health between March 2010 and September 2015 were evaluated previously by multiplexed magnetic bead enzyme linked immune sorbent assay. Here, we analyzed various immune cells which produce the above regulatory cytokines through multi-color flow cytometry in 8 out of the 21 patients (four engrafted and four rejected). We evaluated the cytokine producing capabilities via intracellular cytokine detection among T regulatory (Treg, CD3+CD4+CD25+Foxp3+) cells, Type 1 regulatory (Tr1, CD3+CD4+Foxp3-CD45RA-CD49+LAG3+) T cells, T helper 1 (Th1, CD3+CD4+Foxp3-CD45RO+CXCR3+) cells, T helper 17 (Th17, CD3+CD4+Foxp3-CD45RO+CCR6+) cells, natural killer (NK, CD3-CD56+NKG2D+) cells, B regulatory (Breg, CD3-CD56-CD19+CD24hiCD38hi)cells, polymorphonuclear-myeloid derived suppressor cells (PMN-MDSCs, CD45+CD14-CD15+CD11b+), monocytic-MDSCs (CD45+CD14+CD15-HLADRlow), early-MDSCs (CD45+Lin-HLADR-CD11b+CD33+), myeloid dendritic cells (mDCs, CD45+CD3-CD56-HLADR+CD11c+CD123-), and plasmacytoid dendritic cells (pDCs, CD45+CD3-CD56-HLADR+CD11c-CD123+). Cytokine producing cell frequencies were measured at five timepoints: baseline (day 0) and days 30, 60, 100, and 180 post-transplant (PT). Percentages of intracellular cytokine and cell population frequencies were assessed through flow cytometry analysis and statistical significance was determined by Student's t-test. We noted IL-10-producing Tregs were significantly elevated in engrafted patients at PT day 100 (p&amp;lt; 0.01, see Figure 1). Further, IL-10-producing Th1 cells were significantly higher in engrafted patients on PT day 30 (p&amp;lt; 0.01) and day 100 (p&amp;lt; 0.01). However, rejected patients had significantly higher amounts of IL-10-producing PMN-MDSCs (p&amp;lt; 0.01), and myeloid DCs (p&amp;lt; 0.01, see Figure 2), but their levels were lower than IL10-producing Tregs and Th1 cells of engrafted patients. There were no significantly different alterations of IL-10-producing cell frequencies among other cell populations (Tr1, Th17, NK, Breg, early-MDSCs, monocytic-MDSCs, and pDCs). In addition, there were no significant variations in TGF-β- and IL-7-producing cell frequencies in any of the immune cell populations tested. Overall, the engrafted patients showed higher IL-10-producing Tregs and Th1 cells at PT day 30 and/or day 100, which suggest that the immunosuppressive cytokine IL-10 may play an important role in engraftment. Further analyses with a larger sample size are indicated to evaluate whether IL-10 producing immune regulatory cells may serve as a biomarker to predict transplant outcome. Taken together, continuous regulatory cytokine analysis at serial time points pre- and post-transplant may aid in establishing mechanisms of successful engraftment and tolerance induction. Disclosures No relevant conflicts of interest to declare.

Unmanipulated haploidentical peripheral blood stem cell transplantation for patients with Philadelphia-negative acute lymphoblastic leukaemia in first complete remission

Haploidentical peripheral blood stem cell transplantation (Haplo-PBSCT) is a promising treatment option for patients with Ph-negative acute lymphoblastic leukemia (ALL). In this study, we retrospectively analyzed data from Ph-negative ALL patients who underwent haplo-PBSCT during their first complete remission (CR1), and compared the long-term outcomes between the standard-risk and high-risk patients. The 3-year probability of relapse was 7.6% and 16.7% for the standard- and high-risk group (p = .274). The 3-year probability of disease-free survival (DFS) and overall survival (OS) for the standard-risk versus high-risk groups were 84.6% versus 50% (p = .0063) and 92.3% versus 61.1% (p = .046), respectively. Univariate analysis showed that a diagnosis of high risk with fusion/mutation genes were associated with worse outcomes, which was confirmed by multivariate analysis (p = .016). In summary, haplo-PBSCT may be a promising alternative for patients with Ph-negative ALL in CR1, although the fusion/mutation genes in high-risk patients may relatively impair the long-term efficacy compared with standard-risk patients.

PF762 EFFECTS OF TWO DOSES OF ANTITHYMOCYTE GLOBULIN IN CONDITIONING REGIMENS FOR HAPLOIDENTICAL PERIPHERAL BLOOD STEM CELL TRANSPLANTATION

Background:Antithymocyte globulin (ATG), an important in vivo T‐cell depletion strategy, has been used for graft‐versus‐host disease (GVHD) prophylaxis and shown significant clinical benefit. However, the optimal ATG dose remains unclear.Aims:To assess the effectiveness of ATG at a total dose of 10.0 mg/kg and 7.5 mg/kg for haploidentical peripheral blood stem cell transplantation (PBSCT).Methods:We retrospectively analyzed patients who underwent haploidentical PBSCT, receiving myeloablative conditioning and standard GVHD prophylaxis. ATG (rabbit thymoglobulin) at a total dose of 10.0 mg/kg (2.5 mg/kg on days −5 to −2) and 7.5 mg/kg (2.5 mg/kg on days −4 to −2) were used in the two groups.Results:40 and 35 patients were enrolled in the ATG‐10 and ATG‐7.5 groups, respectively. No significant difference was observed regarding the cumulative incidence of 100‐day grade II‐IV acute GVHD (20.0% vs 14.3%; p = 0.53) and 3‐year chronic GVHD (13.7% vs 15.7%; p = 0.83). The 3‐year probability of overall survival (OS) was 72.6% vs 74.4% (p = 0.81) and the 3‐year probability of GVHD‐free/relapse‐free survival (GRFS) was 69.0% vs 53.0% (p = 0.16). The incidence of relapse in the ATG‐7.5 group (30.9%) was higher compared with the ATG‐10.0 group (17.1%), but this difference was not statistically significant (p = 0.20). In multivariate analysis, the ATG dose was not associated with relapse, while no further respond to therapy (NR) before PBSCT predicted relapse (HR 1.19, p = 0.04). There were 5 patients (12.5%) and 8 patients (22.9%) in NR in the ATG‐10 and ATG‐7.5 groups, respectively (p = 0.19). Additionally, the ATG‐7.5 group had a trend for lower 300‐day incidence of EBV reactivation (92.5% vs 80.0%; p = 0.14) and CMV reactivation (90.5% vs 80.0%; p = 0.16), and lower 100‐day incidence of hemorrhagic cystitis (42.5% vs 28.6%; p = 0.15).Summary/Conclusion:7.5 mg/kg ATG led to lower incidence of EBV reactivation, CMV reactivation and hemorrhagic cystitis without compromising control of grade II‐IV acute GVHD, chronic GVHD and OS when compared with 10.0 mg/kg ATG. Therefore, ATG at a dose of 7.5 mg/kg could be considered for further study.

Low Dose Anti-Thymocyte Globulin Plus Low Dose Post-Transplant Cyclophosphamide As Graft-Versus-Host Disease Prophylaxis in Haploidentical Peripheral Blood Stem Cell Transplantation for Patients with Hematologic Malignancies: A Prospective, Phase II Study

Background:Nowadays, the most wildly used regimens for graft-versus-host disease (GvHD) prophylaxis in haplo-hematopoietic stem cell transplantation (Haplo-HSCT) were based on in vivo T cell depletion (TCD) with anti-thymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). To improve the efficiency of GvHD prophylaxis in haploidentical peripheral blood stem cell transplantation (Haplo-PBSCT), a novel regimen, which is composed of low dose of ATG (5 mg/kg) and low dose PTCy (50mg/kg) for GvHD prophylaxis, was evaluated in a prospective phase II clinical trial (Clinicaltrials.org NCT03395860).Method:Thirty-two patients with hematological malignancies were enrolled in this trial. Median age was 37 years (range, 20 to 62 years). At the time of transplantation, a total of fourteen patients with AML/ALL reached first or subsequent complete response (CR1, ≥CR2); the other eighteen patients had active disease including three ALL, three MDS-EB II, two CMML and ten AML patients. All patients received myeloablative conditioning regimens except for three patients. The GvHD prophylaxis contained ATG 2.5mg/kg administered on day -2 to -1 and cyclophosphamide (Cy) 50 mg/kg on day +3, cyclosporine A (CsA) and mycophenolate mofetil (MMF) initiating on day +4. The PBSC grafts for all patients were mobilized with G-CSF. Unrelated cord blood (UBC) was infused as the third party cells at 4 hours before PBSC graft infusionResults: All patients received PBSC grafts with MNCs 15.5 (7.5-28.3) ×108/kg and CD34+ cells 13.39 (2.4-31.7) ×106/kg. The median nuclear cell number and CD34+ cell number of unrelated third party cord blood were 2.1 (1.4-4.14) ×107/kg and 5.6 (1.52-11.2) ×104/kg, respectively. The median time for neutrophil and platelet engraftment was 12 days (range 9-20) and 16 days (range 12-25), respectively. Chimerism monitoring showed that all the patients were fully donor chimerism between days 14 to 28 after transplantation. There was no chimerism of cord blood cells in all patients on days 14 after transplantation. Primary graft failure occurred in one patient (3.1%).One patient with AML experienced secondary graft failure after CMV pneumonia at day 90. The cumulative incidences (CIs) of grades II-IV and III-IV acute GvHD were 19.4% (95% CI, 5.5-33.3%) (Figure A) and 6.9% (95% CI 0-16.3%) (Figure B) by day 100, respectively. The CIs within six months of moderate-to-severe cGVHD were 18.8% (5/27 cases) (95% CI, 3.9%-33.7%)(Figure C). No patient died from acute and chronic GvHD. The one-year probability of relapse was 25.1% (95% CI, 7.3-42.9%)(Figure D). The one-year probabilities of disease free-survival (DFS) and overall survival (OS) were 59% (95% CI, 33.3%-84.7%) and 78.4% (95% CI, 63%-93.8%)(Figure E), respectively. The CIs of CMV reactivation and EBV reactivation by day 180 were 37.5% (95% CI, 19.8-55.2%) and 40.6% (95% CI, 22.6-58.6%), respectively. Non-relapse mortality (NRM) was 9.4 %.Conclusion: The results suggested that low dose ATG with low dose PTCy as GvHD prophylaxis in Haplo-PBSCT had promising activity. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Reduced-Intensity Conditioning and Dual T Lymphocyte Suppression with Antithymocyte Globulin and Post-Transplant Cyclophosphamide as Graft-versus-Host Disease Prophylaxis in Haploidentical Hematopoietic Stem Cell Transplants for Hematological Malignancies

Haploidentical hematopoietic stem cell transplantation (haploHSCT) with conditioning regimens using post-transplant cyclophosphamide (PTCy) for peripheral blood stem cell (PBSC) grafts is limited by comparably higher rates of acute and chronic graft-versus-host disease (GVHD). Antithymocyte globulin (ATG) may mitigate this risk. We evaluated haploHSCT after reduced-intensity conditioning (RIC) with ATG, PTCy, and cyclosporine to prevent rejection and GVHD. Fifty adults underwent haploHSCT from August 2016 to February 2018. RIC included fludarabine (30 mg/m2/day on days –5 to –2), busulfan (3.2 mg/m2/day on days –3 and –2), and total body irradiation (200 cGy) on day –1. Unmanipulated PBSCs were infused on day 0. GVHD prophylaxis included ATG (4.5 mg/kg over days –3 to –1), PTCy (50 mg/kg/day on days +3 and +4), and cyclosporine from day +5. Median age was 56 years (range, 22 to 70 years); 25 (73.5%) patients were in first complete remission (CR1), 5 (14.7%) were in second complete remission (CR2), and 8 (23.5%) had active disease. Median time to neutrophil engraftment was 16 days (range, 8 to 43 days). At day +100, the cumulative incidence of acute GVHD of any grade, and grades III to IV was 38.3% and 5.2%, respectively. Mild chronic GVHD was seen in 15.5%. Cytomegalovirus (CMV) reactivation occurred in 37 (74%) cases and CMV disease occurred in 4 (11.5%) cases. Epstein-Barr virus (EBV) reactivation occurred in 21 (61.8%) patients. The incidence of histologically confirmed post-transplantation lymphoproliferative disorder (PTLD) was 5.8%. Four patients received rituximab. There were no CMV, EBV, or PTLD-related deaths. Six-month and 1-year overall survival (OS), cumulative incidence of relapse (CIR), and nonrelapse mortality (NRM) were 73.9%, 10.2%, and 19.4%, respectively, and 48.1%, 16% and 38.2%, respectively. Infection was the most common cause of death (18%). Unmanipulated haploidentical PBSC transplantation following RIC with ATG, PTCy, and cyclosporine as a GVHD prevention strategy results in low rates of acute and chronic GVHD.

370 - Outpatient Based Haploidentical Peripheral Blood Stem Cell Transplantation (HSCT) with Post-Transplantation Cyclophosphamide in Refractory/Relapsed Hematological Malignancies. Single Center Experience in Mexico

370 - Outpatient Based Haploidentical Peripheral Blood Stem Cell Transplantation (HSCT) with Post-Transplantation Cyclophosphamide in Refractory/Relapsed Hematological Malignancies. Single Center Experience in Mexico

Diabetes mellitus caused by secondary hemochromatosis after multiple blood transfusions in 2 patients with severe aplastic anemia.

Hemochromatosis is an inherited or secondary disorder caused by excessive iron storage leading to multiple organ damage. We describe 2 patients with diabetes mellitus caused by hemochromatosis secondary to multiple blood transfusions due to severe aplastic anemia. Subject 1, who was diagnosed with severe aplastic anemia at 15 years of age, received multiple red blood cell transfusions before he underwent autologous peripheral blood stem cell transplantation (PBSCT) at 22 years of age. At 21 years of age, hyperglycemia was detected with increased hemoglobin A1c and serum ferritin levels, 9.7% and 12,910 ng/mL (normal range, 20–320 ng/mL), respectively. The 24-hour urine C-peptide level was normal with negative antiglutamic acid decarboxylase antibody. Subsequently, metformin and an iron-chelating agent were administered. However, an intensive insulin regimen was necessary 2 years after the onset of diabetes. Subject 2, who was diagnosed with severe aplastic anemia at 2 years of age, received multiple blood transfusions until she underwent haploidentical PBSCT at 13 years of age. At 11 years of age, she developed diabetes mellitus with a high serum ferritin level (12,559.8 ng/mL). She is currently 18 years old and has been treated with an intensive insulin regimen and estrogen/progesterone replacement therapy because of hypogonadotropic hypogonadism. It is presumed that the loss of insulin secretory capacity and insulin resistance played a role in the pathogenesis of diabetes mellitus due to hemochromatosis in these cases.

Outpatient Haploidentical Peripheral Blood Stem-Cell Transplantation with Post-Transplant Cyclophosphamide in Children and Adolescents

Patients with high-risk hematological malignancies have a poor prognosis without a hematopoietic stem cell transplant. An HLA- haploidentical donor is available in 95% of the cases, and post-transplant cyclophosphamide permits the use of T-cell replete grafts in settings were ex-vivo manipulation is not available. The experience with HLA-haploidentical HSCT with PBSC and post-tranplant Cy in the pediatric and adolescent population is limited; we report the following experience.We retrospectively collected data on 25 patients (0 to 21 years old) with hematological malignancies, who underwent ambulatory haploidentical HSCT with post-transplant Cy from November 2011 to November 2014. The different conditioning regimens are described in Table 1. All patients received high-dose Cy(50mg/kg) on days +3 and +4. Cyclosporine A (CYA; 6mg/kg/d per os) and mycophenolate mofetil (MMF; 15mg/kg two times daily per os) were started on day +5. MMF was discontinued on day +35 and tapering of cyclosporin started day +90 in the absence of GVHD. All patients received anti-microbial prophylaxis for bacteria, fungal, herpes infection and Pneumocystis jiroveci according to institutional practices. First chimerism was performed at day +30, and second chimerism at day +100. Primary graft failure was defined when neutrophil counts did not exceed 0.5 x 109/L by day +30. Acute and chronic GVHD were graded according to NIH criteria.Patient, donor and stem-cell harvest characteristics are described in Table 1. All patients had high risk hematological malignancies. There were 5 patients who underwent their first transplant on 1st CR, 4 with ALL with high risk cytogenetics and 1 with AML. All other patients were defined as high risk because they were refractory/relapsed.Twenty-three patients (92%) had neutrophil engraftment after a median 17 (7-24) days. Platelet engraftment was observed in 20 (80%) patients after a median of 14.5 (11-23) days, 3 (12%) patients did not have platelet counts below 20,000/mcL. One patient was catalogued as a primary failure for not achieving neutrophil and platelet engraftment by day +30. One patient died before engraftment at day +10 of septic shock. Four patients (16%) died before day +30. The only patient that did not have a complete chimerism, had a diagnosis of AML and 30% of donor cells by day +30, by day +45 relapse of disease was documented.After a median follow-up of 157 days, 13 patients (52%) remain alive, with an estimated 1-year OS of 52% (95%CI: 30.4 - 65.6%).Nine patients (36%) died of complications (mainly infectious) not related to relapse at a median time of 66 days (10-579 days) from stem cell infusion. Nine patients (36%) relapsed in a median time of 105 days (45-288 days); three of those patients died at days +150, +113 and + 370 from transplant. Estimated 1 year event-free survival is 40.2% (95%CI: 41.3 - 75.8%) (Figures 1 and 2). Patients transplanted on 1st CR had a median follow-up of 664 days with an OS and EFS of 80% (4 patients), which was statistically different from the rest of the population (p=0.03) (Figure 3).Among those who engrafted (n=21), 9 cases (42.9%) had grade 2-4 acute GVHD and 4 cases (19%) of grade 3-4 acute GVHD. Three patients (14.3%) developed chronic GVHD, two had mild skin or liver cGVHD. One patient had severe (NIH stage 3) skin cGVHD, she was alive and with a grade 2 cGVHD until last follow up at day +893.Outpatient procedure, HLA-haploidentical HSCT including PBSC as a stem cell source, and post-transplant T-cell in vivo depletion using high-dose cyclophosphamide is feasible in children and adolescents, with acceptable rates of response and GVHD.Table 1Patient, donor and harvest characteristicsVariableN=25Age, median(range in years)10 (1-21)Gender, n(%) Male Female17 (68%) 8 (32%)Diagnosis, n(%) ALL-B ALL-T AML CML16 (64%) 2 (8%) 5 (20%) 2 (8%)Time from diagnosis to transplant (months)17.2 (1.9-153.5)Conditioning regimen, n(%) Cy 1500mg/m2 + Flu 75mg/m2 + Bu 9.6mg/kg (IV) Cy 1050mg/m2 + Flu 75mg/m2 + Bu 12 mg/kg (oral) Cy/VP-16/RT Cy/Flu/Mel16 (64%) 6 (24%) 2 (8%) 1 (4%)Donor, n(%) Mother Father Sister20 (80%) 3 (12%) 2 (8%)Donor age, median(range in years)38 (17-49)Infused CD34+ x 106/kg, median(range)11 (3.2-20) [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplantation Cyclophosphamide in Primary Refractory Acute Myeloid Leukemia

In a pilot study, 75 patients with Primary Refractory (PRef) AML without matched family donors were offered post-transplantation cyclophosphamide (PTCY) based haploidentical peripheral blood stem cell (PBSC) transplantation. Twenty-seven patients (36%) opted for haploidentical transplantation with or without further chemotherapy. There was no difference in the patient or disease characteristics amongst patients undergoing transplantation or not. The conditioning regimen comprised of FluCyMel (n=5), FluBuMel (n=17) and FluTreoTBI (n=5). MMF was tapered between days 14 and 21 posttransplant in the absence of GVHD and cyclosporine A was tapered between days 60 and 90. The progression free survival at a median follow-up of 25 months was 36.6% and 0% in the transplant and the non-transplant group (p=0.0001). Prompt engraftment was noted at a median of 14 days irrespective of disease status or conditioning regimens. Cumulative incidences of acute graft-versus-host disease (GVHD) and chronic GVHD were 26.6% and 8% respectively. The overall incidence of infections remained low, with CMV reactivation and invasive aspergillosis occurring in 9 and 2 patients respectively. CMV disease was diagnosed in 2 patients. Non-relapse mortality at 1 year was 16.7%. The incidence of disease progression was 54%. Factors positively impacting progression free survival were < 15% marrow blasts at transplant and a Natural Killer Cell Ligand Mismatch (NKLMM) donor. NKLMM, Haplotype or B scores had no impact on CMV infection or GVHD. However, Bx Haplotype was associated with lower NRM (5%, 95%CI-1-9) compared to 48.6% (95%CI 28.2-69.0) in AA Haplotype (p=0.01). Disease status did not impact the overall survival (p=0.11) in the HSCT cohort. In fact, NKLMM donors with B haplotype had the greatest impact on overall survival in both the HSCT cohort (71.4%, 95%CI 54.3-88.5%) compared to 20% (95%CI 8.8-31.2, p=0.01) in those without the same. Our data suggests PTCY based Haploidentical PBSC transplantation is feasible in patients with PRef AML and donor NKLMM might improve progression free survival, provided the conditioning protocol and the post-grafting therapy offer the optimum platform for alloreactivity of NK cells. DisclosuresNo relevant conflicts of interest to declare.

Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplantation Cyclophosphamide in Children with Advanced Acute Leukemia with Fludarabine-, Busulfan-, and Melphalan-Based Conditioning

Post-transplantation cyclophosphamide (PTCY) therapy has made haploidentical transplantation a global reality in adults, but the literature is largely silent on the feasibility of this approach in children. We conducted a prospective study of 20 patients (median age, 12 years; range, 2-20 years) with advanced acute leukemia to evaluate the feasibility of PTCY-based haploidentical peripheral blood stem cell (PBSC) transplantation in children. The conditioning regimen comprised fludarabine, i.v. busulfan, and melphalan (Flu-Bu-Mel). PTCY on days +3 and +4 was followed by mycophenolate mofetil for 14-21 days and cyclosporine for 60 days. Thirteen patients (65%) had refractory or relapsed myelogenous leukemia, and the remainder had high-risk lymphoblastic leukemia. Prompt engraftment was noted at a median of 14 days, with full donor chimerism by day +28. The cumulative incidence of acute and chronic graft-versus-host disease was 35% and 5%, respectively. Nonrelapse mortality at 1 year was 20%. The incidence of disease progression was 25.7%. The actuarial overall survival at 2 years was 64.3% (95% confidence interval, 53.4%-75.2%). Our data suggest that Flu-Bu-Mel–based conditioning followed by PTCY-based haploidentical PBSC transplantation with reduced duration of immunosuppression is feasible in pediatric patients with advanced leukemia.

Pretransplant Sirolimus Improves Outcome of Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplant Cyclophosphamide for Patients with Severe Aplastic Anemia

In a pilot study, we carried out Haploidentical transplantation for 10 patients with severe aplastic anemia (SAA) using peripheral blood stem cell (PBSC) graft and posttransplantation cyclophosphamide (PTCY). The conditioning comprised of Fludarabine 150 mg/m2, CY 30 mg/kg, horse ATG 45 mg/kg and Melphalan 120 mg/m2, followed by PTCY 50 mg /kg on D+3, +4 and cyclosporine and mycophenolate from D + 5. Prompt engraftment was followed by early alloreactivity, resulting in transplant-related mortality in 4 of the first 5 patients, all with NK Ligand mismatched donors. In the subsequent 5 patients, Sirolimus was introduced from Day -7 to maintain a trough level of 8-14 ng/ml on the day of transplant and was continued for 12 months post-transplant, with a reduced trough level for cyclosporine. All 5 patients had prompt engraftment with 78-100% donor chimerism and mild chronic GVHD in one patient only. The only significant toxicity observed in these patients was Sirolimus associated acneform lesions. Analysis of Regulatory T cells at 45 days posttransplant was 0.09 ± 0.13% in the first 3/5 patients compared to 2.6 ± 0.77% in those receiving Sirolimus (p=0.001). Our study demonstrates that NK cell ligand mismatched donors are associated with early alloreactivity following Haploidentical PBSC transplantation for SAA but addition of Sirolimus to PTCY improves tolerance and outcome.