Lower Incidence Of Chronic Graft-versus-host Disease Research Articles

Lymphocyte Reconstitution after Naïve T Cell-Depleted Hematopoietic Cell Transplantation

Background: Allogeneic hematopoietic cell transplantation (HCT) is curative for many high-risk hematological malignancies. However, graft-versus-host disease (GVHD) causes morbidity, mortality, and reduced quality of life after HCT. Removal of all T cells from hematopoietic cell grafts (pan-T cell depletion; pan-TCD) significantly reduces GVHD but is associated with impaired immune reconstitution and increased non-relapse mortality due partly to opportunistic infections. We developed a novel strategy to remove CD45RA + naïve T cells (T N) from peripheral blood stem cell grafts (PBSC) that is associated with a low incidence of serious acute GVHD (aGVHD) and an exceptionally low incidence of chronic GVHD (cGVHD) (Bleakley, JCO 2022). Although CD45RA-depletion removes T N and other CD45RA-expressing effector T cell populations from PBSC along with most NK and B cells, T N-depletion (T ND) does not appear to increase infections or have a major negative impact on immune reconstitution. Understanding subtle differences in lymphocyte population dynamics after T ND compared to T cell-replete (TR) HCT will enable further graft engineering advances and may provide broader insights into human HCT immunobiology. Objective: To evaluate lymphocyte reconstitution after T ND HCT. Methods and Results: We compared blood lymphocyte populations in T ND HCT recipients (n=47) to those in TR HCT controls (n=19) at days 28, 56, 90, 180, and 360 post-HCT using multiparametric flow cytometry. To complement standard Boolean analysis, we employed a metaclustering approach to simultaneously evaluate ~20 cell surface markers for each class of lymphocytes (CD8 + and CD4 + T cells, NK cells, and B cells) over scores of batches of recipient and control samples. Absolute numbers of total CD8 + T cells were similar in T ND compared to TR at all timepoints, whereas total CD4 + T cell numbers were consistently lower in T ND until 1 year post-HCT. Using conventional gating and high-dimensional clustering analyses, we identified several key differences in T cells after T ND. CD45RA-expressing populations (T N and effector memory re-expressing CD45RA [T EMRA]) in CD8 + and CD4 + T cells were rare in CD45RA-depleted PBSC and remained decreased in T ND HCT recipients until around 1 year (CD8 +, Fig. 1). Activated CD8 + and CD4 + central and effector memory (T CM, T EM) T cells were increased proportionally and in absolute numbers in T ND early post-HCT (CD8 +, Fig. 1). Absolute numbers of regulatory T cells (Treg) were decreased in T ND; consequently, ratios of activated CD8 + and CD4 + to Treg were both markedly increased early post-HCT, despite a similar incidence of aGVHD in T ND and TR recipients. Although most NK cell populations were removed from CD45RA-depleted PBSC, absolute numbers of NK cells in all compartments, including both activated and inhibited, were increased in T ND recipients early post-HCT compared to TR. Like NK cells, most B cells except for plasmablasts and plasma cells were removed by CD45RA-depletion of PBSC. Immature, naïve, and memory B cells were reduced very early post-T ND HCT, but substantial B cell recovery occurred within the first 2-3 months. Conclusions: We present the first detailed description of lymphocyte reconstitution after T ND HCT. Despite the major effect CD45RA-depletion has on graft composition-removing all T N and T EMRA from the T cell compartment and most NK and B cells-NK and B cell recovery occurred early, and by 1 year post-HCT there was little difference in lymphocyte populations between T ND and TR. This is consistent with hematopoietic progenitors, not mature lymphocytes, as the source of B and NK cell reconstitution. Among T cells, the most striking findings were an increase in activated T CM and T EM CD4 + and CD8 + T cells early after T ND HCT, and increased ratios of activated T cells to Treg. Although elevated blood T effector/Treg ratios have been associated with cGVHD, cGVHD was uncommon and steroid-responsive after T ND HCT. Whether increased activated T cells reflect a reduction in Treg-mediated suppression after HCT, bystander T cell activation, activation by antigen (e.g., alloantigen, latent herpes viruses, microbiota), or multiple factors are questions we are now investigating. We are also exploring associations between lymphocyte populations early post-T ND HCT and clinical outcomes; these could serve as biomarkers to facilitate early intervention to prevent or treat GVHD, relapse, or infection.

Outcomes after Bone Marrow Versus Peripheral Blood Stem Cell Matched Unrelated Donor Hematopoietic Stem Cell Transplantation

Background: Matched unrelated donors (MUD) have become an acceptable alternative donor for patients requiring potentially curative hematopoietic stem cell transplantation (HSCT) and lacking a matched sibling donor. Patients may undergo a bone marrow (BM) or peripheral blood stem cell (PBSC) graft, with previous studies showing similar survival outcomes. However, BM grafts have shown a lower incidence of chronic graft-versus-host disease (GVHD) but a higher relapse rate and slower engraftment. We aimed to compare the outcomes of BM versus PBSC in patients undergoing MUD HSCT. Methods: For this retrospective single-center study, we included all (n=276) adult MUD HSCT recipients at the University of Kansas Medical Center who had at least one year of follow-up (August 2016 to July 2021). We conducted a bivariate analysis using chi-squared and ANOVA tests. The Kaplan-Meier and regression analyses were also performed. Data analyses were conducted using SPSS version 28. Statistical significance was considered at p<0.05. Results: Our study included 276 MUD patients including 110 PBSC (40%) and 166 BM (60%) grafts. The median age was 55 (range 21-77) years, and 158 patients (57%) were males. Eighteen patients (6%) were ethnic minorities, and 89 (32%) patients had a Karnofsky performance status of ≥90%. 118 (43%) patients had a hematopoietic cell transplantation-specific comorbidity index of 3 or higher. Hematologic diseases included acute myeloid leukemia (n=119, 43%), myeloid disorders (n=77, 28%), acute lymphoblastic leukemia (ALL) (n=35, 13%), Lymphoma (n=15, 5%), and others (n=30, 11%). Sixty-two percent of patients were in complete remission at the time of transplantation, and patients not in remission included myelodysplastic syndrome, myelofibrosis, and lymphoma patients. Reduced-intensity conditioning (RIC, n=162, 58%) and myeloablative conditioning (MAC) (n=114, 41%) were used. The median follow-up was 55 (21-73) months. Overall survival (OS) was not reached in either BM or PBSC MUD HSCT group, while a median disease-free survival of 45 and 49 months was noted in PBSC and BM groups respectively (p=0.915). We observed similar rates of relapse (25% vs 27%, p=0.413), one-year overall survival (75% vs 72%, p=0.679), one-year disease-free survival (63% vs 62%, p=1.00), and one-year non-relapsed morality (NRM, 23% vs 21%, p=0.779) after PBSC or BM graft. Bone marrow graft recipients had delayed engraftment of neutrophils (20 days vs 16 days, p<0.001) and platelets (>20 K/uL: 24 days vs 16 days, p<0.001; >50 K/uL: 28 days vs 18 days, p=0.006) compared to PBSC recipients. Bone marrow graft recipients had similar rates of grade II-IV acute GVHD (50% vs 52%, p=0.714) and grade III-IV GVHD (12% vs 11%, p=0.847), but lower rates of 1-year chronic GVHD (39 % vs 55%, p=0.014) compared to PBSC recipients. In the subgroup analysis stratified by conditioning intensity, faster engraftment of neutrophils (median 16 vs 21 days, p<0.001) and platelets (>20 K/uL: 18 days vs 27 days, p<0.001; >50 K/uL: 18 days vs 33 days, p<0.001) was observed with PBSC as compared to BM graft in myeloablative transplant recipients, while there was no statistically significant association with the rates of acute or chronic GVHD, NRM, Relapse, DFS, and OS after a PBSC or BM graft. Among the RIC transplant recipients, faster neutrophil engraftment (mean 17 vs 20 days, p<0.001) and higher 1-year extensive chronic GVHD (52% vs 32%, p=0.015) were observed with PBSC compared to BM graft whereas no statistically significant difference was noted in platelet engraftment, acute GVHD, NRM, Relapse, DFS, and OS after a BM or PBSC graft. Conclusions: Allogeneic matched unrelated donor hematopoietic stem cell transplant recipients had similar rates of overall and disease-free survival, relapse, non-relapse mortality, and acute GVHD after a bone marrow or peripheral blood stem cell graft; however, delayed neutrophil and platelet engraftment with a lower incidence of chronic GVHD was noted after a bone marrow graft compared to peripheral blood stem cell graft.

Unrelated female-to-male bone marrow transplantation would be preferred over cord blood transplantation in male patients

Background aimsAllogeneic hematopoietic stem cell transplantation from female donors to male recipients (female-to-male allo-HCT) is a well-established risk factor for a greater incidence of non-relapse mortality (NRM) and chronic graft-versus-host disease (GVHD). In contrast, unrelated cord blood transplantation (UCBT) is associated with a lower incidence of chronic GVHD. In this study, survival outcomes were compared between the UCBT and unrelated female-to-male bone marrow transplantation (UFMBMT) groups. MethodsWe evaluated male allo-HCT recipients who underwent UCBT or UFMBMT between 2012 and 2020 in Japan. There were 2517 cases in the UCBT group, 456 cases in the HLA-matched UFMBMT group and 457 cases in the HLA-mismatched UFMBMT group. ResultsHLA-mismatched UFMBMT was significantly associated with a decreased risk of relapse (hazard ratio [HR] 0.74; 95% confidence interval [CI] 0.57–0.98], P = 0.033) and HLA-matched UFMBMT had the tendency of a decreased risk of relapse (HR 0.78; 95% CI 0.61–1.01, P = 0.059). HLA-matched UFMBMT was also associated with favorable OS (HR 0.82; 95% CI 0.69–0.97, P = 0.021). The relationship between the donor sources and relapse was similarly observed in the lymphoid malignancy cohort. ConclusionsThe difference of graft-versus leukemia effect by H-Y immunity according to donor sources might contribute to the difference in clinical impact. It might be desirable for patients who could sufficiently wait for donor coordination to select BMT rather than UCBT, even if only unrelated female donors are available for male recipients.

Phase II Study of Myeloablative 8/8- or 7/8-Matched Allotransplantation with Post-Transplant Cyclophosphamide, Tacrolimus, and Mycophenolate Mofetil: Marked Reduction in Gvhd Risk without Increased Relapse Risk Compared to Historical Cyclosporine/Methotrexate

Introduction Allogeneic hematopoietic cell transplantation (HCT) is the only potentially curative treatment for many high-risk hematologic malignancies. Myeloablative conditioning (MAC) is currently the standard of care for young and fit patients; however, graft-versus host disease (GVHD) continues to be a major limitation to the success of HCT, increasing post-transplant morbidity and mortality. An ideal HCT is one that combines strategies to reduce the incidence and severity of GVHD, without compromising graft versus-tumor effect. We hypothesized that the GVHD prophylaxis regimen consisting of post-transplant cyclophosphamide (PTCy), tacrolimus (Tac) and mycophenolate mofetil (MMF) would reduce the incidence of chronic GVHD in patients receiving a standard MAC HCT without an increase in risk of malignant relapse. Methods This is an analysis of a phase II study at the University of Minnesota using a MAC regimen of either: 1. total body irradiation (TBI, total dose 1320 cGy administered twice a day from days -4 to -1) or 2. Busulfan 3.2mg/kg daily (cumulative AUC 19,000 - 21,000 μmol/min/L) plus fludarabine 160mg/m2 days -5 to -2 for patients unable to receive further radiation, followed by a GVHD prophylaxis regimen of PTCy (50mg/kg days +3 and +4), Tac and MMF (beginning day +5). The primary endpoint is cumulative incidence of chronic GVHD requiring systemic immunosuppressive treatment at 1 year post-transplant. Eligibility included: age ≤ 60 years, malignant or non-malignant diagnosis, matched related (MRD) or unrelated (MUD) donor with either a bone marrow (BM) or filgrastim-mobilized peripheral blood (PB) graft. We compared those results to our previous MAC protocol which utilized a regimen of either cyclophosphamide (60mg/kg days -6 and -5)/TBI (1320 cGy administered twice a day from days -4 to -1) or busulfan (0.8 mg/kg/dose IV in 4 daily doses days -9 to -6 [total 12.8 mg/kg])/ cyclophosphamide (50 mg/kg days -5 to -2) and GVHD prophylaxis consisted of cyclosporine and methotrexate. Results Through June 2022, we treated 125 patients with a median follow up of 472 days post-transplant. Of those, 48% were female and 22 (17.6%) were ≤ 18 years old with median age at HCT of 38 years (range, 1-59 yrs; Interquartile range [IQR], 22-50 yrs). Donor source was 8/8 MRD in 69 patients (55.2%), 8/8 MUD in 44 (35.2%), and 7/8 MUD in 12 (9.6%). Graft source was bone marrow in 43 patients (34.4%) and PB in 82 (65.6%). Preparative regimen was TBI in 89.6% of patients. 124 of 125 patients achieved primary neutrophil engraftment by 42 days, median 16 days (range, 13-30). 119 of 125 achieved platelet engraftment by 6 months, median 25.5 days (range, 14-98). 91 patients (72.8%) required total parenteral nutrition (TPN) for oral mucositis and regimen-related toxicities during their initial transplant admission. Cumulative incidence of Grade II-IV acute GVHD by day +100 was 16% (95% confidence interval (CI): 9-23%); Grade III-IV acute GVHD was 4% (CI: 0-8%). No patients experienced grade IV GVHD and there were no deaths due to GVHD. At 1 year, only 3 of 105 patients developed chronic GVHD requiring immune suppression, for a cumulative incidence of 4% (CI: 0-8%). Two-year cumulative incidence of relapse was 25% (CI: 15-36%). Two-year overall survival was 80% (CI: 69-87%) and two-year GVHD-free relapse free survival (GRFS) was 57% (CI: 45-67%). Kaplan-Meier curves comparing overall survival and GRFS between this cohort and our previous MAC protocol without PTCy are shown in Figure 1. Figure 2 shows the comparison between these two consecutive cohorts in incidence of acute and chronic GVHD, transplant-related mortality (TRM) and relapse. Discussion Myeloablative HCT with a TBI or Busulfan/Fludarabine-based preparative regimen, followed by a GVHD prophylaxis regimen of PTCy, Tac, and MMF results in extremely low incidence of chronic GVHD, the primary objective of this clinical trial. Importantly, this regimen is feasible and effective for pediatric and adult patients. Further improvement in outcomes could potentially be achieved by incorporating post-transplant relapse mitigating strategies as well as supportive care measures to decrease regimen-related toxicities. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Haploidentical Hematopoietic Cell Transplantation of Ex Vivo Tcrαβ-Depleted Grafts with CD45RA-Depleted Memory T Cell Add-Back Reduces Chronic Graft-Versus-Host Disease and Results in Favourable Gvhd-Relapse Free Survival: 5-Year Follow-up of 107 Patients Treated in a Multicenter Study in Singapore

Background: Haploidentical hematopoietic cell transplantation (HCT) provides an alternative option for patients without HLA-matched donors. Graft-versus-host disease (GVHD), engraftment failure, and infectious complications are main causes of non-relapse mortality (NRM). We hypothesized that selective depletion of TCRαβ+ and CD45RA+ naïve T cells will permit hematopoietic engraftment while effectively reducing GVHD and providing donor immune reconstitution through adoptive transfer of donor's mature NK cells, γδ T cells and CD45RO+ memory T cells. Methods: Mobilized PBSC products were divided into two fractions in 8-9 : 1-2 ratio and depleted using CliniMACS device after labelling with TCRαβ and CD45RA reagents (Miltenyi Biotec, Bergish-Gladbach, Germany) respectively. All except 13 patients received the standard conditioning regimen of fludarabine 160mg/m2 divided daily over 4 days, thiotepa 10mg/kg divided twice daily for 1 day, and melphalan 70 - 140 mg/m2 for 1 day, in combination with either total lymphoid irradiation 6 Gy (n=58) or 7.5 Gy (n=12) over 3 equal fractions, total body irradiation of 2 Gy (n=24), or thymoglobuline (n=2). Short term GVHD prophylaxis was given for 30 days to 1 patient using MMF, 95 using tacrolimus, and 2 using sirolimus. Results: Between January 2017 and July 2022, we transplanted 107 patients, including 100 adults (median age, 52 years; range 19- 70) and 7 children (median age, 13 years, range 7 - 17), with high risk AML (n=60), ALL (n=22), MDS (n=10), plasma cell neoplasm (n=3), mast cell leukemia (n=1), acute undifferentiated leukemia (n=1), CMMoL (n=2), CML (n=2), MPN (n=1) and lymphoma (n=5). Patients were infused with TCRαβ and CD45RA depleted grafts containing a median of 6.18 x 106 (range 2.13 - 20.78) CD34+ cells/kg, 0.00 x 104 (range 0 - 0.97) CD45RA+CD3+ cells/kg, and 1.21 x 106 (range 0.15 - 11.67) CD45RO+CD3+ cells/kg. TCRαβ depleted graft fraction contained a median of 0.37 x 104 (range 0 - 11.30) TCRαβ+ cells/kg, and 7.72 x 106 (range 0.62 - 42.00) TCRγδ+ cells/kg. Only 1 patient experienced primary graft failure with no secondary graft failures. All others had engraftment of ANC > 500 cells/µL at median of 12 days (range 8 - 25) and PLT > 20,000 cells/µL at median of 11 days (range 7 - 17). 10 patients with high donor-specific HLA antibodies (DSA) titres engrafted successfully after desensitisation with plasma exchange, rituximab, immunoglobulin, and irradiated donor buffy coat infusion (n=1). 38 patients (35%) developed acute GVHD of grade II - IV, with a cumulative incidence (CI) of grade II-IV and grade III-IV of 34%, and 12% respectively, at 180 days. Chronic GVHD was seen in only 4 patients at a 2-year CI of 5 % . 1-year CI of non-relapse mortality (NRM) and relapse were 18.4 % and 17.2%, respectively. 4 of the 22 NRM were attributed to aGVHD. Viral reactivation included CMV (n=39), HHV-6 (n=28), EBV (n=19), and adenovirus (n=8). 11 patients (11%) out of the 15 infection-related death (15%) occurred within 180 days. At a median follow up of 23 months (range 0.3- 67.1) in surviving patients, 2-year overall (OS), event-free (EFS), and GVHD-free/relapse-free (GRFS) survival were 69.9 %, 58.7 %, and 57.3 %, respectively (Figure 1). In multivariate analysis, HCT-comorbidity index (HCT-CI) has shown significant impact on OS (p=0.008), EFS (p=0.03), and NRM (p=0.002). Disease risk index (DRI) also showed significant impact on OS (p=0.042), EFS (p=0.02) and relapse (p=0.04). In contrast, NRM was only influenced by HCT-CI (p=0.002). In the subset analysis of 63 patients (adults, n= 58; children, n=5) with favorable HCT-CI score of 0/1 and low/intermediate risk DRI, the 2-year OS, EFS, and GRFS were 75.0 %, 68.6%, and 68.0 %, respectively (Figure 2). Conclusions: Our preliminary results suggest that RIC haplo-HCT with TCRαβ and CD45RA+ depleted grafts allow successful allograft in patients with high-risk haematological malignancies lacking suitable matched donors, including patients with high levels of DSA. Acute GVHD was generally abortive, leading to low incidence of chronic GVHD and favorable GRFS. Best outcomes are seen in patients with favourable HCT-CI and low/intermediate risk DRI. Further efforts are needed to reduce the risk of infection-related death in patients with high risk HCT-CI, and relapse risk in patients with high risk DRI, through optimization of conditioning regimen intensity, anti-microbial prophylaxis or prophylactic infusion of memory-cell DLI. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Naive T Cells in Graft Versus Host Disease and Graft Versus Leukemia: Innocent or Guilty?

The outcome of allogeneic hematopoietic cell transplantation (allo-HCT) largely depends on the development and management of graft-versus-host disease (GvHD), infections, and the occurrence of relapse of malignancies. Recent studies showed a lower incidence of chronic GvHD and severe acute GvHD in patients receiving naive T cell depleted grafts compared to patients receiving complete T cell depleted grafts. On the other hand, the incidence of acute GvHD in patients receiving cord blood grafts containing only naive T cells is rather low, while potent graft-versus-leukemia (GvL) responses have been observed. These data suggest the significance of naive T cells as both drivers and regulators of allogeneic reactions. The naive T cell pool was previously thought to be a quiescent, homogenous pool of antigen-inexperienced cells. However, recent studies showed important differences in phenotype, differentiation status, location, and function within the naive T cell population. Therefore, the adequate recovery of these seemingly innocent T cells might be relevant in the imminent allogeneic reactions after allo-HCT. Here, an extensive review on naive T cells and their contribution to the development of GvHD and GvL responses after allo-HCT is provided. In addition, strategies specifically directed to stimulate adequate reconstitution of naive T cells while reducing the risk of GvHD are discussed. A better understanding of the relation between naive T cells and alloreactivity after allo-HCT could provide opportunities to improve GvHD prevention, while maintaining GvL effects to lower relapse risk.

Incidence of chronic graft versus host disease using post-transplant cyclophosphamide in HLA-matched versus haploidentical donors.

e19044 Background: Allogeneic hematopoietic cell transplant (allo-HCT) is the only potential cure for many hematologic cancers. Graft-versus-host disease (GVHD) is a significant cause of mortality after allo-HCT. Post-transplant cyclophosphamide (PTCy) in haploidentical HCT (haplo-HCT) has yielded survival outcomes similar to those seen in HLA-matched allo-HCT. Single center studies have demonstrated lower rates of chronic GVHD with the use of PTCy in HLA-matched allo-HCT. In this single center study, we analyzed the outcomes of HLA-matched and haplo-HCT in patients (pts) who received PTCy for GVHD ppx. Methods: Pts who received allo-HCT from matched related (MRD), matched unrelated (MUD), and haploidentical donors (Haplo) from Jan 2016 to July 2021 were identified. Pts who did not receive PTCy were excluded. Pts were divided into two groups – MRD/MUD and Haplo. Primary endpoint was cumulative incidence of chronic GVHD. Secondary endpoints were cumulative incidence of relapse, non-relapse mortality (NRM), and overall survival (OS) at 2-years. Comparisons were made based on log-rank test and a model for subhazard function of a failure event of primary interest with p < 0.05 used as cut-off point for statistical significance. Results: 62 pts (45 MRD/MUD,17 Haplo) were included. Baseline characteristics were similar. Median follow-up was 342 days post-transplant. Most had a diagnosis of AML (50%), high/very high DRI (48%), and received RIC (55%). Cumulative incidence of chronic GVHD was 11% overall (95% CI 5.8-21.3%); 6% for MRD/MUD and 27% for Haplo (p = 0.045). Cumulative incidence of relapse was 28% overall (95% CI 18-42%); 34% for MRD/MUD and 13% for Haplo (p = 0.09). Two-year OS was 55% overall (95% CI 39.1- 68.7%); 53% for MRD/MUD and 61% for Haplo (p = 0.043). There was no significant difference in incidence of grade 2-4 acute GVHD or NRM between groups. Conclusions: PTCy resulted in a significantly lower incidence of chronic GVHD in MRD/MUD group compared to Haplo group. Although cumulative incidence of relapse was not statistically different between groups, OS was worse in the MRD/MUD allo-HCT group after PTCy and most deaths were due to relapse.[Table: see text]

Clinical Significance of Haplo-Fever and Cytokine Profiling After Graft Infusion in Allogeneic Stem Cell Transplantation From Haplo-Identical Donors.

Allogeneic stem cell transplantation from haplo-identical donors (haplo-HSCT) has become a well-established therapeutic option for hematological malignancies. The fever of unknown origin (haplo-fever) early after the infusion of T cell repleted graft, which returned to normal right after post-transplantation cyclophosphamide (PTCy), is a unique clinical feature in patients undergoing haplo-HSCT. In the current study, the characteristics of haplo-fever and cytokine profiles during haplo-fever were retrospectively analyzed in a cohort of 37 patients undergoing T cell repleted haplo-HSCT with PTCy as graft versus host disease (GvHD) prophylaxis. In total, 33 patients (89.2%) developed haplo-fever from day 0 to day +7. Patients with high peak temperatures tended to have a lower incidence of chronic GvHD (cGvHD) (p = 0.07), moderate to severe cGvHD (p = 0.08), and superior GvHD and relapse-free survival (GRFS, p = 0.04). During the haplo-fever, there were significant increases in multiple cytokines, such as interferon gamma, interleukin (IL) 6, IL2, IL2 receptor, IL8, IL10, IL17, and tumor necrosis factor (TNF). The increases in IL2 receptor (p = 0.037) and TNF (p < 0.001) on day +4 were correlated with the lower risk of cGvHD. Increased TNF > 1.8055-fold on day +4 was the best predictive threshold for cGvHD, and was correlated with a lower incidence of cGvHD (p < 0.001), moderate to severe cGvHD (p = 0.003), and superior GRFS (p < 0.001). These observations may reflect the early reactivation of donor T cells after haplo graft infusion, which would potentially be eliminated by PTCy. Further studies with larger independent cohorts of patients are warranted, to clarify the clinical significance of haplo-fever, and day +4 TNF as a potential biomarker to predict GvHD and GRFS.

HLA-Haploidentical Hematopoietic Cell Transplantation of Ex Vivo Tcrαβ-Depleted Grafts with CD45RA-Depleted Memory T Cell Add-Back in Adults and Children with Hematological Malignancies: 4-Year Follow-up of Multicenter Study in Singapore

Background: Haploidentical hematopoietic cell transplantation (HCT) provides an alternative option for patients without HLA-matched donors. Graft-versus-host disease (GVHD), engraftment failure, and infectious complications are main causes of non-relapse mortality (NRM). We hypothesized that selective depletion of TCRαβ+ and CD45RA+ naïve T cells will permit hematopoietic engraftment while effectively reducing GVHD and providing donor immune reconstitution through adoptive transfer of donor's mature NK cells, γδ T cells and CD45RO+ memory T cells.Methods: Mobilized PBSC products were divided into two fractions in 9:1 ratio and depleted using CliniMACS device after labelling with TCRαβ and CD45RA reagents (Miltenyi Biotec, Bergish-Gladbach, Germany) respectively. All except 6 patients received the standard conditioning regimen of fludarabine 160mg/m 2 divided daily over 4 days, thiotepa 10mg/kg divided twice daily for 1 day, and melphalan 70 - 140mg/m 2 for 1 day, in combination with either total lymphoid irradiation 6Gy (n=53) or 7.5Gy (n=12) over 3 equal fractions, or total body irradiation of 2Gy (n=17), or thymoglobulin (n=2). Short term GVHD prophylaxis was given for 30 days to 1 patient using MMF, 73 using tacrolimus, and 2 using sirolimus.Results: Between January 2017 and July 2021, we transplanted 85 patients, including 78 adults (median age, 48 years; range 20 - 70) and 7 children (median age, 13 years, range 7 - 17), with high risk AML (n=44), ALL (n=19), MDS (n=9), plasma cell neoplasm (n=4), mast cell leukemia (n=1), acute undifferentiated leukemia (n=1), CMMoL (n=2), CML (n=1) and lymphoma (n=2). Patients were infused with TCRαβ and CD45RA depleted grafts containing median of 6.19 x 10 6 (range 3.54 - 20.78) CD34+ cells/kg, 0.00 x 10 4 (range 0 - 0.97) CD45RA+CD3+ cells/kg, and 1.10 x 10 6 (range 0.15 - 11.67) CD45RO+CD3+ cells/kg. TCRαβ depleted graft fraction contained a median of 0.42 x 10 4 (range 0 - 11.30) TCRαβ+ cells/kg, and 7.61 x 10 6 (range 0.62 - 31.84) TCRγδ+ cells/kg. Only 1 patient experienced primary graft failure with no secondary graft failures. All others had engraftment of ANC > 500 cells/µL at median of 12 days (range 8 - 22) and PLT > 20,000 cells/µL at median of 11 days (range 7 - 17). 6 patients with high donor-specific HLA antibodies (DSA) titres engrafted successfully after desensitisation with plasma exchange, rituximab, and immunoglobulin.29 patients (34%) developed acute GVHD of grade II - IV (Gd II, n=20; Gd III, n=5; Gd IV, n=4), with a cumulative incidence (CI) of grade II-IV and grade III-IV of 31% (95% CI 21-42%) and 11% (95% CI 5-19%) respectively, at 100 days. Chronic GVHD was seen in only 4 patients at a 2-year CI of 6% (95% CI 2-13%).1-year CI of non-relapse mortality (NRM) and relapse were 22.7% (95% CI 13.9 - 32.9%) and 15.7% (95% CI 8.3 - 25.3%) respectively. 4 of the 17 NRM were attributed to aGVHD. Viral reactivation included CMV (n=32), HHV-6 (n=22), EBV (n=15), and adenovirus (n=8). 15 patients (17.6%) died of infection within 180 days, including 6 patients with fatal bacteraemia (bacteria, n=4; candidemia, n=2) and 1 patient from disseminated adenovirus infection. At a median follow up of 448 days (range 16- 1648) in surviving patients, 2-year overall (OS), event-free (EFS), and GVHD-free/relapse-free (GRFS) survival were 64.2 %, 54.0 %, and 49.0%, respectively (Figure 1).In multivariate analysis, only HCT-comorbidity index (HCT-CI) showed significant impact on OS (HR 3.38; 95% CI 1.42 - 8.02; p=0.0059), EFS (HR 2.62; 95% CI 1.18 - 5.76; p=0.0017), and NRM (HR 4.92; 95% CI 1.79 - 13.58; p=0.0021). Disease risk index (DRI) showed a trend in higher risk of relapse (HR 2.83; 95% CI 0.96 - 8.33; p=0.059). 2-year OS, EFS, and GRFS for the subset of 58 patients (adults, n=52; children, n=6) with HCT-CI score of 0 were 76.6 %, 63.4%, and 57.5 %, respectively (Figure 2).Conclusions: Our preliminary results suggest that RIC haplo-HCT with TCRαβ and CD45RA+ depleted grafts allow successful allograft in high-risk patients lacking suitable matched donors, including patients with high levels of DSA. Acute GVHD was generally abortive, leading to low incidence of chronic GVHD. Best outcomes are seen in patients with favourable HCT-CI. Further efforts are needed to reduce the risk of infection-related death in patients with high risk HCT-CI, and relapse in patients with high risk DRI, through optimization of anti-microbial prophylaxis or prophylactic infusion of memory-cell DLI. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Low Incidence of Chronic Graft-Versus-Host Disease in Myeloablative Allogeneic Hematopoietic Cell Transplantation with Post-Transplant Cyclophosphamide Using Matched Related or Unrelated Donors: Phase II Study Interim Analysis

Low Incidence of Chronic Graft-Versus-Host Disease in Myeloablative Allogeneic Hematopoietic Cell Transplantation with Post-Transplant Cyclophosphamide Using Matched Related or Unrelated Donors: Phase II Study Interim Analysis

HLA-Haploidentical Hematopoietic Cell Transplantation after TCR-Αβ and CD45RA+ Depletion Following Reduced Intensity Conditioning in Adults and Children with Hematological Malignancies: Three-Year Follow-up of Multicenter Study in Singapore

Background: Haploidentical hematopoietic cell transplantation (HCT) provides an alternative option for patients without HLA-matched donor. Graft-versus-host disease (GVHD), engraftment failure, and infectious complications continue to be the main causes of non-relapse mortality (NRM). We hypothesized that selective depletion of TCRαβ+ and CD45RA+ naïve T-cells subset will permit hematopoietic engraftment, while effectively reducing GVHD, and provide improved donor immune reconstitution through adoptive transfer of donor's mature NK-cells, γδ T-cells, and CD45RO+ memory T-cells. Methods: Mobilized PBSC products were divided into two fractions in 9:1 ratio and depleted using CliniMACS device after labeling with TCRαβ and CD45RA reagents (Miltenyi Biotec, Bergish-Gladbach, Germany), respectively. The conditioning regimen consisted of fludarabine 160mg/m2 divided daily over 4 days, thiotepa 10mg/kg divided twice daily for 1 day, and melphalan 70-140mg/m2 for 1 day, in combination with total lymphoid irradiation 6Gy (n=35) or 7.5Gy (n=12) over 3 equal fractions, total body irradiation of 2Gy (n=13) or antithymocyte globuline (n=2). Short term GVHD prophylaxis for 30 days was given to 1 patient using MMF, 50 patients using tacrolimus, and 2 patients using sirolimus. Results: We transplanted 62 patients, including 55 adults (median age, 47 years; range 20-69) and 7 children (median age, 13 years, range 7-17) with high risk AML (n=34), ALL (n=15), MDS (n=7), plasma cell neoplasm (n=2), mast cell leukemia (n=1), acute undifferentiated leukemia (n=1), and NK/T-cell lymphoma (n=1). The patients were infused with TCRαβ and CD45RA depleted graft containing a median of 6.79 x 106 (range 3.54-20.78) CD34+ cells/kg, 0.00 x 104 (range 0-0.97) CD45RA+CD3+ cells/kg, and 1.09 x 106 (range 0.15-11.67) CD45RO+CD3+ cells/kg. The TCRαβ depleted graft fraction contained a median of 0.20 x 104 (range 0-11.30) TCRαβ+ cells/kg, and 8.52 x 106 (range 0.62-30.00) TCRγδ+ cells/kg. Only 1 patient experienced primary graft failure. All others had engraftment of ANC &amp;gt; 500 cells/µL at a median of 10 days (range 8-22) and platelet &amp;gt; 20,000 cells/µL at a median of 12 days (range 8-22). There was no secondary graft failure. Six patients with high titers of donor-specific HLA antibodies (DSA) engrafted successfully after effective desensitisation with plasma exchange, rituximab, and immunoglobulin. Twenty-two patients (35%) developed acute GVHD of grade II - IV (Gd II, n=15; Gd III, n=5; Gd IV, n=2). Three patients experienced chronic GVHD, giving 2-year cumulative incidence of 7 %. Day 180 cumulative incidence of NRM and relapse were 24.8% (95% CI 14.3-36.8%) and 14.9% (95% CI 6.3-27.0%), respectively. Four of the 16 NRM were attributed to aGVHD. Viral reactivation included CMV (n=25), HHV-6 (n=14), EBV (n=11), and adenovirus (n=7). Fourteen patients died of infection, including 5 patients who had fatal blood stream infection (bacteria, n=3; candidemia, n=2) and 1 patient from disseminated adenovirus infection within 180 days. With a median follow-up of 298 days (range 21-1298) in surviving patients, the 2-year overall (OS), event-free (EFS), and GVHD-free/relapse-free (GRFS) survival were 58% (95% CI 37.6-73.4%), 43% (95% CI 27-57%), and 39% (95% CI 24-54%), respectively (Figure 1). In multivariable analysis, only HCT-comorbidity index (HCT-CI) showed significant impact on OS (HR 6.24; 95% CI 2.05-19.05; p=0.0013), EFS (HR 4.80; 95% CI 1.73-13.35; p=0.0027), and RRM (HR 6.49; 95% CI 1.44-29.25; p=0.015), whereas disease risk index (DRI) impacts risk of relapse (HR 4.50; 95% CI 1.39-14.52; p=0.012). The 2-year OS, EFS, and GRFS for the subset of 30 patients (adults, n=25; children, n=5) with HCT-CI score of 0 and low/intermediate risk DRI were 68%, 68%, and 60%, respectively (Figure 2). Conclusions: Our preliminary results suggest that RIC haplo-HCT with TCRαβ and CD45RA+ depleted grafts allowed successful allograft in high-risk patients lacking a suitable matched donor, including patients with high level of DSA. Acute GVHD was generally abortive, leading to low incidence of chronic GVHD. The best outcome is seen in patients with favorable HCT-CI and DRI. Further efforts are needed to lower the risk of death due to blood stream infection, and relapse in patients with high risk DRI, such as optimisation of anti-microbial prophylaxis or repeated doses of memory-cell donor lymphocyte infusion (DLI). Disclosures No relevant conflicts of interest to declare.

Clinical outcomes with low dose anti-thymocyte globulin in patients undergoing matched unrelated donor allogeneic hematopoietic cell transplantation

Anti-thymocyte globulin (ATG) has been associated with decreased rates graft versus host disease (GVHD) but with a potential risk of increasing risk of infection and relapse. We retrospectively studied the impact of single dose low dose (2.5 mg/kg) ATG in patients undergoing allogenic hematopoietic cell transplantation (HCT) from 8/8 matched unrelated donors (MUD). Of the total 209 patients identified, 129 received ATG. At baseline, the ATG group had more intermediate and high disease risk index (DRI) (64.6% vs. 54.3%) (28.3% vs. 23.7%) p < .001, respectively, and who received reduced intensity or non-myeloablative conditioning (RIC) (69.0% vs. 47.5%, p .003). There was no significant difference in the overall survival (OS) HR = 1.3, 95% CI [0.99, 1.0], p = .350 or relapse-free survival (RFS) HR = 1.2, 95% CI [0.74, 1.8], p = .526 between the two groups. Patients receiving ATG had a lower incidence of chronic GVHD (cGVHD) (10.1% vs. 25%, p = .007) and less moderate to severe cGVHD (8.5% vs. 25%, p = .002). ATG was associated with a reduced incidence of moderate to severe cGVHD OR = 0.28, 95% CI [0.12, 0.61], p < .01. There was no difference in the incidence of Epstein-Barr Virus (EBV) or cytomegalovirus (CMV) reactivation, CMV disease, invasive fungal infection, or grade III–IV acute GVHD (aGVHD). Our study shows that low dose ATG results in similar OS and RFS with lower rates of cGVHD. Additional prospective studies are needed to confirm these findings.

Reduced-intensity versus Myeloablative Conditioning Regimens for Younger Adults with Acute Myeloid Leukemia and Myelodysplastic Syndrome: A systematic review and meta-analysis.

Background: Historically, reduced-intensity conditioning (RIC) was recommended to be performed for older patients who were considered ineligible for myeloablative conditioning (MAC) before allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the evidence regarding the optimal conditioning intensity in younger patients with AML or MDS is weak and contradictory.Methods: PubMed, Medline, Embase, and other online sources were searched from the initial period to February 25, 2020. Odds ratios and 95% confidence intervals were calculated to estimate pooling effects.Results: Four randomized controlled trials (RCTs) about conditioning intensity involving 633 patients were included. There were no significant differences of 1/2/4/5 years progression-free survival (PFS) and relapse incidence (RI) between two conditioning intensities. Overall survival (OS) was similar at 1/2/4 years, but patients receiving RIC had a higher OS at 5 years. Additionally, RIC were associated with lower non-relapse mortality, less grade II-IV and grade III-IV acute graft-versus-host disease (GVHD), and lower incidence of chronic GVHD compared with MAC regimens. Subgroup analysis showed similar OS and RI for AML patients, and there was a trend towards lower NRM and grade II-IV aGVHD in RIC group. Available data for MDS indicated that OS, PFS, and RI were comparable. For intermediate-risk patients, there was no evidence that RIC is inferior to MAC. However, for high-risk patients, MAC tends to perform better.Conclusions: Based on the above results, it might be concluded that RIC is a feasible treatment option for adults with AML or MDS younger than 66 years, particularly those with intermediate-risk disease. Future RCTs incorporating of risk stratifications are warranted to guide the optimal decision under certain conditions.

Long-Term Outcome of Children with Acute Leukemia (AL) Given Alphabeta T and B-Cell Depleted HLA-Haploidentical Hematopoietic Stem Cell Transplantation (TBdepl-haploHSCT)

Background: TBdepl-haploHSCT is a suitable option for children with AL in need of an allograft, lacking an HLA-compatible donor. We previously published promising results in a cohort of 80 children with AL, given this type of allograft (Locatelli et al., Blood 2017), demonstrating a low incidence of acute and chronic graft-versus-host disease (GvHD) and low non-relapse mortality (NRM), translating into a final outcome comparable to that of patients transplanted from an HLA-compatible donor. We present the long-term follow-up analysis of this study (NCT01810120), now including 134 patients, with a minimum observation time of 100 days after the allograft. Patients and methods: Between October 2010 and April 2019, 134 children with AL in morphological complete remission (CR) received TBdepl-haploHSCT from an HLA-partially matched relative (a parent in 97% of cases) at Ospedale Pediatrico Bambino Gesù in Rome, Italy. All patients were prepared to the allograft using a fully-myeloablative conditioning regimen including a combination of cytotoxic drugs and/or total body irradiation (TBI). Anti-T-lymphocyte globulin (ATLG) was used before transplantation (12 mg/kg total dose, from days -5 to day -3) to modulate bi-directional donor/recipient alloreactivity. Rituximab (200 mg/sqm) was administered on day -1 to prevent post-transplantation EBV-induced lymphoproliferative disorders (PTLD). No patient received any post-transplant GvHD prophylaxis. Results: Characteristics of patients enrolled in the study are shown in Table 1. Median follow-up of surviving patients is 60 months (range: 3 months - 8.7 years). Only 3 patients did not achieve engraftment (all affected by acute myeloid leukemia and who did not receive TBI during conditioning regimen); median time to neutrophil and platelet recovery was 13 (range 9-22) and 11 (range 8-23) days, respectively. Cumulative incidence of grade II-III acute GvHD was 16.5% (95% CI 9.9-22.6). One patient developed gut GvHD, while for all other patients skin was the sole organ involved; no case of grade IV GvHD was recorded. Eight out of the 123 patients at risk developed chronic GvHD, in all cases of limited severity, the cumulative incidence of this complication being 7.6% (95% CI 2.3-12.6). Six patients died for transplant-related complications (2 because of idiopathic pneumonitis and 1 each of disseminated adenovirus infection, cardiac insufficiency, combined CMV/rhinovirus pneumonia and sepsis from Pseudomonas aeruginosa), the 5-year cumulative incidence of NRM being 4.5% (95% CI, 1.8-9.0). Since 25 patients relapsed at a median time of 173 days (range 59-1012) after HSCT, the 5-year cumulative incidence of relapse is 21.1% (95% CI, 14.2-29.1). The 5-year probability of overall and leukemia-free survival (LFS) were 74.6 (95% CI 65.1 -71.9) and 74.4% (95% CI 65.4-81.4) (Figure 1A), respectively. Use of TBI during the preparative regimen, age at transplant above the median value (Figure 1B) and disease status at transplantation (CR1 and CR2, Figure 1C) were associated with better patient's outcome, because of a reduced incidence of relapse (Figure 1D for TBI). All these 3 factors remained statistically significant in multivariable analysis for LFS: hazard ratio (HR) for TBI was 0.16 (95% CI, 0.06- 0.37, p&amp;lt;0.001, HR for age at HSCT was 0.27 (95% CI, 0.11-0.65, p=0.003), while that for disease status was 0.49 (95% CI, 0.26-0.91, p=0.02), respectively. The 5-year GvHD/relapse-free survival was 69.9% (95% CI 60.8-77.3). The median CD3+ cell count on day +30, +90, +180 and +360 were 187, 215, 660 and 1260/mcl, respectively. Conclusions: These data confirm in a larger population and with a longer follow-up that TBdepl-haploHSCT is a safe and effective transplant option, being associated with a low risk of both NRM and acute/chronic GvHD, resulting into a 5-year LFS comparable or even better with that reported in studies using either an HLA-identical sibling or an unrelated volunteer as donor. In particular, the low incidence of chronic GvHD preserves a good quality of life in patients with long life-expectancy. Leukemia recurrence represents the main cause of treatment failure and strategies based either on the use of a titrated number of donor T cells transduced with a safety switch or ex-vivo depleted of the alloreactive component could further improve patient's outcome. Figure 1 Disclosures Merli: Novartis: Honoraria; Sobi: Consultancy; Amgen: Honoraria; Bellicum: Consultancy. Algeri:Miltenyi: Honoraria; Atara Biotherapeutics: Consultancy, Honoraria; Bluebird bio: Consultancy, Honoraria. Locatelli:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Miltenyi: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Graft-Versus-Host Disease-Free, Relapse-Free Survival in Allogeneic Stem Cell Transplantation for Adult T-Cell Leukemia/Lymphoma Provides a Novel Donor Selection Paradigm

Background: Although allogeneic hematopoietic stem cell transplantation (allo-HSCT) can provide sustained remission for adult T-cell leukemia/lymphoma (ATL), its prognosis is still unsatisfactory. Alternative donor sources are often utilized in allo-HSCT for ATL, but advantages and disadvantages of each donor source have not been fully elucidated. Graft-versus-host disease (GVHD) -free, relapse-free survival (GRFS) has been proposed as a novel and clinically meaningful endpoint of allo-HSCT. Whereas GVHD has been relatively accepted in ATL to induce substantial graft-versus-tumor (GVT) effects, severe GVHD is associated with non-relapse mortality and disturbs quality of patients' life. Analyses of GRFS may illustrate important aspects to optimize the balance between regulating GVHD and enhancing GVT effects in ATL patients. Patients and methods: We retrospectively analyzed the data of 1363 patients with ATL who received first allo-HSCT from 2006 through 2015 in Japan. Data were collected from the nationwide database maintained by the Japan Society of Hematopoietic Cell Transplantation. The probability of OS and GRFS was estimated according to the Kaplan-Meier method, and univariate comparisons among the groups were performed using the log-rank test. The Cox proportional hazard model was used for the multivariate analysis of OS and GRFS. Results: Median age was 57 years-old (range: 20-78) and median observation period of survivors was 3.1 years (range: 0.0-10.5). One-year OS and GRFS were 45% and 24%, respectively. OS of cord blood transplantation (CB) (37% at 1 year, n = 359) was worse than those of related bone marrow transplantation (R-BM) (48%, n = 121), related peripheral blood stem cell transplantation (R-PB) (50%, n = 264) and unrelated bone marrow transplantation (UR-BM) (47%, n = 619) (p &lt; 0.001). However, in the cases of complete remission (CR) at allo-HSCT, OS of CB (n = 132) was 52% at 1 year and not inferior to those of R-BM (54%, n = 52), R-PB (57%, n = 88) and UR-BM (58%, n = 280) (p = 0.14). The cumulative incidence of relapse in CB was 47% at 1 year and higher than those of R-BM (40%), R-PB (43%) and UR-BM (35%) (p = 0.002). However, in CR cases, the cumulative incidences of relapse were lower in UR-BM (21% at 1 year) and CB (26%) than those in R-BM (31%) and R-PB (31%), though not significant (p = 0.21). Notably, there were no significant differences in GRFS of CB, R-BM, R-PB and UR-BM (21%, 25%, 21% and 26% at 1 year, p = 0.08, Figure 1A). It was attributed to low incidence of chronic GVHD which needed systemic therapy in CB (9% at 1 year, R-BM: 22%, R-PB: 28% and UR-BM: 18%, p &lt; 0.001, Figure 1B) and low incidence of non-GVHD/relapse mortality in R-PB (9% at 1 year, CB: 20%, R-BM: 13% and UR-BM: 16%, p &lt; 0.001, Figure 1C). In R-BM and UR-BM, there were no significant differences as for OS and GRFS between HLA-matched and HLA-mismatched transplantations. In R-PB, OS of HLA haploidentical transplantation (Haplo, n = 36) was 39% at 1 year and tended to be inferior to those of HLA 6/6-matched (53%, n = 183) and HLA 5/6-matched transplantation (49%, n = 45) (p = 0.11). There was no significant difference as for GRFS among these 3 groups (Haplo: 22%, 6/6-matched: 20%, 5/6-matched: 27% at 1 year, p = 0.69). Finally, multivariate analysis revealed that male sex, higher age (&gt; 50 years), worse PS (&gt; 1) and non-CR at allo-HSCT were associated with lower OS and GRFS. Importantly, donor sources and HLA mismatch were not associated with OS and GRFS. Conclusions: Our results imply that all donor sources are feasible for CR cases and can be selected depending on their clinical characteristics such as frailty and history of infection. While the main issue of CB is high non-GVHD/relapse mortality, it is warranted to suppress severe GVHD in R-PB. Thus, GRFS provides important clues to improve the outcome of allo-HSCT for ATL. Figure Disclosures Shindo: Novartis: Research Funding. Nakano:Novartis: Honoraria. Ichinohe:Astellas Pharma: Research Funding; Chugai Pharmaceutical Co.: Research Funding; CSL Behring: Research Funding; Eisai Co.: Research Funding; Kyowa Hakko Kirin Co.: Research Funding; Ono Pharmaceutical Co.: Research Funding; Pfizer: Research Funding; Nippon Shinyaku Co.: Research Funding; MSD: Research Funding; Otsuka Pharmaceutical Co.: Research Funding; Repertoire Genesis Inc.: Research Funding; Sumitomo Dainippon Pharma Co.: Research Funding; Taiho Pharmaceutical Co.: Research Funding; Takeda Pharmaceutical Co.: Research Funding; Zenyaku Kogyo Co.: Research Funding; Alexion Pharmaceuticals: Honoraria; Bristol-Myers Squibb: Honoraria; Celgene: Honoraria; JCR Pharmaceuticals: Honoraria; Janssen Pharmaceutical K.K.: Honoraria; Mundipharma: Honoraria; Novartis: Honoraria. Atsuta:CHUGAI PHARMACEUTICAL CO., LTD.: Honoraria; Kyowa Kirin Co., Ltd: Honoraria.

Post-Transplant Cyclophosphamide (PT-Cy) Based Haploidentical Cell Transplantation (Haplo) Versus Rabbit Anti-Thymocyte Globulin (r-ATG) Based HLA Matched Unrelated Donor (MUD) Transplantation in Patients (pts) with Relapsed/Refractory Lymphoma

Background PT-Cy has emerged as an effective strategy for graft-versus-host disease (GVHD) prophylaxis in Haplo. The reported risk of GVHD with non-PT-Cy in pts receiving MUDs varies between centers. In this report, we compared the engraftment rates, survival, risk of GVHD and comorbidities between PT-Cy Haplo and r-ATG-based MUDs approach in pts with relapse/refractory lymphoma receiving an allogeneic transplantation. Method We retrospectively evaluated 160 adult pts with lymphoma who received Haplo (n=35) or r-ATG-MUDs (n=125) at our center between 2012 and 2018. Pts received GVHD prophylaxis of r-ATG (2-4 mg/kg total on days -3 to -1), tacrolimus and methotrexate if MUD, and tacrolimus and mycophenolate mofetil in addition to PT-Cy (50 mg/kg on days+3, +4) if Haplo. Tacrolimus taper was initiated at 6 months after transplantation in pts with no active GVHD. The study was IRB-approved. Results Haplo pts were more likely to be younger (median age 47 vs 55 yrs; P=0.032), have a lower HCT-Comorbidity Index (median 2 vs 3; P=0.048), and to include more diffuse large b-cell lymphoma (31% vs 22%, and Hodgkins disease (29% vs 16%) (P=0.015). Significant differences were also observed in the conditioning intensity and cell source of transplants between the 2 groups. The majority of Haplo pts (80%) received a reduced intensity-conditioning (RIC) of melphalan/fludarabine +/- 2Gy TBI; the remaining received a myeloablative (MA) busulfan-based regimen (9%) or nonmyeloablative (NMA) (11%) conditioning. In comparison, the percentage of MUDs pts receiving RIC, MA and NMA [bendamustine, fludarabine, rituximab or fludarabine, cyclophophamide, rituximab were 31%, 22% and 46%, respectively (P&lt;0.001). The percentage of pts receiving bone marrow as a source of cells in the Haplo and MUDs groups were 74% vs 14%, respectively (P&lt;0.001). There was no difference in the # of prior therapies received (median = 3, in both), the # of pts who failed a prior autologous (37% vs 26%; P=0.21), disease status (CR vs PR vs refractory; P=0.3), IPI &gt;2 (25% vs 19%, P=0.73) or PET-positive status (55% vs 44%, P=0.33) at study entry between the 2 groups. PT-Cy Halplo group had a significantly higher incidence of symptomatic BK- induced hemorrhagic cystitis compared to r-ATG MUD group (49% vs 10%, P&lt; 0.001). Delayed engraftment was noted in PT-Cy Haplo group compared to r-ATG MUD group with median time to achieve ANC &gt; 500 (18 days vs 10 days; P&lt;0.001), and platelets &gt; 20k were 25.5 days vs 10 days (P&lt;0.001), respectively. The median follow-up time for pts treated with PT-Cy Haplo and r-ATG MUD pts was 12.1 and 20.8 months, respectively. Similar survival and non-relapse mortality (NRM) rates were observed between the 2 groups. The 1-year OS rates were 64% vs 67% (P=0.76) and the 1-year PFS rates were 52% vs 58% (P=0.67). The cumulative incidence (CI) of 1-year NRM was 30% vs 26%, respectively (P=0.66). Chemo-sensitivity (Figure 1), NMA conditioning (Figure 2), and HCT-Comorbidity Index of &lt; 4 were associated with a better OS and PFS in univariate and multivariable analyses. Among histologies, pts with follicular lymphomas had the best OS and PFS. T-cell lymphoma had the worse outcomes. In addition, cystitis was associated with a lower survival rate by univariate analysis (P=0.036). The CI of acute 2-4 GVHD (26% vs 33%, P=0.43), acute 3-4 GVHD (14% vs 12%, P=0.66), and 1-year CI of chronic GVHD (6% vs 15%, P=0.19) were not statistically different between PT-Cy Haplo and r-ATG MUD. By univariate analysis, bone marrow source of graft was the only factor that was found to be significantly associated with a lower risk of chronic GVHD (HR 0.34; P=0.041) (Figure 3). Conclusion Our data show similar survival rates and risk of acute and chronic GVHD in pts with lymphoma who received PT-Cy Haplo and r-ATG MUD. The use of bone marrow graft was the only predictor of a lower incidence of chronic GVHD. Considering the statistically significant delayed time to engraftment and the higher risk of hemorrhagic cystitis, a MUD remains the donor of choice in lymphoma pts who have this option. Disclosures Jabbour: Takeda: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Adaptive: Consultancy, Research Funding; Cyclacel LTD: Research Funding; AbbVie: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; BMS: Consultancy, Research Funding. Bashir:Imbrium: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Spectrum: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; StemLine: Research Funding; Acrotech: Research Funding; Celgene: Research Funding. Oran:Astex pharmaceuticals: Research Funding; AROG pharmaceuticals: Research Funding. Kebriaei:Kite: Honoraria; Amgen: Research Funding; Jazz: Consultancy; Pfizer: Honoraria. Popat:Bayer: Research Funding; Incyte: Research Funding; Jazz: Consultancy. Champlin:Johnson and Johnson: Consultancy; Sanofi-Genzyme: Research Funding; Actinium: Consultancy.

Impact of low-dose anti-thymocyte globulin on immune reconstitution after allogeneic hematopoietic cell transplantation.

How low-dose anti-thymocyte globulin (ATG) for prophylaxis of graft-versus-host disease (GVHD) influences immune reconstitution after allogeneic hematopoietic stem cell transplantation (allo-HCT) remains incompletely understood. We prospectively enrolled 41 consecutive adult patients and conducted cytometry-based immunophenotyping for 12months after allo-HCT. Rabbit ATG (Thymoglobulin) was administered at a median total dose of 1.75mg/kg in 16 of the 41 patients. Compared with patients who did not receive ATG, those who did had a significantly smaller number of naïve T cells (especially CD4+ ) within three months after allo-HCT. No significant difference was observed between the two groups in the reconstitution of other T cells (effector, memory, Th1, Th2, Th17, Treg, and Tfh), B cells (transitional, naïve, memory, and plasmablast), NK cells (regulatory and cytolytic), or dendritic cells (myeloid and plasmacytoid). Patients with fewer CD4+ naïve T cells than the median count (7.60 cells/µL) at two months after allo-HCT developed chronic GVHD less frequently than those with CD4+ naïve T cells above the median count (2-year cumulative incidences were 0.31 and 0.53, respectively; p = 0.133). This pilot study suggests low-dose Thymoglobulin suppresses the recovery of naïve T cells after allo-HCT, which may contribute to a lower incidence of chronic GVHD.

Comparison of characteristics and outcomes of late acute and NIH chronic GVHD between Japanese and white patients

Although differences in the incidence of chronic graft-versus-host disease (GVHD) across the races have been suggested, these have not been systematically investigated. This study compared the incidence, sites, severity, and outcomes of late acute GVHD and chronic GVHD according to National Institutes of Health (NIH) consensus criteria between Japanese (n = 413) and white (n = 708) patients after first allogeneic hematopoietic cell transplantation. Analysis was stratified according to bone marrow transplantation (BMT) or peripheral blood stem cell transplantation (PBSCT). Japanese patients, compared with white patients, had a similar incidence of late acute GVHD (BMT, 19% vs 16%; PBSCT, 19% vs 16%) but experienced more frequent liver late acute GVHD as defined by transaminase elevation (BMT, 79% vs 8%; PBSCT, 92% vs 33%) and less frequent gastrointestinal late acute GVHD (BMT, 11% vs 58%; PBSCT, 20% vs 68%). Japanese patients were more likely to discontinue systemic immunosuppression after late acute GVHD than white patients (hazard ratio, 3.68; 95% confidence interval, 1.96-6.94; P < .001). Japanese patients, compared with white patients, had a lower incidence of chronic GVHD (BMT, 15% vs 30% [P = .002]; PBSCT, 37% vs 45% [P < .001]) and experienced more frequent chronic GVHD of the mouth, eyes, and liver and less frequent gastrointestinal chronic GVHD. The duration of immunosuppressive treatment of NIH chronic GVHD was similar between the races. These differences could not be entirely attributed to practice variation between the centers. This study shows that the incidence, affected sites, severity, and clinical outcomes of late acute GVHD and NIH chronic GVHD differ between Japanese and white patients.

A prospective observational study of immune reconstitution following transplantation with post-transplant reduced-dose cyclophosphamide from HLA-haploidentical donors.

Allogeneic hematopoietic cell transplantation (HCT) from HLA-haploidentical donors with post-transplantation high-dose cyclophosphamide (PT/Cy-haplo) now predominates worldwide. However, to our knowledge, no prospective study has compared immune reconstitution after PT/Cy-haplo with that after conventional HCT. The mechanism by which chronic graft-versus-host disease (GVHD) is inhibited by PT/Cy-haplo also remains unknown. We prospectively compared immune recovery patterns of lymphocyte subsets among four groups of adult patients with hematological disease who received HCT from either HLA-matched related or HLA-matched unrelated donors, cord blood transplantation, or reduced-dose PT/Cy-haplo. Counts of CD4+ T-cell subsets, CD8+ T-cell subsets, and NK cells on days 30 and 60 were often lower in PT/Cy-haplo than those in HLA-matched related HCT. The immune recovery pace in PT/Cy-haplo subsequently caught up with that of the other grafts. The regulatory T cells (Tregs) to conventional CD4+ T-cell (Tcon) ratio was significantly higher until day 90 in PT/Cy-haplo. In multivariate analysis, a higher Tregs-to-Tcon ratio on day 60 was significantly associated with a lower incidence of chronic GVHD (P<0.01). The preservation of Tregs by PT/Cy in the early phase might have resulted in a lower incidence of chronic GVHD.

Allogeneic peripheral blood stem cell transplantation with anti-thymocyte globulin versus allogeneic bone marrow transplantation without anti-thymocyte globulin.

We compared severe graft-versus-host-disease (GvHD) free and relapse-free survival and other transplantation outcomes of acute myeloid leukemia (AML) patients given bone marrow (BM) without anti-thymocyte globulin (ATG) versus peripheral blood stem cells (PBSC) with ATG after myeloablative conditioning. In the cohort of patients receiving grafts from a human leukocyte antigen (HLA)-matched sibling donor, patients given PBSC with ATG (n=1,021) and those given BM without ATG (n=1,633) presented comparable severe GvHD-free relapse-free survival (GRSF)(hazard ratio [HR]=0.9, 95% confidence interval [CI]: 0.8-1.1, P=0.5) and overall survival (HR=1.0, 95% CI: 0.8-1.2, P=0.8). They had however, a lower incidence of chronic GvHD (cGvHD) (HR=0.7, 95% CI: 0.6-0.9, P=0.01). In the cohort of patients receiving grafts from HLA-matched unrelated donor , patients given PBSC with ATG (n=2,318) had better severe GvHD-free and relapse-free survival (GRFS) than those given BM without ATG (n=303) (HR=0.8, 95% CI: 0.6-0.9, P=0.001). They also had a lower incidence of cGvHD (HR=0.6, 95% CI: 0.5-0.8, P=0.0006) and better overall survival (HR=0.8, 95% CI: 0.6-1.0, P=0.04). In summary, these data suggest that PBSC with ATG results in comparable (in the case of sibling donor) or significantly better (in the case of unrelated donor) severe GRFS than BM without ATG in patients with AML in complete remission receiving grafts after myeloablative conditioning.