T-cell Depletion Of Graft Research Articles

T-cell depleted allogeneic hematopoietic stem cell transplant for the treatment of Fanconi anemia and MDS/AML.

The only curative approach for myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) arising in patients with Fanconi anemia (FA) is allogeneic hematopoietic stem cell transplantation (HCT); however, HCT approaches are inconsistent and limited data on outcomes exist. We retrospectively evaluated outcomes of thirty patients with FA and MDS/AML who underwent first allogeneic HCT with a T-cell depleted (TCD) graft at our institution. Patients were transplanted on successive protocols with stepwise changes in cytoreduction and GVHD prophylaxis. All but two patients (93%) experienced durable hematopoietic engraftment. With median follow-up of 8.7 years, 5-year OS was 66.8% and DFS 53.8%. No significant differences in survival were found in patients with high-risk prognostic features (age ≥20 years, AML diagnosis, alternative donor graft) or when stratified by conditioning regimen. The 5-year cumulative incidences of relapse and NRM were 24.3% and 21.9%, respectively. NRM was higher in patients ≥20 years at HCT but did not otherwise differ. We herein demonstrate promising outcomes following allogeneic HCT for patients with FA and MDS/AML using TCD grafts, particularly in a cohort of high-risk patients with 50% ≥20 years and a majority receiving mismatched grafts. Future prospective studies are needed to compare this approach with other HCT platforms.

Donor-Host Lineage-Specific Chimerism Monitoring and Analysis in Pediatric Patients Following Allogeneic Stem Cell Transplantation: Influence of Pretransplantation Variables and Correlation with Post-Transplantation Outcomes

The impact of donor-host chimerism in post-hematopoietic stem cell transplantation (HSCT) outcomes is poorly understood. We were interested in studying whether pre-HSCT variables influenced lineage-specific donor-host chimerism and how lineage-specific chimerism impacts post-HSCT outcomes. Our main objective was to study pre-HSCT variables as predictors of lineage-specific donor-host chimerism patterns and to better characterize the relationship between post-HSCT lineage-specific chimerism and adverse outcomes, including graft failure and disease relapse. We conducted a retrospective data analysis of all patients who underwent allogeneic HSCT at the Pediatric Transplantation and Cellular Therapy service at Memorial Sloan Kettering Cancer Center between January 2010 and June 2015 and had at least 2 measurements of split-lineage chimerism. The trend of lineage-specific donor-host chimerism post-HSCT and the impact of age, disease, graft type, and pretransplantation conditioning regimen on chimerism at 3 months and 12 months post-HSCT were studied. The Wilcoxon signed-rank test, Mann-Whitney-Wilcoxon test, and Cox proportional hazard models were used for statistical analyses. A total of 137 patients were included (median age, 11.3 years). Most patients had a hematologic malignancy (n=95), and fewer had a nonmalignant disorder (n=27) or primary immune deficiency (n=15). Myeloablative conditioning regimens (n=126) followed by T cell-depleted (TCD) peripheral blood stem cell or bone marrow grafts (n=101) were most commonly used. Mixed chimerism (MC) of total peripheral blood leukocytes (PBLs) did not predict loss of donor chimerism in all lineages and when stable was not associated with graft failure or rejection in this analyses. Split chimerism with complete donor chimerism (CC) of myeloid, B, and natural killer cells, but not T cells, occurred early post-HSCT, but full donor T cell chimerism was achieved at 12 months post-HSCT by most patients. MC within the T cell lineage was the major contributor to PBL MC, with lower median donor T cell chimerism at 3 months than at 12 months (91%) post-HSCT (51% versus 91%; P < .0001).Predictors of MC at 3 and 12 months were (1) age <3 years (P=.01 for PBLs and P=.003 for myeloidlineage); (2) nonmalignant disorder (P=.007 for PBLs); and (3) the use of reduced-intensity conditioning regimens. TCD grafts produced lower donor T cell chimerism at 3 months post-HSCT compared with unmodified grafts (P < .0001), where T cell lineage CC was achieved early post-HSCT. The donor T cell chimerism was similar at 12 months in the 2 types of grafts. Umbilical cord blood grafts had CC in all lineages at all time points post-HSCT. Loss of donor B cell chimerism was associated with increased risk of relapse in hematologic malignancies (hazard ratio, 1.33; P=.05). Age, underlying disease, conditioning regimen, and graft manipulation can impact post-HSCT donor-host chimerism and be predictors for early MC. MC in total PBLs and T cells was not related to graft failure or disease relapse. Whole-blood PBL chimerism analysis is not sufficient to assess the significance of post-HSCTdonor-host status; rather, lineage-specific chimerism, particularly for myeloid, T, and B cells, should be analyzed to guide interventions and inform outcomes.

The role of early natural killer cell adoptive infusion before engraftment in protecting against human herpesvirus-6B encephalitis after naïve T-cell-depleted allogeneic stem cell transplantation.

Naïve T-cell-depleted grafts have been employed as an ex vivo T-cell depletion (TCD) platform to prevent graft-versus-host disease (GvHD) and improve immune reconstitution by providing rapid donor memory T-cell reconstitution after allogenic hematopoietic stem cell transplantation (allo-HSCT). CD45RA- memory T cells confer protection against viruses such as cytomegalovirus, Epstein-Barr virus, and adenovirus; however, reports have shown an unexpectedly high incidence of human herpesvirus (HHV)-6B encephalitis among pediatric allo-HSCT patients. We report the first 18 consecutive allo-HSCT, 16 haplo-HSCT, and two human leukocyte antigen-matched related donors implanted with naïve TCD grafts. All donors were administered three cell products: first, a CD34+ stem cell product; second, a CD45RA+ TCD graft, followed by an adoptive natural killer (NK) cell infusion within 10 days after HSCT. The study's primary endpoint was the incidence of HHV-6B encephalitis. Engraftment was achieved in 94.5% of cases; 2-year overall survival, event-free survival, and GvHD/relapse-free survival were 87.2% (95% CI 78.6-95.8), 67.3% (95% CI 53.1-81.5), and 64% (95% CI 50.5-78.1), respectively. HHV-6B reactivation occurred in 7 of the haplo-HSCT patients, six of who received a cell infusion with an NK/CD4 ratio <2. None of the patients developed encephalitis. In this clinical study, we show that early adoptive NK cell infusion after a 45RA+ TCD allo-HSCT graft is safe and can prevent HHV-6B encephalitis. We recommend infusing adoptive NK cells after allo-HSCT using CD45RA+ TCD grafts.

Haploidentical stem cell transplantation for aplastic anemia: the current advances and future challenges.

Haematopoietic stem cell transplantation (HSCT) is a curative option for severe aplastic anemia (SAA). Finding a suitable matched donor in a timely manner is a challenge. The availability of haploidentical donors and their successful use in transplantation have expanded valid choices for SAA. In recent decades, haploidentical HSCT (haplo-HSCT) for the treatment of SAA has been continuously attempted, and great strides have been made. Nowadays, haplo-HSCT using different regimens has overcome the difficulty of graft failure and severe graft-versus-host disease (GvHD), and achieved inspiring survival outcomes in SAA. The regimens consist mainly of granulocyte colony-stimulating factor (G-CSF) plus antithymocyte globulin (ATG), posttransplantation cyclophosphamide (PT-Cy), and ex vivo graft T-cell depletion (TCD). In particular, the G-CSF and ATG-based regimen includes the largest sample size and the successful wide use of the G-CSF and ATG-based regimen has promoted haplo-HSCT a higher priority in SAA patients without matched related or unrelated donors in China. Recent studies have also indicated that haplo-HSCT using PT-Cy or TCD regimen is a practicable alternative, but the sample size is relatively small. Here, we offer an overview of clinical results obtained through the use of haploidentical transplantation in SAA, mainly focusing on current advances and future challenges.

Haploidentical transplantation in pediatric non-malignant diseases: A retrospective analysis on behalf of the Spanish Group for Hematopoietic Transplantation (GETH).

Describe the GETH haploidentical stem cell transplantation (haplo-HSCT) activity in non-malignant disease (NMDs). We retrospectively analyzed data from children with NMDs who underwent haplo-HSCT. From January 2001 to December 2016, 26 pediatric patients underwent 31 haplo-HSCT through ex vivo T cell-depleted (TCD) graft platforms or post-transplantation cyclophosphamide (PT-Cy) at 7 Spanish centers. Five cases employed unmanipulated PT-Cy haplo-HSCT, 16 employed highly purified CD34+ cells, and 10 employed ex vivo TCD grafts manipulated either with CD3+ CD19+ depletion, TCRαβ+ CD19+ selection or naive CD45RA+ T-cell depletion. Peripheral blood stem cells were the sole source for patients following TCD haplo-HSCT, and bone marrow was the source for one PT-Cy haplo-HSCT. The most common indications for transplantation were primary immunodeficiency disorders (PIDs), severe aplastic anemia, osteopetrosis, and thalassemia. The 1-year cumulative incidence of graft failure was 27.4%. The 1-year III-IV acute graft-versus-host disease (GvHD) and 1-year chronic GvHD rates were 34.6% and 16.7%, respectively. The 2-year overall survival was 44.9% for PIDs, and the 2-year graft-versus-host disease-free and relapse-free survival rate was 37.6% for the other NMDs. The transplantation-related mortality at day 100 was 30.8%. Although these results are discouraging, improvements will come if procedures are centralized in centers of expertise.

Early CD4+ T Cell Reconstruction As Predictor for Outcomes after Allogeneic Hematopoietic Cell Transplantation in Pediatric and Young Adult Patients: A Validation Cohort Analyses

BackgroundAn association between early CD4+ recovery and survival after T-replete allogeneic Hematopoietic Cell Transplantation (HCT) in pediatric and young adult patients was previously reported (Admiraal et al, JACI 2017). However, validation in a separate cohort and in patients undergoing ex vivo T cell depleted (TCD) HCT is lacking. Therefore, we studied the relation between CD4+ T cell immune reconstitution (IR) and clinical outcomes, in a setting where a majority of patients received a TCD HCT.MethodsWe performed a retrospective analysis of data on children and young adults receiving their 1st allo-HCT for any indication between Jan-2008 and Dec-2017. The main goal was to relate CD4 IR (measured every 2-4 wks), within 100 days after HCT to the outcomes of interest. The main outcome of interest was overall survival (OS). Other outcomes of interest were non-relapse mortality (NRM), event-free survival (EFS), relapse and acute graft-versus-host-disease (aGvHD) grade 2-4. CD4 IR was defined according to previous studies, as having more than 50 CD4+ T cells/uL at 2 consecutive measurements within 100 days. Cox-proportional hazard and Fine and Gray competing risk models were used (R version 1.2.1335)Findings315 patients (220 Malignant, 95 non-malignant indications) were included, with a median age of 10.4 years (IQR 5.0–16.5yr). 66.0% (208/315) of the patients received a TCD graft, 12.7% (40/315) received cord blood, and 21.2% (67/315) T-replete bone marrow. The CI of CD4+ IR at 100 days was 66.7%. Incidence of achieving CD4 IR after TCD was lower compared to other cell sources, 54.7% vs 90.0% after cord blood and 89.6% after T-replete bone marrow (HR 0.47, P<0.001). The other multivariate predictors for CD4+ IR were age (continuous; 0.97, p=0.002) and mismatch MUD (HR 0.5, p=0.005). No impact of CD4+ IR on relapse or aGvHD grade 2-4 was found. Absence of CD4 IR was found to be a predictor for inferior OS (HR: 2.35, 95% CI 1.46-3.79, P<0.001; Fig 1A), and EFS (HR: 1.80, 95% CI 1.20–2.69, P=0.004) and increased NRM (HR: 6.58, 95% CI 2.82–15.38, P < 0.001; Fig 1B).InterpretationWe confirmed, in a separate HCT cohort, that early CD4 IR is a strong predictor for outcomes. Early CD4+ IR is an excellent biomarker for outcomes after HCT and should therefore be considered as a standard outcome measure. Finding strategies to better predict CD4+ T cell recovery after HCT may influence outcomes/survival in the future. An association between early CD4+ recovery and survival after T-replete allogeneic Hematopoietic Cell Transplantation (HCT) in pediatric and young adult patients was previously reported (Admiraal et al, JACI 2017). However, validation in a separate cohort and in patients undergoing ex vivo T cell depleted (TCD) HCT is lacking. Therefore, we studied the relation between CD4+ T cell immune reconstitution (IR) and clinical outcomes, in a setting where a majority of patients received a TCD HCT. We performed a retrospective analysis of data on children and young adults receiving their 1st allo-HCT for any indication between Jan-2008 and Dec-2017. The main goal was to relate CD4 IR (measured every 2-4 wks), within 100 days after HCT to the outcomes of interest. The main outcome of interest was overall survival (OS). Other outcomes of interest were non-relapse mortality (NRM), event-free survival (EFS), relapse and acute graft-versus-host-disease (aGvHD) grade 2-4. CD4 IR was defined according to previous studies, as having more than 50 CD4+ T cells/uL at 2 consecutive measurements within 100 days. Cox-proportional hazard and Fine and Gray competing risk models were used (R version 1.2.1335) 315 patients (220 Malignant, 95 non-malignant indications) were included, with a median age of 10.4 years (IQR 5.0–16.5yr). 66.0% (208/315) of the patients received a TCD graft, 12.7% (40/315) received cord blood, and 21.2% (67/315) T-replete bone marrow. The CI of CD4+ IR at 100 days was 66.7%. Incidence of achieving CD4 IR after TCD was lower compared to other cell sources, 54.7% vs 90.0% after cord blood and 89.6% after T-replete bone marrow (HR 0.47, P<0.001). The other multivariate predictors for CD4+ IR were age (continuous; 0.97, p=0.002) and mismatch MUD (HR 0.5, p=0.005). No impact of CD4+ IR on relapse or aGvHD grade 2-4 was found. Absence of CD4 IR was found to be a predictor for inferior OS (HR: 2.35, 95% CI 1.46-3.79, P<0.001; Fig 1A), and EFS (HR: 1.80, 95% CI 1.20–2.69, P=0.004) and increased NRM (HR: 6.58, 95% CI 2.82–15.38, P < 0.001; Fig 1B). We confirmed, in a separate HCT cohort, that early CD4 IR is a strong predictor for outcomes. Early CD4+ IR is an excellent biomarker for outcomes after HCT and should therefore be considered as a standard outcome measure. Finding strategies to better predict CD4+ T cell recovery after HCT may influence outcomes/survival in the future. Figure 1.Figure 1 View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Rabbit Anti-Thymocyte Globulin (ATG) Exposure after Ex Vivo T-Cell Depleted Hematopoietic Cell Transplantation Is Highly Variable and Impacts Immune Reconstitution in Pediatric and Young Adult Patients

<h3>Background</h3> Rabbit anti-thymocyte globulin (rATG) is used in allogeneic hematopoietic cell transplantation (HCT) to prevent graft-versus-host-disease and graft failure. Its main and unpredictable toxicity includes poor immune reconstitution (IR) associated with higher mortality: patients who early reconstitute CD4+ have lower non-relapse mortality (NRM) and higher survival. Recently, a population pharmacokinetic (PK) pharmacodynamic rATG model described the optimal ATG exposure in various T-replete HCT settings. No data is however available in EX VIVO T-Cell Depleted (TCD) HCT. The goal of this study is to determine the optimal exposure of rATG in a pediatric and young adult patient EX VIVO TCD HCT setting, allowing early IR. <h3>Methods</h3> Pediatric and young adult patients receiving their first allogeneic EX VIVO TCD HCT at Memorial Sloan Kettering Cancer Center (2008–2018) were included. No restrictions were applied in terms of donor source, indication, conditioning, and age. Only patients receiving rATG (alone) or no ATG were included in analyses. We estimated exposure of rATG, before, after and total as area under the curve; (AUC) (mg*d/L) for all patients using an established PK model (Admiraal et al.,Lancet Hematology 2017). Outcomes of interest were CD4+ IR,defined as CD4+ levels >50/uL at two consecutive measures within 100 days, overall survival (OS), and NRM. We evaluated the association between ATG exposures and IR using a smoothed exposure to define optimal ATG exposure after HCT.Cox proportional hazard models, and multi-state competing risk models were used for analyses. <h3>Results</h3> 223 underwent a TCD HCT. 186 were included in the analysis as they received rATG (n=165) or no ATG (n=21).120(65%) had malignant and 66 (35%) had non-malignant indications for HCT. Median age was 10.5 (0.2–44) years. For those who received rATG, median rATG exposure after HCT was 34.2(range 0.622-104). A lower post AUC was associated with higher probability of IR (p<0.0001:Fig 1), increased OS(p=0.01), and lower NRM (p=0.01). The threshold for better IR and outcomes was found to be <20mg*d/L. Probability of CD4+ IR varied depending on the ATG exposure; No ATG vs.<20 vs. >20 (p<0.0001:Fig 2). There was a difference in NRM according to the ATG exposure;<20 vs. >20 (p=0.03:Fig 3), and in NRM according CD4 IR at day 100 (IR:CI 4+/- 4% vs. No IR; CI 30+/-10%;p <0.0001). <h3>Conclusions</h3> In patients who received EX VIVO TCD graft, rATG plays crucial role in probability of CD4+ IR. Patients who had rATG exposure <20 mg*d/L had highest IR, higher OS and lower NRM. These results emphasize the importance of individualizing ATG dosing to target to a low ATG exposure after HCT to improve early CD4+ reconstitution, decrease NRM, and increase survival chances.

Stepwise methodology for processing marrow products from matched siblings for possible T-cell depletion in patients with fanconi anemia

Background & Aim Post-transplant GvHD risk is increased in patients with aplastic anemia and Fanconi anemia (FA). T-cell depletion (TCD) is considered the most efficient GvHD prophylaxis. in hematopoietic stem cell transplantation (HCT). Overall risk of GvHD is less than 10% at our center using grafts from unrelated or mismatched, related donors for HCT to treat FA. Grafts with higher cell numbers (e.g. adults to children) are often used, providing increased cell numbers. For HCT in HLA matched siblings, most centers use unmodified grafts since TCD is problematic in young, comparably sized donors. Red blood cell (RBC) depletion due to ABO mismatch results in further loss. We studied the feasibility of TCD in a stepwise manner for the processing of marrow products from matched siblings in 2 patients with Fanconi anemia and aplastic anemia, both with a minor ABO mismatch requiring RBC depletion. Methods, Results & Conclusion At HCT, the first patient was 10.5 years old (22.1kg ( 90th%tile for age)). The second patient was 8.7 years old (24.4kg (10th%tile for age)). His sibling was 9.9 years of age (55kg (>90th %tile for age)). Volumes after collection, heparin addition, and stepwise processing are provided in table 1. Initial cell doses were above the threshold for proceeding to TCD (≥5.2 × 106). Products were RBC depleted (CD34+ recovery in table 1). The decision to proceed to TCD was made at this point with the aim for final doses of 2-4 × 106 CD34 cells/kg likely to occur post CD34 selection, even with moderate recovery using a threshold of ≥4.3 × 108 TNC/Kg. We would have proceeded to added GvHD prophylaxis and unmodified grafts should the CD34 cell doses have been lower post RBC depletion. TCD was performed using CliniMACS columns (Miltenyi) (table 1 shows CD34 recovery). The final CD3 cell doses of the two grafts were 3.6 and 0.9 × 103 CD3 cell doses/kg respectively (4.2 and 4.7 log reductions). Both patients engrafted with neutrophil engraftment (day +13), and platelet count of 50,000 (day +32). Patients are alive and disease free approx. 1 yr. post-transplant with complete hematologic and immune reconstitution and chimerism showing 100% myeloid donor engraftment. Careful, stepwise processing can be done in TCD of marrow for HCT in patients using HLA matched sibling donors. (1) Adequate and safe volume must be collected from donors. (2) Cell doses post RBC depletion must be assessed prior to proceeding with unmodified or TCD grafts.

A Chemotherapy-Only Regimen of Busulfan, Melphalan, and Fludarabine, and Rabbit Antithymocyte Globulin Followed by Allogeneic T-Cell Depleted Hematopoietic Stem Cell Transplantations for the Treatment of Myeloid Malignancies

We sought to develop a myeloablative chemotherapeutic regimen to secure consistent engraftment of T-cell depleted (TCD) hematopoietic stem cell transplantations (HSCT) without the need for total body irradiation, thereby reducing toxicity while maintaining low rates of graft-versus-host disease (GVHD) and without increasing relapse. We investigated the myeloablative combination of busulfan (Bu) and melphalan (Mel), with the immunosuppressive agents fludarabine (Flu) and rabbit antithymocyte globulin (r-ATG) as cytoreduction before a TCD HSCT. No post-transplantation immunosuppression was administered. Between April 2001 and May 2008, 102 patients (median age, 55 years) with a diagnosis of primary or secondary myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) underwent cytoreduction with Bu/Mel/Flu, followed by TCD grafts. TCD was accomplished by CD34+-selection followed by E-rosette depletion for peripheral blood stem cell grafts and, for bone marrow grafts, by soybean agglutination followed by E-rosette depletion. Donors included matched and mismatched, related and unrelated donors. Risk stratification was by American Society for Blood and Marrow Transplantation risk categorization for patients with primary disease. For patients with secondary/treatment-related MDS/AML, those in complete remission (CR) 1 or with refractory anemia were classified as intermediate risk, and all other patients were considered high risk. Neutrophil engraftment occurred at a median of 11 days in 100 of 101 evaluable patients. The cumulative incidences of grades II to IV acute and chronic GVHD at 1 year were 8.8% and 5.9%, respectively. Overall- and disease-free survival (DFS) rates at 5 years were 50.0% and 46.1%, respectively, and the cumulative incidences of relapse and treatment-related mortality were 23.5% and 28.4%, respectively. Stratification by risk group demonstrated superior DFS for low-risk patients (61.5% at 5 years) compared with intermediate- or high-risk (34.2% and 40.0%, respectively, P = .021). For patients with AML, those in CR1 had superior 5-year DFS compared with those in ≥CR2 (60% and 30.6%, respectively, P = .01), without a significant difference in incidence of relapse (17.1% and 30.6%, respectively, P = .209). There were no differences in DFS for other patient, donor, or disease characteristics. In summary, cytoreduction with Bu/Mel/Flu and r-ATG secured consistent engraftment of TCD transplantations. The incidences of acute/chronic GVHD and disease relapse were low, with favorable outcomes in this patient population with high-risk myeloid malignancies.

Low Dose Unfractionated Heparin (UFH) Prophylaxis Is a Safe Strategy for the Prevention of Hepatic Sinusoidal Obstruction Syndrome (SOS) in Adult Allogeneic Stem Cell Transplant (HSCT) Recipients

Background: Hepatic SOS is a serious complication after allogeneic HSCT. It has been reported elsewhere that in the period between 1979-2007, the overall mean incidence of hepatic SOS was 13.7% (95%CI:13-15). While prophylactic procedures are widely used, there is no uniform consensus on the optimal strategy for the prevention of this disease. Low dose UFH have been used but its benefit in the prevention of SOS and the potential associated risk of serious bleeding complications have not been fully established.Methods: We evaluated 730 adult allograft recipients transplanted 01/2003-12/2013 for hematologic malignancies [401 (55%) acute leukemia/ MDS, 235 (32%) lymphoma, 64 (9%) multiple myeloma, 30 (4%) CML/myeloproliferative disorder]. The majority received myeloablative conditioning (n = 466, 65%) with either total body irradiation-based (n = 243) or busulfan-based (n = 233), followed by non-myeloablative conditioning (n = 143, 19%) and reduced intensity (RIC) (n = 111, 15%). Approximately half of the patients had T-cell depleted (TCD) grafts (402, 55%). All patients had SOS prophylaxis with low dose heparin 100 units/kg given as continuous IV over 24 hours from admission to day +21 or engraftment. Prior allogeneic HSCT, non-malignant or refractory disease, dual prophylaxis with UFH/ursodiol or therapeutic anticoagulation at the time of allograft admission were all excluded.Results: The median age was 51 (range 21-65) years, and 415 (56%) were male. During the 10 year study period only 15 patients developed hepatic SOS with a day 100 incidence of 2% (95%CI:1-3). When evaluated by conditioning intensity, myeloablative and reduced intensity conditioning recipients had a day 100 incidence of 3% (95%CI:2-4) (Figure) whereas none of the NMA recipients developed SOS. Univariate analysis showed that age, HLA-match, previous hepatitis B or C exposure did not influence SOS development (Table). There was a significantly higher incidence of hepatic SOS in recipients of unmodified (3%) versus TCD grafts (1%), p= 0.025. The median time to SOS onset was 29 days (range 5-57). Six patients received supportive care only whereas 9 had defibrotide therapy. Of those, 7 patients developed severe SOS resulting in multi-organ failure (5 supportive care, 2 defibrotide). Four of 15 patients diagnosed with hepatic SOS are alive at last follow up (7 deaths attributed to SOS). Bleeding complications occurred in 26/730 patients (4%) of which only 4 (0.5%) patients had significant grade 3-4 bleeding. The day 100 grade II-IV and III-IV acute liver GVHD is 2% (95%CI:1-3) and 0.5% (95%CI:0.2-1), respectively. The incidence of day 100 TRM was 9% (95%CI:7-11) for the entire cohort of patients.Conclusion: To our knowledge, this is the largest analysis evaluating the use of low dose UFH for the prevention of hepatic SOS. We demonstrated that UFH prophylaxis is associated with a low incidence of hepatic SOS, is well tolerated, and severe bleeding complications are uncommon. Low dose UFH may be consider as a strategy for the prevention of hepatic SOS in selected patients. Further prospective studies comparing UFH to other hepatic SOS prophylaxis methods are warranted.TableUnivariate analysis of variables potentially associated with day 100 SOS.Variable(95% CI)p-valueAge (years)0.745< 402% (1-6)≥ 402% (1-3)HLA-match0.8578/82% (1-4)≤ 7/82% (1-5)Graft0.025TCD1% (0.3-2)Unmodified3% (2-6)Conditioning regimen0.054Myeloablative/RIC3% (2-4)Non-Myeloablative0 (NA)Myeloblative conditioning type0.353Busulfan-based2% (1-5)TBI-based3% (2-6)Hepatitis B & C Serologies0.089Negative2% (1-3)Positive8% (0.4-30) [Display omitted] DisclosuresBhatt:Spectrum: Consultancy. Off Label Use: Use of low dose unfractionated heparin for the prevention of hepatic SOS. van den Brink:Boehringer Ingelheim: Consultancy, Other: Advisory board attendee; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Regeneron: Honoraria; Merck: Honoraria; Tobira Therapeutics: Other: Advisory board attendee. Giralt:TAKEDA: Consultancy, Honoraria, Research Funding; AMGEN: Consultancy, Research Funding; JAZZ: Consultancy, Honoraria, Research Funding, Speakers Bureau; SANOFI: Consultancy, Honoraria, Research Funding; CELGENE: Consultancy, Honoraria, Research Funding.

Second Allogeneic Stem Cell Transplantation for Hematologic Malignancies Using Chemotherapy Only Cytoreduction with Clofarabine, Melphalan, and Thiotepa

Background:Allogeneic hematopoietic stem cell transplantation (alloHSCT) plays an important role in the treatment of patients with high-risk hematologic malignancies. However, relapse of disease remains the primary cause of mortality post HSCT. Treatment options for these patients remain limited, and outcomes after salvage attempts are often poor, due to both increased toxicity and high rates of relapse. We describe a chemotherapy-only cytoreductive regimen consisting of clofarabine (Clo), melphalan (Mel) and Thiotepa (Thio) for the treatment of patients undergoing a second or third HSCT (HSCT2 or HSCT3).Methods: Between November 2005 and December 2012, 19 patients with hematologic malignancies who had relapsed after prior alloHSCT received a HSCT2 (N=17) or HSCT3 (N=2) using this regimen. There were 12 males and 7 females aged 4.5-44 years (median 20.2 years). Diagnoses and stages at the time of HSCT2/3 included: ALL in second complete remission (CR2; N=4) or CR3 (N=8); AML in CR2 (N=2) or CR3 (N=4); and CML in 2nd chronic phase (N=1). Seven patients had extramedullary disease, including CNS (N=5), testicle (N=1), and bone (N=1). Time to relapse following prior HSCT was 0-6 months (N=6), 6-12 months (N=7), or >12 months (N=6). Median time between most recent and present HSCT was 15 months (range 8.5 – 225 months). Thirteen patients received allografts from the same donor used for prior alloHSCT, while 6 pts received allografts from different donors. Grafts comprised conventional/unmodified marrow (cBMT) (N=7), peripheral blood (cPBSCT) (N=6), double umbilical cord blood units (N=1), or T-cell depleted (TCD) PBSCT (N=5). Cytoreduction included Clo 20 (N=18) or 30 (N=1) mg/m2/dose x 5, Thio 10 mg/m2 x 1, and Mel 70 mg/m2/dose x 2. GvHD prophylaxis included tacrolimus + methotrexate or mycophenolate for the unmodified grafts, while recipients of TCD grafts received ATG only pre-transplant for rejection prophylaxis. TCD was achieved by CD34+ selection, with the addition of E-rosetting in one case. All patients received filgrastim from day +7 until neutrophil engraftment.Results: Neutrophil engraftment occurred in all patients at a median of 12 days (range 9-25). Platelet recovery occurred in 17 evaluable patients at a median of 22 days (range 14-98). Transplant related mortality was limited to 2 patients, one who died of veno-occlusive disease 27 days post-transplant and the other of EBV lymphoma 11 weeks post-transplant. Neither of these patients recovered their platelet counts. Regimen related toxicity included: grade 3-4 mucositis (N=5), grade 4 renal toxicity (N=2), grade 3-4 hypoxia (N=3). Fifteen patients developed grade 3-4 transaminitis beginning immediately following clofarabine administration, which completely resolved in 14/15 cases. Five patients, all recipients of unmodified grafts, developed grade 2-4 acute GvHD, two of whom developed chronic GvHD; one patient who received a cPBSCT developed de novo chronic GvHD.Seven patients relapsed at a median of 14.6 months (range: 3.5-25.3 months) post-HSCT2/3, and all died of their disease. Ten of 19 patients are alive and disease free with median follow-up of 50.1 months (range 22.8-90.4). Overall and disease-free survival probabilities were 51.5% and 52.6% respectively. There were no statistically significant difference in OS or DFS for the following factors: (1) patient age < or ≥ 21 years, (2) grafts from same or different donor, (3) myeloid vs. lymphoid disease, (4) CR2 vs. CR3 at HSCT, (5) TCD vs. unmodified grafts. Outcome was significantly superior for patients whose relapse occurred > 6 months from prior HSCT, with an OS of 75.2% compared with 0% (p<0.0001) in patients whose relapse was ≤ 6 months. Of the 6 patients who received HSCT2/3 for relapse within 6 months of their first HSCT, 4 died from relapse, and 2 died from transplant related mortality.Conclusions: This cytoreductive regimen has allowed secondary transplants in a cohort of high-risk patients with ALL and AML who relapsed following a prior transplant using various graft and donor options. Overall, the regimen is well tolerated and has yielded promising results, specifically in patients who relapse more than 6 months from their prior transplant. This salvage treatment merits further study and evaluation in collaborative group studies. DisclosuresOff Label Use: Clofarabine, melphalan, and thiotepa all off label for bone marrow transplant.. Boulad:Genzyme Sanofi: Trials partially funded by Genzyme Sanofi Other.

Allo- HSCT for Advanced Myelodysplastic Syndrome:MSKCC Vs MDACC

Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) is the only curative treatment for myelodysplastic syndrome (MDS). Relapse, infections and graft-versus-host disease (GvHD) are the main causes of treatment failure. We compared the outcomes of patients receiving T cell depleted (TCD) grafts at Memorial Sloan-Kettering Cancer Center (MSKCC) with patients receiving unmodified grafts at MD Anderson Cancer Center (MDACC) for advanced MDS (RAEB-1 and 2).Adult patients transplanted between 2001 -2012 were included in this retrospective analysis. All recipients of TCD grafts (N=60) received myeloablative conditioning (MAC) and antithymocyte globulin (ATG) to prevent graft rejection. None of them received post-transplant GvHD prophylaxis. Of the 129 recipients of unmodified grafts, 87 received MAC and 42 reduced intensity conditioning (RIC); GvHD prophylaxis consisted of tacrolimus and mini-dose methotrexate in the majority of patients (N=113). ATG was given to all matched unrelated donor (MUD) recipients. Patients in the unmodified group had more therapy-related MDS (MDS-t), very poor risk cytogenetics by IPSS-R at diagnosis and bone marrow (BM) blast count >5% at transplant. Only the TCD group had mismatched donors (Table 1).Univariate analysis identified a lower incidence of grade II-IV acute GvHD in the TCD group with 100-day cumulative incidence (CI) of 13.3% vs. 34.1% in the unmodified group (p=0.031). There was no difference in grade III-IV acute GvHD with a 10% CI in both groups at day-100 (p=0.546). The incidence of chronic GvHD was lower in the TCD group with a CI at 3-yrs of 3.4% vs. 44.3% in the unmodified group (p < 0.001). The non-relapse mortality (NRM) in both groups was similar. CIs at day 100, 1yr, and 3 yrs in the TCD group were 8.3%, 20.2% and 32.7% vs. 12.4%, 22.5% and 28.1% in the unmodified group (p=0.628). Relapse was lower in the TCD group, with CI at 1 and 3 yrs of 8.5% and 15.5%, vs. 31.0% and 39.4% in the unmodified group (p=0.002). Since the unmodified recipients had worse disease characteristics, further analyses in patients with good/intermediate risk cytogenetic showed that the relapse incidence was similar between these subgroups, with 3-yr CIs of 7.9% in TCD vs. 18% in unmodified group (p=0.185). The most common causes of death in the TCD group were infections (32%) and relapse (28%), while in the unmodified group it was relapse (55%), GVHD (20%) and infections (13%). Considering the differences in disease characteristics between the groups, multivariate regression models were performed for relapse-free survival (RFS) and overall survival (OS) adjusting for MDS-t, high-risk cytogenetics at diagnosis and high blast count at HSCT. No significant differences were observed between the groups for RFS (HR=1.44, p=0.128) and OS (HR= 1.35, p=0.236) (Table 2). High-risk cytogenetics at diagnosis (very poor risk) was the only significant prognostic factor for RFS (HR=5.32, p<0.001) and OS (HR=4.81, p<0.001).Allo-HSCT is an effective treatment for patients with MDS with similar long term survival with either unmodified or TCD allografts. TCD is associated with a lower incidence of acute and chronic GVHD and without an increased risk of relapse.Table 1CharacteristicsTCD (N=60)Unmodified (N= 129)p-valueMedian follow-up, months (range)43.4 (3.8-119.5)49.4 (12.2-136.3)Age, years (range)57.1 (21.9-72.0)57.0 (19.0-72.0)0.769Female gender34 (56.7%)45 (34.9%)0.008MDS-t7 (11.7%)43 (33.3%)0.003Cytogenetic risk at diagnosis ( IPSS-R)0.009Good25 (42.4%)48 (37.2%)Intermediate15 (25.4%)19 (14.7%)Poor11 (18.6%)15 (11.6%)Very poor8 (13.6%)47 (36.4%)Missing1Blasts at transplant< 0.001< 5%48 (81.4%)57 (46.3%)5-9%11 (18.6%)35 (28.5%)10-19%031 (25.2%)Missing16Donor type< 0.001MRD21 (35.0%)65 (50.4%)MUD25 (41.7%)64 (49.6%)MMD14 (23.3%)0Stem cell source0.002BM5 (8.3%)46 (35.7%)PB55 (91.7%)83 (64.3%)Table 2:Multivariate analysisVariablesOS HR (95% CI)RFS HR (95% CI)Disease etiology0.5180.511De novo11MDS-t0.87 (0.56-1.34)0.87 (0.56-1.33)Cytogenetic risk at diagnosis IPSS-R)< 0.001 < 0.001 Good11Intermediate1.41 (0.74-2.68)1.39 (0.73-2.64)Poor2.06 (1.13-3.73)2.49 (1.40-4.44)Very poor4.81 (2.88-8.02)5.32 (3.22-8.80)Blasts at transplant0.2860.502< 5%115-9%1.11 (0.70-1.77)1.03 (0.65-1.62)10-19%1.57 (0.91-2.71)1.37 (0.80-2.34)Type of transplant0.2360.128TCD11Unmodified1.35 (0.82-2.19)1.44 (0.90-2.31) DisclosuresNo relevant conflicts of interest to declare.

CD34+ Selection Avoids Methotrexate and Reduces the Severity of Oral Mucositis in TBI-Based Allogeneic Stem Cell Transplantation

▪Oral Mucositis (OM) is a frequent and debilitating complication of standard myeloablative T-replete allogeneic stem cell transplantation (allo-SCT), often requiring narcotic analgesia, total parenteral nutrition (TPN) and prolonged hospitalization. The incidence of World Health Organization (WHO) grade 3-4 OM after total body irradiation (TBI) based myeloablative conditioning can exceed 50% when methotrexate is used for graft versus host disease (GVHD) prophylaxis. Ex vivo T cell depleted (TCD) allo-SCT is known to be associated with improved GVHD-free survival. However its impact on early transplant outcomes, particularly the incidence of OM has not been described. We conducted a single institution retrospective analysis of the severity and incidence of OM and its related outcomes in 105 consecutive recipients of ex vivo T cell depleted (TCD) allo-SCT from their 6/6 matched sibling donors between 2006 to 2014. All subjects received a fully myeloablative conditioning regimen consisting of fludarabine (25mg/m2/day) from day -8 thru day -4, age-adapted fractionated TBI from day -7 thru day -4 followed by cyclophosphamide (60 mg/kg/day) on day -3 and day -2. TBI was delivered in 8 fractions at a total dose of 1200cGy with lung shielding to 600cGy for subjects <age 55 years and 400-600cGy for subjects ≥age 55 years (21% of subjects). None of the subjects received palifermin or intravenous methotrexate. On day 0, subjects received a G-CSF mobilized peripheral blood stem cell product selected for CD34+ progenitors using the Miltenyi CliniMACS system along with a T- lymphocyte dose of 5 to 50 x10e4 CD3+/kg (resulting in a 3-4 log TCD graft). Low dose cyclosporine until day 21 was the only GVHD prophylaxis. OM was graded by WHO and Bearman toxicity scales until day +21. All subjects achieved successful primary engraftment with a median time to neutrophil engraftment of 12 days (range 9-25 days) and a median length of stay (LOS) of 28.5 days. The incidence of WHO grade 2-4 and 3-4 OM were 46.7% and 34.3%, respectively, with a median severity of 0.5. By the Bearman toxicity scale, the incidence of grade 1, 2 and ≥3 OM were 53.3%, 15.2% and 0% respectively, with a median grade of 1. OM grading was strongly correlated between the WHO and Bearman toxicity scales (r= 0.69, p <0.0001). The severity of Grade 3-4 OM (WHO) mucositis was even lower in subjects who received 400-600cGy versus 1200 cGy TBI for conditioning (4.5% versus 42.1%, p<0.001). 62 subjects (59.1%) required at least intermittent narcotic analgesia (median duration of 6 days; range: 0 - 21 days) but only 16 (15.2%) of these subjects required continuous infusion of narcotic analgesics (median duration of 0 days; range: 0 - 11 days). Thirty six subjects (34.3%) required TPN support for a median duration of 9 days (range 1 -21 days). There were significant correlations between the severity of mucositis and the requirement for intravenous narcotic medications (r= 0.29, p =0.003) and the LOS (r= 0.24, p = 0.01). These findings extend the known benefits of TCD allo-SCT to an improvement in the quality of life to the early transplant phase. In conclusion, CD34+ selected allo-SCT is associated with significant reductions in the incidence and severity of OM, duration of narcotic analgesia and TPN use after TBI-based myeloablative conditioning compared to historical controls. The magnitude of the benefit is at least comparable to published reports of the impact of palifermin in standard T-replete transplantation. DisclosuresNo relevant conflicts of interest to declare.

Outcomes In Patients With Acute Lymphoblastic Leukemia In First Or Second Complete Remission Receiving Ex-Vivo T-Cell Depleted Or Unmodified Allografts: Comparison Of Results At Two Institutions

Ex vivo T-cell depleted (TCD) allogeneic hematopoietic stem cell transplants (HCT) in patients with acute myeloid leukemia in complete remission (CR)lead to survival and relapse rates comparable to those with unmodified grafts, but with significantly less graft versus host disease (GVHD). TCD-HCT is also effective in patients with acute lymphoblastic leukemia (ALL), however it is not known how outcomes compare with those of patients receiving conventional grafts. In this study we compared the outcomes of patients receiving TCD-HCT at Memorial Sloan-Kettering Cancer Center (MSKCC) with patients receiving conventional grafts at MD Anderson Cancer Center (MDACC) for ALL in first or second CR.Patients 18 years of age or older, undergoing HCT between 2000 and 2010 were included in this retrospective analysis. 52 patients at MSKCC received TCD grafts and 129 patients at MDACC received conventional grafts. All patients at MSKCC received myeloablative HCT conditioning (MAC). No GVHD prophylaxis was given. At MDACC, 115 patients received MAC and 14 received reduced intensity conditioning; GVHD prophylaxis consisted of tacrolimus and mini-dose methotrexate, plus antithymocyte globulin for total dose 4 mg/kg for unrelated donors.Patient characteristics and outcomes are summarized in the Table. A greater percentage of patients in the conventional graft group received transplants from a matched related donor and from bone marrow as a stem cell source. Patients in the TCD group almost exclusively received grafts from peripheral blood. [Display omitted] A significant difference in acute GVHD incidence was observed between the TCD and conventional groups, with 100-day cumulative incidence estimates of 17.3% and 40.3%, respectively (Gray's test p-value=0.007). A significant difference was also observed in chronic GVHD rates, with three-year estimates of 13.5% and 34.8% for the TCD and unmodified groups, respectively (Gray's test p-value=0.004). There was no statistical difference between TCD and unmodified groups with regards to OS (log-rank p-value=0.89, 3 year estimates 42.6% vs. 43.2%) or RFS (log-rank p-value=0.64, 3 year estimates 42.8% and 36.0%). The NRM at day 100, 1 year and 3 years were 15.4%, 26.9% and 37.8% in the TCD group and 10.1%, 23.5% and 28% in the unmodified group (Gray's test p-value=0.22). There was a lower relapse rate among patients who received TCD versus unmodified grafts (3 year estimates 19.4% vs. 36.0%, Gray's test p-value=0.05). Age >50 and was the only factor associated with inferior RFS (HR=1.74, p=0.01) and OS (HR=1.85, p=0.006).HCT is an effective treatment modality for patients with ALL with favorable results with either conventional or TCD allografts. Although the relapse rate was significantly lower after TCD-HCT, this would need to be confirmed in a prospective study. While 3-year OS rates are similar in both groups, TCD effectively reduces the rate of both acute and chronic GVHD.*: Median (range)* *: P-values were estimated using a chi-square test or Fisher's exact test for categorical variables and a Wilcoxon rank-sum test for continuous variables. OS and RFS were compared using a logrank statistics, while NRM, aGVHD and cGHVD were compared using Gray's test.^: Good risk: Hyperdiploidy, del(9p); poor risk: Ph+, t(4;11), t(8;14); complex karyotype (≥5 abnormalities), hypodiploidy/near triploidy; standard risk: other.TCD-T-cell depleted; CR- Complete Remission; TKI- Tyrosine Kinase Inhibitors; RIC-Reduced Intensity Conditioning; MAC- Myeloablative Conditioning; RFS-Relapse Free Survival; OS- Overall Survival; NRM- Non-Relapse Mortality; aGVHD- acute Graft Versus Host Disease; cGVHD- chronic Graft Versus Host Disease [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Ex Vivo T Cell–Depleted versus Unmodified Allografts in Patients with Acute Myeloid Leukemia in First Complete Remission

This study was conducted to retrospectively compare the clinical outcomes after transplantation of T cell–depleted (TCD) and unmodified allografts in patients with acute myeloid leukemia (AML) in first complete remission (CR1). Patients received TCD grafts at Memorial Sloan-Kettering Cancer Center (MSKCC, N = 115) between 2001 and 2010 using the following preparative regimens: hyperfractionated total body irradiation (HFTBI)+thiotepa+fludarabine; HFTBI+thiotepa+cyclophosphamide; or i.v. busulfan+melphalan+fludarabine. TCD was performed by 1 of 2 immunomagnetic CD34+ cell selection methods for peripheral blood grafts or by soybean lectin agglutination followed by sheep red blood cell–rosette depletion for bone marrow grafts. No additional graft-versus-host disease (GVHD) prophylaxis was administered. Patients received unmodified grafts at M.D. Anderson Cancer Center (MDACC, N = 181) after conditioning with busulfan+fludarabine and GVHD prophylaxis with tacrolimus+mini-methotrexate. Patients with unrelated or human leukocyte antigen–mismatched donors received anti-thymocyte globulin (ATG) at both centers, with some recipients of matched related donor TCD transplants also receiving ATG, depending upon the preparative regimen. TCD graft recipients were more likely to be older, receive a mismatched transplant, and have peripheral blood used as the graft source. The incidences rates of grades 2 to 4 acute GVHD and chronic GVHD were significantly lower in the TCD graft group (5% versus 18%, and 13% versus 53%). Three-year relapse-free and overall survival rates were 58% and 57%, respectively, in recipients of TCD grafts, and 60% and 66% in recipients of unmodified grafts (P = not significant). Survival and relapse-free survival are similar after TCD and conventional transplants from related/unrelated donors in patients with AML in CR1, but TCD significantly reduces GVHD.

Bone Marrow Mixed Chimerism Is a Risk Factor for Relapse After T-Cell Depleted Allogeneic Stem Cell Transplant

AbstractAbstract 4145 Background:Full donor chimerism following non myeloablative unmodified stem cell transplants (SCTs) is important for disease control and SCT outcome. The impact of mixed chimerism (MC) after myeloablative unmodified SCT remains controversial, and there are limited reports about its prognostic significance after T-cell depleted (TCD) SCT. Treatment of MC, including reduction of immunosuppression or infusion of donor leucocytes (DLI), can lead to the development of graft versus host disease (GVHD). In order to optimize the graft vs leukemia (GVL) effect of a TCD allograft while minimizing GVHD risk, we sought to determine the significance of MC on TCD SCT outcomes and to identify a subgroup that would benefit from intervention. Methods:From 2000–2010, 447 adult patients with acute myeloid and lymphocytic leukemia (AML, ALL) and myelodysplastic syndrome (MDS) underwent bone marrow (BM) or peripheral blood stem cell (PBSC) TCD SCT. Conditioning regimens were total body irradiation (TBI)/Thiotepa with Cyclophosphamide or Fludarabine, Clofarabine/Melphalan/Thiotepa or Busulfan/Melphalan/Fludarabine. Like-gender donor-recipient chimerism was analyzed using semi-quantitative PCR for polymorphisms; PCR and/or cytogenetics were used for unlike gender pairings. Relapse was cytogenetic or hematologic evidence of disease. BM chimerism and disease status were evaluated at approimately 6, 12, 18 and 24 months. BM chimerism and outcome data were reviewed to determine whether 6 month BM MC (defined as < 95% donor chimerism) was associated with 2 year post-SCT relapse, transplant-related mortality (TRM) and disease-free survival (DFS). The 6 month landmark was chosen as a reasonable time point for intervention, such as DLI, if needed. Patients who received DLI prior to landmark were excluded. Patient and SCT characteristics were compared using Wilcoxon’s rank-sum test or Fisher’s exact test. DFS was estimated using Kaplan-Meier methods, and time-to-relapse and TRM were estimated using cumulative incidence functions. Results:300 of the 447 patients survived, were disease free, and had BM chimerism data at 6 months. Median age was 50.6 years. Most patients received PBSC grafts (89%). 131 (44%) and 9 (3%) related, and 86 (29%) and 74 (24%) unrelated donors, were matched and mismatched, respectively. Only patients in remission or with low level disease (BM blasts < 10%) were transplanted with TCD grafts. The majority of patients were conditioned with Busulfan/Melfalan/Fludarabine and TBI/Thiotepa/Fludarabine, 45% and 32%, respectively. 251 pts (84%) received antithymocyte globulin. 25% demonstrated MC in the BM at 6 mos. The majority (60%) with MC had a donor component of 75–95%. Diagnosis was not associated with MC at 6 months. Stem cell source and degree of HLA-match had no impact on BM chimerism. There was a significant difference in chimerism based on donor-recipient gender pairing (P = 0.04): male grafts into female patients having the greatest risk of MC and female grafts into female patients having the least. There was also a significant difference in the degree of chimerism based on conditioning regimen: Busulfan/Melphalan/Fludarabine was most likely to result in MC (P = <0.001). TRM was not significantly different between the mixed and full donor chimerism groups. However, relapse was significantly higher in the MC group (P = 0.03): 10% (95% CI: 6–14%) with full chimerism and 18% (95% CI: 7–28%) with MC at 2 years (Figure 1). Diagnosis had no impact on relapse among patients with MC. Conclusions:25% of TCD SCT recipients had MC in the BM. Although the incidence of relapse was low for patients who survived to 6 months in the full and MC groups (10% and 18%, respectively), the difference was statistically significant. There was also a significant difference in incidence of MC based on conditioning regimen and donor-recipient gender pairings. The low percentage of relapse in the MC group precluded subset analyses to identify a group who would benefit from the GVL effect of DLI. Lineage-specific PB chimerism analysis is ongoing and may provide information about subgroups that would benefit from intervention for MC. Analyses of outcomes, i.e., GVHD, in recipients of DLI or TCD stem cell boost for MC may help to determine the risk-benefit ratio of such interventions. [Display omitted] Disclosures:Goldberg:SOBI Biovitrum: Research Funding. Perales:SOBI Biovitrum: Research Funding.

Graft-versus-Host Disease: State of the Science

Despite concerted research efforts, prevention and treatment of graft-versus-host disease (GVHD) have not changed significantly over the past 3 decades. The goal of this session is to provide an outline of the current state of the science with respect to the prevention, treatment, and evaluation of acute and chronic GVHD. In addition, we detail those strategies most likely to be at the forefront of clinical research in the upcoming years.

Graft-Versus-Host Disease: Have We Solved the Problem?

Graft-Versus-Host Disease: Have We Solved the Problem?

Ex-Vivo T Cell-Depleted Versus Unmodified Allografts in Patients with Acute Myeloid Leukemia in First Complete Remission: A Comparison of Outcomes in Two Institutions

Abstract 2013Allogeneic stem cell transplantation (ASCT) with T-cell depleted (TCD) allograft has been used to decrease the risk of graft-versus-host disease (GVHD). How outcomes of ASCT with TCD grafts compares to transplant with unmodified grafts in the context of ablative, reduced toxicity conditioning with busulfan /fludarabine is unknown. We sought to compare ASCT with and without TCD grafts, by studying the outcomes of pts with acute myeloid leukemia (AML) in first complete remission (CR1) who had TCD allografts at Memorial Sloan Kettering Cancer Center (MSKCC) with those who had unmodified allografts at MD Anderson Cancer Center (MDACC).Transplants at MSKCC (N=115) and MDACC (N=181) were performed between 2001 and 2010. Preparative regimens at MSKCC included: 1) Hyperfractionated total body irradiation (HFTBI) 1375 cGy over 4 days, thiotepa 5 mg/kg/day × 2 days & fludarabine 25 mg/m2/day × 5 days (n=29); 2) HFTBI 1375 cGy over 4 days, thiotepa 5 mg/kg/day × 2 days & cyclophosphamide 60 mg/kg/day × 2 days (n=25); or 3) busulfan 0.8 mg/kg intravenously every 6 hours for 10 doses(n=42) or 12 doses (n=19), melphalan 70 mg/m2/day × 2 days & fludarabine 25 mg/m2/day × 5 days (total n=61). Peripheral blood (PB) grafts underwent CD34+ cell selection using the ISOLEX 300i system, followed by sheep red blood cell (sRBC)-rosette depletion (n=85); or CD34+ cell selection using the CliniMACS system alone (n=22). Bone marrow (BM) grafts were T cell depleted by sequential soybean lectin agglutination and sRBC-rosette depletion (n=8). No additional GVHD prophylaxis was administered at MSKCC.Fludarabine 40 mg/m2 and busulfan 130 mg/m2 intravenously once daily for 4 days were used for conditioning at MDACC, with tacrolimus and mini-methotrexate for GVHD prophylaxis. Pts with unrelated or HLA-mismatched donors treated at MDACC and MSKCC received equine (total 60 mg/kg) or rabbit (total 2.5–5 mg/kg) anti-thymocyte globulin. Cytogenetic risk stratification considered complex cytogenetics, -5, -5q, -7, -7q, 11q23 aberrations, inv(3), t(3;3), t(6;9), and t(9;22) as poor risk.Pt characteristics and outcomes are summarized in the Table. TCD recipients were more likely to be older, receive a mismatch transplant, and have PBSC used as a graft source. Overall, only one pt, who had received an unmodified graft, experienced primary graft failure. Eleven (10%) and 33 (18%) pts experienced grade ≥2 acute GVHD within 100 days after transplants with TCD and unmodified grafts, respectively (p=0.05). Three-year relapse-free and overall survival rates were 58% and 57% in pts who received TCD grafts, and 60% and 66% in pts who received unmodified grafts (P=NS; Figure). There was a trend towards lower early non-relapse mortality among pts who received unmodified grafts (3% vs. 8% at 100 days, p=0.07). Of age, sex, secondary disease, risk status, donor, and graft type, secondary AML was the only risk factor found to significantly influence overall survival (HR: 1.7, 95% CI: 1.1–2.8). Survival outcomes were still comparable between recipients of TCD and unmodified grafts after adjusting for secondary AML. None of these factors significantly predicted relapse-free survival. Conclusion:Myeloablative ASCT with TCD or unmodified allografts lead to comparable outcomes in this high-risk cohort of AML pts in CR1 with a lower acute GVHD rate observed after TCD transplants.CharacteristicsFrequency, n (%)TCD, N=115Unmodified, N=181pTime CR1 to transplant, days*83 (12–304)97 (8–455)0.040Age, years*52 (19–71)48 (18–63)<0.001>50 years66 (57)76 (42)0.010Sex = Female58 (50)90 (50)NSEtiologyde novo60 (52)144 (80)<0.001Secondary38 (33)24 (13)Therapy-related17 (15)13 (7)Cytogenetic risk statusNSGood1 (1)2 (1)Intermediate72 (63)103 (57)Poor42 (37)76 (42)Donor typeMRD56 (49)103 (57)MUD32 (28)64 (35)MM27 (23)14 (8)<0.001Graft typeBM8 (7)57 (32)<0.001PB107 (93)124 (68)Outcome (95% CI)3-year RI18% (12%–27%)25% (19%–33%)NS100 day NRM8% (4%–15%)3% (1%–7%)0.071-year NRM18% (12%–27%)13% (9%–19%)NS3-year NRM24% (17%–34%)16% (11%–23%)NS3-year RFS58% (47%–67%)60% (51%–67%)NS3-year OS57% (47%–67%)66% (58%–74%)NSTCD: T-cell depleted, CR1: First complete remission, MRD: Matched related donor, MUD: Matched unrelated donor, MM: HLA-mismatch donor, BM: Bone marrow, PB: Peripheral blood, RI: Relapse incidence, NRM: Non-relapse mortality, RFS: Relapse-free survival, OS: Overall survival.*: Median (range). [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Improved Early Outcomes with T-Cell Replete (TCR) Compared with T-Cell Depleted (TCD) Haploidentical Stem Cell Transplantation (HaploSCT)

Abstract 320▪▪This icon denotes a clinically relevant abstract Background:HaploSCT has been commonly performed with a TCD graft using CD34+ selection; however, this has been limited by a higher non-relapse mortality (NRM) primarily related to infectious complications. An alternative approach using a TCR bone marrow graft and high-dose post-transplant cyclophosphamide (HDPTCy) in the setting of non-myeloablative conditioning has been reported to have lower NRM and acceptable rates of GVHD. Methods:We hypothesized that TCR HaploSCT using HDPTCy is associated with improved immunologic reconstitution, less NRM and better early outcomes compared with TCD HaploSCT, and analyzed 65 consecutive patients (pts) treated at UTMDACC with the same conditioning regimen, fludarabine (40mg/m2/day × 4), melphalan (140mg/m2) and thiotepa (10mg/kg). TCD HaploSCT pts were treated between 2001 and 2009, while TCR patients after 2009. 6 pts in the TCR group >55 years/comorbidities received reduced doses of melphalan (100mg/m2) and thiotepa (5mg/kg). There was no GVHD prophylaxis in the TCD group, while TCR group received HDPTCy (50mg/kg/day × 2) followed by tacrolimus and mycophenolate. Results:The median follow-up was 10 months (range 3.5–25) for the TCR group and 44 (11–79) months for the TCD group. Median age was 45 years (range 20–63) in the TCR group and 36 years (range 18–56) in the TCD group (p=0.02). 28% were > 50 years in the TCR compared with 6% in the TCD group (p=0.02). Diagnoses were: AML/MDS 50% vs. 79%, ALL 13% vs. 12%, CML 16% vs. 6%, lymphoma/CLL 9% vs. 3% in the TCR vs. TCD groups, respectively. Only 13 (41%) and 12 (36%) of pts were in remission at transplant in both groups, respectively (p=0.7). 10/16 (62.5%) pts with AML/MDS in the TCR group had poor risk cytogenetics vs. 13/26 (50%) pts in the TCD group. The donors were 5/10 allele match in 20/32 (63%) and 16/31 (52%) in the two groups, respectively. Median numbers of CD34+ cells infused were 2.5×10e6/kg in the TCR group and 10.5×10e6/kg in the TCD group. All pts in the TCD group had peripheral blood selected CD34+ cells while all but one received bone marrow stem cells in the TCR group.One pt had early death in each group. Primary engraftment was achieved in 94% in the TCR group and 81% in the TCD group (p=0.1). Day-100 NRM for all pts was 9% in the TCR group vs. 21% for the TCD group, and for pts in remission at transplant 0% vs. 42%, respectively (p=0.01). NRM at 1 year for all pts was 16% for the TCR group vs. 42% for the TCD group (p=0.03) (Figure1), while for pts in remission was 0% vs. 67% (p=0.001). The cumulative incidences of grade II-IV aGVHD was 27% vs. 11% (p=0.5) and cGVHD was 8% vs. 18%, in the TCR and TCD group, respectively (p=0.03). OS and PFS at 1 year post-transplant were 66% vs. 30% (p=0.02) and 45% vs. 21% (p=0.03) for the whole group, and 92% vs. 33% (p=0.03) and 80% vs. 25% (p=0.02) for pts in remission at transplant, respectively (Figure1). [Display omitted] Improved NRM in the TCR group was related to significantly better immunologic reconstitution of T-cell subsets. On day 30 post transplant there was a significantly better recovery of absolute CD4 cells in the TCR group (median 24 vs. 2, p=0.004) and CD8 cells (median 20.5 vs. 1.5, p=0.036). CD4 cells remained significantly lower in the TCD group until after day 180 when the median CD4 count was 200.5 vs. 64 in the TCR group (p=0.04) while the difference in CD8 counts became non-significantly higher in the TCR after day 90 (median 119 vs. 29, p=0.23). Conclusion:TCR HaploSCT is associated with better immunologic reconstitution and improved early outcomes compared with TCD HaploSCT. Disclosures:No relevant conflicts of interest to declare.