Addition Of Antithymocyte Globulin Research Articles

Post-transplant cyclophosphamide plus anti-thymocyte globulin decreased serum IL-6 levels when compared with post-transplant cyclophosphamide alone after haploidentical hematopoietic stem cell transplantation

BackgroundPost-transplantation cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG) are common prophylactic strategies for graft-versus-host disease (GVHD) after haploidentical hematopoietic stem cell transplantation (haplo-HSCT). Interleukin (IL)-6 is a surrogate marker for cytokine release syndrome (CRS) and acute GVHD.MethodThe clinical outcomes and complications of haplo-HSCT with PTCy plus ATG versus PTCy monotherapy were compared according to serum IL-6 levels at Chungnam National University Hospital (Daejeon, South Korea) from January 2019 to February 2023.ResultsForty patients who underwent haplo-HSCT were analyzed. A significant difference in IL-6 levels was observed between the PTCy plus ATG and PTCy alone groups (7.47 ± 10.55 vs. 117.65 ± 127.67; p = 0.003). More patients in the PTCy plus ATG group had a CRS grade of 0 than in the PTCy alone group (p < 0.001). Serum IL-6 levels were associated with grades II–IV acute GVHD (r = 0.547, p < 0.001). The cumulative incidence (CI) of grades II–IV acute GVHD was significantly higher in the PTCy alone group (67.9% vs. 4.8%; p < 0.001). No significant difference in the CI for chronic GVHD was detected between the PTCy plus ATG and PTCy alone groups (72.1% vs. 82.0%; p = 0.730). The CI of 1-year non-relapse mortality was significantly higher in the PTCy alone group than in the PTCy plus ATG group (42.2% vs. 15.9%; p = 0.022). The 1-year overall survival (OS) was significantly better in the PTCy plus ATG group (75.9% vs. 35.3%; p = 0.011). The 1-year GVHD-free, relapse-free survival rate was 29.4% in the PTCy alone group and 54.0% in the PTCy plus ATG group (p = 0.038).ConclusionSerum IL-6 levels were higher in the PTCy alone group than in the PTCy plus ATG group. The addition of ATG before stem cell infusion affected IL-6 levels and reduced the incidences of CRS and grade II–IV acute GVHD in haplo-HSCT patients. This study suggests that PTCy plus ATG as GVHD prophylaxis in haplo-HSCT is beneficial in terms of clinical outcomes and complications of HSCT.

Transfusion-dependent non-severe aplastic anemia: characteristics and outcomes in the clinic.

Transfusion-dependent non-severe aplastic anemia (TD-NSAA) is a rare condition of bone marrow failure that can persist for a long time or develop into severe aplastic anemia (SAA). Little is known about the clinical and laboratory characteristics, and disease prognosis and outcomes in TD-NSAA patients. The clinical and laboratory data of 124 consecutive TD-NSAA patients in the Chinese Eastern Collaboration Group of Anemia from December 2013 and January 2017 were analyzed retrospectively. In 124 TD-NSAA patients, the median age was 32 years (range: 3-80) and the median disease course was 38 months (range: 3-363). Common complications were iron overload (53/101, 52.5%), liver and kidney dysfunction (42/124, 33.9%), diabetes mellitus/impaired glucose tolerance (24/124, 19.4%), and severe infection (29 cases, 23.4%). 58% of patients (57/124) developed severe aplastic anemia with a median progression time of 24 months (range: 3-216). Patients with absolute neutrophil count (ANC) <0.5×109/L, severe infection, or iron overload had a higher probability of progression to SAA (P=0.022, P=0.025, P=0.001). Patients receiving antithymocyte globulin (ATG) plus Cyclosporin A (CsA) had a higher overall response rate compared to those receiving CsA alone (56.7% vs 19.3%, P < 0.001). The addition of ATG was the favorable factor for efficacy (P=0.003). Fourteen patients developed secondary clonal hematologic disease: eleven patients with paroxysmal nocturnal hemoglobinuria, two patients with myelodysplastic syndromes, and one patient with acute myeloid leukemia, respectively. Ten patients (8.1%) died with a median follow-up of 12 months (range: 3- 36 months). Patients with TD-NSAA usually have a prolonged course of disease, and are prone to be complicated with important organ damage and disease progression to SAA. Intensive immunosuppressive therapy based on ATG might be an appropriate approach for TD-NSAA. Clinical trial registration: http://www.chictr.org.cn/edit.aspx?pid=125480&htm=4, identifier ChiCTR2100045895.

Antithymocyte Globulin Plus Post-Transplant Cyclophosphamide Combination as an Effective Strategy for Graft-versus-Host Disease Prevention in Haploidentical Peripheral Blood Stem Cell Transplantation for Children with High-Risk Malignancies.

Haploidentical hematopoietic stem cell transplantation using post-transplant cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis has emerged as a valid alternative transplant strategy for patients lacking a suitable HLA-matched related donor. The high risk of severe GVHD remains the major clinical challenge in this setting. The addition of antithymocyte globulin (ATG) in PTCy-based regimens for GVHD reduction in haploidentical hematopoietic stem cell transplantation is rational and was reported in adult series. However, its feasibility is unknown in pediatric patients. Here, we firstly describe our experience of 15 consecutive children with high-risk malignancies receiving haploidentical peripheral blood stem cell transplantation using ATG plus PTCy for GVHD prophylaxis. Only three patients developed grade 1-2 acute GVHD, limited to skin. No grade 3-4 acute GVHD and chronic GVHD were observed. Viral reactivations were frequently seen but manageable. Six patients relapsed, as the main cause of death in our series. None died from events related to GVHD. Our data suggest that ATG plus PTCy is an effective strategy for GVHD prevention in haploidentical peripheral blood stem cell transplantation and is feasible in children with high-risk malignancies.

Should anti-thymocyte globulin be added in post-transplant cyclophosphamide based matched unrelated donor peripheral blood stem cell transplantation for acute myeloid leukemia? A study on behalf of the Acute Leukemia Working Party of the EBMT.

In this registry-based study which includes acute myeloid leukemia patients who underwent a matched unrelated donor allogeneic peripheral-blood stem cell transplantation in complete remission and received post-transplant cyclophosphamide (PTCY) as graft-versus-host disease (GvHD) prophylaxis, we compared 421 recipients without anti-thymocyte globulin (ATG) with 151 patients with ATG. The only significant differences between PTCY and PTCY + ATG cohorts were the median year of transplant and the follow-up period (2017 vs 2015 and 19.6 vs 31.1 months, respectively, p < 0.0001). Overall, 2-year survival was 69.9% vs 67.1% in PTCY and PTCY + ATG, respectively, with deaths related to relapse (39% vs 43.5%), infection (21.9% vs 23.9%) or GvHD (17.1% vs 17.4%) not differing between groups. On univariate comparison, a significantly lower rate of extensive chronic GvHD was found when ATG was added (9.9% vs 21%, p = 0.029), a finding which was not confirmed in the multivariate analysis. The Cox-model showed no difference between PTCY + ATG and PTCY alone with respect to acute and chronic GvHD of all grades, non-relapse mortality, relapse, leukemia-free survival, overall survival, and GvHD-free-relapse-free survival between study cohorts. Our results highlight that the addition of ATG in PTCY does not provide any extra benefit in terms of further GvHD reduction, better GRFS or better survival.

P3.01: Similar Graft-Versus-Host Disease (GVHD) Incidence Among Unrelated and Identical Sibling Donor Transplantation With the Use of Anti-thymocyte Globulin (ATG)

Introduction: GVHD is the main cause of morbidity and mortality associated with allogeneic hematopoietic stem cell transplantation (HSCT) with an incidence rate of 40-60%. Addition of ATG has shown to reduce its incidence. We report the GVHD outcomes with the use of ATG as part of the prophylaxis regimen in a group of patients (pts) undergoing HSCT. Methods: From March 2018 to June 2021 we conducted a prospective multicenter study including 95 consecutive pts.: 33 transplanted with an identical sibling donor (ISD), 33 with an HLA-matched unrelated donor(MUD) and 18 with an HLA 1 miss-matched donor (MMUD). Conditioning regimen was according to institutional protocol. GVHD prophylaxis included tacrolimus and methotrexate plus ATG (Timoglobulina®Sanofi) 2.25 mg/kg days -3 and -2. GVHD incidence, relapse and death were recorded. Acute GVHD (aGvHD) and chronicGVHD (cGVHD) were defined using Glucksberg criteria and NIH clinical grading respectively. Median and interquartile range (IQR) were used to describe non-parametric data, group comparison with X2, Kaplan Meyer curve and multi-sample log Rank test for survival analysis, considering a statistically significant p value of less than 0.05. Results: 42 pts were male and donors were female in 56% (n:54). Conditioning regimen was myeloablative in 81% (n:77). Median time to neutrophil and platelet engraftment were 17 days (range 15-21) and 17 days (range 12-20) respectively. 6/95 pts presented graft failure. aGVHD incidence was 36% (n:34), grades I-II 19% (n:19) and III-IV 16% (n:15). Incidence of grades III-IV did not varied according to donor: 15% (n:7) for ISD, 9% (n:3) for MUD and 27% (n:5) for (X2 3.06, p0.21) Overall incidence of cGVHD was 23% MMUD (n:21): Grades mild 6% (n:6), moderate 11% (n:11) and severe 4% (n:4). According to donor type, severe cGVHD was 2% (n:1), 3% (n:1) and 11% (n:2) using ISD, MUD and MMUD respectively (X2 2.65, p0.26). At one year, 15/79 pts (19%) were under immunosuppressive treatment. Transplant related mortality at day 100 was 9% (n:9). Most frequent cause was sepsis (n:4). In 31 pts CMV reactivation was detected (more than one reactivation in 6 pts of which 5 had GVHD) and 7 reactivated EBV infection. None evolved to PTLD. Median follow-up time was 524 days (IQR 168-833). cGVHD–free and relapse-free survival (combined endpoint) at 1 year was 57% (n:54) of 79 evaluables patients. cGVHD and relapse free survival at 1 year was 48% for IDS (33-63%CI), 66% for MUD (47-81%CI) and 38% for MMUD (21-60%CI). No significant difference was found according to donor type (X2 4.98; p0.083). Conclusion: With the use of ATG no difference was observed in the incidence of aGVHD grades III-IV and severe cGvHD between the different types of donor. This results should be confirmed with a higher level of evidence study.

Addition of Anti-thymocyte Globulin in Allogeneic Stem Cell Transplantation With Peripheral Stem Cells From Matched Unrelated Donors Improves Graft-Versus-Host Disease and Relapse Free Survival

Anti-thymocyte globulin (ATG) is commonly used to prevent graft-versus-host disease (GvHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT).To evaluate the impact of ATG as part of the GvHD prophylaxis in our institution, we report the outcome of 415 patients with matched unrelated donors (MUD) transplanted for hematological malignancies with or without ATG from 2005 to 2019 at Oslo University Hospital, Norway. The following groups were compared: (1) 154 patients transplanted with peripheral blood stem cells (PBSC) without ATG 2005-2014. (2) 137 patients transplanted with bone marrow stem cells (BMSC) 2005-2019. (3) 124 patients transplanted with PBSC and ATG (PBSC + ATG) 2014-2019.Three years survival was similar in the groups, 61% following allografting with PBSC, 54% with BMSC, and 59% with PBSC + ATG. Acute GvHD grade III-IV was 14%, 14%, and 7%; chronic GvHD was 81%, 32, and 26%; and extensive cGvHD 44%, 15%, and 6% in the corresponding groups. Both acute and chronic GvHD were significantly reduced in the PBSC + ATG-versus the PBSC group (p < 0.05 and p < 0.001 respectively).Transplant-related mortality (TRM) was 33%, 25%, and 17% (p = 0.18). Graft versus host disease and relapse free survival (GRFS) at 3 years was 43 %, 43%, and 64% in the groups.Adding ATG to the GvHD prophylaxis regimen of MUD allo-HSCT with PBSC resulted in a substantial reduction of both acute and chronic GvHD without compromising the disease control, reflected in a superior 3 years GRFS.

Comparison of Clinical Outcomes of Induction Regimens in Patients Undergoing Liver Transplantation for Acute Liver Failure.

Spontaneous survival rates in acute liver failure (ALF) are vastly improved by liver transplantation (LT). However, the value of induction agents beyond steroids continues to be debated. To understand the potential benefit of different induction regimens in the ALF population, we compared overall survival of recipients undergoing LT in the United States for ALF. Using the Scientific Registry of Transplant Recipients, we assessed the impact of induction immunosuppression (IS) in a cohort of 3754 first-time LT recipients with a diagnosis of ALF from 2002 to 2018. Induction IS therapy was grouped into steroid-only induction, use of antithymocyte globulin (ATG), or interleukin 2 receptor antibody. Other regimens were excluded from analysis. Survival analysis was estimated via Cox proportional hazards models and expressed as hazard ratios (HRs). In LT for ALF, the use of induction agents beyond steroids is increasingly frequent over the last 2 decades. The use of ATG is associated with worse overall survival, even after adjusting for donor and recipient factors, with HR of 1.24 (95% confidence interval, 1.00-1.53; P = 0.05). An elevated serum creatinine, recipient and donor age, and Black ethnicity, were all associated with reduced survival, whereas maintenance IS with calcineurin inhibitors (CNIs) was associated with improved survival. Although adjunct induction therapy has become more common, our analysis shows that compared with a steroid-only induction regimen, the addition of ATG is associated with worse overall survival after LT for ALF. CNI maintenance was highly protective, suggesting that an IS strategy focusing on corticosteroid-only induction followed by CNI maintenance may offer the best overall survival rate.

Post-Transplant Cyclophosphamide Versus Antithymocyte Globulin in Patients with Acute Myeloid Leukemia Undergoing Allogeneic Stem Cell Transplantation from HLA-Identical Sibling Donors: A Retrospective Analysis from the Acute Leukemia Working Party of the EBMT

Introduction. In patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) from an HLA-identical matched sibling donor (MSD), use of cyclosporine A in association with methotrexate has been the main graft-versus-host disease (GVHD) prophylaxis strategy. Addition of antithymocyte globulin (ATG), especially when using peripheral blood stem cells (PBSC) as source, has also been shown to favor lower rates of chronic GVHD. More recently, use of post-transplant cyclophosphamide (PTCY) in the haploidentical setting resulted in low incidences of both acute and chronic GVHD. Its use has therefore been subsequently reported in other donor settings, including MSD. The aim of our study was to compare GVHD prophylaxis containing either PTCY or ATG in patients diagnosed with acute myeloid leukemia and undergoing allo-HSCT from a MSD. Methods. This was a retrospective study from the EBMT registry. Included were adult patients undergoing their first allo-HSCT during the period 2008-2018 and who were in complete remission at time of allo-HSCT. Results. Globally, 197 and 1,913 patients receiving either PTCY or ATG, respectively, were identified who fulfilled inclusion criteria. Patients in the PTCY group were younger (median age 47 versus 54 years, p&amp;lt;0.01) and had undergone allo-HSCT more recently (median year of allo-HSCT: 2015 versus 2014, p&amp;lt;0.01). Peripheral blood was the more frequently used stem cell source, this being significantly more frequent in the ATG group (95% versus 70%) than in the PTCY group (p&amp;lt;0.01). The conditioning regimen was more frequently myeloablative in the PTCY group (59% versus 48% in the ATG group, p&amp;lt;0.01). Cyclosporine-A alone was the most used systemic immunosuppressive agent associated with either PTCY (22%) or ATG (28%), while 34% and 29% of patients in the ATG group and 7% and 12% in the PTCY group also received either methotrexate or mycophenolate mofetil along with cyclosporine A. No statistical differences were observed for incidence of grade II-IV acute GVHD at 100 days after allo-HSCT, this being 19% versus 17% in the PTCY and ATG groups, respectively (p=0.81). On the other hand, a significantly higher incidence of chronic GVHD at 2 years was observed with the use of PTCY (37% versus 30%, p&amp;lt;0.02) and for extensive chronic GVHD (16% versus 12%, p&amp;lt;0.01) as compared to ATG. There was no impact of conditioning intensity on GVHD incidence. No statistical differences were observed on univariate analysis for all other transplant outcomes, with a leukemia-free survival (LFS) of 55% versus 58%(p=0.75), overall survival (OS) of 64% versus 65% (p=0.61), GVHD-free, relapse-free survival (GRFS) of 44% versus 49% (p=0.19), relapse incidence (RI) of 36% versus 32% (p=0.56) and non-relapse mortality (NRM) of 8% versus 10% (p=0.78). Of note, the cumulative incidences of death due to GVHD were 4.4% and 4% in the PTCY and ATG groups, respectively (p=0.53). Also, there were no differences between the 2 groups for death due to infections: 6% in the PTCY group and 6.3% in the ATG group, respectively (p=0.49). On multivariate analysis, these results were confirmed, with a higher risk of chronic GVHD of any grade (HR=1.41, 95%CI 1.03-1.92; p&amp;lt;0.01) and extensive chronic GVHD (HR=1.68, 95%CI, 1.07-2.62; p&amp;lt;0.01) with PTCY, and no differences with respect to the other outcomes. We also observed that, regardless of the use of PTCY or ATG, use of PBSC was associated with lower RI (HR=0.64, 95% CI 0.46-0.89; p&amp;lt;0.01), higher LFS (HR=0.71, 95% CI 0.53-0.95; p&amp;lt;0.03), and OS (HR=0.72, 95% CI 0.52-0.99; p&amp;lt;0.05). On the other hand, we found no statistical differences in terms of both acute GVHD (HR=0.73, 95%CI, 0.48-1.12; p=0.15) and chronic GVHD (HR=0.83, 95% CI 0.56-1.21; p=0.33) according to stem cell source. These results were also confirmed in a matched-pair analysis. Conclusion. In conclusion, our results highlight that in the HLA-identical sibling setting, the use of ATG provides similar outcomes to those seen with PTCY except for chronic GVHD for which a protective effect of ATG is confirmed as previously reported by different other studies. Disclosures Blaise: Sanofi: Honoraria; Molmed: Consultancy, Honoraria; Pierre Fabre medicaments: Honoraria; Jazz Pharmaceuticals: Honoraria. Chevallier:Incyte: Consultancy, Honoraria; Jazz Pharmaceuticals: Honoraria; Daiichi Sankyo: Honoraria. Socie:Alexion: Consultancy. Mohty:Jazz Pharmaceuticals: Honoraria, Research Funding.

Unrelated Cord Blood Transplantation and Post-Transplant Cyclophosphamide (PT-CY)

Background .There has been a decrease in the use of unrelated cord blood transplants (UCBT) in the past years: this is probably due to slow hematologic and immune recovery, resulting in a relatively high non relapse mortality (NRM). The addition of anti-thymocyte globulin (ATG) in the conditioning prevents graft versus host disease (GvHD) but makes immune recovery very slow. In addition there is a growing competition of unmanipulated haploidentical transplants. Aim of the study. We have opened a pilot study to test whether high dose post-transplant cyclophosphamide (PT-CY) would prevent GvHD but still allow for robust immune and hematologic recovery . Methods. We have grafted 10 patients with an unrelated CB unit and PT-CY. The conditioning regimen was thiotepa (10 mg/kg), busulfan 9.6 mg/kg and fludarabine 150 mg/m^2 (TBF). GvHD prophylaxis was cyclosporin (CSA) starting day 0 (3 mg/kg/day(i.v.), mycophenolate (MMF) 30 mg/kg starting day +1 (p.o) , and PT-CY 30 mg/kg days +3 and +5. The median patients' age was 58 (43-66), and the median weight was 75 kg (54-85) the diagnosis was AML in 8 patients, Ph'+ALL in one and RAEB in one patient; 6 patients were in remission and 4 had active disease. CB units. The HLA matching of the CB unit was 5/8 antigens/alleles (A,B,C,DRB1) in six patients, 4/8 in two and 2/8 in one. The median nucleated cell dose was 3.1x10^7/kg (range 1.8- 4.5). The ABO was mismatched in all 10 patients. Hematologic recovery: median time to neutrophils 0.5x10^9/l was day 23 days (range 17-27) and the median time to a platelet count of 20x10^9/L was 38 days (range 34-40). The median counts on day +50 were as follows: Hb 9,1 gr/dL (range 8.7-11.1), Neutrophils 2,3 x10e9/L (range 1-5), PLTs 56 x10e9/L (10-90). One patient failed to engraft and received a second transplant from an unrelated donor, which was successful. No patient developed pure red cell aplasia despite 9/10 being ABO major mismatched. CD4 recovery : the median CD4 count on day +50 was 74 /cmm (range 67-116) and on day +100 it was 111/cmm(range 100-136). CMV pre-emptive therapy occurred in 3/6 evaluable patients Outcome: two patients with advanced disease, died early of infections, within day +20. GvHD was seen in 1 patient as a transient rash. No patient was treated for GvHD. No patient developed chronic GvHD. No patient relapsed. Eight patients survive in remission, with a median follow up of 6 months, and a projected one year actuarial survival of 80%. Readmissions were extremely rare. Conclusions. These first 10 patients suggest that UCBT followed by PT-CY, CSA, MMF, as GvHD prophylaxis is feasible and leads to encouraging hematologic and immunologic recovery. We were particularly impressed with the lack of GvHD, the absence of relapses and the good quality of life. Figure Disclosures No relevant conflicts of interest to declare.

Impact of in vivo T cell depletion in HLA-identical allogeneic stem cell transplantation for acute myeloid leukemia in first complete remission conditioned with a fludarabine iv-busulfan myeloablative regimen: a report from the EBMT Acute Leukemia Working Party

BackgroundThe impact of the use of anti-thymocyte globulin (ATG) in allogeneic stem cell transplantation performed with HLA-identical sibling donors following fludarabine and 4 days intravenous busulfan myeloablative conditioning regimen has been poorly explored.MethodsWe retrospectively analyzed 566 patients who underwent a first HLA-identical allogeneic stem cell transplantation with this conditioning regimen for acute myeloid leukemia in first complete remission between 2006 and 2013 and compared the outcomes of 145 (25.6%) patients who received ATG (ATG group) to 421 (74.4%) who did not (no-ATG group). The Kaplan-Meier estimator, the cumulative incidence function, and Cox proportional hazards regression models were used where appropriate.ResultsPatients in the ATG group were older, received more frequently peripheral blood stem cell grafts from older donors, and were transplanted more recently. With a median follow-up of 19 months, patients in the ATG group had reduced 2-year cumulative incidence of chronic graft-versus-host disease (GVHD) (31 vs. 52%, p = 0.0002) and of its extensive form (8 vs. 26%, p < 0.0001) but similar relapse incidence (22 vs. 27%, p = 0.23) leading to improved GVHD and relapse-free survival (GRFS) (60 vs. 40%, p = 0.0001). In multivariate analyses, the addition of ATG was independently associated with lower chronic GVHD (HR = 0.46, p = 0.0001), improved leukemia-free survival (HR = 0.67, p = 0.027), overall survival (HR = 0.65, p = 0.027), and GRFS (HR = 0.51, p = 4 × 10−5). Recipient age above 50 years was the only other factor associated with worse survivals.ConclusionsThese results suggest that the use of ATG with fludarabine and 4 days intravenous busulfan followed by HLA-identical sibling donor allogeneic stem cell transplantation for acute myeloid leukemia improves overall transplant outcomes due to reduced incidence of chronic GVHD without increased relapse risk.

Does anti-thymocyte globulin have a place in busulfan/fludarabine conditioning for matched related donor hematopoietic stem cell transplantation?

Background/Aims:There is controversy about the prophylactic effect of anti-thymocyte globulin (ATG) on graft versus host disease (GVHD) in the setting of matched related-donor hematopoietic stem cell transplantation (HSCT). This study assessed the inf luences of ATG on the incidences of acute and chronic GVHD and other clinical outcomes in matched related-donor HSCT.Methods:Sixty-one patients received allogeneic HSCT from human leukocyte antigen-matched, related donors. Patients received busulfan/fludarabine conditioning regimens and standard GVHD prophylaxis with or without additional ATG.Results:There was no significant difference in the cumulative incidences of overall acute GVHD, grade II to IV acute GVHD at day 100, and chronic GVHD during the follow-up period between the ATG and non-ATG groups. Three-year overall survival rates were very similar, but three year disease-free survival of the non-ATG group was higher than that of the ATG group (56.2% for ATG vs. 63.1% for non-ATG, p = 0.597). Relapse rate at 3 years in the ATG group was slightly higher than that of the non-ATG group (37.5% vs. 20%, p = 0.29). Non-relapse mortality rate at 3 years was lower in the ATG group (6.25% vs. 15.6%, p = 0.668).Conclusions:Although the addition of ATG doesn’t guarantee a reduction in the incidences of acute and chronic GVHD, pre-transplantation ATG may result in lower non-relapse mortality in the context of matched related-donor HSCT with a busulfan/fludarabine conditioning regimen. However, caution is needed when using ATG because of a possibility to increase relapse rate.

An International Multicenter Comparative Analysis of Tacrolimus Plus Sirolimus with or without Antithymocyte Globulin As Graft-Versus-Host Disease Prophylaxis in HLA-Mismatched Allogeneic Hematopoietic Cell Transplantation

Background: There is lack of consensus in regards to the optimal regimen for graft-versus-host disease (GVHD) prophylaxis in patients undergoing HLA-mismatched unrelated donor (MMUD) allografting. A regimen combining tacrolimus plus sirolimus (TAC-SIR) has been shown to be effective as GVHD prophylaxis in HLA-matched related (MRD) or matched-unrelated donor (MUD) allogeneic hematopoietic cell transplantation (HCT). Addition of antithymocyte globulin (ATG) has been shown to reduce incidence of acute GVHD but it is associated with a high rate of infectious complications. Here, we retrospectively compare post-transplant outcomes using TAC-SIR or TAC-SIR-ATG in 104 patients who underwent a MMUD allogeneic HCT between June 2008 and December 2014 at 5 Spanish and 1 transplant center (MCC) in the United States.Patients and methods: Forty-three (MCC=5, Spanish Centers=38) patients received TAC-SIR whereas 61(MCC=41, Spanish Centers=20) received TAC-SIR-ATG as GVHD prophylaxis for MMUD allogeneic HCT. Patient-, disease-, and transplant characteristics are summarized in Table 1.Results: The median follow-up (months) for all, TAC-SIR, and TAC-SIR-ATG patients were 29 (5-83), 27 (5-64), and 30 (6-83) months, respectively. Patients receiving TAC-SIR had faster platelets (12 vs. 15 days, p=0.005) but slightly slower neutrophil engraftment (16 vs. 15 days, p=0.037). Addition of ATG resulted in a lower incidence of acute GVHD (grade 2-4) (44% (95%CI=33-59%) vs. 67% (95%CI=55-83%), p=0.055) and over two-fold lower incidence, albeit not statistically significant, of moderate/severe chronic GVHD (17% (95%CI=10-30%) vs. 38% (95%CI=25-60%), p=0.086). Non-relapse mortality (NRM) (2-year) was two-fold higher, but not statistically significant, in the TAC-SIR-ATG group (TAC-SIR-ATG=35% (95%CI=24-50%) vs. TAC-SIR=17% (95%CI=10-35%), p=0.078) mainly attributable to a 3-fold higher number of non-relapse deaths attributed to infections (9 vs. 3). There was no difference in cumulative incidence of relapse (2-year) (TAC-SIR=28% (95%CI=17-46%) vs. TAC-SIR-ATG=26% (95%CI=17-41%), p=0.858) or in 2-year OS (TAC-SIR=56% (95%CI=40-72%) vs. TAC-SIR-ATG=47% (95%CI=34-60%), p=0.244) between the groups. These and other outcomes are summarized in Table 2.Conclusion: In MMUD allogeneic HCT, addition of ATG to TAC-SIR results in a lower incidence of grade 2-4 acute GVHD but does not improve OS. The two-fold higher 2-year NRM with addition of ATG is probably explained by a higher incidence of resulting infectious complications with in vivo T-cell depletion. While these results are intriguing, a prospective randomized study is certainly needed to confirm these findings. Table 1Patient-, disease-, and transplant-related characteristics.VariablesCategoriesTAC-SIRTAC-SIR-ATGMCC (N=5)Spanish Centers (N=38)MCC (N=41)Spanish Centers (N=20)Median age (range), years53 (25-64)51 (17-69)52 (24-67)55 (30-68)Gender mismatch(Donor→recipient)F→M F→F M→M,F Missing1 1 3 07 5 25 110 13 18 02 0 10 8 HLA-mismatchA B C DRB1 Missing1 1 3 0 010 14 8 6 024 13 4 0 08 3 3 5 1DiagnosesALL AML CLL CML HL MDS MF MM NHL Other1 2 0 0 0 1 0 0 1 03 10 3 1 3 7 1 1 10 04 18 3 2 1 5 1 0 7 01 6 1 0 1 3 0 1 5 2Preparative regimenFLU-BU FLU-MEL3 218 2035 611 7CIBMTR riskNone Low Intermediate High0 2 1 20 24 2 121 13 15 120 18 2 0Cell sourceBM PBSC0 58 300 411 19Median CD34 cells (range) x106/recipient Kg body weight7.99 (4.08-10.0)6 (1.2-11.0)8.57 (2.81-23.01)6.08 (0.67-9.5)Recipient/donor CMV serologic status+/+ +/- -/- -/+ Missing1 2 2 0 018 16 2 2 018 14 7 2 07 6 0 0 7Table 2Post-transplant outcomes.OutcomesTAC-SIRTAC-SIR-ATGP-valueMedian days (range) to ANC>500/µL16 (10-29)15 (9-24)0.037Median days (range) to platelets engraftment12 (6-26)15 (0-50)0.005Cum incidence acute GVHD (grade 2-4) (at 100 day)67% (55-83%)44% (33-59%)0.055Cum incidence acute GVHD (grade 3-4) (at 100-day)16% (8-32%)10% (5-21%)0.347Chronic moderate or severe (at 2-year)38% (25-60%)17% (10-30%)0.086Cum incidence of NRM (at 100-day)12% (5-27%)13% (7-25%)0.078Cum incidence of NRM(2-year)17% (10-35%)35% (24-50%)0.078Cum Incidence of relapse (2-year)28% (17-46%)26% (17-41%)0.858EFS (2-year)54% (38-69%)38% (26-52%)0.191OS (2-year)56% (40-72%)47% (34-60%)0.244 DisclosuresOff Label Use: Sirolimus for GVHD prophylaxis. Perkins:PDL Biopharma: Research Funding. Falantes:Celgene: Honoraria. Valcárcel:Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Antithymocyte Globulin and Role Of Stem Cell Source On Outcome In Myeloablative Conditioning Of Allogeneic Hematopoietic Stem Cell Transplantation With Identical Sibling and Matched Unrelated Donors - A Retrospective Study Of French Society Of Bone Marrow Graft Transplantation and Cellular Therapy -

ObjectivesAllogeneic hematopoietic stem cell transplantation (AHSCT) is an effective treatment modality for a number of hematological malignancies. Several retrospective studies demonstrate that the addition of antithymocyte globulin (ATG) to standard GvHD prophylaxis in myeloablative conditioned AHSCT resulted in a reduction of the incidence of acute and chronic GvHD. However the impact of rabbit ATG incorporated within a standard myeloablative conditioning regimen (MAC) prior to AHSCT on overall survival (OS) has never been clearly assessed. The purpose of this study is to evaluate retrospectively the long term influence of ATG on OS in a large cohort. MethodsAll AHSCT with matched sibling donor (MSD) and matched unrelated donor (MUD) performed between 2001-2010 in France and reported to Promise database were retrospectively studied. Patients fulfilling the requirements for this study had received a MAC such as total body irradiation (TBI)-cyclophosphamide or busulfan-cyclophosphamide (Bu-Cy) with or without ATG. Results1980 AHSCT were reported in 32 transplant centers. One hundred and fifty (8%) patients received ATG (25 with MSD and 125 with MUD), whereas 1830 (92%) did not receive ATG (1441 with MSD and 389 with MUD). Diagnosis were 1452 acute leukemia (73%), 340 myelodysplasia (MDS) and/or myeloproliferative syndrome (MPS) (17%), 157 lymphoma (8%), 9 myeloma and 21 chronic lymphocytic leukemia (CLL) (2%). 1385 patients received a TBI 12 Gy based regimen with cyclophosphamide whereas 595 patients received Bu-Cy. Bone marrow (1468 patients) or peripheral blood stem cells (512 patients) were infused 24-48h after the last cyclophosphamide administration (day 0). Median age at transplantation was 37.5 years in the ATG group and 39.2 years in the non ATG group. Median follow-up was of 79.8 months [19.2-138.8]. Using multivariable analysis, OS was adversely significantly influenced by age of recipient older than 39.1 years, bone marrow stem cell source, MUD, non-complete remission status before HSCT, GvHD grade 2-4, age of donor older than 38.3 years and the use of GvHD prophylaxis other than cyclosporine and methotrexate. ATG was not an independent variable influencing OS. The use of different model of multivariate analyses including propensity score trends to demonstrate that the influence of ATG on OS remain strongly correlated to donor type (MSD vs MUD). According to our results, patient with MSD presented better OS (not reached) than patient with MUD (37 months) (p<0.01). Interestingly, OS rates were lower in the ATG group compared to the non ATG group for patients who received bone marrow (median OS 81 months vs 112 months p=0.033). In this group, in the long term, patients who received ATG trend to have more relapse (median PFS 22 months vs 69 p=0.015). This difference is not observed for patient who received peripheral blood (PB), probably because PB induces more GvHD (49% vs 41%, p=0.001), which is usually correlated with less relapse. In this group, the use of ATG or not has no impact on OS. ConclusionThe use of ATG does not influence OS. However, this use is strongly influenced by stem cell source with a negative impact of ATG for the group of patients who received BM. Its usefulness should be discussed. Disclosures:No relevant conflicts of interest to declare.

Sirolimus, Tacrolimus and Low-Dose Methotrexate Based Graft-Versus-Host Disease (GVHD) Prophylaxis After Non-Ablative or Reduced Intensity Conditioning in Related and Unrelated Donor Allogeneic Stem Cell Transplantation: Decreased Severe Early aGVHD but Persistence of Late Acute Gvhd

AbstractAbstract 4194 Background:The morbidity and mortality associated with acute and chronic graft-versus-host disease (GVHD) remain significant after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Encouraging results have been reported with the combination of sirolimus, tacrolimus, and low-dose methotrexate after non-myeloablative allogeneic peripheral blood stem cell transplantation (PBSCT) (Alyea EP et al, Biol Blood Marrow Transplant 2008). We conducted a retrospective analysis of 74 patients with hematologic malignancies who underwent a non-myeloablative (NMA) or reduced intensity (RIC) allo-HSCT using sirolimus, tacrolimus, and low-dose methotrexate for GVHD prophylaxis. Methods:Between April 2008 and June 2011, 74 patients (M/F: 45/29), median age 51 years (range: 23–69) were transplanted for non-Hodgkin’s lymphoma (63%), chronic lymphocytic leukemia/small lymphocytic lymphoma (20%), Hodgkin lymphoma (12%) and acute lymphoblastic leukemia or myelodysplasia (3%). At transplantation, 36 patients (49%) were in complete remission and 38 patients (51%) had chemotherapy sensitive active disease. Conditioning regimen was NMA in 59 patients and RIC in 15 patients. Donors were HLA-matched related (MRD, n = 30, 41%), matched unrelated (MUD, n = 37, 50%) or 9/10 HLA-mismatched unrelated (MMUD, n = 7). All patients received peripheral blood mobilized grafts. GVHD prophylaxis consisted of sirolimus and tacrolimus that were started on day -3 and doses were adjusted to maintain target serum trough levels of 3–12 ng/mL and 5–10 ng/mL, respectively, followed by methotrexate 5 mg/m2 on days +1, 3, 6. Tapering of sirolimus and tacrolimus began at day 60 in the absence of GVHD or relapse, with the goal of complete discontinuation of immunosuppressants by 6 months or earlier if patients were not in CR at transplant. Recipients of MUD (31 of 37) or MMUD (7 of 7) grafts were given 2 doses of anti-thymocyte globulin (ATG) on days −3, and −2. Forty-eight patients with CD20+ malignancies (65%) received rituximab at day -8 and +21, 28, 35, 42. Acute GVHD (aGVHD) was scored by IBMT Severity Index and chronic GVHD (cGVHD) based on NIH consensus criteria. Results:The cumulative incidence of Grade B-D and C-D classic aGVHD at day +100 were 14.9% and 2.7%, respectively. The cumulative incidence of aGVHD at 1-year was 31.1 % for grade B-D and 5.4 % for grade C-D, due to late-onset Grade B-D and Grade C-D aGVHD rates of 16.2% and 2.7%, respectively. The incidence of cGVHD at 1 and 2 years was 15% and 28%, respectively. The use of peri-transplant rituximab did not affect the incidence of Grade B-D aGVHD (p=0.55) or cGVHD (p=0.94). There was no difference in the incidence of Grade B-D aGVHD at day 100 between ATG (13.9%) and no ATG (15.8%) cohorts. There was a trend towards a modestly higher 2-year incidence of cGVHD in patients who did not receive ATG, despite the fact that these were predominantly recipients of MRD (37% vs. 21% in ATG cohort, p=0.12). Two patients (2.7%) developed thrombotic microangiopathy and 4 patients (5.4%) had renal toxicity, requiring modification of the immunosuppressant treatment. No sinusoidal obstructive sydrome was reported. To date, 15 patients have died; causes of death include disease recurrence (n=9) and GVHD (n=6). The cumulative incidence of non-relapse mortality and relapse at 1 year were 4% and 27%, respectively. The 1-year relapse rate in the ATG and no ATG cohorts was 11% and 28%, respectively (p=0.10). With a median follow up 2.6 (range: 0.8–3.9) years, progression-free and overall survival at 2 years were 64 % and 77 %, respectively. Conclusions:As previously reported this GVHD prophylaxis regimen is safe and effective, providing lower rates of acute GVHD compared to historical data. The incidence of chronic GVHD by NIH criteria was low due to an increase in late-onset acute GVHD. Rituximab therapy did not affect the incidence of acute and chronic GVHD. The addition of ATG in MUD and MMUD recipients resulted in a trend toward lower rates of chronic GVHD with no increase in the rate of relapse. Future strategies will need to focus on decreasing the incidence of late onset acute and chronic GVHD without increasing the risk of relapse. Disclosures:No relevant conflicts of interest to declare.

A Novel Reduced Intensity Conditioning Regimen Induces a High Incidence of Sustained Donor Neutrophil and Platelet Engraftment After Double-Unit Cord Blood Transplantation

AbstractAbstract 4155 Introduction:Cord blood (CB) transplant (CBT) can be curative for patients with high-risk hematologic malignancies. However, patients of older age and/or with significant co-morbidities do not tolerate CBT with high-dose myeloablative conditioning. Non-myeloablative (NMA) conditioning can reduce transplant-related mortality (TRM) and extend transplant access to older or infirm patients, but it is limited by the risks of graft rejection in patients without extensive prior chemotherapy and relapse. While the addition of anti-thymocyte globulin (ATG) may reduce rejection, it increases the risk of viral infections, including Epstein-Barr virus lymphoproliferative disease, and may also increase relapse risk. Methods:We investigated the safety and efficacy of an ATG-free regimen of intermediate intensity prior to double-unit CBT in 30 patients with acute leukemias and myelodysplasia. Units were 4–6/6 HLA-A, B antigen, DRB1 allele matched to the patient. The conditioning regimen included cyclophosphamide 50 mg/kg (day -6), fludarabine 30 mg/m2/day × 5 (days -6 to -2), thiotepa 5 mg/kg/day × 2 (days -5 and -4), total body irradiation 200 cGy × 2 (days -2 and -1), and cyclosporine-A/mycophenolate mofetil immunosuppression. The indication for this regimen was one or more risk factors for TRM including age > 50 years, extensive prior therapy, and/or significant co-morbidities. The hematopoietic cell transplant co-morbidity index (HCT-CI) score of Sorror was retrospectively assigned. Results:The median age was 56 years (range 18–69). All but one patient had high-risk disease. Twenty-one had AML (16 CR1, 5 CR2) with all CR1 patients having high-risk features, including high-risk cytogenetics (n = 3), FLT-3 ITD mutation (n = 5), therapy-related disease or prior MDS (n = 6), and/or > 3 consecutive induction chemotherapies (n = 2). Five had ALL (4 CR1, 1 CR3); the 4 in CR1 had BCR/ABL mutations (n = 3) or prior refractory CNS disease (n = 1). Four patients had MDS with 3 having an IPSS score > 2. The median HCT-CI score was 2.5 (range 1–5). Median infused TNC doses were 2.6 (larger unit) and 1.9 (smaller unit) × 107/kg, respectively. Ninety-seven percent of patients engrafted (95%CI: 87–100) at a median of 26 days (range 13–43). The median day 21 total donor bone marrow chimerism was 100% (range 71–100). All surviving patients were 100% donor by day 100, and sustained hematopoiesis has been mediated by a single unit in all but one patient. The cumulative incidence of platelet recovery > 20 × 109/L by day 180 was 93% (95%CI: 83–100), and occurred at a median of 46 days (range 30–79). Day 180 TRM and 2-year relapse incidences were 20% and 11%, respectively. With a median 26.5 months (range 9–53) follow-up of survivors, the 2-year overall survival and disease-free survival (DFS) are both 60% (95%CI: 44–82). There was a hierarchy in 2-year DFS according to the Sorror HCT-CI score (Figure): the 11 patients (median age 55 years) with a score of 1 had a DFS of 82%. This compared with a 2-year DFS of 62% in the 9 patients (median age 51 years) with a score of 2–3, and 40% in the 11 patients (median age 58 years) with a score of 4–5 (p = 0.13). Discussion:This reduced intensity regimen combined with double-unit CBT reliably facilitates sustained donor engraftment without ATG. This regimen is associated with less toxicity than high-dose myeloablative conditioning. While other approaches are needed in patients with high comorbidity scores, this regimen is highly effective in older patients who are otherwise reasonably fit, as evidenced by the 82% 2-year DFS in patients with a median age of 55 years. Given the relatively low risk of relapse, it also represents a promising alternative to high-dose conditioning in younger patients. [Display omitted] Disclosures:Giralt:Onyx: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millenium: Membership on an entity's Board of Directors or advisory committees.

Donor-Type Aplasia After Bone Marrow Transplantation in Children with Aplastic Anemia: A Nationwide Retrospective Study

AbstractAbstract 959Survival after bone marrow transplantation (BMT) in children with aplastic anemia (AA) has improved markedly over the last 3 decades. However, we have experienced a certain number of patients who presented with bone marrow aplasia with full donor chimerism after BMT (donor-type aplasia), especially in the recent years. Since the 2000s, fludarabine (FLU)-based conditioning regimen has been often used for Japanese children with AA. The present study therefore evaluated whether patient and transplantation characteristics (especially the FLU regimen) could associate with donor-type aplasia in a large population of children with AA.To identify the risk factors for donor-type aplasia, we reviewed the clinical data of 660 patients (< 20 years) with AA who received BMT from 1980 to 2010 and whose records were available in the Japan Society for Hematopoietic Cell Transplantation Registry. The influence of potential risk factors on donor-type aplasia was assessed according to patient and transplantation characteristics, including the conditioning regimen. The median age at transplantation was 11 years, and 238 patients received immunosuppressive therapy (IST) before BMT. The median interval between diagnosis and BMT was 9 months. Regarding transplantation, 419 patients received BMT from related donors, whereas 241 received BMT from unrelated donors. Totally, 220 patients received a regimen that included FLU.Primary graft failure was observed in 25 patients. Of the 635 patients who achieved primary engraftment, 46 developed secondary graft failure or relapse: 11 were of the recipient-type and 35 were of the donor-type. The cumulative incidence of donor-type aplasia was 5.7%, and the 10-year overall survival of patients who presented with donor-type aplasia was 87%. Notably, the incidence of donor-type aplasia was significantly higher in FLU regimen group than in non-FLU regimen group (11.6% vs. 2.7%; P < 0.0001), and multivariate analysis confirmed that the FLU regimen was an independent risk factor for donor-type aplasia. Low infused cells (≤ 3×108/kg) (P = 0.008) and IST before BMT (P = 0.04) were also associated with a high incidence of donor-type aplasia. Age at BMT, gender, etiology, severity, interval between diagnosis and BMT, transfusion times, donor type (related or unrelated), human leukocyte antigen disparity, acute or chronic graft versus host disease (GVHD), GVHD prophylaxis, and viral reactivation or infection did not influence the incidence of donor-type aplasia in multivariate analysis.When FLU was introduced in the regimen for Japanese children with AA, the dose of cyclophosphamide (CY) was reduced by half, to reduce the toxicity; the conventional dose of CY was 200 mg/kg before the introduction of FLU. Therefore, we investigated the impact of the dose reduction of CY in the FLU regimen group. In patients receiving the FLU regimen, the incidence of donor-type aplasia in the CY half-dose group (n = 175) was 14%, whereas donor-type aplasia was not observed in the CY full-dose group (n = 35) (P = 0.04). In contrast, the addition of antithymocyte globulin or irradiation did not influence the incidence of donor-type aplasia in the FLU regimen group. Of note, the incidence of heart failure as a result of CY administration was higher in the CY full-dose group (5.7%) than in the CY half-dose group (0.6%), although this difference was not statistically significant.In conclusion, the FLU regimen was identified as an independent risk factor for donor-type aplasia in children with AA, which could possibly be ascribed to the CY dose reduction. However, the high incidence of heart failure associated with the regimen including a full dose of CY is an important issue that needs to be resolved. To develop optimal treatment, the conditioning regimen for children with AA needs to be reconsidered. Disclosures:No relevant conflicts of interest to declare.

Costimulation blockade in pig artery patch xenotransplantation - a simple model to monitor the adaptive immune response in nonhuman primates.

CD154 blockade-based immunosuppression successfully prevents both humoral and cellular adaptive immune responses in baboons receiving α1,3-galactosyltransferase gene-knockout (GTKO) pig organs. Using a GTKO pig artery transplantation model in baboons, we evaluated the efficacy of CD28/B7 costimulatory pathway blockade in comparison with CD154 blockade. Baboons received artery patch grafts from GTKO pigs, with no (Group1), anti-CD154mAb-based (Group2), or CTLA4-Ig-based (Group3) immunosuppressive therapy. Anti-pig IgM and IgG antibody and cellular responses were monitored. Xenografts were immunohistologically evaluated for antibody and complement deposition, and cellular infiltration. Group1 baboons developed increased IgM and IgG antibody and cellular responses against GTKO antigens. In Group2, anti-CD154mAb alone prevented the development of both IgM and IgG antibody and cellular responses,but not cellular infiltration of the graft. In the single baboon that received anti-thymocyte globulin (ATG) + mycophenolate mofetil (MMF) + anti-CD154mAb, cellular infiltration of the graft was not seen. In Group3, CTLA4-Ig with ATG + MMF inhibited the cellular proliferative response to pig antigens but did not prevent the IgG response or cellular infiltration. (i) Artery patch transplantation is a simple model to monitor the adaptive immune response to xenografts; (ii) anti-CD154mAb prevents sensitization but not cellular infiltration (but, without anticoagulation, may result in early thrombosis of a pig xenograft); (iii) although in only one baboon, the addition of ATG and MMF prevents cellular infiltration and (iv) replacement of anti-CD154mAb by CTLA4-Ig (at the doses used), even in combination with ATG and MMF, prevents the cellular proliferative response to GTKO pig antigens but is insufficient to prevent the development of anti-pig antibodies.

Impact of antithymocyte globulin (ATG)-containing conditioning regimens on patients undergoing allogeneic stem cell transplantation (allo-CST) for poor risk cytogenetic IPSS myelodysplastic syndrome (PRC-MDS): A report from the French Society of Stem Cell Transplantation and Cell Therapy (SFGM-TC).

6542 Background: Due to a risk of relapse of underlying disease in patients with PRC-MDS, the use of ATG, incorporated within the conditioning regimen prior to allo-SCT, is still controversial. Methods: Inclusion criteria included patients aged over 18 (n=101) who received allo-SCT transplanted between 1999 and 2009 from either a sibling (n=68) or HLA-allele-MUD (10/10) (n=33) for PRC-MDS. HLA matching was double-checked by the national Bone Marrow Donor Registry. Results: According to the FAB/WHO classification at diagnosis, 22 pts had RA/RARS/RCMD, 40 RAEB1, 30 REAB2 and 9 RAEB-t/AML. 34 pts had progressed to a more advanced disease before allo-SCT. At diagnosis, 89 patients had an IPSS int-2 or higher. At transplant, 36 pts were responders (CR, PR, CRm) and 62 with progressive disease (relapsed/refractory, untreated or stable disease without hematological improvement). Median age at transplantation was 54 years (range, 22-69). Pts received myeloablative conditioning (n=46) and nonmyeloablative (n=55). In this series, 48 patients received ATG as part of conditioning ('ATG' group), whereas 53 did not ('no-ATG’ group). As of April 1st 2011, 44 patients died of relapse and 22 of TRM. 3-year relapse, overall and event-free survival rates were not significantly different between the two groups. In contrast, the cumulative incidence of grade 2-4 acute GVHD was 48% in the no-ATG group and 30% ATG group (P &lt;.005). Although the cumulative incidence of chronic GVHD was similar in the no-ATG and ATG groups, a trend for a lower TRM was observed in the ATG group (p=.06). In multivariate analysis, the absence of use of ATG was associated with an increased risk of acute grade 2-4 [HR = 1.92, p=.044]. Conclusions: The addition of ATG to the conditioning regimen resulted in a decreased incidence of acute GVHD without increasing relapse rates and compromising survival of patients undergoing allo-SCT for poor risk cytogenetic MDS.

A Novel Reduced Intensity Conditioning Can Induce a High Incidence of Sustained Donor Engraftment After Double Unit Cord Blood Transplantation (CBT) without Anti-Thymocyte Globulin

AbstractAbstract 2351CBT can be curative for patients with high-risk hematologic malignancies. However, patients of older age, those with extensive prior therapy, or significant co-morbidities may not tolerate high-dose myeloablative conditioning. Reduced intensity (RI) or non-myeloablative (NMA) conditioning has been successfully used in CBT, especially in patients with lymphomas. However, patients with myeloid malignancies without extensive prior therapy have an increased risk of graft rejection following NMA CBT. Further, the addition of anti-thymocyte globulin (ATG) to enhance engraftment increases the risk of serious infections and Epstein-Barr virus post-transplant lymphoproliferative disease, and could increase the risk of relapse. Therefore, we investigated the efficacy and safety of a novel ATG-free RI conditioning prior to double unit CBT in patients with acute leukemias and myelodysplasia with the hypothesis that this regimen can induce a high incidence of sustained donor engraftment. Conditioning consisted of cyclophosphamide 50 mg/kg (day -6), fludarabine 30 mg/m2/day × 5 (days -6 to -2), thiotepa 5 mg/kg/day × 2 (days -5 and -4), and total body irradiation 200 cGy × 2 (days -2 and -1). All patients received cyclosporine-A and mycophenolate mofetil for graft-versus-host disease (GVHD) prophylaxis. Between 10/01/07-04/30/10, 20 patients were transplanted. The median age was 56 years (range 18–69). Thirteen (65%) had AML (9 CR1, 4 CR2), 4 (20%) had ALL (3 CR1, 1 CR3), and 3 (15%) had MDS (with one patient also having follicular lymphoma). The majority had high-risk disease. Indications for RI conditioning were the risk factors for transplant-related mortality (TRM) with high-dose conditioning of age ≥50 years, and/or extensive prior therapy, and/or significant co-morbidities. Thirteen patients had only 1 of these risk factors, whereas 7 had ≥2 risk factors. Units were predominantly 4–5/6 HLA-matched to the recipient (one 6/6, twenty-four 5/6, fifteen 4/6). The median infused cell doses of the larger units were 2.7 × 107 total nucleated cells/kg (range 1.46–5.56) and 0.95 × 105 CD34+ cells/kg (range 0.35–3.32), and 1.89 × 107/kg total nucleated cells/kg (range 1.42–2.47) and 0.59 × 105/kg CD34+ cells/kg (range 0.18–1.52) for the smaller units, respectively. The cumulative incidence of sustained donor engraftment at day 45 was 95% (95%CI: 81–100). The single patient with graft failure was 100% donor in the day 21 bone marrow, but died early post-transplant of multi-organ failure without count recovery. The median time to neutrophil recovery ≥0.5 × 109/l was 25 days (range 13–43). The median total donor chimerism in the day 21 bone marrow was 94% (both units combined, range 71–100), and sustained engraftment was accounted for by one unit in 18/19 engrafting patients. The incidence of grade II-IV acute GVHD at day 100 was 55% (95%CI: 32–78), and 46% (95%CI: 21–71) of patients have had late acute GVHD requiring ongoing therapy or chronic GVHD to date. The incidence of day 100 transplant-related mortality (TRM) was 20% (95%CI: 2–38). Notably, none of the 13 patients with only one risk factor died of transplant-related causes. By contrast, 5/7 (71%) patients with ≥2 risk factors died of TRM by day 100 (p=0.03, Table 1). Two additional patients died of relapse. With a median follow-up of 13 months (range 3–31), 1 year progression-free survival is 74% (95%CI: 55–94) (Figure 1). We demonstrate that this ATG-free RI conditioning is associated with a high incidence of sustained donor engraftment, and acceptable toxicities in older patients without other risk factors. While longer follow-up is needed, progression-free survival is encouraging provided multiple risk factors are not present. This conditioning combined with double unit grafts warrants further investigation, and may also be a promising alternative to high-dose conditioning in younger patients.Table 1Day 100 TRM according to number of risk factors (age ≥50 years, extensive prior therapy, significant co-morbidities).Risk FactorsDay 100 TRMP Value1 (N = 13)0/13 (0%)0.03≥2 (N = 7)5/7 (71%) [Display omitted] Disclosures:Giralt: Celgene: Honoraria, Speakers Bureau; Millenium: Honoraria, Speakers Bureau.

Evaluating the Impact of Antithymocyte Globulin on Lung Function at 1 Year after Allogeneic Stem Cell Transplantation

The use of antithymocyte globulin (ATG) in hematopoietic stem cell transplantation (HSCT) conditioning regimens has reduced the incidence of graft-versus-host disease, particularly in its chronic form. The impact of this approach on the prevention of lung dysfunction has not been well characterized, however. We performed a retrospective analysis of pulmonary function in patients who underwent HSCT after conditioning with oral busulfan followed by either cyclophosphamide or fludarabine with or without the addition of ATG. A total of 393 patients were included; 75 patients received ATG, and 318 did not. No differences between the 2 groups were seen in the mean percentage of the predicted values for forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), total lung capacity, and lung CO diffusing capacity at 80 days or 1 year after transplantation. However, the mean value of FEV(1)/FVC ratio at 1 year was higher in the patients who received ATG. The difference in mean change in pulmonary function parameters from baseline to 1 year post-HSCT was statistically nonsignificant for all parameters except FEV(1)/FVC ratio, which demonstrated less decline in the ATG group. The risk of developing severe airflow obstruction or a restrictive pattern was similar in the 2 treatment groups at 1 year post-HSCT. Incorporation of ATG into the HSCT conditioning regimen provided protection against a decline in FEV(1)/FVC ratio but did not decrease the risk of other pulmonary events that we evaluated within the first year after HSCT. Further evaluations in larger numbers of patients are needed to better clarify the role of ATG in the development of delayed pulmonary complications.