Antithymocyte Globulin Administration Research Articles

Significance of Busulfan Dose Intensity On Outcomes of Hematopoietic Cell Allografting for AML in Second Complete Remission or Beyond: A Report From the EBMT Acute Leukemia Working Party

AbstractAbstract 1929 Background:Allogeneic hematopoietic cell transplantation (HCT) is associated with inferior outcomes in patients with more advanced stage AML. In such cases, reducing the ablative intensity of the preparative regimen could potentially compromise its efficacy. We hereby compare transplant outcomes of two preparative regimens, known as FB2 and FB4, in patients (pts) with AML transplanted in second complete remission (CR2) or beyond at EBMT participating centers. Materials and methods:Between 2003 and 2010, 128 (FB2=88 (69%), FB4=40 (31%)) pts with a median age of (FB2=60 (22–70) years, FB4=42 (19–65) years, p<0.0001), with AML in ≥CR2 (FB2 (CR2=85 (97%), CR3=3 (3%)); FB4 (CR2=38 (95%), CR3=2 (5%)), p=0.67, underwent allogeneic HCT. FB2 comprised intravenous (IV) busulfan cumulative dose of 6.4 ± 10% mg/kg, while FB4 cumulative dose was 12.8 ± 10% mg/kg. Cytogenetic risks groups were similar: FB2 (good=17, int=31, poor=6) and FB4 (good=6, int=7, poor=0), p=0.35. For pts treated with FB2, donor source consisted of matched-related donors (MRD)=32, matched unrelated donor (MUD)=39, mismatched unrelated donors (MMUD)=8, unknown=9. For FB4, donor source consisted of MRD=17, MUD=15, MMUD=6, unknown=2. Use of peripheral blood stem cells (PBSC) was higher in the FB2 group (92% vs. 70%, p=0.001). Administration of anti-thymocyte globulin (ATG) was also higher in FB2 conditioned patients (89% vs. 45%, p<0.0001). Results:Median follow-up time was 24 (3–76) months. Median time to absolute neutrophil count engraftment (days) was 16 (5–38) and 16 (9–29) days, for FB2 and FB4, respectively (p=0.45). The 2-year leukemia-free survival (LFS), cumulative incidence of relapse (CI-R), and of non-relapse mortality (NRM) was: LFS (FB2=47±5% vs. FB4=70±8%, p=0.01), CI-R (FB2=27±5% vs. FB4=19±7%, p=0.24), and NRM (FB2=25±5% vs. FB4=10±5%, p=0.06). The 2-year cumulative incidence of chronic GVHD was similar (FB2=41±6% vs. FB4=43±8%, p=0.8). On multivariable analysis, favorable impact on 2-year LFS was observed with FB4 conditioning (HR 0.66 (95%CI: 0.46–0.97), p=0.03) and with longer interval from diagnosis to transplantation (> median) (HR=0.49 (95%CI: 0.29,0.85), p=0.01). When the analysis was performed by age groups, the statistical advantage of FB4 on LFS was lost, likely because of small numbers in each subgroup. Indeed, for pts <50 yrs. (n=43; FB2=16, FB4=27), LFS was (FB2=50±13% vs. FB4=72±9%, p=0.11), whereas for pts ≥50 yrs. (n=85, FB2=72, FB4=13), LFS was (FB2=47±6% vs. FB4=67±13%, p=0.18). Conclusion:Although limited by the small number of patients, these results suggest that FB4 is a reasonable preferred conditioning in patients with AML in ≥CR2. Disclosures:No relevant conflicts of interest to declare.

Anti-Thymocyte Globulin (ATG) Differentially Depletes naïve and Memory T Cells and Permits Memory-Type Regulatory T Cells

Abstract 4670Anti-thymocyte globulin (ATG) has been used in clinic for the treatment of allograft rejection and autoimmune diseases. However, its mechanism of action is not fully understood. To our knowledge, how ATG therapy affects naïve and memory T cells has not been well investigated. In this study, we have employed nonobese diabetic mouse model to investigate how administration of anti-thymocyte globulin (ATG) affects memory and naïve T cells as well as CD4+CD25+Foxp3+ regulatory T cells in peripheral blood and lymphoid organs; We also investigate how ATG therapy affects antigen-experienced T cells. Kinetic studies of peripheral blood CD4+ and CD8+ T cells post-ATG therapy shows that both populations decline to their lowest levels at day 3, while CD4+ T cells return to normal levels more rapidly than CD8+ T cells. We find that ATG therapy fails to eliminate antigen-primed T cells, which is consistent with the results that ATG therapy preferentially depletes naïve T cells relative to memory T cells. CD4+ T cell responses post-ATG therapy skew to T helper type 2 (Th2) and IL-10-producing T regulatory type 1 (Tr1) cells. Intriguingly, Foxp3+ regulatory T cells (Tregs) are less sensitive to ATG depletion and remain at higher levels following in vivo recovery compared to controls. Of note, the frequency of Foxp3+ Tregs with memory-like immunophenotype is significantly increased in ATG-treated animals, which might play an important role in controlling effector T cells post ATG therapy. In summary, ATG therapy may modulate antigen-specific immune responses through modulation of naïve and memory T cell pools and more importantly through driving T cell subsets with regulatory activities. This study provides important data for guiding ATG therapy in allogenieic hematopoietic stem cell transplantation and other immune-mediated disorders. Disclosures:No relevant conflicts of interest to declare.

Severe Acute Hepatitis Following Administration of Rabbit Antithymocyte Globulin in Reduced Intensity Conditioning Regimen Before Allo-SCT. A Single Center Experience

Abstract 4135Antithymocyte globulin (ATG) can be used in reduced intensity conditioning regimen before allogeneic stem cell transplantation (RIC allo) with the aim of reducing the incidence and severity of graft-versus-host disease (GVHD). The liver toxicity of ATG in this setting does exist, but its knowledge is limited by the scarcity of available data. Thus, in an effort to explore the incidence, the characteristics and the potential consequences of severe acute liver toxicity of ATG administered in RIC regimen, we undertook a retrospective analysis in our center between January 1, 2008 and April 30, 2012.During this period, 186 RIC allo were performed with the same regimen of fludarabine (30 mg/m2/day from d-5 to d-1), IV busulfan (0.8 mg/kg × 4/day at d-4 and d-3) and rabbit ATG (Thymoglobulines,® 2.5 mg/kg/day at d-2 and d-1). After reviewing all records, 27 patients (pts, 14%) developed a severe acute hepatitis (SAH) defined by aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) > 10 × ULN shortly after the administration of ATG. Their median age was 57 years (22–65). There were 15 females. Diagnoses were AML (n=7), ALL (n=2), T cell lymphoma (n=4), Hodgkin’s disease (n=4), high-grade B cell lymphoma (n=1), multiple myeloma (n=5), myelodysplastic syndrome (n=3) and CLL (n=1). Status at transplant were CR1 (n=13), ≥ CR2 (n=6), PR1 (n=1), ≥ PR2 (n=5), SD (n=1) and untreated (n=1). The median number of lines of treatment before allo was 1 (0–5). Donors were matched related (n=15), matched unrelated (n=7) or mismatched unrelated (n=5, all C mismatch). The source of stem cells was peripheral blood in all cases with a median number of 7.5 × 106 CD34+ cells/kg (2.8–21.6).No patient had evidence of hepatic involvement by the hematological malignancy before allo. One patient had a chronic C hepatitis before allo while none had a history of B hepatitis. Twenty-six patients had transaminases < 2 × ULN before the administration of ATG, while 1 had ALT at 3 × ULN with normal AST. All pts had a normal renal function. All developed fever the 1st day of ATG and received acetaminophen. Of note, they also received acetaminophen afterwards, during aplasia, without recurrence of hepatitis. No patient was receiving azoles at the time of hepatitis. No bacterium was isolated from blood cultures during fever except Enterococcus sp. in 1 patient. No virus was detected in blood by PCR (EBV, CMV, B and C hepatitis). The maximum median levels of AST and ALT were 22 × ULN (4–113) and 26 × ULN (9–109), respectively. The second day of ATG was cancelled in 8 patients when SAH was noted immediately after the 1st day. No patient died of liver failure and the liver function tests improved in all cases with a median time to reach transaminases <5 × ULN and <2 × ULN of 7 days (4–19) and 14 days (4–22), respectively. The prothrombin test was below normal in 15 pts with a median of 40% (19%-68%) but rapidly went back to normal in less than 1 week. No patient developed VOD or acute GVHD of the liver. One patient developed chronic GVHD of the liver 11 months after transplant.The median times to reach ANC > 500/mm3, platelets > 20,000/mm3 and > 50,000/mm3 were 18 days (13–31), 11 days (8–15) and 13 days (9–20), respectively. One patient transplanted for a CLL did not engraft, relapsed at 14 months and died of disease at 29 months. Prophylaxis of GVHD consisting of cyclosporine (CsA) in 14 pts and CsA+mycophenolate mofetil (MMF) in 2 pts were unchanged during SAH. Eleven pts were planned to receive CsA+methotrexate (at days +1, +3, +6). Methotrexate was replaced by MMF in 7 of them because of significant persistent hepatitis at day+1. With a median follow-up of 20 months (3–44), the 2-year OS, EFS, NRM, and relapse incidence were 75% ± 10%, 61% ± 11%, 6% ± 6%, and 32% ± 10%, respectively. The cumulative incidences of acute GVHD II-IV and extensive chronic GVHD were 15% ± 7% and 15% ± 8%, respectively. All these results (survival, NRM, relapse, GVHD) were similar in pts receiving 1 or 2 days of ATG.We conclude that the incidence of SAH following ATG in RIC regimen is 14%. We also report that transaminases rapidly normalized in all patients, that no patient developed severe liver failure, VOD, or acute GVHD of the liver. Finally, our study does not provide any evidence that SAH following ATG might favor NRM and thus adversely affect the outcome of RIC allo. However, a comparative study is warranted to draw firm conclusions and delineate risk factors of SAH following ATG. Disclosures:No relevant conflicts of interest to declare.

Effect of Antithymocyte Globulin Dosage for Prophylactic Gvhd On Epstein-Barr Virus Reactivation and Diseases in Allogeneic Hematopoietic Stem Cell Transplantation

Abstract 4486 Background:Antithymocyte globulin (ATG) is one of the main risk factors for Epstein-Barr virus (EBV) reactivation and disease in allogeneic hematopoietic stem cell transplantation (allo-HSCT), however, whether there is a correlation between ATG dose and EBV reactivation is unsure. Aim of this single-center prospective study is to explore the relationship between ATG dose and EBV reactivation in allo-HSCT. Methods:Ninety-nine patients with hematologic malignancies underwent allo-HSCT and administration of ATG for graft versus host disease (GVHD) prophylaxis were enrolled in this study in Nanfang hospital from February 2008 to February 2012. Sixty-one patients were unrelated donor transplants, thirty-eight were HLA-mismatched related donor transplants. GVHD prophylactic regimen was cyclosporine A+Methotrexate+ATG. According to donors’ HLA matching, we chose three dosage groups of prophylactic ATG: low dose group with ATG dose of 5.0∼6.0mg/kg (n=28), medium dose group with ATG dose of 7.0∼8.0mg/kg (n=55), and high dose group with ATG doses of ≥10mg/kg (n=16). The levels EBV-DNA in plasma were regularly monitored by quantitative real-time polymerase chain reaction (RQ-PCR). Results:With a median follow-up of 21 (range, 1–50) months post allo-HSCT, the cumulative incidence of EBV viremia and EBV-associated diseases was 17.6% (5/28) and 17.6% (5/28) in low dose group, respectively, with 32.7% (18/55) and 29.1% (16/55) in medium dose group, respectively, with 50.0% (8/16) and 31.3% (5/16) in high dose group, respectively. There were statistical significances of the incidence (χ2□□9.555, P=0.008). Logistic regression models showed that ATG prophylaxis was one of the main risk factors for EBV infection (RR=16.728, P=0.000) while bivariate correlation analysis presented that the incidence of EBV reactivation was positively correlated with ATG prophylaxis dosage (rpearman = 0.452, P = 0.000). The cumulative incidence of high degree (II∼IV°) aGVHD was 35.7% (10/28) in low dose group, with 39.6% (21/53) in total and 50.0% (6/12) in relapsed leukemia with HLA-mismatched related transplantation in medium dose group, with 68.8% (11/16) in high dose group. There were not statistical significances of the incidence (χ2□□6.971, P=0.137). Conclusion:EBV reactivation might be positively correlated with ATG prophylaxis dosage. According to donors' HLA matching, reducing ATG prophylaxis dose appropriately could prevent EBV reactivation in allo-HSCT without increasing high degree aGVHD. Disclosures:No relevant conflicts of interest to declare.

Polyclonal anti-thymocyte globulins for the prophylaxis of graft-versus-host disease after allogeneic stem cell or bone marrow transplantation in adults.

Allogeneic haematopoietic stem cell transplantation (HSCT) is an established treatment for many malignant and non-malignant haematological disorders. Graft-versus-host disease (GVHD), a condition frequently occurring after HSCT, is the result of host tissues being attacked by donor immune cells. One strategy for the prevention of GVHD is the administration of anti-thymocyte globulins (ATG), a set of polyclonal antibodies directed against a variety of immune cell epitopes, leading to immunosuppression and immunomodulation. To assess the effect of ATG used for the prevention of graft-versus-host disease (GVHD) in patients undergoing allogeneic HSCT with regard to overall survival, incidence and severity of acute and chronic GVHD, incidence of relapse, incidence of infectious complications, non-relapse mortality, early mortality within 100 days of transplantation, progression-free survival, quality of life and adverse events. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 3), MEDLINE (January 1950 to February 2012), trials registries and conference proceedings. The search was conducted in October 2010 and was updated in July 2011 and February 2012. We did not apply any language restrictions. We included randomised controlled trials (RCTs) investigating the impact of ATG on GVHD prophylaxis in adults suffering from haematological diseases and undergoing allogeneic HSCT. Treatment arms had to differ only in the addition of ATG to the standard GVHD prophylaxis regimen. Two review authors screened abstracts, extracted data and analysed the data independently. We contacted study authors for additional information. We included in the meta-analysis six RCTs which met the pre-defined selection criteria, involving a total of 568 participants. Quality of data reporting was heterogeneous among these studies with a lack of detailed information in the early studies.The primary outcome of overall survival was not significantly changed by the addition of ATG for the prophylaxis of GVHD (harms ratio (HR) 0.88; 95% CI 0.67 to 1.15, P = 0.33).The incidence of treatment-requiring or severe acute GVHD (grade II to IV) was significantly lower in patients who received ATG (risk ratio (RR) 0.68; 95% CI 0.55 to 0.85, P = 0.009; number needed to treat (NNT) 8). Also, the incidence of severe acute GVHD (grade III to IV) was significantly reduced (HR 0.53; 95% CI 0.33 to 0.85, P = 0.0005; NNT 7) but comparable data were available for rabbit ATG only. However, pooled study results regarding the incidence of acute GVHD of all grades (I to IV) showed no significant benefit of ATG treatment (RR 0.89; 95% CI 0.74 to 1.06, P = 0.20).Meta-analysis of data regarding the incidence of overall chronic GVHD (both, limited and extensive) was not possible. Nevertheless, studies reporting on extensive chronic GVHD (only studies evaluating rabbit ATG) suggested a lower incidence of extensive chronic GVHD whereas others that only reported on overall chronic GVHD did not show an advantage for ATG.Pooled results regarding the incidence of relapse were not significantly different (RR 1.13; 95% CI 0.75 to 1.68, P = 0.56), as well as pooled results regarding non-relapse mortality (HR 0.82; 95% CI 0.55 to 1.24, P = 0.35).Due to the lack of comparable data, we could not perform meta-analysis of data regarding the incidence of chronic GVHD, relapse-related mortality, progression-free survival, quality of life, adverse events and engraftment. Our systematic review suggests that the addition of ATG during allogeneic HSCT significantly reduces the incidence of severe grades (II to IV) of acute GvHD, whereas the incidence of overall acute GVHD (grades I to IV) was not significantly lowered. This indicates a reduction of the severity but not the incidence of acute GVHD. However, this effect did not lead to a significant improvement of overall survival, which may be due to the severe potential side effects of the consecutively increased immunosuppression.Furthermore, future research is needed to clarify the effect of ATG on the incidence and severity of chronic GVHD and consequently on all aspects of quality of life.From the currently available data, no recommendation on the general use of ATG in allogeneic HSCT can be supported. Therefore, a careful consideration of the use of ATG based on the patient's condition and the risk factors of the transplantation setting should be made.

Amelioration of renal damage by administration of anti-thymocyte globulin to potential donors in a brain death rat model

Brain death (BD), a non-immunological factor of renal injury, triggers an inflammatory process causing pathological signs of cell death in the kidney, such as necrosis and apoptosis. Kidneys from brain dead donors show lower success rates than kidneys from living donors and one strategy to improve transplantation outcome is to precondition the donors. For the first time, anti-rat thymoglobulin (rATG) was administered in an experimental brain death animal model to evaluate if it could ameliorate histopathological damage and improve organ function. Animals were divided into three groups: V (n=5) ventilated for 2h; BD (n=5) brain death and ventilated for 2h; and BD+rATG (n=5) brain death, ventilated for 2h, rATG was administered during brain death (10mg/kg). We observed lower creatinine levels in treatment groups (means): V, 0·88±0·22 mg/dl; BD, 1·37±0·07 mg/dl; and BD+rATG, 0·64±0·02 mg/dl (BD versus BD+rATG, P<0·001). In the BD group there appeared to be a marked increase of ATN, whereas ATN was decreased significantly in the rATG group (V, 2·25±0·5 versus BD, 4·75±0·5, P<0·01; BD+rATG, 2·75±0·5 versus BD 4·75±0·5 P<0·01). Gene expression was evaluated with reverse transcription-polymerase chain reaction; tumour necrosis factor (TNF)-α, interleukin (IL)-6, C3, CD86 showed no significant difference between groups. Increased IL-10 and decreased CCL2 in BD+rATG compared to BD (both cases P<0·01). Myeloperoxidase was increased significantly after the brain death setting (V: 32±7·5 versus BD: 129±18). Findings suggest that rATG administered to potential donors may ameliorate renal damage caused by BD. These findings could contribute in the search for specific cytoprotective interventions to improve the quality and viability of transplanted organs.

Anti-thymocyte globulin for conditioning in matched unrelated donor hematopoietic cell transplantation provides comparable outcomes to matched related donor recipients

Rabbit anti-thymocyte globulin (ATG) is used as prophylaxis against GVHD following allogeneic hematopoietic cell transplantation (HCT). At our institution, ATG is exclusively used in the conditioning of matched unrelated donor (URD) transplant recipients. A total of 50 URD HCT recipients who received ATG (ATG group) were retrospectively compared with 48 matched related donor (MRD) HCT recipients who did not receive ATG (no ATG group). There were no significant differences between the groups in rates of day 100 mortality, acute GVHD or relapse. Chronic GVHD incidence was significantly lower in the ATG group (P = 0.007). At a median follow-up of 36 months in the entire cohort, 50% patients are alive in the ATG group and 63% of the patients are alive in the no ATG group (P = 0.13). We conclude that the administration of ATG to patients undergoing URD HCT preserves the anti-leukemia benefit of the transplant, while reducing the risk of developing GVHD, resulting in OS rates that are comparable to MRD HCT recipients.

Pre-transplant administration of antithymocyte globulin increases its efficacy in inhibiting anti-donor memory T cell responses (126.9)

Abstract Antithymocyte globulin (ATG) is a lymphoablative agent used in transplant patients. In this study, we tested how murine analog of ATG (mATG)affects pre-existent donor-reactive memory T cells. mATG treatment of heart allograft recipients on d.-7 and -4 (pre-TP)led to better outcome than treatment on d.0 and d.4 (peri-TP). Pre-TP mATG resulted in lower frequencies of donor-specific IFNγ-secreting T cells than peri-TP mATG(72000 vs 12500spots/million CD44hi cells). Studies in recipients injected with tracer subsets of donor-reactive T cells showed that while both mATG regimens depleted naïve T cells equally well, pre-TP mATG was four times more efficient in depleting pre-existing memory T cells. IFNγ production by donor-specific memory T cell was diminished by 99% with pre-TP mATG and only by 70% with peri-TP mATG. Transfer of TCR transgenic Ld-reactive 2C memory CD8 cells into recipients of Ld+ or Ld- heart allografts showed that memory T cells resistance to peri-TP mATG depletion depended on the systemic inflammation after transplantation but not on their antigen specificity. In summary,pre-TP ATG is more efficient in targeting pre-existing alloreactive memory T cells and anti-donor T cell responses. Our findings may guide the future use of ATG in sensitized transplant patients.

Factors influencing lymphocyte reconstitution after allogeneic hematopoietic stem cell transplantation in children

BackgroundImmune reconstitution (IR) after hematopoietic stem cell transplantation (HSCT) reduces transplantation-related complications such as infection and improves HSCT outcomes.MethodsWe retrospectively analyzed IR of lymphocyte subpopulations in 38 pediatric patients for hematologic malignant diseases after allogeneic HSCT from April 2006 to July 2008. T-cell-, B-cell-, and natural killer (NK) cell-associated antigens were assayed in peripheral blood by flow cytometry analysis of 5 lymphocyte subsets, CD3+, CD3+/CD4+, CD4+/CD8+, CD16+/CD56+, and CD19+, before and 3 and 12 months after transplantation.ResultsReconstitutions of CD16+/CD56+ and CD3+/CD8+ lymphocytes were achieved rapidly, whereas that of CD3+/CD19+ lymphocytes occurred later. Age was not related to reconstitution of any lymphocyte subset. Total body irradiation (TBI) and anti-thymocyte globulin (ATG) administration were related to delayed reconstitution of total lymphocytes and CD3+ lymphocytes, respectively. Reconstitutions of CD3+/CD4+ lymphocytes and CD3+/CD8+ lymphocytes were significantly delayed in patients who received umbilical cord blood stem cells. In patients with chronic graft-versus-host disease (cGVHD), recovery of the total lymphocyte count and CD19+ lymphocytes at 3 months post-transplant were significantly delayed. However, acute GVHD (aGVHD) and cytomegalovirus (CMV) reactivation did not influence the IR of any lymphocyte subset. Further, delayed reconstitution of lymphocyte subsets did not correspond to inferior survival outcomes in this study.ConclusionWe observed that some lymphocyte reconstitutions after HSCT were influenced by the stem cell source and preparative regimens. However, delayed CD19+ lymphocyte reconstitution may be associated with cGVHD.

Management of children undergoing cardiac transplantation with high Panel Reactive Antibodies

Highly sensitised children in need of cardiac transplantation have overall poor outcomes because of increased risk for dysfunction of the cardiac allograft, acute cellular and antibody-mediated rejection, and vasculopathy of the cardiac allograft. Cardiopulmonary bypass and the frequent use of blood products in the operating room and cardiac intensive care unit, as well as the frequent use of homografts, have predisposed potential recipients of transplants to allosensitisation. The expansion in the use of ventricular assist devices and extracorporeal membrane oxygenation has also contributed to increasing rates of allosensitisation in candidates for cardiac transplantation. Antibodies to Human Leukocyte Antigen can be detected before transplantation using several different techniques, the most common being the "complement-dependent lymphocytotoxicity assays". "Solid-phase assays", particularly the "Luminex® single antigen bead method", offer improved specificity and more detailed information regarding specificities of antibodies, leading to improved matching of donors with recipients. Allosensitisation prolongs the time on the waiting list for potential recipients of transplantation and increases the risk of complications and death after transplantation. Aggressive reduction of antibodies to Human Leukocyte Antigen in these high-risk patients is therefore of vital importance for long-term survival of the patient and cardiac allograft. Strategies to decrease Panel Reactive Antibody or percent reactive antibody before transplantation include plasmapheresis, intravenous administration of immunoglobulin, and specific treatment to reduce B-cells, particularly Rituximab. These strategies have resulted in varying degrees of success. Antibody-mediated rejection and cardiac allograft vasculopathy are two of the most important complications of transplantation in patients with high Panel Reactive Antibody. The treatment of antibody-mediated rejection in recipients of cardiac transplants is largely empirical and includes the use of high-dose corticosteroids, plasmapheresis, intravenous administration of immunoglobulins, anti-thymocyte globulin, and Rituximab. Cardiac allograft vasculopathy is believed to be secondary to chronic complement-mediated endothelial injury and chronic vascular rejection. The use of proliferation signal inhibitors, such as sirolimus and everolimus, has been shown to delay the progression of cardiac allograft vasculopathy. In some non-sensitised recipients of cardiac transplants, the de novo formation of antibodies to Human Leukocyte Antigen after transplantation may increase the likelihood of adverse clinical outcomes. The use of serial testing for donor-specific antibodies after cardiac transplantation may be advisable in patients with frequent episodes of rejection and patients with history of sensitisation. Allosensitisation before transplantation can negatively influence outcomes after transplantation. A high incidence of antibody-mediated rejection and graft vasculopathy can result in graft failure and decreased survival. Current strategies to decrease allosensitisation have helped to expand the pool of donors, improve times on the waiting list, and decrease mortality. Centres of transplantation offering desensitisation are currently using plasmapheresis to remove circulating antibodies; intravenous immunoglobulin to inactivate antibodies; cyclophosphamide to suppress B-cell proliferation; and Rituximab to deplete B-lymphocytes. Similar approaches are also used to treat antibody-mediated rejection after transplantation with promising results.

Response to Immunosuppressive Therapy with Antithymocyte Globulin (ATG) In Older Patients with Aplastic Anemia

Abstract 4374Immunosuppressive therapy (IST) with antithymocyte globulin in combination with prednisolone and cyclosporine is the treatment of choice for patients with aplastic anemia who are ineligible for transplant either because of age or because of absence of a HLA identical donor. Limited data that exists on the role of immunosuppressive therapy in older patients with aplastic anemia suggest that responses were poorer. This retrospective analysis was aimed at determining whether older patients with aplastic anemia had an inferior response to IST compared with younger patients.Between October 1985 to December 2010, 322 adult patients (>12 years) were treated at our centre with antithymocyte globulin (ATG) in combination with prednisolone and with/without cyclosporine. Either ATGAM (Pharmacia Upjohn, USA) at 40 mg/kg/day × 4 days or Lymphoglobulin (Pasteur Merieux, France) at 15 mg/kg/day × 5 days was used. Prednisolone at 1 mg/kg in 3 divided doses were started one day after completion of ATG and tapered from Day +14 if there was no evidence of serum sickness. Cyclosporine at the dose of 6 mg/kg/day in 2 divided doses was started once steroids were tapered and then continued for 12 months and then tapered depending upon response. Patients were divided into 3 age groups - Ages 12 – 29 [n=116], ages 30 – 49 [n = 116] and > 50 years [n = 90]. The baseline characteristics are detailed in the table below – Thirty one patients were above the age of 60 years. The older age group had significantly higher % of males, more use of ATGAM compared with Lymphogloblin and a higher number was given Cyclosporine (CSA) post ATG. The severity of aplastic anemia (severe vs non-severe) and the median time from diagnosis to administration of ATG was not significantly different between the 3 groups. The number of patients who developed serum sickness was significantly lower in the older age group (21.1%) compared to the age group of 30 – 49 (35.3%) and 12 – 29 years (48.3%) [p = 0.000]. The overall response to ATG was similar in all 3 groups (63.8% in age 12 –29, 64.7% in ages 30 – 49 and 54.4% in age > 50 yrs) [p = 0.233]. The response in patients above the age of 60 years was 51.6%. Six patients received a second course of ATG while 3 patients underwent HLA identical sibling donor transplantation. At a median follow up of 32 months (range: 1 –145), 221 patients (68.6%) are alive. The overall survival is similar for the older age group compared with the younger age groups (66.7% with age>50 years, 68.1% with age 30–49 and 70.7% with age 12 –29) [p= 0.817]. In conclusion, immunosuppressive therapy with ATG has a reasonable outcome in older patients (> 50 years) with aplastic anemia.Table 1:Demographic characteristics and outcome of IST among the 3 age groupsVariables12 – 29 yrs (n = 116)30 – 49 yrs (n = 116)>50 yrs (n = 90)p valueMale84 (72.4%)87 (75%)52 (57.8%)Female32 (27.6%)29 (25%)38 (42.2%)0.019Severity of AA86 (74.1%)77 (66.4%)63 (70%)0.581VSAA + SAA30 (25.9%)39 (33.6%)27 (30%)NSAAType of ATG45 (38.8%)33 (28.4%)53 (58.9%)0.000ATGAM71 (61.2%)83 (71.6%)37 (41.1%)LymphoglobulinCSA used92 (79.3%)103 (88.8%)85 (94.4%)0.005Yes24 (20.7%)13 (11.2%)5 (5.6%)NoResponse74 (63.8%)75 (64.6%)49 (54.4%)0.233Overall response34 (29.3%)28 (24.1%)15 (16.7%)Complete response (CR)40 (34.5%)47 (40.5%)34 (37.8%)Partial response (PR)42 (36.2%)41 (35.3%)41 (45.6%)No response (NR)Overall survival82 (70.7%)79 (68.1%)60 (66.7%)0.817Alive34 (29.3%)37 (31.9%)30 (33.3%)Dead Disclosures:No relevant conflicts of interest to declare.

Antithymocyte Globulin-induced Acute Lung Injury During Transplantation for Aplastic Anemia

A 10-year-old boy with acquired, very severe aplastic anemia developed acute lung injury after the administration of equine antithymocyte globulin, during conditioning for allogenic bone marrow transplantation. Limited cases of antithymocyte globulin-induced acute lung injury have been described in adults. The respiratory worsening was sudden and required mechanical ventilation. The clinical course was complicated by sepsis with Escherichia coli, vancomycin-resistant enterococci, and Stenotrophomonas maltophilia. Implications for treatment are discussed and earlier literature is reviewed.

The Telomere Length In Peripheral Blood Lymphocytes Is a Useful Predictor of the Response to Immunosuppressive Therapy In Patients with Acquired Aplastic Anemia

AbstractAbstract 2042 Introduction:The ability to predict the response to immunosuppressive therapy (IST) in patients with aplastic anemia (AA) will avoid unnecessary and possibly harmful treatment. To this end, several in vitro tests have been proposed as useful predictors of response in adult patients. However, we previously reported that the presence of either human leukocyte antigen (HLA)-DR15, a minor population of paroxysmal nocturnal hemoglobinuria (PNH)-type cells, or of autoantibodies to postmeiotic segregation increased 1 (PMS1) in children with AA, were not useful predictors of the response to IST, suggesting a different etiology of AA between adults and children (Yoshida, N et al Br J Haematol. 2008). Telomeres in peripheral blood cells from AA patients are shorter than those from normal individuals in 30% of patients. This shorter telomere length in AA patients is thought to result from genetic abnormalities in the genes related to telomere maintenance, stressed hematopoiesis due to immunological attack, and increased cell division. An NIH group and we reported that cryptic forms of dyskeratosis congenita (DC) are present in just under 5% of patients with AA who do not have physical abnormalities, but who harbour the gene mutation associated with telomere maintenance (Yamaguchi, H et al. N Engl J Med. 2005, Liang, J et al. Haematologica 2006). To identify such patients is important because those who have these mutations might respond poorly to IST. However, the presence of cryptic forms of DC does not explain the causes of short telomeres in the other patients. We hypothesized that patients with short telomeres may respond poorly to IST, and thus evaluated the relationship between telomere length in hematopoietic cells before IST and the response to IST in patients with AA. Patients and Methods:We enrolled 40 newly diagnosed children with AA (median age, 10 years; range, 1 to 16 years) who received IST. We obtained peripheral blood lymphocytes from the patients with AA at the time of diagnosis and prospectively measured the telomere length of lymphocytes prior to IST by flow-fluorescence in situ hybridization (flow-FISH) using Telomere PNA kits (Dako Cytomation, Glostrup, Denmark). After gating diploid cells based on propidium iodine staining, lymphocytes were isolated according to size and granularity. Relative telomere length (RTL) was calculated as the ratio between the telomere signal of each sample and the telomere signal of the control cell line. Because telomeres shorten with age, we obtained age-adjusted measurements for comparison from 71 normal age-matched individuals. Delta RTL of each patient with AA was calculated using the distance of the RTL from the line of age-adjusted normal telomere length. Results:Of the 40 patients, at diagnosis AA was very severe in 12, severe in 13, and non-severe in 15. All received IST with horse antithymocyte globulin (ATG) and cyclosporine. The causes of AA were idiopathic in 38 patients and hepatitis in 2. In total, 25 of the 40 patients (63%) responded to IST at 6 months after administration of ATG. Between the responder and non-responder groups, no significant differences in gender, age, etiology, disease severity or interval from diagnosis, and IST were observed. Univariate analysis for IST response did not find any significant differences in median WBC count, neutrophil count, Hb level, reticulocyte count, platelet count or minor PNH clone positivity between the groups. However, delta RTL was significantly lower in non-responders than in responders (p=0.035). Multivariate analysis for response to IST revealed that only delta RTL was significantly lower in non-responders than responders (p = 0.049). Conclusion:The telomere length in lymphocytes is promising not only to identify cryptic DC but also to predict the response to IST of patients with AA. A further larger analysis is warranted to evaluate the correlation between telomere length and the response to IST in AA patients. Disclosures:No relevant conflicts of interest to declare.

Pre-Transplant Rituximab Is Associated with Reduced Rate of Acute GvHD After RIC-Allosct In Lymphoma Patients: Results From A Retrospective Monocenter Analysis.

AbstractAbstract 1319 Introduction:both B and T cells are implicated in the pathophysiology of graft-versus-host disease (GvHD) after allogeneic hematopoietic stem cell transplantation (AlloSCT). Anti-thymocyte globulin (ATG) administered during conditioning has been shown to reduce both acute and chronic GvHD, while rituximab has been claimed to reduce incidence of GvHD: previous studies indicated a reduced incidence of acute and/or chronic GvHD, but sometimes with controversial results. Here we present results from a retrospective, monocenter analysis on a selected population of lymphoma patients undergoing reduced-intensity (RIC) AlloSCT, with or without ATG in the conditioning regimen. Methods:adult patients receiving RIC-AlloSCT from a HLA-identical sibling donor for relapsed CD20+ lymphoproliferative disease at our Institution were included in the analysis. Data on patients and donors, conditioning regimen, use of rituximab and cumulative dose during the six and three months before AlloSCT were collected. Rituximab was administered in association or not with chemotherapy, according to each patient's treatment strategy. Analysis was conducted separately on patients receiving ATG (ATG cohort) or not (non-ATG cohort). Correlation analysis between ATG, rituximab cumulative dose before AlloSCT and grade 2–4, grade 3–4 acute GvHD (aGvHD), or limited/extensive chronic GvHD (cGvHD) was performed. Results:a total of 57 patients transplanted between Avril 1999 and November 2009 were included in the study, 18 and 39 in the non-ATG and ATG group respectively. Of these 57 patients, 32 were treated with rituximab for a median (range) cumulative dose within 6 months before AlloSCT of 1500 (375-3375) mg/mq, ending at a median (range) of 43 (5-177) days prior to transplant. Details are shown in table 1. Median follow-up was 749 days (146-4051). No significant differences existed between patients receiving rituximab vs. those without rituximab, with the exception of a different number of patients with CLL or FCL. Among the 18 non-ATG patients, we observed a slightly reduced rate of severe (grade 3 or 4) aGvHD in those patients who received >= 375 mg/mq rituximab within three months before AlloSCT (n=13) compared to those receiving < 375 mg/mq or no rituximab (n=5): 2/13 vs. 2/5 (p=ns). In the ATG cohort, rituximab use at a dose >= 375 mg/mq (n=10) within three months was associated with a reduced rate of severe aGvHD compared with < 375 mg/mq or no rituximab (n=29): 0/10 vs. 7/29 (p=0.08). Reduction of grade 2–4 aGvHD rate was also observed: 1/10 vs. 14/29 (p=0.03). No effect on cGvHD appeared in the two cohorts. Discussion:present data suggest a role of rituximab administered before AlloSCT in reducing the incidence of aGvHD. This effect was more pronounced when concomitant administration of ATG was performed during conditioning regimen, indicating a possibly sinergistic effect of both T- and B-cell depletion in preventing GvHD. Although retrospective and small-sized, the present analysis, conducted on a quite homogeneous population of patients, confirms previous findings and enhances further investigations on larger number of patients.VariableMedianRangeRituximab cohortNo–rituximab cohortN. patients3225Median age (range)5227–6851 (34–68)52 (27–68)DiagnosisDLBCL75Folliculaire113Manteau77Foll transf20L prolymphocytaire B10LLC49Waldenstrom01Disease status at HSCTCR137PR1514SD11REFR33 Disclosures:Off Label Use: Zevalin is off-label use in conditioning regimen in France.

Patterns of HLA-DR Surface Expression on CD14+ Monocytes During Adverse Events After Hematopoietic Stem Cell Transplantation.

AbstractAbstract 1499The human leukocyte antigen DR (HLA-DR) surface expression on CD14+ monocytes reflects the degree of activation of these cells. In line with the central role of monocytes and macrophages in the immune system, a decreased HLA DR expression on CD14+ monocytes has been shown to be a hallmark of an altered immune status during the systemic inflammatory response syndrome (SIRS). We therefore hypothesized that HLA-DR expression might likewise be altered after hematopoietic stem cell transplantation (HSCT).HLA-DR surface expression of CD14+ monocytes was assessed by flow cytometry in 30 pediatric patients (below 15 years, n=23) and young adults (15 years and above, n=7) up to one year after HSCT (7 autologous and 23 allogeneic stem cell transplants). Normal values were derived from a control group of healthy children (n=18) and young adults (n=22).During the conditioning period, a significant increased HLA-DR expression in pediatric patients and young adults was observed. This increase could not be attributed to the administration of anti-thymocyte globulin (ATG). After HSCT, HLA-DR expression was not altered in general. However, HLA-DR expression decreased significantly up to 5 days before (p<0.05) and during (p<0.01) bacterial infections or sepsis. In contrast, HLA-DR expression levels were increased 7–10 days before and at the time of diagnosis of viral infections. HLA-DR expression was also elevated during acute graft-versus-host disease (GVHD). At the time of hepatic veno-occlusive disease (VOD), HLA-DR expression on CD14+ monocytes was reduced. Neither the administration of granulocyte colony-stimulating factor (G-CSF) nor the occurrence of a relapse was associated with a change of HLA-DR expression.In conclusion, adverse events after HSCT were associated with altered HLA-DR expression levels. Therefore, HLA-DR expression on CD14+ monocytes appears as a promising parameter which might allow identifying patients at risk after HSCT. Disclosures:No relevant conflicts of interest to declare.

Guidelines on the use of irradiated blood components prepared by the British Committee for Standards in Haematology blood transfusion task force

Search terms included: Transfusion-associated graft-versus-host disease, Transfusion-associated graft-versus-host, TA-GvHD. The last guideline covering this topic was published in 1996 (British Committee for Standards in Haematology (BCSH) Blood Transfusion Task Force, 1996. The writing group produced the new draft guideline, which was subsequently revised by consensus by members of the Haemato-oncology and Blood Transfusion Task Forces of the BCSH. The guideline was then reviewed by a sounding board of approximately 100 UK haematologists, the BCSH and the committee of the British Society for Haematology and amended, again by consensus. Criteria used to quote levels and grades of evidence are according to the GRADE system (Guyatt et al, 2006). Strong recommendations (grade 1, ‘recommended’) are made when there is confidence that the benefits either do or do not outweigh the harm and burden and costs of treatment. Where the magnitude of benefit or not is less certain a weaker grade 2 recommendation (‘suggested’) is made. Grade 1 recommendations can be applied uniformly to most patients whereas grade 2 recommendations require judicious application. The quality of evidence is graded as A (high quality randomized clinical trials), moderate (B) or low (C). This publication reports the key recommendations of the Writing Group. It is also accessible at http://www.bcshguide lines.com.

Early CMV Viremia Is Associated with Impaired Viral Control following Nonmyeloablative Hematopoietic Cell Transplantation with a Total Lymphoid Irradiation and Antithymocyte Globulin Preparative Regimen

The reconstitution of immune function after hematopoietic cell transplant (HCT) plays an important role in the control of viral infections. Both donor and recipient cytomegalovirus (CMV) serostatus has been shown to contribute to effective immune function; however, the influence of a nonmyeloablative preparative (NMA) regimen using total lymphoid irradiation (TLI) and antithymocyte globulin (ATG) on antiviral immune reconstitution has not yet been described. In 117 recipients of NMA HCT patients following ATG and TLI, not unexpectedly, CMV viremia was seen in approximately 60% of the seropositive patients regardless of donor serostatus, and recipient seropositivity significantly increased the odds of CMV viremia after transplant in a multivariate analysis. The administration of ATG and TLI resulted in a strikingly earlier viremia in the posttransplant period when compared to the previously reported timing of viremia following myeloablative preparative regimens, especially for transplant recipients who were seropositive for CMV with seronegative donors. Furthermore, early viremia in the setting of a CMV naïve donor was associated with a delay in functional antiviral control. These observations demonstrate the dynamic nature of immunity in relation to CMV antigen exposure in the complex environment resulting from NMA conditions where both donor and residual recipient immune response affect viral control.

Epstein–Barr virus-related lymphoproliferative disorder induced by equine anti-thymocyte globulin therapy

Post-transplant lymphoproliferative disorder (PTLD) is generally caused by an uncontrolled B-cell proliferation induced by Epstein-Barr virus (EBV) in the setting of impaired EBV-specific T-cell immunity. PTLD has been described in allogeneic hematopoietic stem cell transplant (HSCT) and rarely in autologous HSCT. Anti-thymocyte globulin (ATG) is being increasingly utilized for acute rejection in organ transplantation, severe autoimmune diseases and aplastic anemia. Mainly, the use of rabbit ATG has been associated with PTLD, which is considered to be more immunosuppressive than equine ATG. The sole administration of equine ATG has rarely been associated with PTLD. Due to the increased use of these potent and novel immunosuppressive agents, it is paramount to be aware of these complications. We present a 55-year-old man with an autologous HSCT who presented with an unusual case of monoclonal plasmacytic PTLD. His lymphoproliferative disorder occurred 3years after his HSCT and 1month after the use of equine ATG administered for severe aplastic anemia. We review current concepts of EBV-PTLD, including risk factors, the potential for preemptive therapy and various management strategies.

Co-transfusion of haplo-identical hematopoietic and mesenchymal stromal cells to treat a patient with severe aplastic

A 3-year-old girl with severe aplastic anemia (SAA) that was unresponsive to steroid, cyclosporine and filgrastim treatments received bone marrow (BM) mesenchymal stromal cells (MSC; 1.25 x 10(6)/kg), granulocyte colony-stimulating factor (G-CSF)-mobilized BM and peripheral blood stem cell grafts from her father. Prior to stem cell transplantation, she had experienced repeated bacterial infections and received 44 blood transfusions during 8 months after diagnosis. The conditioning regimen consisted of fludarabine, cyclophosphamide and busulfan, and prophylaxis of acute graft-versus-host disease (GvHD) was performed by administration of anti-CD25 monoclonal antibody, cyclosporine A, methotrexate, mycophenolate mofetil and anti-thymocyte globulin. The patient achieved rapid hematopoietic engraftment of donor origin and no acute or chronic GvHD was observed. She is now alive with a good performance status, and the dose of cyclosporine A is being tapered. The novel regimen described here might be a suitable option for children with SAA who lack immediate access to HLA-matched sources.

Acute renal failure following antithymocyte globulin therapy for aplastic anaemia—report of two cases and review of literature

Dear Editor, Immunosuppressive therapy with antithymocyte globulin (ATG) with ciclosporine is the standard of care in patients with aplastic anaemia who are not eligible for bone marrow transplantation. ATG is an animal protein and its predominant toxicities include allergic reactions and serum sickness. Acute renal failure attributable to ATG has rarely been described. We report two patients with aplastic anaemia who developed acute renal failure during ATG therapy. Both patients developed oliguric acute renal failure with temporal relation to ATG administration and absence of other etiological factors. One of the patients had complete recovery of renal function with supportive treatment while the other died of sepsis and multi-organ dysfunction.