Antithymocyte Globulin Treatment Research Articles

LFA-3/CD2 Pathway, Potential Target For Immunosuppressive Therapy In Aplastic Anemia: A Phase I/II Trial Of Alefacept In Patients With Relapsed/Refractory Aplastic Anemia

Aplastic Anemia (AA) is a rare bone marrow failure disorder characterized by pancytopenia, and an empty bone marrow. The disease can develop from unknown causes (idiopathic) or can be secondary to drugs, toxins, chemotherapy (acquired). Hematopoietic bone marrow transplant is a potential cure for idiopathic AA patients. Pharmacologic therapies remain the foremost therapy for patients who lack suitable donors or ineligible for bone marrow transplant. Antithymocyte globulin (ATG) is a first line treatment for these patients. However, relapsed and refractory cases of AA can occur even after ATG treatment. Patients with relapsed/ refractory AA may benefit from alternative immunosuppressive therapies. Alefacept is a novel immunosuppressive agent that targets the CD2-LFA3 pathway important in various T cell functions especially T cell activation. The occurrence of relapsed/ refractory cases of AA coupled with the side effect profile of ATG prompted us to test alefacept in refractory AA. This Phase I/II study was fully approved by the Institutional Review Board of the Cleveland Clinic and conducted in patients with relapsed/ refractory AA. This trial was registered under ClinicalTrial.Gov Identifier Number: NCT01267643. A total of four patients were successfully enrolled in this trial. All four patients had refractory AA. Antecedent treatment for three patients was immunosuppressive therapy: ATG in one case, cyclosporine in one, and both plus daclizumab in one case. All patients are female. Patient ages at the beginning of the study were 39, 57, 83, and 90 years. Three of the four patients were ECOG performance status 1 and one patient was ECOG 2. Three patients received dose level 1 (7.5 mg/ week) while one patient was treated at dose level 2 (10 mg/week). All patients received once weekly treatments for a total of 12 weeks. All 4 patients have been followed for 15, 13, 12, and 11 months, respectively. None of the patients had a PNH clone at presentation. Blood parameters at the beginning of the alefacept treatment indicated that two patients had three cytopenias (Hgb<10 g/dL, platelets<100 K/mL, ANC<1.5 K/mL) and two patients had two (platelets and ANC). Three of the four patients achieved a partial response. Side effects were very mild and included a grade 2 cough and grade 1 sore throat and nasal congestion in one patient and grade 1 muscle aches in a second. All side effects were transient and resolved after 2 weeks of treatment. No severe infections or grade 3 or 4 adverse events were reported. Complete blood cell count of two representative patients are shown below. Routine test values (absolute reticulocytes, ANC, Hgb, and platelets) are shown one per month for pre- and post-treatment while one per week during the treatment. We performed a flow cytometric measurement of intracellular cytokine profile before, during and after Alefacept treatment. Peripheral blood mononuclear cells were stimulated with PMA/ ionomycin for 6 hours in culture. We found a decrease in IFN-gamma, a cytokine implicated in AA pathogenesis post-treatment (Patient A: CD4 IFN-gamma 11.1 vs 1.7%,CD8 IFN-gamma 60.8% vs 16.9%; Patient B: CD4 IFN-gamma 32% vs 7% vs 5.7% ,CD8 IFN-gamma 76.7% vs 30.6% vs. 25.8%). Conversely we found an increase in IL-17, post-treatment (Patient A: CD4 IL-17 0.7 vs 56%,CD8 IL-17 61% vs 57.4%; Patient B: CD4 IL-17 1.6% vs 1.9% vs 29.4% ,CD8 IL-17 4.2% vs 6% vs. 31.9%) To date, three out of four patients who achieved a PR continue to be transfusion independent and none are on any other immunosuppressive therapies such as cyclosporine. All four patients remain progression-free and none have developed any PNH clone. On December, 2011 Astellas Pharma US announced that the company has voluntarily discontinued the promotion, manufacturing, distribution and sales of alefacept because of business needs but not related to safety issues. In conclusion, this pilot study even if conducted in a limited number of patients suggests targeting CD2-LFA-3 pathway using alefacept is a viable and safe option for treating patients with relapsed/ refractory AA. Disclosures:No relevant conflicts of interest to declare.

Deferasirox treatment improved hematopoiesis and led to complete remission in a patient with pure red cell aplasia

A 64-year-old woman developed pure red cell aplasia (PRCA) 4years after thymectomy for thymoma. During anti-thymocyte globulin treatment, the patient developed cytomegalovirus pneumonia and was thus unable to continue immunosuppressive therapy and became transfusion dependent. Deferasirox was started for treatment with iron overload when serum ferritin increased to >1000ng/mL. Seven months after initiation of deferasirox treatment, serum ferritin level decreased the normal range and the patient has remained transfusion independent thereafter. Deferasirox was discontinued when serum ferritin level decreased below 500ng/mL, and she has maintained in complete remission over the last 15months. Hypotheses have been raised regarding the improvement of hematopoiesis by deferasirox treatment, but the mechanism whereby this might be achieved remains unclear. Deferasirox treatment may be clinically beneficial both by reducing iron overload and by improving hematopoiesis in patients with PRCA.

Comparison of the Clinical Characteristics of Renal Transplant Recipients Who Underwent Early Versus Late Graft Nephrectomy

BackgroundGraft nephrectomy is the last-resort option for renal transplant recipients. The aim of this study was to compare the clinical characteristics of patients who underwent graft nephrectomy according to the time after renal transplantation. MethodsFrom 2005 to 2012, 42 patients underwent graft nephrectomy after transplant failure. We divided these patients into early (n = 17) and late graft nephrectomy (n = 25) groups based on graft survival to 6 months, comparing their causes for nephrectomy and clinical characteristics. ResultsThe patients included 29 men and 13 women, with an overall mean age of 45 years (range, 10–71 years). The main causes for early and late graft nephrectomy were irreversible acute rejection (71%) and graft intolerance syndrome (95%), respectively. The clinical characteristics did not significantly differ between the early and late graft nephrectomy groups except for operative-related complications. Bleeding was more common among patients who underwent early (n = 10) versus late (n = 3) graft nephrectomy (59% vs 12%; P = .01). Of the 10 patients with perioperative bleeding, 8 had a bleeding tendency, such as low platelet count or prolonged prothrombin time at the time of the operation. These complications occurred after antirejection therapy involving plasma exchange or antithymocyte globulin treatment. Allograft nephrectomy was associated with a mortality rate of 2.38%. ConclusionsThe cause for graft nephrectomy and type of perioperative complication differed according to timing of graft nephrectomy. Antirejection therapy appeared to contribute to postoperative complications such as bleeding.

Antithymocyte Globulin Treatment for Bronchiolitis Obliterans Syndrome in Lung Transplant Recipients

Antithymocyte Globulin Treatment for Bronchiolitis Obliterans Syndrome in Lung Transplant Recipients

Antithymocyte globulin treatment for patients with recent-onset type 1 diabetes: 12-month results of a randomised, placebo-controlled, phase 2 trial

Type 1 diabetes results from T-cell-mediated destruction of β cells. Findings from preclinical studies and pilot clinical trials suggest that antithymocyte globulin (ATG) might be effective for reducing this autoimmune response. We assessed the safety and efficacy of rabbit ATG in preserving islet function in participants with recent-onset type 1 diabetes, and report here our 12-month results. For this phase 2, randomised, placebo-controlled, clinical trial, we enrolled patients with recent-onset type 1 diabetes, aged 12-35 years, and with a peak C-peptide of 0.4 nM or greater on mixed meal tolerance test from 11 sites in the USA. We used a computer generated randomisation sequence to randomly assign patients (2:1, with permuted-blocks of size three or six and stratified by study site) to receive either 6.5 mg/kg ATG or placebo over a course of four days. All participants were masked and initially managed by an unmasked drug management team, which managed all aspects of the study until month 3. Thereafter, to maintain masking for diabetes management throughout the remainder of the study, participants received diabetes management from an independent, masked study physician and nurse educator. The primary endpoint was the baseline-adjusted change in 2-h area under the curve C-peptide response to mixed meal tolerance test from baseline to 12 months. Analyses were by intention to treat. This is a planned interim analysis of an on-going trial that will run for 24 months of follow-up. This study is registered with ClinicalTrials.gov, number NCT00515099. Between Sept 10, 2007, and June 1, 2011, we screened 154 individuals, randomly allocating 38 to ATG and 20 to placebo. We recorded no between-group difference in the primary endpoint: participants in the ATG group had a mean change in C-peptide area under the curve of -0.195 pmol/mL (95% CI -0.292 to -0.098) and those in the placebo group had a mean change of -0.239 pmol/mL (-0.361 to -0.118) in the placebo group (p=0.591). All except one participant in the ATG group had both cytokine release syndrome and serum sickness, which was associated with a transient rise in interleukin-6 and acute-phase proteins. Acute T cell depletion occurred in the ATG group, with slow reconstitution over 12 months. However, effector memory T cells were not depleted, and the ratio of regulatory to effector memory T cells declined in the first 6 months and stabilised thereafter. ATG-treated patients had 159 grade 3-4 adverse events, many associated with T-cell depletion, compared with 13 in the placebo group, but we detected no between-group difference in incidence of infectious diseases. Our findings suggest that a brief course of ATG does not result in preservation of β-cell function 12 months later in patients with new-onset type 1 diabetes. Generalised T-cell depletion in the absence of specific depletion of effector memory T cells and preservation of regulatory T cells seems to be an ineffective treatment for type 1 diabetes.

Rabbit Antithymocyte Globulin Treatment in Childhood Acquired Severe Aplastic Anemia

Acquired severe aplastic anemia (SAA) is a life threatening bone marrow failure characterized by pancytopenia and hypocellular bone marrow. Matched sibling donor is not available for majority of the patients and many children receive immunosuppressive therapy (IST). Although horse antithymocyte globuline (ATG) is the preferred option, our patients received rabbit ATG; since horse ATG is not available in Turkey. We reviewed the medical records of children with SAA who were treated with rabbit ATG, cyclosporine, and granulocyte colony stimulating factor (GCSF) between 2006 and 2012. Fifteen children with SAA aged between 1.5 and 17 years received rabbit ATG as first line treatment. Only two of them showed partial response and the others did not give any response at 3rd, 6th, and 12th months after the first course of IST. The second course of ATG was given to 8 of the patients; Rabbit ATG at the same dosage was used for 3 of them, and others were given horse ATG. None of the patients responded to the second course of ATG. Invasive fungal infection (IFI) which was seen in 80% of the patients was the most significant problem. Overall survival rate was 60%. The median time between the diagnosis and initiation of IST was 57 (range; 29–144) days. This delay might be significantly contributed to unresponsiveness. In our series, the use of rabbit ATG was not effective for these patients as first line treatment modality. Response rate was very low and the incidence of fungal infections was very high in the SAA patients who received rabbit ATG.

High-dose cyclophosphamide compared with antithymocyte globulin for treatment of acquired severe aplastic anemia

A modified regimen of high-dose cyclophosphamide (CTX) plus cyclosporine (CsA) was adopted for patients with severe or very severe aplastic anemia, and the effectiveness was compared with a regimen of antithymocyte globulin (ATG) plus CsA. A total of 121 patients enrolled in this study received either CTX plus CsA (CTX group, 48 cases) or ATG plus CsA (ATG group, 73 cases). The early death rate was 4.2% in the CTX group and 8.2% in the ATG group, showing no significant difference (p = 0.312). The total response rate in the CTX and ATG groups was 54.2% and 57.5% at 3 months, 64.6% and 72.6% at 6 months, and 72.9% and 78.1% at 12 months, respectively (p > 0.05). The overall 5-year survival rate was 81.2% and 80.7%, and the event-free survival rate was 68.2% and 67.3% in the CTX and ATG groups, respectively (p > 0.05). The total medical cost of the CTX group was 54.8% less than that of ATG regimen (p = 0.000). In summary, treatment of severe or very severe aplastic anemia with CTX plus CsA has effectiveness that is comparable to a conventional regimen and less costly.

Hematologic improvement with deferasirox following tandem antithymocyte globulin treatment in a transfusion-dependent patient with severe aplastic anemia

Hematologic improvement with deferasirox following tandem antithymocyte globulin treatment in a transfusion-dependent patient with severe aplastic anemia

In vivo T-Cell Depletion with Antithymocyte Globulins Improves Overall Survival after Myeloablative Allogeneic Stem Cell Transplantation in Patients with Hematologic Disorders

To assess the effect of prophylactic treatment with antithymocyte globulin (ATG) on graft-versus-host disease (GvHD) in myeloablative transplant patients, we performed a meta-analysis of randomized and cohort studies. Medline, Embase, the Cochrane Controlled Trial Register and the Science Citation Index were searched for studies on ATG treatment in patients with hematologic disorders undergoing myeloablative transplantation. Four randomized controlled trials, six retrospective and one prospective cohort study were included, covering 1,549 patients. The summary hazard ratios (HRs) for overall survival were 0.84 [95% confidence interval (CI) 0.63–1.12; p = 0.23] for randomized studies, 0.70 (95% CI 0.57–0.88; p = 0.002) for cohort studies and 0.75 (95% CI 0.63–0.89; p = 0.001) for all studies combined. The corresponding HRs for treatment-related mortality (TRM) were 0.81 (95% CI 0.54–1.22; p = 0.32) for randomized studies, 0.70 (95% CI 0.49–0.99; p = 0.05) for cohort studies and 0.74 (95% CI 0.57–0.95; p = 0.02) for all studies combined. The corresponding HRs for relapse mortality were 1.18 (95% CI 0.69–2.02; p = 0.55) for randomized studies, 1.02 (95% CI 0.65–1.61; p = 0.93) for cohort studies and 1.05 (95% CI 0.74–1.50; p = 0.79) for all studies combined. In conclusion, the addition of ATG to standard GvHD prophylaxis might improve survival due to improved TRM without decreasing relapse mortality.

Quantitative Polymerase Chain Reaction Profiling of Immunomarkers in Rejecting Kidney Allografts for Predicting Response to Steroid Treatment

Steroid-resistant acute rejection is a risk factor for inferior renal allograft outcome. From 873 kidney transplant recipients (1995-2005), 108 patients with a first rejection episode were selected for study using strict inclusion criteria and clinical endpoint definition. We aimed to predict response to corticosteroid treatment using gene expression of 65 transcripts. These reflect cytokines, chemokines, and surface and activation markers of various cell types including T cells, macrophages, B cells, and granulocytes. Steroid resistance (40% of the patients) was defined as requirement for antithymocyte globulin treatment within 2 weeks after corticosteroid treatment. None of the clinical and histomorphologic parameters showed a significant association with response to treatment. Univariate logistic regression analysis resulted in 11 messenger RNA markers, including T-cell-related transcripts CD25, lymphocyte activation gene-3, Granzyme B, and interleukin-10, and macrophage-specific transcripts mannose receptor and S100 calcium-binding protein A9, which significantly discriminated steroid resistant from steroid-responsive rejections (P<0.05). In multivariate logistic regression, the combination of T-cell activation markers CD25:CD3e ratio (odds ratio, 8.7; confidence interval, 2.4-31.2) and lymphocyte activation gene-3 (odds ratio, 3.3; confidence interval, 1.4-7.7) represented the best predictive model for steroid response (P<0.0001). Specificity and sensitivity were 78% and 60%, respectively. After internal stratified 10-fold cross-validation, the model remained significant. Inclusion of clinical variables into the model with molecular variables did not enhance prediction. Differences in intragraft expression profiles reflect variability in the response to antirejection treatment. In acute rejection, molecular markers, particularly those reflecting T-cell activation, offer superior prognostic value compared with conventional parameters.

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.

Antibodies against Carbonic Anhydrase in Patients with Aplastic Anemia

Background/Aims: Antibodies against carbonic anhydrase (CA) have been detected in patients with an aplastic anemia (AA)-like syndrome after autologous stem cell transplantation. Methods: We analyzed sera of 53 bona fide AA patients before and after treatment with anti-thymocyte globulin (ATG) or bone marrow transplantation for the presence of anti-CA antibodies. Results: Anti-CA antibodies were detected in 20 patients (38%) and were associated with older age at diagnosis of AA. Antibody-positive patients showed poor response to ATG treatment (complete response 14%) and inferior long-term survival (36% at 10 years), when compared to antibody-negative patients (complete response and 10-year survival both 64%). Two thirds of patients with antibodies at diagnosis of AA became antibody negative after treatment with ATG. Clearance of the antibody did not appear to be associated with hematological improvement. Conclusion: Antibodies against CA are detected frequently at diagnosis of AA, and their presence identifies a subset of patients with poor response to immunosuppressive treatment.

Rapid T cell repopulation after rabbit anti-thymocyte globulin (rATG) treatment is driven mainly by cytomegalovirus

Rabbit anti-thymocyte globulin (rATG) induces a long-lasting lymphocytopenia. CD4(+) T cells remain depleted for up to 2 years, whereas the CD8(+) T cell compartment is refilled rapidly by highly differentiated CD27(-) CD45RA(+) CD57(+) effector-type cells. Because the presence of these highly differentiated CD8(+) T cells has been associated with cytomegalovirus (CMV) infection, we questioned to what extent restoration of CMV T cell immunity contributes to the re-emergence of T cells following rATG treatment. We compared T cell repopulation in six CMV-seropositive patients with CMV reactivation (reactivating CMV(+) ) to that in three CMV(+) patients without reactivation (non-reactivating CMV(+) ), and to that in three CMV-seronegative recipients receiving a kidney from a CMV-seronegative donor (CMV(-/-) ). All patients received rATG because of acute allograft rejection. Total CD4 and CD8 counts, frequency and phenotype of virus-specific CD8(+) T cells were determined. In reactivating CMV(+) patients, total CD8(+) T cells reappeared rapidly, whereas in non-reactivating CMV(+) patients they lagged behind. In CMV(-/-) patients, CD8(+) T cell counts had not yet reached pretransplant levels after 2 years. CMV reactivation was indeed followed by a progressive accumulation of CMV-specific CD8(+) T cells. During lymphocytopenia following rATG treatment, serum interleukin (IL)-7 levels were elevated. Although this was most prominent in the CMV-seronegative patients, it did not result in an advantage in T cell repopulation in these patients. Repopulated CD8(+) T cells showed increased skewing in their Vβ repertoire in both CMV(-/-) and reactivating CMV-seropositive patients. We conclude that rapid T cell repopulation following rATG treatment is driven mainly by CMV.

Ex Vivo Expansion of Human Tregs by Rabbit ATG Is Dependent on Intact STAT3-Signaling in CD4+ T Cells and Requires the Presence of Monocytes

The addition of low, nondepleting doses of rabbit antithymocyte globulin (ATG) to human peripheral blood mononuclear cells has been shown to expand functional CD4(+) CD25(+) FoxP3(+) regulatory T cells (Tregs) in vitro. This report is the first to elucidate the exact cellular mechanisms of ATG-mediated Treg expansion. CD4(+) T cells require monocytes, but not other antigen presenting cell subsets, to be present in coculture to expand Tregs. However, T cells do not require direct cell-cell contact with monocytes, suggesting the importance of soluble factors. Moreover, ATG initially "reprograms" CD4(+) T cells, but not monocytes, and induces STAT3 and STAT5 signaling in CD4(+) cells. These reprogrammed CD4(+) T cells subsequently secrete GM-CSF and IL-10 only in case of intact STAT3 signaling, which in turn promote the generation of tolerogenic CD14(+) CD11c(+) dendritic cells characterized by enhanced IL-10 and decreased IL-12 production. Treg expansion following ATG treatment is accompanied by enhanced gene expression of both GM-CSF and Bcl-2, but not TGF-β, in peripheral blood mononuclear cells. These results demonstrate that ex vivo expansion of human Tregs by ATG is due to its ability to reprogram CD4(+) T cells in a STAT3-dependent but TGF-β-independent manner, leading to the generation of monocyte-derived dendritic cells with a tolerogenic cytokine profile.

The Efficacy of Rabbit Antithymocyte Globulin (Thymoglobulin®) with Cyclosporin As First-Line Treatment in Aplastic Anemia,

Abstract 3430 Background:Antithymocyte globulin (ATG) is the drug of choice for immunosuppressive therapy (IST) in patients with aplastic anemia (AA) unsuitable for hematopoietic stem cell transplantation. The standard ATG preparation in AA had been horse ATG because of the larger experience and the results already reported with this preparation. Due to the unavailability of the horse ATG since 2006, rabbit ATG became the only available ATG preparation in Korea. But, there are only limited data about the therapeutic efficacy of rabbit ATG as first-line IST in AA. Method:We retrospectively investigated the outcome of 58 evaluable patients among 62 patients with AA treated with IST using rabbit ATG as front line between March 2006 and April 2010 at our institution. 70.7% of enrolled patients were very severe (n=18) or severe AA (n=23). All patients received rabbit ATG (Thymoglobulin®, 2.5mg/kg per day for 5 days) with methylprednisolone and cyclosporine A. Response rate (RR) was assessed at 3, 6, 9, 12 and 18 months after IST. Results:After IST, overall RR was 27.8%, 50.8%, 52.8%, 52.8% and 56.7% after 3, 6, 9, 12 and 18 months, respectively. Complete response (CR) rates were 0.8%, 1.8%, 5.6%, 9.6% and 21.2% after 3, 6, 9, 12 and 18 months, respectively. Median time to achieve partial response (PR) and CR were 93 (range; 12∼977 days) and 381 (range; 12–614) days. Among 31 responders, 10 patients (32.3%) relapsed. Median time between response and relapse were 396 days (range; 254∼681 days).Estimated overall survival and failure free survival at 3 years from ATG treatment were 85.8% and 42.8%, respectively. Age (>45) at the use of ATG was an independent predictor of overall survival and overall response (p=0.033 and 0.027) in univariate analysis. Other factors such as disease severity, pre-ATG hematological parameters (absolute lymphocyte count and absolute reticulocyte count) were not associated with overall survival and failure free survival. Conclusion:These data indicate that rabbit ATG was as effective as horse ATG based on other recently published data. But, the response time of rabbit ATG treatment is longer than that of horse ATG treatment. Especially, more than half of patients who achieved CR required time over 1 year after ATG treatment. Rabbit ATG can be effective IST regimen comparable to horse ATG, but it takes longer time to achieve sufficient response. Disclosures:No relevant conflicts of interest to declare.

Phase 1 Dose-Ranging Study of Oral Ezatiostat Hydrochloride (Telintra®, TLK199) in Combination with Lenalidomide (Revlimid®) in Patients with Non-Deletion(5q) Low to Intermediate-1 Risk Myelodysplastic Syndrome (MDS)

Abstract 2778 Introduction:Lenalidomide is approved for the treatment of del(5q) MDS in US and Japan. In Low to Intermediate-1 (Int-1) risk non-del(5q) MDS, lenalidomide treatment is less effective with a lower response rate (25%) and shorter response duration [Raza A. et al, Blood, 2008.111,1]. Ezatiostat, a glutathione S-transferase P1-1 (GST P1-1) inhibitor, activates Jun kinase, promoting the growth and maturation of hematopoietic progenitors while inducing apoptosis in malignant cells. Based on the novel mechanism of action, response rates, non-overlapping toxicities, and tolerability observed in a single agent ezatiostat Phase 2 study in MDS, a study of the combination of ezatiostat and lenalidomide was conducted to determine the safety and efficacy of ezatiostat with lenalidomide in non-del(5q) Low to Int-1 risk MDS. Methods: In this multicenter Phase 1 dose-ranging study, ezatiostat was given at a starting dose of 2000 mg in combination with lenalidomide at 10 mg, days 1–21 of a 28-day cycle. In stage 1, 3–6 patients in a standard 3+3 design were treated before escalation to the ezatiostat/lenalidomide 2500/10 mg dose level. Treatment was given until lack of MDS response or unacceptable toxicity. Hematologic improvement-erythroid (HI-E) rates were determined by the MDS International Working Group (IWG; 2006) criteria. Results: Eighteen pts (median age 73 yrs; range 57–82; 72% male), with World Health Organization classifications: 4 refractory anemia (RA), 2 RA with excess blasts-1, 4 refractory cytopenia with multilineage dysplasia (RCMD), 5 RCMD with ring sideroblasts, 2 MDS-unclassified, 1 MDS/myeloproliferative disorder-U were enrolled. Thirteen pts (72%) were Int-1 risk, 5 (28%) Low risk; 4 pts (22%) had abnormal cytogenetics. Twelve RBC transfusion-dependent pts (67%) required a median of 6 units (range 4–10)/8-weeks. Two pts (11%) were platelet transfusion dependent. A total of 67 treatment cycles were given (median 3.5 cycles/pt [range 1–11]) and only 6 cycles (9%) required dose reductions and 8 (12%) dose delays. Two of 6 pts reported DLTs (Grade 3 diarrhea and Grade 3 rash) at 2500/10 mg, with 9 additional pts receiving the recommended combination dose of 2000/10 mg. Eleven of 18 pts were evaluable (4 at 2500/10 mg and 7 at 2000/10 mg), and 3 pts are still on therapy with insufficient treatment duration to be evaluable. The HI-E rate was 43% (3/7; 95% CI, 10%–82%) for pts at the recommended 2000/10 mg dose and 6 pts are continuing therapy at the time of analysis. Three of 8 (38%; 95% CI, 9%–76%) RBC transfusion-dependent evaluable pts achieved transfusion independence including 1 responder who did not respond to prior lenalidomide. In responders, the median increase in hemoglobin level was 3.4 g/dL (from 7.9 g/dL). In 2 of 4 thrombocytopenic pts, a HI-platelet (HI-P) response was observed. A bilineage (HI-E and HI-P) response in 2 of 4 pts with anemia and thrombocytopenia was reported. One RBC and platelet transfusion-dependent pt who had a poor response to prior anti-thymocyte globulin treatment achieved complete RBC and platelet transfusion independence. The combination was generally well tolerated with no unexpected toxicities. Most common treatment-related non-hematologic adverse events (AEs) were Grades 1 and 2 including: fatigue (6%, 28%), swelling (0%, 11%), anorexia (11%, 6%), rash (0%, 6%), skin odor (11%, 6%), nausea (39%, 11%), diarrhea (22%,17%), vomiting (28%,17%), upper abdominal pain (5.6%, 5.6%), and constipation (11%, 0%). Grade 3 events were rash (11%), nausea (6%), diarrhea (17%), and vomiting (6%). Most common hematologic-related AEs were Grades 1 and 2 thrombocytopenia (11%, 6%) and neutropenia (0%, 11%). Grade 3–4 AEs were thrombocytopenia (11%, 17%), neutropenia (17%, 11%), anemia (6%, 6%), and febrile neutropenia (11%, 0%). Conclusions: Ezatiostat is the first GST P1-1 inhibitor to cause clinically significant reductions in RBC and platelet transfusions, including RBC and platelet transfusion independence. Since ezatiostat is non-myelosuppressive, it is a good candidate for combination with lenalidomide and in this study, the combination was well tolerated. Interestingly, ezatiostat may also have the potential to enhance lenalidomide’s efficacy. The recommended doses of this combination regimen for future studies is the ezatiostat/lenalidomide 2000/10 mg. Disclosures:Off Label Use: Lenalidomide was used off-label in patients with non-del5q MDS. Mulford:Celgene: Speakers Bureau. Brown:Telik, Inc.: Employment, Equity Ownership. Meng:Telik, Inc.: Employment, Equity Ownership. Lyons:Incyte: Research Funding; Telik: Research Funding; Alexion: Consultancy, Honoraria; Novartis: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding. Sekeres:Celgene: Consultancy, Honoraria, Speakers Bureau. Mesa:NS Pharma: Research Funding; Astra Zeneca: Research Funding; SBio: Research Funding; Lilly: Research Funding; Incyte: Research Funding; Celgene: Research Funding.

Worsening Bradycardia Following Antithymocyte Globulin Treatment of Severe Aplastic Anemia

Immunosuppressive regimens, which include antithymocyte globulin (ATG), are widely used for the treatment of severe aplastic anemia (SAA). However, bradycardia has been reported only as a rare side effect of ATG therapy in the manufacturer's product information and, in rare cases, in the adult literature. We present an adolescent with SAA and preexisting bradycardia who underwent immunosuppression therapy with ATG, methylprednisolone, and tacrolimus and developed profound sinus bradycardia with successive doses of ATG.

Thymic function, anti-thymocytes globulins, and cancer after renal transplantation

Background Prolonged CD4 T cell lymphopenia after polyclonal antithymocyte globulins (ATG) is associated with an increased rate of cancers. Here, we examined whether pre-transplant thymic function estimated by TREC levels is predictive of cancer occurrence following ATG treatment. Patients and methods The impact of TREC on cancer occurrence was analyzed in 115 consecutive incident renal transplant recipients having received ATG. Results Mean follow-up was 7.5 ± 2.6 years. After ATG induction, patients with the lowest pre-transplant TREC values had lower post-transplant CD4 + and CD4 + CD45RA + CD45RO − T cell counts, and a higher frequency of T cells with a regulatory phenotype (CD127 +CD4 +CD25 +Foxp3 +). Log-transformed pre-transplant TREC values were significantly lower in patients who developed cancer after transplantation ( p < 0.0001). The cumulative incidence of cancer was higher in patients having the lowest pre-transplant TREC values (T1 [low]: 47.4%, T2 [medium]: 12.5%, and T3 [high]: 2.7%; p < 0.0001). In multivariate analysis, pre-transplant TREC value was the only predictive factor of cancer (HR, 0.39; 95% CI, 0.16 to 0.97, for one log (TREC/10 6 PBMC); p = 0.046). Conclusions Pre-transplant thymic function is associated with an increased rate of post-transplant cancer in patients having received ATG. Omitting ATG in recipients with low pre-transplant TREC values should be considered.

BK polyoma viral infection in renal allograft recipients

BK polyoma viral nephropathy (BKVAN) has emerged as a significant cause of renal allograft loss. The literature on BK viral infection from India is scarce. The study was therefore undertaken to evaluate impact of BK polyoma viral (BKV) infection on renal allograft recipients in Indian scenario from a service renal transplantation centre. Renal allograft recipients who underwent graft biopsy formed the part of this descriptive cross-sectional study group. The clinicopathological profile of the patients was analysed. The diagnostic modalities employed were histopathology, immunohistochemistry using antibody for Simian virus 40 large T antigen along with real time quantification of the BK viral DNA load in the urine and the serum. One hundred forty seven renal allograft recipients were evaluated. 73.47 percent (108/147) patients presented with graft dysfunction and rest were protocol biopsies. There were 53 cases of rejection related diagnosis, 8 cases of graft pyelonephritis, 64 cases showed normal histology and rest exhibited miscellaneous causes. Nineteen percent (28/147) cases were positive for BKV DNA (viruria 26/147, 17.6% and viraemia 8/147, 5.44%. 3.4 percent (5/147) exhibited histological and immunohistochemical evidence of BKVAN. Nuclear enlargement, smudging and intranuclear inclusions along with plasma cell rich interstitial nephritis were important features observed on histopathology. Concomitant acute rejection was seen in 4/5 cases of BKVAN. All cases of BKVAN exhibited viraemia (> 2500 copies/mL), though cut-off values could not be defined statistically due to small sample size. Positive statistical correlation was observed between use of anti-thymocyte globulin (induction therapy and/or treatment of steroid resistant rejection, Pearson ×(2) value 6.9, P=0.008) and rejection episodes (Pearson ×(2) value 9.8, P = 0.007) with BKV infection. BK polyoma nephropathy should be added to the list of differential diagnosis considered for a renal allograft dysfunction. Renal biopsy remains the gold standard for diagnosis supplemented by non-invasive molecular techniques for screening and monitoring of BKV infection.

Treatment of childhood aplastic anemia with antithymocyte globulin, management of side effects and long-term follow-up

To evaluate the efficacy of antithymocyte globulin (ATG) based immunosuppression therapy for childhood aplastic anemia, to reduce the adverse effects and to observe the long-term outcome. Thirty-five children with aplastic anemia (AA) were enrolled in this study. Six of the cases had very severe AA (VSAA), 11 had severe AA (SAA)-I, 8 had SAA-II and 10 had moderate AA (MAA). All these patients were treated with ATG plus Cyclosporin A (CSA). The following measures were taken during the ATG therapy: infection of the patients had been controlled before ATG treatment. Comprehensive anti-allergic measures were implemented. Close attention was paid to the hemorrhage related with platelet reduction caused by ATG and severe infection of the patients. Shortly after the ATG usage, all the patients had a significant decrease of absolute peripheral lymphoblast count by more than 60 percent. With a mean follow-up time of 28 months, the total effective rate was 77.14% (27/35), significant response rate was 57.14%(20/35). There was no significant difference among VSAA, SAA and MAA groups in the response rate. Adverse reactions included the following: (1) 48.6% (17/35) patients presented mild anaphylactoid reaction during the first day of ATG treatment; (2) 42.9%(15/35) cases presented serum sickness 5 - 11 days after the last dose of ATG with a mean duration of 3.6 days, all the patients were cured effectively with methylprednisolone; (3) 25.7% (9/35) patient's peripheral blood platelet count was reduced, might be caused by ATG, to below 10 × 10(9)/L, but no patient had severe hemorrhagic complication after platelet transfusion was performed; (4) 22.9%(8/35)of patients got infection within a month after ATG therapy, including 3 cases with clinical septicemia, all the 3 cases recovered after antibiotics treatment. There was no ATG treatment-related death in this series. ATG is a very effective therapy for children with SAA and MAA. Comprehensive measures are needed to prevent and handle the side effects to avoid treatment-related death. Long-term supportive therapy and proper follow up contribute to the favourable outcomes of the patients.