rATG Administration Research Articles

Porcine antilymphocyte globulin versus rabbit antithymocyte globulin for intensive immunosuppressive therapy of acquired aplastic anemia: A meta-analysis and systematic review.

Several studies have reported that porcine antilymphocyte globulin (pALG) has a significant effect on aplastic anemia (AA), but their conclusions are inconsistent. To objectively evaluate its efficacy and safety, a meta-analysis was conducted. We systematically searched the relevant literature on pALG vs. rabbit antithymocyte globulin (rATG) as the first-line treatment in AA patients until August 31, 2022, in electronic databases: PubMed, Cochrane Library, Web of Science, etc. Two researchers independently extracted data and evaluated the quality of the study. Stata 14.0 was used for statistical analysis. 50 studies were included in the analysis. The overall responses at 3, 6, and 12 months between the pALG group and rATG group were equivalent. We analyzed early mortality, total mortality, relapse rates, and 5-year survival after the administration of pALG or rATG, and there was no significant difference between the pALG and rATG groups. In our study, the incidence of infection in the pALG group was better than that in the rATG group, OR=0.63, 95% CI (0.44-0.88), p=0.008, which showed a statistically significant difference. The efficacy of pALG in AA patients is equivalent to that of rATG. rATG was associated with a significantly higher incidence rate of infection than pALG.

Optimized Rabbit Antithymocyte Globulin Protocol Plus Sequential Cyclosporine and Levamisole Regimen for Newly Diagnosed Severe Aplastic Anemia: A Single-Arm, Single-Centre, Prospective, Phase 2 Trial

Background The inferior effect of rATG is due to the early fatal blow caused by the more potent immunosuppression. In order to retain its sustainable immunosuppression while weakening the early fatal blow. We explored a modifying schedule of administration of rATG by prolonging the course of rATG administration based on the equality of total dose, and then reported the better response and survival in severe aplastic anemia (SAA). And previously, we reported the encouraging effectiveness of cyclosporine alternately combined with levamisole (CSA and LMS regimen) in moderate AA, refractory or relapsed SAA, and SAA. We aim to establish whether the optimized rATG protocol plus sequential CSA and LMS regimen could improve SAA outcomes. Methods We conducted a single-arm, prospective, phase 2 trial at The Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Science & Peking Union Medical College (CAMS & PUMC). Patients aged 6 years or older with confirmed, newly diagnosed SAA were eligible. Patients received optimized rATG administration (1.97 mg/kg/d for 9 days) based on the equality of total does with standard protocol (3.55 mg/kg/d for 5 days). And then CSA and LMS were alternatively administrated every other day from day 14. The initial dose of CSA was 3mg/kg/day in adults and 5mg/kg/day in children (6-18 years old). Oral LMS was alternatively administrated at a dose of 150 mg per day in adults and 2.5 mg/kg per day in children (< 40 kg) in three divided doses. The primary endpoint was overall response rate at 6 months. The trial is registered at www.clinicaltrials.gov as NCT02203396. Results: Between Aug 1, 2014 and Sep 30, 2017, 40 patients with newly diagnosed SAA were treated (median age 24 years [range 7-57 years]; 19 [47.5%] male; 18 [45%] VSAA; 1[2.5%] post-hepatitis). All of these patients were transfusion dependent. Demographic data and clinical characteristics of these patients are outlined in Table 1. The 3-month overall response rates (ORRs) was 40.0%, including 2.5% CR and 37.5% PR. The ORRs increased to 60% (15% CR and 45% PR) at 6 months and 72.5% (42.5% CR and 30% PR) at 12 months. With a median follow-up of 77 months (range 0.1-97 months), estimated 8-year OS rate and event-free survival rate were 84.9% (95% CI, 69.35-92.9%) and 66.5 (95%CI, 49.1-79.1%), respectively. No patient discontinued therapy because of treatment-related toxicity. There were two deaths-one due to infection and another due to cerebral hemorrhage. In this cohort, 4/40 patients (5.7%) evolved to clonal disorders. Of the 4 patients, 1 patients progressed to overt PNH, 2 MDS and 1 acute myeloid leukemia (AML). Cytogenetic abnormalities involved chromosome 7 occurred in one cases with AML. A total of 2 (7.1%) patients relapsed at 33 and 79 months after initial response. Both of the 2 relapsed patients acquired response again with the administration of CSA. Conclusions: Front-line sequential optimized rATG protocol with CSA and LMS regimen resulted in encouraging long-term survival. Future randomized studies should evaluate the optimized IST regimen in the treatment of patients with SAA.

Clinical Dissection of Infectious Event Following ATG Treatment for Aplastic Anemia and Hypoplastic Myelodysplastic Syndrome Reveals Urgent Need for Anti-Aspergillus Prophylaxis

▪BackgroundInfection is the leading cause of death in patients with aplastic anemia (AA) and hypoplastic myelodysplastic syndrome (hMDS). Prolonged neutropenia and lymphopenia followed by immunosuppressive treatment (IST) are the major risk factor for the development of infections. While IST responses occur after 3-6months after ATG treatment, aggravation of transient neutropenia and lymphopenia is provoked by ATG treatment. As such, increasing of mortality associated with infection is obviously predictable following ATG treatment. In this study, we analyzed the detailed infection profile so as to guide adequate prophylaxis after ATG treatment in AA and hMDS. More specifically, we studied the relation between invasive fungal infection (IFI) and treatment outcome and predictive factor of IFI after ATG treatment for AA and hMDS.Patient and MethodsWe retrospectively reviewed the medical records of AA and hMDS patients who were treated with rATG based immunosuppressive treatment between January 2005 to July 2016 in two institutions (Seoul National University Hospital and Seoul National University Bundang Hospital). Patients who did not complete the ATG course for 5days and visit the clinic after IST for at least 6months were excluded. Patients treated with hematopoietic stem cell transplantation within 6months after rATG administration were also excluded. The response was evaluated at 3 and 6 months after IST. Assessment of response to IST was performed according the criteria of European Group for Blood and Marrow Transplantation (EBMT). Infection events occurred within 6 months after rATG administration were studied. Only proven and probable IFIs were considered according to the European Organization for Research and Treatment of Cancer/Mycosese Study Group (EORTC/MSG) criteria. Overall survival (OS1) was defined as the time from diagnosis to last follow-up or death from any cause. The time of IST treatment to death was defined as OS2 and also evaluated. To assess t the optimal cut-off value of total white blood cells (WBCs), ALC (Absolute Lymphocyte Count) and ANC (Absolute Neutrophil Count), WBCs, ALC and ANC of the initiation of treatment, 3months after IST and 6months after IST were analyzed by using receiver operating characteristics (ROC) curves.ResultsA total of 139 patients (median age, 51.0; range 15-82, male:female 75:64) were evaluated. Eighty-two percent of the patients were SAA (n=114) at treatment. Response was observed in 97(CR 9.4 %, PR 60.4 %) patients at 3months and in 103 (CR 29.5%, PR 44.6%) patients at 6months after IST. A total of 88 infection events were observed in 75 patients and the most frequent infection was bacterial infection (40 cases, 45.4%). IFIs were observed in 26 cases and invasive aspergillosis (IA) was the most common fungal infection (23 cases, 88.4%). Other fungal infections included one proven mucormycosis by biopsy of nasal cavity and two yeast (Candida tropicalis and Candida albicans) fungemia. The most frequent organ involved by IFI was lung (21cases, 80.7%). The mean time to infection events was 1.6months in 75 patients and 2.0 month in 26 patients with IFIs. 33 patients died during the study period, and 26 of them were related with infection. 13 deaths were directly due to IFIs with median time of IST treatment to death was 17 weeks (range: 2-139weeks) and eight of them expired within 6months after IST. IFIs following ATG was significantly related with shorter OS (HR 4.4; CI 1.925-10.074; P= <0.0001). ALC less than 500/ml (sensitivity 71.4%; specificity 76.9%; AUC 0.768 CI95 0.630-0.906; P=0.002) at 3months after IST was a significant predictive factor for IFIs related death (OR 8.3; CI 2.167-32.044; P=0.002). Interestingly, infections other than IFI were not significantly related to infection related death or shorter OS.ConclusionInvasive fungal infection is the leading cause of death in patients who receive IST for AA or hMDS. Our findings strongly suggest need for antifungal prophylaxis such as posaconzole following ATG based IST in this population. DisclosuresNo relevant conflicts of interest to declare.

Rabbit antithymocyte globulin induces human lymphocyte activation, proliferation, and apoptosis in the absence of complement: an experimental study.

Rabbit antithymocyte globulin (rATG) has become the first choice for induction therapy in HLA-presensitized patients undergoing organ transplantation. Meanwhile, complement inhibitors have been approved for preventing or treating antibody-mediated rejection in these patients. The biological effects of rATG on lymphocytes in cases of complement deficiency or significant inhibition are not yet clear. We measured lymphocyte activation, proliferation, and apoptosis in response to rATG treatment in the absence of complement. T-cell subsets were analyzed transcriptomically features to rATG stimulation. Activation-related phenotypes on T cells were determined in patients after rATG administration. We found that rATG treatment led to lymphocyte activation and proliferation in vitro without the addition of complement. A dose-dependent apoptosis in rATG-treated lymphocytes was detected, which was partially caspase-3-dependent but Fas/FasL-independent. T cells were more sensitive to rATG stimulation than were non-T cells. Both CD4+ T cells and CD8+ T cells upregulated a series of genes related to cell activation, cytokine production and apoptosis to rATG stimulation. CD69 and CD25 levels in surviving T cells were increased in patients after rATG administration. These findings indicate that rATG can stimulate lymphocyte activation, proliferation, and apoptosis in the absence of complement. Biologic effects of rATG other than complement-dependent cytotoxicity need to be concerned.

Effect of Rabbit Antithymocyte Globulin on Acute and Chronic Active Antibody-Mediated Rejection After Kidney Transplantation

BackgroundRabbit antithymocyte globulin (rATG) induction is associated with reduction in the occurrence of de novo donor-specific antibody (DSA) and antibody-mediated rejection (AMR). Therefore, rATG administration is considered as a treatment for AMR. However, only a few studies have investigated the treatment of AMR with rATG after kidney transplantation. MethodsBetween April 2013 and March 2018, 162 consecutive de novo kidney transplantations were performed with induction immunosuppressive therapy comprising tacrolimus, mycophenolate mofetil, methylprednisolone, and basiliximab. AMR was diagnosed on the basis of the presence of DSA and episode biopsy findings. For DSA-positive recipients, plasmapheresis was performed to remove DSA before rATG administration (1.5 mg/kg for 5 days). Patients treated with rATG against active AMR were retrospectively analyzed for graft function. ResultsA total of 13 kidney transplant recipients developed active AMR within 302 days after transplantation. After rATG administration, the mean serum creatinine and urine protein levels significantly declined from 3.03 mg/dL to 1.68 mg/dL (P = .002) within 46 days and from 3.01 g/gCr to 0.54 g/gCr (P = .006) within 106 days, respectively. The peripheral blood lymphocyte count rapidly decreased after rATG administration and remained low for 12 months. With regard to adverse events, fever (84.6%), cytomegaloviremia (84.6%), thrombocytopenia (61.5%), anemia (30.8%), and neutropenia (15.4%) occurred within 3 months after rATG administration. ConclusionsrATG improved graft function by suppressing peripheral blood lymphocytes in kidney transplant recipients with active AMR. The rATG administration as a treatment for active AMR may contribute to positive graft outcomes after kidney transplantation.

Risk factors for delayed graft function in deceased donor kidney transplantation; a potential preventive role for intraoperative thymoglobulin

Introduction: Delayed graft function (DGF) is associated with significant adverse outcomes in deceased donor kidney transplantation (KT) including lower graft survival. However, risk factors and potential preventive strategies like intraoperative rabbit antithymocyte globulin (rATG; thymoglobulin) have not yet been fully evaluated. Objectives: The aim of this study was to investigate DGF risk factors and determine the association of intraoperative rATG with the risk of DGF in deceased donor kidney recipients. Patients and Methods: We retrospectively examined medical records of 163 first time deceased donor kidney transplant recipients at two major kidney transplant centers from 2014 to 2016. All the donors were standard heart-beating, brain death donors. Risk factors for DGF in recipients were evaluated using multivariate logistic regression analysis. Results: The mean recipients’ age was 43±13 years and the majority of participants were male (64%). The overall rate of DGF was 27%. Intraoperative rATG was significantly associated with a lower rate of DGF (adjusted odds ratio [AOR], 0.33, 95% CI, 0.11-0.95). Intraoperative transfusion (AOR, 3.7, 95% CI, 1.4-9.9) and diabetes mellitus (AOR, 3.7, 95% CI, 1.5-8.9) were significantly associated with higher risk of DGF. Conclusion: This study showed that intraoperative blood transfusion and diabetes mellitus were associated with increased risk of DGF. Meanwhile, administration of intraoperative rATG was associated with reduced odds ratio of DGF. Future studies are needed to evaluate the potential role of rATG in DGF-related renal outcomes.

Safety and Feasibility of Outpatient Rabbit Antithymocyte Globulin Induction Therapy Administration in Kidney Transplant Recipients.

Kidney transplant induction therapy often includes inpatient administration of rabbit antithymocyte globulin (rATG) over multiple days. To reduce hospital length of stay (LOS) and drug expenditures, the rATG induction course was completed in the outpatient setting via peripheral intravenous administration. The present study assesses early readmission trends ascribable to an outpatient rATG administration protocol to ensure initial reduction in hospital LOS is sustained early after discharge. This was a retrospective study of kidney recipient outcomes for patients transplanted between January 1, 2008, and February 29, 2016, immediately following implementation of an outpatient rATG protocol. Readmission data within 7days of outpatient rATG administration were collected. The relatedness of rATG administration to an adverse drug reaction resulting in readmission was determined by the World Health Organization-Uppsala Monitoring Centre Causality Assessment Scale and the Naranjo Adverse Drug Reaction Probability Scale. A total of 1104 patients received outpatient doses of rATG and were included. An upward trend in kidney transplant volume and outpatient rATG administrations per year was found from 2008-2015. Following protocol implementation, the percentage of overall readmissions ranged from 9% to just over 12% from 2008-2014 and remained less than 10% for 2014 through 2016. The percentage of outpatient rATG infusions that potentially led to rATG-related readmissions was less than 4% per year over the study period. A total of 1124 hospital days were saved, 125days per year on average. Outpatient administration of rATG is feasible, safe, and did not increase readmissions in the period directly following administration. The findings of this analysis support our continued use of the outpatient rATG protocol at our institution.

Correlation of rabbit antithymocyte globulin serum levels and clinical outcomes in children who received hematopoietic stem cell transplantation from an alternative donor.

We analyzed the correlation between rabbit ATG (rATG) serum levels and clinical outcomes in 37 children who received rATG at a total dose of 10 or 15 mg/kg during HSCT conditioning from an alternative donor. Fourteen patients had advanced malignant diseases, 13 had severe AA, and 10 had inherited disorders. Complete engraftment was achieved in all patients, and no rejection occurred. The cumulative incidence of grades II-IV acute GVHD and extensive chronic GVHD was 27% (95% CI, 12.5-39.6%) and 8.1% (95% CI, 0-23.1%), respectively. Multivariate analysis identified lower rATG levels at week 4 as an independent risk factor in the development of grades II-IV acute GVHD (p = 0.037). Serious infections were not observed in any patient following HSCT. No correlation was found between EBV reactivation and rATG levels at week 2 and week 4 after HSCT. Furthermore, no correlation was found between relapse and rATG levels two and four wk post-transplantation. The probability of five-yr OS among patients was 70.3% (95% CI, 59.8-79.2%). Our results suggest that targeted rATG administration may protect patients from severe acute GVHD without increasing the risk of EBV reactivation or relapse.

Methylene blue treatment for cytokine release syndrome-associated vasoplegia following a renal transplant with rATG infusion: A case report and literature review.

Rabbit anti-thymocyte globulin (rATG) is an infusion of polyclonal rabbit-derived antibodies against human thymocyte markers, which can be used to prevent and treat acute rejection following organ transplantation. However, the product monograph issued by the manufacturer (Sanofi Canada) reports that serious immune-mediated reactions have been observed following the use of rATG, consisting of anaphylaxis or severe cytokine release syndrome (CRS), which is a form of vasoplegic syndrome (VS), in which distributive shock occurs refractory to norepinephrine (NE) and vasopressin (VP). Severe infusion-associated reactions are consistent with CRS and can cause serious cardiac or respiratory problems, or in certain cases, mortality. CRS is a form of systemic inflammatory response syndrome (SIRS). In SIRS, the substantial activation of endothelial inducible nitric oxide synthase (iNOS) and smooth muscle guanylate cyclase (GC) is observed, which can produce severe hypotension that is unresponsive to conventional vasopressors. Methylene blue (MB) is a direct inhibitor of iNOS and GC and has been used as an effective treatment for VS following cardiothoracic surgery. In the present study, the successful use of MB as a rescue therapy for CRS in a patient receiving rATG following a renal transplant was reported. Following an uneventful cadaveric kidney transplant involving the intravenous (IV) administration of rATG for the induction of immunological tolerance, the patient became markedly hypotensive and tachycardic. The patient required high doses of VP and NE infusions. Following the protocol described for treating refractory VS in post-cardiac surgery patients, the decision was made to initiate the patient on an IV MB infusion. This treatment protocol was shown to improve the hemodynamic status of the patient, which enabled the withdrawal of vasopressors and suggests an important role for methylene blue in the management of refractory VS.

Induction of suppressive allogeneic regulatory T cells via rabbit antithymocyte polyclonal globulin during homeostatic proliferation in rat kidney transplantation.

Experimental studies have shown that rabbit antithymocyte polyclonal globulin (ATG) can expand human CD4+CD25++Foxp3+ cells (Tregs). We investigated the major biological effects of a self-manufactured rabbit polyclonal anti-rat thymoglobulin (rATG) in vitro, as well as its effects on different peripheral T-cell subsets. Moreover, we evaluated the allogeneic suppressive capacity of rATG-induced Tregs in an experimental rat renal transplant model. Our results show that rATG has the capacity to induce apoptosis in T lymphocyte lymphocytes as a primary mechanism of T-cell depletion. Our in vivo studies demonstrated a rapid but transient cellular depletion of the main T cell subsets, directly proportional to the rATG dose used, but not of the effector memory T cells, which required significantly higher rATG doses. After rATG administration, we observed a significant proliferation of Tregs in the peripheral blood of transplanted rats, leading to an increase in the Treg/T effector ratio. Importantly, rATG-induced Tregs displayed a strong donor-specific suppressive capacity when assessed in an antigen-specific allogeneic co-culture. All of these results were associated with better renal graft function in rats that received rATG. Our study shows that rATG has the biological capacity immunomodulatory to promote a regulatory alloimmune milieu during post-transplant homeostatic proliferation.

Pharmacokinetic and pharmacodynamic studies of two different rabbit antithymocyte globulin dosing regimens: Results of a randomized trial

Rabbit antithymocyte globulin (rATG; Thymoglobulin®) is currently used to prevent acute rejection in kidney transplantation. The dose and regimen of rATG have not been optimized. Moreover, the impact of different treatment regimens on T-cell phenotype reconstitution remains unknown. We conducted a prospective randomized study of 17 renal transplant patients to determine the pharmacokinetics of total and active (bound to human cells) rATG and T-cell phenotype reconstitution after rATG administration. Patients received rATG at a total dose of 6mg/kg, administered either as 1.5mg/kg/day on days 0–3 (Group 1, n=8) or 3mg/kg on days 0 and 3 (Group 2, n=9). All patients received tacrolimus, mycophenolate mofetil and steroids. Blood samples were assayed for total rATG by enzyme linked immunosorbent assay and active rATG by flow cytometry. Maximum concentrations and terminal half-lives were similar between the two groups but at month 3 Group 1 had significantly lower values for total rATG (concentration was 6.2±1.1μg/mL versus 10.2±2.9μg/mL in Group 2, p=0.027) and total rATG dose-normalized AUC (374±83dayg/mL versus 508±149dayg/mL in Group 2, p=0.046). Time to sub-therapeutic levels (<1μg/mL) of active rATG was significantly shorter in Group 1 (18.75±6.9days versus 20±7.5days in Group 2, p<0.001). rATG induced significant depletion followed by slow reconstitution of CD3+, CD4+ and CD8+ cells, with no marked differences between groups. B-cell count was unaffected, whereas CD3−CD56+ NK-cell depletion was observed in both groups. rATG induced a significant decrease in the proportion of naïve CD4+ T-cells, which plateaued after month 1 in Group 1 and after month 6 in Group 2. The proportion of central memory CD4+ T-cells increased to a similar extent in both groups (Group 1: 38±18% at baseline, 74±23% at one year, p=0.009; Group 2: 32±14% at baseline, 65±14% at one year, p=0.001). In conclusion, our results suggest that the dosing regimen for rATG induction influences pharmacokinetic parameters without affecting the quality of immune reconstitution.

Donor preconditioning with rabbit anti-rat thymocyte immunoglobulin ameliorates ischemia reperfusion injury in rat kidney transplantation

A major concern in transplantation is the preservation of organ function. Ischemia time and microcirculatory disturbance of the organ cannot be avoided and may result in ischemia reperfusion injury (IRI), increasing the risk of delayed graft function (DGF) and acute and chronic rejection. Anti-thymocyte immunoglobulin (rATG) is a polyclonal antibody preparation with multiple effects when administered to recipients. Our objective has been to evaluate whether the administration of rATG to kidney donors instead of recipients, in an experimental model of syngeneic rat transplantation, ameliorates IRI and facilitates immediate graft function recovery. Urea and creatinine levels and necrosis severity scores were significantly lower in kidneys from donors that had received rATG (urea: control: 211±8mg/dl vs. treatment: 110±15mg/dl, p<0.001; creatinine: control: 4.6±0.24mg/dl vs. treatment: 2.6±0.22mg/dl, p<0.001; necrosis severity scores: control: 2.3 vs. treatment: 1.6, p<0.05). TUNEL staining showed 80±13 positive cells in control group and 9±3 (p<0.001) in treatment group. In situ expression of proinflammatory cytokines TNF-α, IL-6, IL-21 and TGF-β1 was reduced in rATG group (p<0.01); the same was observed for KIM-1 and caspase 8 (p<0.001). Cytoprotective genes Bcl2 and HO-1 were upregulated in situ in treatment group (p<0.001). In situ expression of IL-17, caspase 9, IL-23a, CxCl3 and ICAM1 showed no difference between groups (p>0.05). Findings suggest ATG administered to donors may ameliorate the IRI process in kidney transplantation, expressed by lower necrosis and apoptosis scores and the improvement of renal function, which may be explained through the diminished in situ expression of inflammatory mediators.

Rabbit Anti-Thymocyte Globulin (rATG) Administrated Concomitantly with Liver Delivery of AAV2-hFIX Can Promote Inhibitor Formation In Rhesus Macaques.

AbstractAbstract 3765Adeno-associated viral (AAV) vectors are one of the most extensively studied vector platforms for gene therapy applications. Our group is currently developing AAV vectors for the therapeutic treatment of hemophilia B (HB) in humans. The first clinical trial using an AAV2 vector to express human Factor IX (hFIX) (AAV2-hFIX16) from the liver of HB patients revealed a cytotoxic T lymphocyte (CTL) response directed against AAV capsid that occurred 4–6 weeks following treatment that was associated with a decline in transgene expression. Thus, immunosuppressive (IS) therapies may be required during AAV2 vector administration at high doses to prevent or to halt the immune mediated destruction of transduced hepatocytes. Previous work in murine and non-human primate (NHP) models has shown that sustained AAV-mediated expression of transgenes can induce tolerance, and that this is in part, dependent on CD4+ CD25+ FoxP3+ regulatory T cells (Tregs). Here we investigate the safety of a Treg sparing anti-T cell IS regimen in the context of liver mediated AAV2 gene transfer. Rabbit anti-thymocyte globulin (rATG) is an immune suppressive drug that is used in solid organ transplant and autoimmune disease. rATG has been shown to dramatically deplete the majority of T-cells, however some studies have shown that rATG spares Tregs and can induce tolerance in human T cells. rATG was administered to rhesus macaques (along with an 8-week course of Mycophenolate Mofetil (MMF) and sirolimus) either at the time of AAV vector administration (AAV2-hFIX16), or 5 weeks post-vector administration (rescue therapy). The administration of ATG at week 5 had no detrimental effect on hFIX expression and was not associated with inhibitor formation (n=3) indicating that rATG might be safe to use as an IS ‘rescue’ agent, after the detection of an ongoing immune response against transduced cells. Interestingly we observed that early administration of rATG prevented tolerance induction and resulted in inhibitor formation in 2 of 3 animals upon withdrawal of IS. The inhibitor formation was associated with transient elevations in circulating levels of IL-2, IL-4, IL-10 and IFN-g. These results are comparable to previous findings in NHP using an anti-CD25 IS regimen (Daclizumab) at the time of vector administration (Blood 2007, 110(7):2334-41). We conclude that the timing of IS regimens is critical, and that IS regimens that alter the numbers, frequency, and/or function of T-cells at the time of vector administration can result in neutralizing antibodies (inhibitors) to the transgene product (hFIX). These data suggest that there might be multiple mechanisms responsible for maintaining tolerance in this model, and that Tregs alone might not be sufficient. This study highlights the critical need for safety studies in large animal models of potential immune suppressive regimens in the context of gene transfer before translating to the clinic. Disclosures:High:Genzyme, Inc: Consultancy, Patents & Royalties; Third Rock Ventures: Consultancy; Novo-Nordisk: Consultancy; Shire, Inc.: Consultancy.

Analysis of infusion-site reactions in renal transplant recipients receiving peripherally administered rabbit antithymocyte globulin as compared with basiliximab

Antithymocyte globulin rabbit (r-ATG) has been used for the treatment and prevention of acute rejection in renal transplant recipients (RTR). Current manufacturer recommendations for r-ATG dictate the need for administration through a high-flow vein (central line). Previous studies have shown peripheral administration of r-ATG to be safe; however, these studies suggest the co-administration of heparin and hydrocortisone and did not compare the infusion-site reaction rates to a control group. A retrospective analysis was conducted of adult RTR receiving r-ATG or basiliximab between January 2004 and October 2006. Each agent was administered through a dedicated peripheral line. The primary endpoint was the incidence of infusion-site reactions. Other endpoints included the need to replace the intravenous catheter and the incidence of systemic thrombosis within 1 month of transplantation. During the study period, 152 peripheral infusions of r-ATG and 92 peripheral infusions of basiliximab were administered. No difference in infusion-site reactions was noted between the groups. There was also no difference either in the need for peripheral line replacement or the rates of systemic thrombosis. Peripheral administration of r-ATG is safe and can be infused without concomitant heparin and hydrocortisone. This method of r-ATG infusion was shown to be as safe as peripherally administered basiliximab.

Prospective Phase II Study of Pre-Administration of Rabbit Antithymocyte Globulin (rATG, Thymoglobulin ®) to Maximize Early T-Cell Chimerism Following Allogeneic Reduced Intensity Conditioning Transplant (RICT) through Differential in-Vivo Depletion of Recipient Versus Donor T-Cells.

Abstract 3371Poster Board III-259 Background:Failure to achieve high levels of donor T-cell chimerism in the early period after RICT may be associated with eventual graft rejection, disease relapse and poor disease-free survival [Maris et al Blood 102:2021-2030 (2003); Saito et al Biol Blood Marrow Transplant 14:1148-1155 (2008)]. We hypothesized that pre-administration of reduced-dose rATG two weeks prior to stem cell transplant (SCT) would produce selective in-vivo depletion of host but not donor T-cells due to in-vivo decay of active rATG levels. Patients and methods:Twenty-two pts with HLA-identical sibling donors were enrolled on this study. The median age 57 yrs (24-68); F (n=10) M (n=12); NHL (n=9), MDS (n= 7), MPS (n=2), AML (n=2), HD (n=1), MM (n=1). Seven pts had a prior auto transplant. Disease status at transplant was CR (n=8), PR (n=4), HI (n=3), not in remission (n=5), untreated (n=2). CIBMTR risk stratification was high (n=12), intermediate (n=6) and low (n=4). RIC consisted of rATG 1 mg /kg d-16 & 3.5 mg/kg d-15, fludarabine 30 mg/m2/d (d-7 to -3), busulfan 130 mg/m2 IV (d -4, -3), and cylophosphamide 1.5 g/m2 d-2. Mobilized PBSC were infused on d 0. GVHD prophylaxis consisted of tacrolimus and methotrexate. All pts were admitted on d -16,-15 for rATG administration and were then discharged to receive the remaining therapy in the outpatient clinic. Results:Median active rATG levels at day -14, -7, and 0 were 4.4 mcg/mL (1.37-12.2), 1.35 mcg/mL (0.2-2.6), and 0.5 mcg/mL (0-3.2). Fifteen evaluable pts (83%) had a sub therapeutic active ATG level (<1 mcg/mL) on day 0. Of evaluable pts, the median (range) peripheral blood CD 3+ cell chimerism on day 15, 30, 60, 90 & 360 was 93% (75-100%), 95% (75-100%), 100% (87-100%), 100 (88-100%) and 100% (93-100%) respectively. Median CD 33+ cell chimerism was consistently > 95% (range 90-100%) at all time points. Readmission prior to d 100 occurred in 17 pts and was most commonly due to febrile neutropenia (n=7), GI toxicity (n=6) and acute GVHD (n=4). The median length of hospitalization was 5 days (range 1-34 days). Post transplant infections included CMV reactivation (n=5), Adenovirus (n=1), BK virus (n=3), Parainfluenza (n=1), HSV oral (n=1), Candida Parapsilosis (n=1), C.Difficile (n=3), Pseudomonas (n=4) Giardia (n=1), MRSE (n=17), MRSA (n=1) Gram positive organisms (other; n=9) and other bacteria (n=5). Estimated cumulative incidence of treatment related mortality (TRM) at d 100 and 1 year was 0% and 17.9%.The maximum cumulative incidence of aGVHD grade II-III and grade III-IV was 44% and 5% respectively. Chronic GVHD (all stages) developed in 70% of evaluable patients but was extensive severe for only 8%. One patient developed steroid refractory GVHD. Estimated probability of 2 year overall survival & progression-free survival are 59.9% and 39.8%. Cause of death included progression of malignancy (n=2), chronic GVHD (n=1), bacterial infection (n=1), pulmonary failure (n=1). Conclusions:Pre-administration of rATG (on d-16 and -15) with this RIC regimen results in sub-therapeutic serum active rATG levels on d 0 in the majority of patients thus avoiding significant in-vivo donor T-cell depletion. It produces high levels of early and sustained donor T-cell chimerism without an apparent increase in TRM or GVHD. Disclosures:Off Label Use: Anti-thymocyte globulin off label use for stem cell transplant. Bashey:Genzyme: Research Funding.

Modern Approaches to Combining Sirolimus With Calcineurin Inhibitors

Routine renal transplantation maintenance immunosuppression at the University of Nebraska Medical Center consists of rabbit anti-thymocyte globulin (rATG) induction with early steroid withdrawal followed by maintenance with sirolimus and tacrolimus, a regimen we have used with >900 patients. Induction consists of 6 mg/kg rATG in 4 doses of 1.5 mg/kg each on days 0, 2, 4, and 6. Prednisone is used only in association with rATG administration. Maintenance agents are introduced gradually depending on renal function. Since April 2004, we have been conducting a prospective, randomized trial of this regimen versus 2 modifications: administering the rATG induction dose (6 mg/kg) in a single infusion over 24 hours; and, after 6 months, replacing tacrolimus with mycophenolate mofetil (MMF) in half of the study subjects. This study has shown several benefits of single-dose rATG induction, including significantly improved early graft function with both living and deceased donor kidneys and improved 2- to 12-month function in deceased donor organs ( P = .026). Single-dose lymphocyte counts return to baseline sooner (2.2 vs 15.3 years; P < .05) without increased rejection (1 year; 8.5% single vs 12.5% divided; P = NS), and single-dose induction reduces chronic allograft nephropathy at 1 year ( P = .05). Preliminary results of replacing tacrolimus with MMF show immediately improved renal function (months 1 and 2; P = .02 and .05; months 1–6, P = .058) without increased rejection.

A Randomized Trial of Rabbit Anti-Thymocyte Globulin, Given on Day+7 after Alternative Donor Transplants.

Background. We have shown that the risk of transplant mortality (TRM) can be predicted by using laboratory values, on day+7 after an allogeneic hemopoietic stem cell transplant (HSCT) (Sormani et al, Bone Marrow Transpl.2003). TRM in patients with low, intermediate and high risk on day+7, is 15%, 40% and 69%: increased mortality is mainly, but not exclusively, due to increased acute graft versus host disease (GvHD). In a pilot study we have shown that a small dose of rabbit anti-thymocyte globulin (rATG) (Thymoglobulin, Genzyme), was feasible and reduced GvHD and TRM.Aim of the study. We have therefore opened a randomized trial testing this hypothesis in patient undergoing an unrelated donor HSCT, with rATG (7.5 mg/kg) in the conditioning regimen.Patients. 170 were eligible: all patients received rATG 3.75 mg/kg x2 pre-transplant, and on day+7 they were scored and randomized to receive an additional dose of rATG (1,25 mg/kg day +7 and day+9) (n=84) or to receive no further treatment (n=86) (control arm). The two groups were balanced for age, disease phase and day+7 score.Results. The predictive value of day+7 score on TRM was confirmed in the control arm (18% vs 42% for intermediate and high risk patients, p=0.03), whereas in the day+7 ATG arm, there was no difference (29% vs 29%, p=1.0). TRM was overall reduced from 35% in the control arm to 29% in the ATG day+7 arm (p=0.37) : the difference was more pronounced in patients with early disease and high risk on day 7 (35% vs 15% p=0.08). Acute GvHD grade III–IV was reduced overall from 16% to 6% (p=0.04), and chronic GvHD was reduced 32% to 14% (p=0.02). In multivariate COX analysis TRM and overall survival was predicted by risk score day7 and disease phase.Conclusions. We confirm that patients with different risk of TRM can be identified on day+7 after HSCT. Administration of rATG on day+7 can influence the risk of TRM, by reducing acute and chronic GvHD. Additional intensified supportive care (including anti-infectious therapy) may further reduce TRM in patients with a high risk score on day+7.

In Vitro Monitoring of in Vivo Development of Human Anti-Thymoglobulin Antibodies by ELISA

Thymoglobulin (rATG), polyclonal immunoglobulin, is prepared from rabbits immunized with human thymocytes. It is effective in prevention and treatment of renal allograft rejection. Human antibodies against antilymphocyte preparations can reduce efficacy by accelerating drug clearance or by inducing serum sickness. We developed an enzyme-linked immunosorbent assay (ELISA) to study posttreatment development of anti-rATG. In an Institutional Review Board–approved trial, we tested 101 allograft recipients for anti-rATG antibodies. Patients received rATG intravenously at 1.25 to 2.0 mg/kg/d for 2 to 14 days. Serum samples were obtained pretreatment and at weeks 1, 2, 4, 6, and months 3 and 6 post-rATG. ELISA plates were coated with rATG (10 μg/mL). Samples were diluted 1:100 and tested in quadruplicate. Positive samples were titrated. Horseradish peroxidase-conjugated (HRPO) affinity-purified goat anti-human immunoglobulin G (H&L) antibody reacted with bound human antibody. A chromagenic substrate for HRPO was added and optical density (OD, 490 nm) was read. An OD of twice the negative control was considered positive. Mean ODs of negative and positive controls were 0.113 ± 0.030 and 1.042 ± 0.196, respectively. Ten patients had detectable anti-rATG before rATG administration (1:100). Thirty-five of 101 patients (35%) developed anti-rATG antibody. Patients showed an initial positive anti-rATG antibody from days 8 to 59 after infusion and titers from 1:100 to 1:4000. In spite of rATG’s postulated anti-B-cell activity, this study confirms that rATG induces sensitization at a frequency and titer seen with other xenogeneic antilymphocyte antibodies. Formation of such antixenoantibodies can have a negative impact on treatment response and hence warrant monitoring.

Intramuscular administration of RATG in the heart transplant patient

Articles| February 01 1993 Intramuscular administration of RATG in the heart transplant patient A Pedersen; A Pedersen Search for other works by this author on: This Site PubMed Google Scholar JL Groves; JL Groves Search for other works by this author on: This Site PubMed Google Scholar RB Coleman; RB Coleman Search for other works by this author on: This Site PubMed Google Scholar MM Edwards; MM Edwards Search for other works by this author on: This Site PubMed Google Scholar BM Gresov; BM Gresov Search for other works by this author on: This Site PubMed Google Scholar G Shaeffer-McCall; G Shaeffer-McCall Search for other works by this author on: This Site PubMed Google Scholar S Staring S Staring Search for other works by this author on: This Site PubMed Google Scholar Crit Care Nurse (1993) 13 (1): 22–26. https://doi.org/10.4037/ccn1993.13.1.22 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Get Permissions Citation A Pedersen, JL Groves, RB Coleman, MM Edwards, BM Gresov, G Shaeffer-McCall, S Staring; Intramuscular administration of RATG in the heart transplant patient. Crit Care Nurse 1 February 1993; 13 (1): 22–26. doi: https://doi.org/10.4037/ccn1993.13.1.22 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentCritical Care Nurse Search Advanced Search You do not currently have access to this content.