Improved long-term results with thymoglobuline induction therapy after cardiac transplantation: a comparison of two different rabbit-antithymocyte globulines

Impact of varied immunosuppressive agents and posttransplant diabetes mellitus on prognosis among diverse transplant recipients (Experimental studies)

The success of solid organ transplantation (SOT) and the use of immunosuppressive agents offer hope to patients with end-stage diseases. However, the impact of posttransplant diabetes mellitus (PTDM) on SOT patients has become increasingly evident. In our study, we utilized the Scientific Registry of Transplant Recipients (SRTR) database to investigate the association between PTDM and patient survival in various types of organ transplantations, including liver, kidney, intestinal, heart, lung, and combined heart-lung transplantations (all P<0.001). Our findings revealed a negative effect of PTDM on the survival of these patients. Furthermore, we examined the effects of both generic and innovator immunosuppressive agents on the development of PTDM and the overall survival of different SOT populations. Interestingly, the results were inconsistent, indicating that the impact of these agents may vary depending on the specific type of transplantation and patient population. Overall, our study provides a comprehensive and systematic assessment of the effects of different immunosuppressive agents on prognosis, as well as the impact of PTDM on the survival of patients undergoing various types of SOT. These findings emphasize the need for further research and highlight the importance of optimizing immunosuppressive regimens and managing PTDM in SOT patients to improve their long-term outcomes.

Comparison of Thymoglobulin and Grafalon as Induction Agents in Renal Transplantation: A Prospective Study

BACKGROUND

Induction immunosuppression is used to reduce the incidence of acute rejection and prevent delayed graft function. The 2 rabbit anti-thymocyte globulins- thymoglobulin and Grafalon (ATG Fresenius) have been commonly used for induction immunosuppression and treatment of acute rejection in solid organ transplantation. There are very few studies comparing the efficacy and side effects of both the anti-thymocyte globulins therefore this prospective study comparing the 2 types of anti-thymocyte globulins would be of clinical interest.

PATIENTS AND METHODS

This prospective single center study was conducted at Rabindranath Tagore International Institute of Cardiac Sciences, Kolkata, India from April 2019 to June 2020. Sixty-two ABO-compatible renal transplant recipients were included in the study. They were divided in 2 groups of 31 patients each. One group received thymoglobulin (3 mg/kg) and the second group received Grafalon (6 mg/kg). All patients were followed up for 12 months and the 2 groups were compared for incidence of rejections, infections, graft function, patient survival, and graft survival.

RESULTS

There was no significant difference in the incidence of rejections, infective episodes, graft function, posttransplant diabetes mellitus, graft survival and patient survival in thymoglobulin or Grafalon groups. The hematological parameters were similar in both groups at 7 days, 1 month, and 6 months of follow-up. The absolute lymphocyte count was significantly lower in the thymoglobulin group at 12 months posttransplant.

CONCLUSIONS

Thymoglobulin and Grafalon were found to be equivalent in terms of safety and efficacy in short term, with no difference in rejections, infections, graft survival, or patient survival.

Thymoglobulin vs. ATG-Fresenius as Induction Therapy in Kidney Transplantation: A Bayesian Network Meta-Analysis of Randomized Controlled Trials

Background: Thymoglobulin (THG) and antithymocyte globulin-Fresenius (ATG-F) have not been compared directly as induction therapies in kidney transplantation. Materials and Methods: We performed a Bayesian network meta-analysis to compare THG with ATG-F by pooling direct and indirect evidence. Surface under the cumulative ranking curve (SUCRA) values were used to compare the superiority of one method over the other. Results: A total of 27 randomized controlled trials (RCT) were eligible for the network meta-analysis. Efficacy endpoints, as well as safety indicators, were statistically comparable. For efficacy endpoints, THG seemed inferior to ATG-F in preventing delayed graft function [odds ratio (OR): 1.27; SUCRA: 78% vs. 58%], patient deaths (OR: 2.78; SUCRA: 83% vs. 34%), and graft loss (OR: 1.40; SUCRA: 83% vs. 59%), but superior to ATG-F in biopsy-proven acute rejection (BPAR; OR: 0.59; SUCRA: 78% vs. 39%) and steroid-resistant BPAR prevention (OR: 0.61; SUCRA: 76% vs. 49%) within the first year. For safety endpoints, THG was associated with higher risk of infection (OR: 1.49, SUCRA: 79% vs. 54%), cytomegalovirus infection (OR: 1.04; SUCRA: 40% vs. 37%), de novo diabetes (OR: 1.10; SUCRA: 90% vs. 30%), and malignancy (OR: 8.40; SUCRA: 89% vs. 6%) compared to ATG-F. A subgroup analysis of patients at high risk for immunologic complications revealed similar results, but THG performed better for graft loss (OR: 0.82; SUCRA: 68% vs. 54%). Conclusion: ATG-F seemed to be more effective than THG in improving the short-term kidney transplantation outcomes. Prospective head-to-head comparison of THG and ATG-F with larger sample sizes and longer follow-up is still required.

Impact of Rabbit Antithymocyte Globulin Dose on Long-term Outcomes in Heart Transplant Patients

BACKGROUND

Optimal dosing strategies have not been established for rabbit antithymocyte globulin (rATG) after heart transplantation, and there is currently wide variability in rATG regimens with respect to both dose and duration.

METHODS

In a retrospective, single-center analysis, 523 patients undergoing heart transplantation during 1996 to 2009 were stratified by cumulative rATG dose: less than 4.5 mg/kg (group A), 4.5 to 7.5 mg/kg (group B) or greater than 7.5 mg/kg (group C).

RESULTS

Survival at 1 year after transplantation was 80% in group A, 90% in group B, and 88% in group C (P = 0.062). Incidence of acute rejection per 1000 patient-years was significantly higher in group A (hazards ratio [HR], 54.8; 95% confidence interval [95% CI], 33.9-83.8) compared to groups B (19.6; 95% CI, 11.4-31.4) and C (23.6; 95% CI, 17.5-31.3). Incidence of severe infection 10 years after transplantation was higher in group C (45%) than groups A (37%) or B (23%) (P < 0.001); cytomegalovirus infection rates were 35%, 20% and 23%, respectively (P = 0.009). Multivariable Cox regression showed an HR of 0.51 (95% CI, 0.25-1.02) for acute rejection with group B versus group A, and 0.54 (95% CI, 0.33-0.88; P = 0.013) for severe infection. The rate of malignancy per 1000 patient-years was higher in groups B (13.85) and C (14.95) than group A (7.83).

CONCLUSIONS

These retrospective data suggest that a cumulative rATG dose of 4.5 to 7.5 mg/kg may offer a better risk-benefit ratio than lower or higher doses, with acceptable rates of infection and posttransplant malignancy. Prospective trials are needed.

Induction Therapy With Antithymocyte Globulin in Patients Undergoing Cardiac Transplantation Is Associated With Decreased Coronary Plaque Progression as Assessed by Intravascular Ultrasound

BACKGROUND

Antithymocyte globulin (ATG) is used as induction therapy after cardiac transplant for enhancing immunosuppression and delaying the initiation of nephrotoxic drugs. It is unknown if ATG induction is associated with decreased coronary plaque progression by intravascular ultrasound (IVUS).

METHODS AND RESULTS

Patients transplanted between March 2010 and December 2012 with baseline and 1-year IVUS were included. All patients transplanted were included in a secondary analysis. Change in plaque progression was measured in a blinded fashion on matched coronary segments and contrasted between patients induced with ATG and those who were not. One hundred and three patients were included in IVUS arms. Mean age at transplant was 55.8 ± 12.6 years, and 33.0% were female. Patients induced with ATG were more sensitized (54.3% versus 14.3%). Plaque progression was attenuated in patients who received ATG by changes in maximal intimal area (1.0 ± 1.2 versus 2.3 ± 2.6 mm(2); P = 0.001), maximal percent stenosis (6.3 ± 7.9 versus 12.8 ± 12.3%; = 0.003), maximal intimal thickness (0.2 ± 0.2 versus 0.3 ± 0.3 mm; P = 0.035), and plaque volume (0.5 ± 0.7 versus 1.0 ± 1.3 mm(3)/mm; P = 0.016). Rapid plaque progression by maximal percent stenosis (≥ 20%) occurred less frequently in the ATG arm (4.3% versus 26.3; P = 0.003). Survival (P = 0.242) and any treated rejection (P = 0.166) were not statistically different between groups. Patients receiving ATG had a higher rate of first-year infection (P = 0.003), perhaps related to increased intravenous antibiotic use immediately postoperatively, and a trend toward more biopsy-proven rejection (P = 0.073).

CONCLUSIONS

Induction therapy with ATG is associated with reduced first-year coronary plaque progression as assessed by IVUS, despite an increased prevalence of sensitized patients with a trend toward more rejection.

Immunosuppressive T-cell antibody induction for heart transplant recipients

BACKGROUND

Heart transplantation has become a valuable and well-accepted treatment option for end-stage heart failure. Rejection of the transplanted heart by the recipient's body is a risk to the success of the procedure, and life-long immunosuppression is necessary to avoid this. Clear evidence is required to identify the best, safest and most effective immunosuppressive treatment strategy for heart transplant recipients. To date, there is no consensus on the use of immunosuppressive antibodies against T-cells for induction after heart transplantation.

OBJECTIVES

To review the benefits, harms, feasibility and tolerability of immunosuppressive T-cell antibody induction versus placebo, or no antibody induction, or another kind of antibody induction for heart transplant recipients.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 11, 2012), MEDLINE (Ovid) (1946 to November Week 1 2012), EMBASE (Ovid) (1946 to 2012 Week 45), ISI Web of Science (14 November 2012); we also searched two clinical trial registers and checked reference lists in November 2012.

SELECTION CRITERIA

We included all randomised clinical trials (RCTs) assessing immunosuppressive T-cell antibody induction for heart transplant recipients. Within individual trials, we required all participants to receive the same maintenance immunosuppressive therapy.

DATA COLLECTION AND ANALYSIS

Two authors extracted data independently. RevMan analysis was used for statistical analysis of dichotomous data with risk ratio (RR), and of continuous data with mean difference (MD), both with 95% confidence intervals (CI). Methodological components were used to assess risks of systematic errors (bias). Trial sequential analysis was used to assess the risks of random errors (play of chance). We assessed mortality, acute rejection, infection, Cytomegalovirus (CMV) infection, post-transplantation lymphoproliferative disorder, cancer, adverse events, chronic allograft vasculopathy, renal function, hypertension, diabetes mellitus, and hyperlipidaemia.

MAIN RESULTS

In this review, we included 22 RCTs that investigated the use of T-cell antibody induction, with a total of 1427 heart-transplant recipients. All trials were judged to be at a high risk of bias. Five trials, with a total of 606 participants, compared any kind of T-cell antibody induction versus no antibody induction; four trials, with a total of 576 participants, compared interleukin-2 receptor antagonist (IL-2 RA) versus no induction; one trial, with 30 participants, compared monoclonal antibody (other than IL-2 RA) versus no antibody induction; two trials, with a total of 159 participants, compared IL-2 RA versus monoclonal antibody (other than IL-2 RA) induction; four trials, with a total of 185 participants, compared IL-2 RA versus polyclonal antibody induction; seven trials, with a total of 315 participants, compared monoclonal antibody (other than IL-2 RA) versus polyclonal antibody induction; and four trials, with a total of 162 participants, compared polyclonal antibody induction versus another kind, or dose of polyclonal antibodies.No significant differences were found for any of the comparisons for the outcomes of mortality, infection, CMV infection, post-transplantation lymphoproliferative disorder, cancer, adverse events, chronic allograft vasculopathy, renal function, hypertension, diabetes mellitus, or hyperlipidaemia. Acute rejection occurred significantly less frequently when IL-2 RA induction was compared with no induction (93/284 (33%) versus 132/292 (45%); RR 0.73; 95% CI 0.59 to 0.90; I(2) 57%) applying the fixed-effect model. No significant difference was found when the random-effects model was applied (RR 0.73; 95% CI 0.46 to 1.17; I(2) 57%). In addition, acute rejection occurred more often statistically when IL-2 RA induction was compared with polyclonal antibody induction (24/90 (27%) versus 10/95 (11%); RR 2.43; 95% CI 1.01 to 5.86; I(2) 28%). For all of these differences in acute rejection, trial sequential alpha-spending boundaries were not crossed and the required information sizes were not reached when trial sequential analysis was performed, indicating that we cannot exclude random errors.We observed some occasional significant differences in adverse events in some of the comparisons, however definitions of adverse events varied between trials, and numbers of participants and events in these outcomes were too small to allow definitive conclusions to be drawn.

AUTHORS' CONCLUSIONS

This review shows that acute rejection might be reduced by IL-2 RA compared with no induction, and by polyclonal antibody induction compared with IL-2 RA, though trial sequential analyses cannot exclude random errors, and the significance of our observations depended on the statistical model used. Furthermore, this review does not show other clear benefits or harms associated with the use of any kind of T-cell antibody induction compared with no induction, or when one type of T-cell antibody is compared with another type of antibody. The number of trials investigating the use of antibodies against T-cells for induction after heart transplantation is small, and the number of participants and outcomes in these RCTs is limited. Furthermore, the included trials are at a high risk of bias. Hence, more RCTs are needed to assess the benefits and harms of T-cell antibody induction for heart-transplant recipients. Such trials ought to be conducted with low risks of systematic and random error.

A review on comparing two commonly used rabbit anti-thymocyte globulins as induction therapy in solid organ transplantation

INTRODUCTION

Two rabbit anti-thymocyte globulins (ATGs) (Thymoglobulin™ and ATG-Fresenius (ATG-F)™) have been used commonly for induction immunosuppression and treatment of acute rejection in solid organ transplantation. Therefore, literature review on comparative efficacy and side-effect profile of them would be of clinical interest.

AREAS COVERED

This review evaluated all comparative studies in English language, focusing on the solid organ transplant patients who received Thymoglobulin or ATG-F as induction therapy. This review concluded that compared to ATG-F, Thymoglobulin possibly provides better protection against acute rejection and improves patient and graft survival but may result in more cytomegalovirus infection and post-transplant malignancy. Thymoglobulin produced more leukocyte depletion with a greater delay to recover, while ATG-F had more reduction effects on platelet and erythrocyte counts with an increased need to erythropoiesis-stimulating agent.

EXPERT OPINION

The benefits of induction therapy with ATGs must be weighed against the costs and post-transplant complications. It is suggest that there is no substantial clinical difference between these two rabbit ATGs and each may be considered as induction therapy for solid organ transplantation based on availability and drug cost. Of special importance is adding antiviral therapy to the treatment regimen of patients who receive ATGs as induction therapy.

Posttransplantation lymphoproliferative disorder in kidney and heart transplant recipients receiving thymoglobulin: a systematic review

Posttransplantation lymphoproliferative disorder (PTLD) is an important complication of transplantation. Risk factors include increased overall immunosuppression exposure and inadequate antiviral prophylaxis; however, the effects of T-cell-depleting agents on PTLD are unclear. A systematic literature review was conducted to assess PTLD in clinical studies published 1999-2009 in transplant patients with ≥ 3 years follow-up who received Thymoglobulin for induction. Twenty studies were identified (12 kidney, 7 heart, and 1 liver), of which 3 were excluded for insufficient PTLD reporting. The final study group comprised 2,246 kidney and heart transplant recipients (liver study excluded) who received Thymoglobulin. At a median follow-up of 5 years, the incidence of PTLD was 0.98% (kidney, 0.93%; heart, 1.05%) among Thymoglobulin-treated patients. The cumulative Thymoglobulin dose reported in these studies was not associated with the development of PTLD (P = NS). However, incidence of PTLD was significantly lower with antiviral prophylaxis (0.63%) than without (1.87%; P = .013). Heart transplant recipients not receiving antiviral prophylaxis had the highest PTLD incidence, possibly attributable to a greater overall immunosuppressive burden. This analysis revealed that PTLD incidences in kidney and heart transplant recipients receiving Thymoglobulin were low overall and perhaps related more to concomitant anti-viral prophylaxis use.

Rabbit antithymocyte globulin (thymoglobulin): 25 years and new frontiers in solid organ transplantation and haematology

The more than 25 years of clinical experience with rabbit antithymocyte globulin (rATG), specifically Thymoglobulin, has transformed immunosuppression in solid organ transplantation and haematology. The utility of rATG has evolved from the treatment of allograft rejection and graft-versus-host disease to the prevention of various complications that limit the success of solid organ and stem cell transplantation. Today, rATG is being successfully incorporated into novel therapeutic regimens that seek to reduce overall toxicity and improve long-term outcomes. Clinical trials have demonstrated the efficacy and safety of rATG in recipients of various types of solid organ allografts, recipients of allogeneic stem cell transplants who are conditioned with both conventional and nonconventional regimens, and patients with aplastic anaemia. Over time, clinicians have learnt how to better balance the benefits and risks associated with rATG. Advances in the understanding of the multifaceted mechanism of action will guide research into new therapeutic areas and future applications.

In vitro end points for the assessment of cellular immune response-modulating drugs

BACKGROUND

The concept of immunotoxicology and the development of a battery of immune-function assays to screen potential immunotoxic compounds have been increasingly used in the past. Immunotoxic outcome generally seems appropriate to evaluate the risk in drug development. Improving this approach is possible, by using methods now available, to study the effect of a chemical compound on the immune system.

OBJECTIVE

The goal of this review is to provide an overview of the current and recent methodologies for testing the immunological effect and immunotoxic risks in drug candidates.

METHODS

The methodological details here discussed include a synthetic description of the immunocompetent cells in cell-mediated immunity and the choice of the most appropriate assay (bioassays, immunoassays, molecular biology techniques, flow cytometry).

CONCLUSION

This review offers an assessment of in vitro models to study the toxic impact of (bio)pharmaceuticals on cellular immune system and aid drug scientists in understanding the significance and the methods to approach immunotoxicology.

Effect of Induction Therapy on Kinetic of Procalcitonin Following Uncomplicated Heart Transplantation

BACKGROUND

The aim of the study was to determine the early postoperative kinetics of serum procalcitonin (PCT) levels in uncomplicated heart transplant patients under induction therapy using antithymocyte globulin (ATG).

METHODS

PCT serum concentrations were measured for 7 days in 30 adult patients (26 males, 4 females, mean age 54.5 +/- 7.7 years) undergoing uncomplicated orthotopic heart transplantation. Of the 30 patients, 28 received ATG and 2 with the same immunosuppression regimen had no induction therapy. The induction therapy consisted of 100 mg/day ATG and was started 6 hours postoperatively.

RESULTS

Mean PCT levels immediately before HTX were <0.3 ng/mL in both groups. After the first ATG infusion patients developed a significant (p < 0.05) elevation in PCT plasma levels without any incidence of infectious disease with peak levels up to 11.7 +/- 19.7 ng/mL on postoperative day (POD) 1. Thereafter values continuously decreased independently of further ATG administration in all patients (6.7 +/- 10.5 ng/mL on POD 3, 3.2 +/- 7.4 ng/mL on POD 5 and 1.2 +/- 3.0 ng/mL on POD 7). In the non-ATG group a mild postoperative rise in the serum PCT was observed. The values peaked on POD 2 with 2.0 +/- 1.6 ng/mL and normalized within four days.

CONCLUSIONS

Perioperative administration of ATG is associated with significantly increased PCT levels even in uncomplicated heart transplant recipients. This phenomenon should not be misinterpreted as systemic infection, as systemic inflammatory reaction that seems to be induced by ATG therapy is responsible for increased PCT production.

Induction Therapy in Cardiac Transplantation: When and Why?

Induction therapy has continued to be a subject of controversy in heart transplantation for more than 20 years. It is an example of a therapy that is logical, and ought to be better than "doing without." However, a careful review of the evidence suggests otherwise. Except for patients where the benefits clearly outweigh the short and long-term risks, the use of induction therapy should be avoided. In immunosuppression, as in life, there is no "free lunch." Clinicians need to be certain they fully understand what they are ordering when asking for induction therapy to be administered to their patients.

Heart Transplantation Provides Long-Term Survival Benefit in Stable Patients Experiencing Heart Failure Without Reverse Left Ventricular Remodeling

BACKGROUND

Heart transplantation does not provide short-term survival benefit in stable patients experiencing chronic heart failure (CHF) with optimized medical therapy. This study compared the outcome of stable patients with CHF with patients after heart transplantation in the long-term.

METHODS

Between January 1995 and September 1997, 318 potential transplant candidates (New York Heart Association class III or IV, left ventricular ejection fraction [LVEF] <35%) were evaluated. After three months of therapeutic optimization, 108 patients were stable outpatients with maximally uptitrated neurohormonal antagonists. Seventy of the 318 patients underwent transplantation between January 1995 and December 1997.

RESULTS

After an observation period of 7 to 10 years, stable patients with CHF had a significantly lower survival compared with transplanted patients (hazard ratio, 0.90; 95% confidence interval, 0.83-0.98; P=0.01). One-year LVEF (> or =30%) was the best independent predictor of long-term survival. Patients with an LVEF > or =30% had a similar survival; patients with an LVEF <30% had a significantly lower survival (hazard ratio, 0.82; 95% confidence interval, 0.75-0.90; P<0.001) compared with transplanted patients.

CONCLUSION

Not in the short term (1.5 years) but in the long term (7-10 years), heart transplantation seems to provide survival benefit in stable patients with CHF except in patients with improved LVEF (> or =30%) after medical optimization.

Basiliximab Versus Rabbit Anti-thymocyte Globulin for Induction Therapy in Patients After Heart Transplantation

BACKGROUND

The use of basiliximab or rabbit anti-thymocyte globulin (RATG) for induction therapy has significantly reduced the incidence of acute rejection episodes post-transplantation. The purpose of this study was to compare the safety and efficacy of basiliximab vs RATG in a population of adult heart transplant recipients.

METHODS

We retrospective analyzed the safety and efficacy of basiliximab compared with RATG among 48 adult heart transplant recipients at our center. Twenty-five patients received basiliximab (20 mg on days 0 and 4 after heart transplantation), and 23 patients received RATG (1.5 mg/kg for 3 days). A standard triple-drug immunosuppression regimen was administered to all patients.

RESULTS

The average biopsy score (ABS) at 1 month was 0.79 +/- 0.18 in the Basiliximab Group vs 0.47 +/- 0.2 in the RATG group (p = 0.023) and at 3 months was 0.75 +/- 0.24 in the Basiliximab Group vs 0.46 +/- 0.12 in the RATG Group (p = 0.032). At 6 months after transplantation, the difference between groups was not statistically significant (0.97 +/- 0.23 vs 0.58 +/- 0.17, p = .14). At 12 months the ABS was 0.85 +/- 0.4 in the Basiliximab Group vs 0.63 +/- 0.15 in the RATG Group (p = 0.12), and the number of episodes of infection was similar in both groups (19 vs 26; p = 0.16). There was no correlation between cumulative cyclosporine doses and rejection. Creatinine clearance levels were not statistically different between groups at baseline and up to 12 months after heart transplantation. Three patients died in the Basiliximab Group, and 2 patients died in the RATG Group.

CONCLUSIONS

Rabbit anti-thymocyte globulin is more effective than basiliximab for prevention of rejection episodes after heart transplantation. Both induction agents provide similar safety profile.

Comparison of two dosages of thymoglobulin used as a short-course for induction in kidney transplantation

Thymoglobulin is used effectively as an induction agent in kidney transplantation, but the optimal dose is not well established. We evaluated the degree and durability of T-cell clearances with two different thymoglobulin regimens in adult kidney transplant recipients (KTR). Seven KTR received a 3-day thymoglobulin-based induction of 1.0 mg/kg/day while nine received 1.5 mg/kg/day, in addition to maintenance immunosuppression. Lymphocyte subsets were monitored for 6 months. Renal function, infections and malignancies were monitored for 24 months. T-cell subsets were significantly lower by day 30 with the thymoglobulin 1.5 mg/kg/day regimen when compared with the 1.0 mg/kg/day regimen; this trend was sustained at 6-month (CD3(+): 438 +/- 254 vs. 1001 +/- 532 cells/mm(3), P = 0.016). Renal function between the two groups was not significantly different at 6- and 24-months post-transplant. One case of BK Virus viremia in the 1.5 mg/kg/day thymoglobulin group was detected. No acute rejection episodes, cytomegalovirus infections, or malignancies were noted in either group. Thymoglobulin induction was efficacious in both groups, but with a significantly sustained T-cell clearance in the 1.5 mg/kg/day regimen. A more profound T-cell clearance within the first 6 months postinduction therapy may translate into a decreased risk of immunological injury and improved long-term outcome after kidney transplantation.

In vivo visualization of the effect of polyclonal antithymocyte globulins on the microcirculation after ischemia/reperfusion in a primate model

BACKGROUND

Ischemia-reperfusion injury (IRI) leads to increased leukocyte adherence enhancing acute cellular rejection and microvascular dysfunction. Polyclonal antithymocyte globulins (ATGs) induce T-cell depletion and functional impairment of nondepleted lymphocytes in peripheral blood. ATGs represent an important option in the treatment of acute cellular rejection but little is known about their effects on the microcirculation in IRI.

METHODS

In a perfusion system, 19 cynomolgus monkeys were used to evaluate the influence of three different ATGs on the leukocyte-endothelium interaction after cold ischemia. ATGs were administered to human blood 30 min prior to reperfusion of primate extremities. Using intravital fluorescence microscopy the postreperfusion microcirculation of skeletal muscle was visualized.

RESULTS

Significant differences were found between ATG-treated and ATG-free groups concerning blood flow velocity, leukocyte count, and leukocyte-endothelium interaction. ATGs reduced microvascular leukocyte adhesion, count, and blood flow impairment.

CONCLUSION

ATGs have a favorable impact on early mechanisms of IRI. Due to reduced leukocyte adherence to the antigen-presenting endothelial cells, recognition events cannot take place in the posttransplant period of reperfusion. In addition to inhibiting acute transplant rejection, increase of posttransplant blood flow supports the use of ATGs as pretransplant induction therapy.

Incidence and prognosis of cancer following heart transplantation using RATG induction therapy

Cancer limits survival following heart transplantation. The study's objectives were to evaluate the incidence and risk factors for cancers after heart transplantation and to assess the association between i.v. thymoglobuline induction therapy [rabbit antithymocyte immunoglobulin, (RATG)] and neoplasia. From 1982 to 2002, prospective data were gathered for 207 heart transplant recipients. Except from 1982 to 1987, all patients received a 3-day course of i.v. RATG following transplantation. Forty-three malignant neoplasms (21%) were diagnosed. The most common were: skin (42%), lung (12%), prostate (9%), genitourinary (9%) and lymphoma (5%). Mean length of follow-up after transplantation was 99 +/- 57 months. Mean survival after diagnosis was 52 +/- 44 months. Multivariate analysis showed no significant increase in the incidence of cancer with recipient age, sex, number of rejection episodes, the type of immunosuppression or the use of RATG. Patients receiving RATG developed their malignancies significantly earlier after transplantation (P =0.007) and succumbed faster after the diagnosis (P = 0.06). Cancer is a limiting event for long-term survival after heart transplantation. No individual risk factors allow predicting its development. In the present cohort, RATG does not have carcinogenic effects following transplantation, but is associated with a more precocious development of malignancies.

Transplant coronary artery disease: Incidence, progression and interventional revascularization

BACKGROUND

Allograft coronary artery disease (CAD) remains the main factor responsible for late graft loss. This analysis describes data on incidence and progression of allograft CAD at our institute, as well as our experience with coronary interventions in heart transplant recipients.

METHODS

Angiographic results of cardiac transplant patients undergoing coronary angiography were prospectively selected and analyzed. Angiographic outcome at follow-up were assessed for all coronary revascularizations in denovo lesions.

RESULTS

Four hundred thirty-two coronary angiographies were performed in a total of 246 patients. Seventy-six patients (30.9%) showed angiographic evidence of CAD with %DS>50%, of which 48 patients revealed significant stenosis with %DS>70% (19.5%). Within the first 5 years after the transplantation, 10.1% show angiographic signs of a CAD; at the time of 10.1 years, 50% of all heart transplant patients have developed a CAD. Once a CAD with %DS between 50% and 60% has evolved, the disease shows fast progression. Coronary intervention was performed in 28 vessels at an average time of 9.5 years after heart transplantation. Follow-up angiography was available for 27 vessels (1 death before re-angiography) within a mean follow-up period of 19.3 months. Binary restenosis was found in 7 out of 27 vessels (25.9%). Comparison of the occurrence of total occlusion in vessels with %DS>70% which were not revascularized to the occurrence of MACE after successful revascularization revealed better long term results in the group of patients with coronary intervention (p=0.04).

CONCLUSION

Whereas coronary artery disease is found in rare cases within the first 5 years after heart transplantation, the incidence grows in exponential manner after this period. Mid-term follow-up after coronary intervention exhibit restenosis-rates which are similar to the ones of other high risk patients. Comparison of coronary intervention versus conservative treatment in vessels with %DS>70% show significant better mid-term outcome in the interventional group.

Induction Therapy for Pediatric and Adult Heart Transplantation: Comparison Between OKT3 and Daclizumab

BACKGROUND

Induction therapy can reduce morbidity and early mortality in pediatric and adult heart transplant recipients. Monoclonal and polyclonal agents are most widely used; they nonspecifically deplete the T-cell pool and are thus associated with drug-induced side effects. The cytokine release syndrome is one of the most problematic events associated with induction. Daclizumab, a highly humanized, specific interleukin-2 receptor blocker, may be efficacious to the monoclonal agent, OKT3. Due to its specific action and properties, the safety profile of this agent may be superior to OKT3.

METHODS

Forty subjects received daclizumab and their clinical outcomes were compared against a historical group of 40 subjects who received OKT3. Three- and six-month outcome measures included survival, rejection history, steroid burden, and complications.

RESULTS

Mortality was low between the groups with equivalent 6-month survival. No differences in rejection profile or time to the first significant rejection event were detected; no subject had severe acute rejection within the first 180 days. Steroid requirement for maintenance immunosuppression and treatment of rejection was also similar between the groups. Six-month prevalence for complications were significantly different; 55% of OKT3-treated subjects having at least one event compared to 33% of daclizumab-treated subjects (P=0.04). The likelihood of complications occurred within the first month after transplantation.

CONCLUSIONS

Daclizumab induction therapy is as efficacious as OKT3 in the prevention of early acute rejection after heart transplantation among pediatric and adult subjects. Complications related to the induction agent are significantly lower in the humanized product.

Role of Immunosuppressive Regimen on the Incidence and Characteristics of Cytomegalovirus Infection in Heart Transplantation: A Single-Center Experience With Preemptive Therapy

OBJECTIVE

This retrospective single-center report sought to evaluate the relation of immunosuppressive regimen with the incidence and characteristics of cytomegalovirus (CMV) infection from 1999 to 2003.

PATIENTS AND METHODS

Immunosuppression consisted of cyclosporine microemulsion (Neoral), azathioprine (AZA), and prednisolone associated with either thymoglobulin or ATG high-dosage induction from 1999 to 2000 (AZA, 64 patients [AZA-Thymo = 38 patients and AZA-ATG 26 patients]), or cyclosporine microemulsion (Neoral), mycophenolate mofetil (MMF), and prednisolone with low-dose thymoglobulin induction from 2001 onward (n = 52 patients). Ganciclovir preemptive therapy was guided by pp65 antigenemia monitoring without CMV prophylaxis.

RESULTS

The study groups were homogeneous with respect to major perioperative risk factors. Comparing the two AZA subgroups no difference emerged as to percentage of pp65 antigenemia-positive, preemptively treated patients reflecting CMV disease incidence and relapses. AZA-Thymo patient showed significantly shorter time to first positive pp65-antigenemia and higher viral load (AZA-Thymo vs AZA-ATG, P = .004 and P = .009). The two subgroups did not differ with regard to incidence of rejection, superinfection, and graft coronary disease. By shifting from AZA to MMF no difference emerged as to incidence and characteristics of CMV infections, but there was a significant reduction in acute rejection and superinfection (AZA vs MMF P = .001 and P = .008).

CONCLUSIONS

The distinct immunological properties of thymoglobulin versus ATG significantly altered the pattern of CMV expression. MMF with reduced-dose induction did not engender a higher CMV morbidity.

Effectivity of a T-Cell-Adapted Induction Therapy With Anti-Thymocyte Globulin (Sangstat)

BACKGROUND

Cytolytic induction therapy with anti-thymocyte globulin (ATG) should induce effective immunosuppression, with a low rate of rejection in the initial phase after heart transplantation. Induction therapy with ATG allows post-operative renal recovery without the negative effects of highly nephrotoxic cyclosporine levels. An increased rate of infection is a common problem, however, and has been associated with "over-immunosuppression" early after transplantation. Therefore, we investigated whether reduced T-cell-adapted ATG induction therapy could be performed without increasing the risk of graft loss by rejection and whether reductions in infection rates and costs are possible.

METHODS

Between March 1999 and December 2002, T-cell-adapted ATG induction therapy with ATG (Sangstat) (1.5 mg/kg) was given to 62 heart transplant recipients (study group) starting on post-operative Days 1 to 6. T-lymphocyte sub-populations were screened daily using flow cytometry. If total lymphocytes were <100/microl (reference 1,300 to 2,300/microl), T-helper lymphocytes (CD4+) <50/microl (reference >500/microl) and T-suppressor cells (CD8+) <50/microl (reference >300/microl), then no ATG was given. Further immunosuppression was continued with triple therapy consisting of methylprednisolone, azathioprine and cyclosporine. An historic group of heart transplant recipients given a full-dose ATG regimen for 8 days served as controls. These recipients were treated with ATG (Merieux 1.5 mg/kg) until reaching monoclonal cyclosporine levels of >300 mg/dl. Additional immunosuppressive treatment did not differ. Patients in both groups received systemic antibiotics (Imipenem) peri-operatively. Results of routine endomyocardial biopsies and rates of infections were examined.

RESULTS

Study group patients were older (52 +/- 10 vs 49 +/- 14 years). In the study group, mean cumulative ATG dose was reduced significantly to 596 +/- 220 mg (p < 0.05) for 3.9 +/- 1.6 days compared with 1,159 +/- 376 mg for 6.9 +/- 1.1 days in the control group. The rate of cytomegalovirus (CMV) seroconversion was 23% in the study group compared with 13% in the control group. Rate of deep sternal infections was lower in the study group (1.6% vs 3.2%). The mean rejection rate in the first 3 months was 0.4 +/- 0.7 for the study patients (185 biopsies) vs 1.1 +/- 1.7 for controls (237 biopsies). All biopsies with ISHLT Grade >2 were treated successfully with 1,000 mg of methylprednisolone intravenously for 3 days. Both groups showed a similar 1-year survival rate (study 88%, control 89%).

CONCLUSIONS

T-cell-adapted ATG induction therapy can be a helpful tool for individualized immunosuppression. It is not associated with an increased rate of rejection. Lower doses of immunosuppression help to minimize the rates of infection. In addition, cytolytic induction therapy combined with reduced ATG results in significant cost reduction.

Use of cyclosporine in thoracic transplantation

The use of cyclosporine (CyA) in clinical thoracic transplantation has markedly improved the survival and quality of life of patients in the past 2 decades. In the mid-1990s a significant advance in formulation design took place with the introduction of Neoral. This new microemulsion formulation of CyA demonstrates reduced intersubject and intrasubject variability in absorption and improved oral bioavailability compared with the oil-based CyA formulation. Moreover, C2 measurements of CyA could result in an even better method to avoid overimmunosuppression. On the other hand, generic alternatives of CyA could potentially reduce costs to transplant recipients as well as to the general community. Since the initiation of tacrolimus, mycophenolate mofetil, and rapamycin, slow but expanding variations of immunosuppressive protocols have taken place. Transplantation medicine is thus becoming an increasingly exciting and innovative field, in which CyA continues to play a central role as the core immunosuppressant of choice for the majority of patients.

Fludarabine, cyclophosphamide plus thymoglobulin conditioning regimen for unrelated bone marrow transplantation in severe aplastic anemia

Antithymocyte globulin (ATG) has been used in severe aplastic anemia (SAA) as a part of the conditioning regimen. Among the many kinds of ATG preparations, thymoglobulin had been found to be more effective in preventing GVHD and rejection of organ transplants. As the fludarabine-based conditioning regimens without total body irradiation have been reported to be promising for bone marrow transplantation (BMT) from alternative donors in SAA, thymoglobulin was added to fludarabine and cyclophosphamide conditioning to reduce GVHD and to allow good engraftment in unrelated BMT. Five patients underwent BMT with cyclophosphamide (50 mg/kg once daily i.v. on days -9, -8, -7 and -6), fludarabine (30 mg/m2 once daily i.v. on days -5, -4, -3 and -2) and thymoglobulin (2.5 mg/kg once daily i.v. on days -3, -2 and -1) from HLA-matched unrelated donors. Complete donor type hematologic recovery was achieved in all patients. No serious complication occurred during BMT. Only one patient developed grade I acute GVHD resolved spontaneously. Except for one who had rupture of hepatic adenoma 78 days after BMT, all the other four patients are still alive with median 566 days. Fludarabine, cyclophosphamide plus thymoglobulin conditioning allows for the promising results of good engraftment, tolerable toxicity and minimal GVHD.

Midterm results of a prospective randomized comparison of two different rabbit-antithymocyte globulin induction therapies after heart transplantation

This prospective randomized study compared the effects in heart transplant recipients of thymoglobulin and ATG, two rabbit polyclonal antithymocyte antibodies available for induction therapy. Among 40 patients (29 men and 11 women, mean age: 40.7 +/- 14 years) undergoing orthotopic heart transplantation, 20 were randomly allocated to receive induction with thymoglobulin (group A) and 20 to ATG-fresenius (group B). Comparisons between the two groups included early posttransplant (6 months) incidence of acute rejection episodes (grade >/= 1B), bouts of steroid-resistant rejection, time to first rejection, survival, graft atherosclerosis, infections, and malignancies. The study groups displayed similar preoperative and demographic variables. No significant difference was found with regard to actuarial survival (P =.98), freedom from rejection (P =.68), number of early rejections > 1B (P =.67), mean time to first early cardiac rejection (P =.13), number of steroid-resistant rejections (P =.69). Cytomegalovirus reactivations were more frequent among group A (65%) than group B (30%; P =.028). New infections due to cytomegalovirus occurred only in group A (four patients; 20%; P =.05). No cases of malignancies were observed at a mean follow-up of 32.8 +/- 8.9 months. Although thymoglobulin and ATG showed equivalent efficacy for rejection prevention, they have different immunological properties. In particular, thymoglobulin seems to be associated with a significantly higher incidence of cytomegalovirus disease/reactivation.

Relationship between endomyocardial biopsy score and cyclosporine 2-h post-dose levels (C2) in heart transplant patients receiving anti-thymocyte globulin induction

BACKGROUND

Cyclosporine (CsA) 2-h post-dose levels (C(2)) correlate better with the area-under-the-curve compared with trough levels. The purpose of this study was to determine the relationship between C(2) and endomyocardial biopsy (EMB) score in heart transplant patients receiving anti-thymocyte globulin (ATG)-induction.

METHODS

We reviewed 517 EMB performed during the first year in 39 adult heart transplant patients receiving ATG-induction, corticosteroids, mycophenolate mofetil and CsA. C(2) obtained on the day of EMB was related to the International Society for Heart and Lung Transplantation classification (score </=2 or >/=3A). Furthermore, EMB were related to C(2) (ng/mL), sorted according to the lower recommended range in liver (0-3 months: 850; 4-6 months: 700; 7-12 months: 500) or renal transplantation (0-1 month: 1500; 2-3 months: 1200; 4-6 months: 1000; 7-12 months: 800).

RESULTS

Overall, C(2) did not significantly differ in patients with EMB </=2 or >/=3A. However, during the first month, EMB </=2 was associated with a trend towards a higher mean C(2) compared with EMB >/=3A (750 ng/mL vs. 530 ng/mL). When C(2) were sorted according to the lower recommended range in liver or renal transplantation, no significant difference was observed when EMB was </=2 or >/=3A.

CONCLUSIONS

In heart transplant patients receiving ATG-induction, C(2) did not significantly differ according to EMB </=2 or >/=3A. No significant relationship was found between EMB score and C(2) based on the lower recommended range in liver or renal transplantation. However, mean C(2) >750 ng/mL appears to be associated with a lower rejection score during the first month.

Cathepsin-B-dependent apoptosis triggered by antithymocyte globulins: a novel mechanism of T-cell depletion

Antithymocyte globulins (ATGs), the immunoglobulin G (IgG) fraction of sera from rabbits or horses immunized with human thymocytes or T-cell lines, are used in conditioning regimens for bone marrow transplantation, in the treatment of acute graft-versus-host disease, in the prevention or treatment of acute rejection in organ transplantation, and in severe bone marrow aplasia. In nonhuman primates, ATGs induce rapid, dose-dependent, T-cell depletion in peripheral lymphoid tissues, where apoptotic cells can be demonstrated in T-cell zones. We show here that increasing ATG concentrations in vitro resulted in reduced lymphocyte proliferative responses, associated with a rapid increase in the percentage of apoptotic cells. Apoptosis did not require prior exposure to interleukin-2, nor did it result in CD178/CD95 or tumor necrosis factor/tumor necrosis factor receptor (TNF/TNF-R) interactions; it was therefore clearly different from activation-induced cell death. Cytochrome c release, caspase-9, and caspase-3 activation were not implicated, excluding a direct involvement of the intrinsic mitochondrial pathway. The cysteine protease inhibitor E64d and cathepsin-B-specific inhibitors conferred significant protection, whereas apoptosis was associated with the release of active cathepsin B into the cytosol. These data demonstrate a role for cathepsin B in T-cell apoptosis induced by ATGs at concentrations achieved during clinical use.

CD32-mediated platelet aggregation in vitro by anti-thymocyte globulin: implication of therapy-induced in vivo thrombocytopenia

Induction therapy with polyclonal antithymocyte-globulin (ATG) is widely used in the prophylaxis and treatment of acute cardiac-allograft rejection. Thrombocytopenia, however, is a major side-effect of ATG therapy and its mechanisms are poorly understood. The influence of ATG on platelet aggregation was studied aggregometrically, expression of platelet surface activation antigens CD62P and CD63 was determined by flow cytometry analysis, and electron microscopy was utilized to determine thrombocyte morphology. Treatment of platelets with ATG markedly induced aggregation, whereas OKT3 or anti-IL-2R antibodies did not. Furthermore, platelets incubated with ATG featured an up-regulation of the surface activation markers CD62P and CD63, secretion of platelet-bound sCD40L (CD154) and increased signs of aggregation in electron microscopy analysis. The capacity of ATG to induce platelet aggregation was completely blocked by antibodies against the low-affinity Fc IgG receptor (CD32). Since blocking of CD32 abrogates platelet aggregation, we suggest that CD32 plays a crucial role in ATG-induced thrombocytopenia.

Thymoglobuline use in pediatric heart transplantation

The literature has few data regarding the use of polyclonal anti-thymocyte globulin in pediatric cardiac transplantation. We describe our single-center, retrospective study of the use of Thymoglobuline in a pediatric population. We included in the study 31 consecutive heart transplant recipients (mean age, 7.8 years; median age, 9 years; range, 4 months-17 years), who all survived surgery. To induce immunosuppression, all patients received Thymoglobuline therapy at age-dependent doses (1-1.5 mg/kg/day between 0 and 1 year; 1.5-2 mg/kg/day from 1 year to 8 years; and 2.5 mg/kg/day >8 years). Duration of treatment was 1 to 7 days. In patients <1 year, the total number of lymphocytes was maintained at >500/mm(3). Thirty of 31 patients are alive at the end of follow-up. During the first 3 months, 3 Grade 3A and 10 Grade 1A (Working Formulation grading system) rejection episodes occurred. All reversed after steroid treatment. Eleven viral infections, 2 bacterial infections, and 1 fungal infection occurred. Not all patients with infection were symptomatic but all responded successfully to treatment. One episode of post-transplantation lymphoproliferative disease regressed after decreasing immunosuppression therapy and after acyclovir therapy. At the end of follow-up, 19 patients are without steroids. Immunosuppression therapy with Thymoglobuline is safe in the pediatric age group if the number of lymphocytes is monitored strictly.

Impact of cyclosporine 2-h level and mycophenolate mofetil dose on clinical outcomes in de novo heart transplant patients receiving anti-thymocyte globulin induction

BACKGROUND

Cyclosporine (CsA) 2-h post-dose level (C2) correlates better than trough levels (C0) with the area under the curve. We evaluated the clinical impact of C2 and mycophenolate mofetil (MMF) dose in adult heart transplant patients receiving anti-thymocyte globulin (ATG) induction.

METHODS

Two immunosuppressive strategies were sequentially evaluated. In Group 1 (13 patients), simultaneous C0/C2 (ng/mL) were analyzed. CsA dose monitoring was initially based on C0 : <3 months: 200-300, 4-6 months: 150-250, 6-9 months: 100-200, and on C2 thereafter (as in Group 2). In Group 2 (nine patients), C2 monitoring was implemented: <3 months: 600-800, 4-6 months: 500-700, >6 months: 400-600. All patients received ATG induction, corticosteroids, and MMF (1.0 g b.i.d. in Group 1 and 1.5 g b.i.d. in Group 2).

RESULTS

Patients in Group 2 received higher MMF doses during the first trimester. C2 at 1, 3, 6, 12, 24, and 36 months was, respectively, 1199 +/- 476, 1202 +/- 587, 999 +/- 467, 664 +/- 203, 593 +/- 208, and 561 +/- 147 in Group 1, and 809 +/- 160 (p = 0.02), 644 +/- 178 (p = 0.003), 664 +/- 169 (p = 0.02), 616 +/- 221, 464 +/- 234, and 451 +/- 165 in Group 2. The incidence of acute rejection (grade > or =3A) at 6, 12, 24, and 36 months was, respectively, 38.5, 38.5, 46, and 54% in Group 1, and 11, 44, 56, and 56% in Group 2 (p = NS). At 3 months, the creatinine clearance was 25% lower in Group 1. Thereafter, renal function remained stable in both groups.

CONCLUSION

Our results suggest that heart transplant patients receiving ATG induction may experience similar outcomes with either a higher C2 and a lower MMF dose or a lower C2 and a higher MMF dose. These results could be considered to design prospective studies to optimize C2 monitoring, to reduce the incidence of acute rejection without increasing the risk of renal dysfunction.

Functional antibodies to leukocyte adhesion molecules in antithymocyte globulins

BACKGROUND

Polyclonal antithymocyte globulins (ATG) induce T-cell depletion and functional impairment of nondeleted lymphocytes. Interference of ATG with the main leukocyte surface molecules involved in cellular adhesion and leukocyte-endothelium interaction was investigated in the present study.

METHODS

In three rabbit ATG, the authors measured antibodies to integrins, beta2-integrin ligands, and chemokine receptors by flow cytometry; chemotactic responses; and down-modulation of cell surface expression on lymphocytes, monocytes, and neutrophils.

RESULTS

Antibodies to CD11a/CD18 (leukocyte function-associated antigen-1 [LFA-1]) present in ATG induced a dose-dependent down-modulation of cell surface expression of this beta2 integrin on lymphocytes, monocytes, and neutrophils. In contrast, anti-LFA-1 monoclonal antibodies did not induce LFA-1 modulation unless cross-linked by a second antibody. ATG also contained functional antibodies to the beta1 integrin CD49d/CD29 (VLA-4), the alpha4beta7 integrin, CD50, CD54, and CD102 but not to CD62L. ATG were shown to bind to CXCR4 and CCR7 on lymphocytes, CXCR4, and CCR5 on monocytes; to down-modulate cell surface expression of CCR7; and to decrease monocyte chemotactic response to CCL5 (RANTES) and lymphocyte chemotactic response to CCL19 (MIP-3beta).

CONCLUSION

These results show that ATG may interfere with leukocyte responses to chemotactic signals but mostly inhibit the expression of integrins required for firm cellular adhesion. The latter property of inhibition is not shared by monoclonal antibodies, and it may contribute to decreasing graft cellular infiltration during acute rejection and possibly after postischemic reperfusion.

Association between pretransplant Thymoglobulin and reduced non-relapse mortality rate after marrow transplantation from unrelated donors

A matched cohort study was designed to test the efficacy of polyclonal rabbit antiserum specific for human T cells (Thymoglobulin), administered in vivo on days 1-5 (2 mg/kg/day) before T cell-replete unrelated donor marrow transplantation. Thymoglobulin was given to 52 leukemic patients at Huddinge Hospital. Control patients matched for diagnosis, disease stage, age and treated with a similar regimen, apart from the omission of Thymoglobulin, were selected in Seattle during the same period (n = 104). All received conditioning with cyclophosphamide and TBI. In the study group all patients received 10 Gy single dose TBI, while the controls were given 12-14.4 Gy fractionated TBI. GVHD prophylaxis was cyclosporine and methotrexate. Patients were treated for grade I acute GVHD in the study group, and for grade II GVHD in the control group. Multivariable analyses were adjusted for patient and donor age and CMV serology, HLA matching, donor gender and marrow cell dose. Non-relapse mortality was lower in the study patients (hazard ratio = 0.30, 95% CI 0.12-0.75, P value = 0.005). The 5-year cumulative incidence of non-relapse mortality was 19% in the study cohort, and 35% in the control cohort. Overall mortality was also lower in study patients (hazard ratio 0.51, 95% CI 0.27-0.97, P value = 0.03). No significant difference in the risk of relapse was seen (P = 0.63). This suggests that Thymoglobulin during conditioning may reduce non-relapse mortality after unrelated donor marrow transplantation.

Use of antithymocyte globulin for treatment of steroid-refractory acute graft-versus-host disease: an international practice survey

Antithymocyte globulin (ATG) is accepted as a treatment option for steroid-refractory acute graft-versus-host disease (GVHD). We conducted an international survey to determine how steroid refractoriness is defined and how ATG is used in clinical practice. Responses were received from 153 centers in 36 countries. The most common threshold steroid dose to define steroid refractoriness was 2 mg/kg/day (67% of respondents), and the median duration of treatment before failure was declared varied from 3 to 5.5 days, depending on whether failure was defined as 'progressed', 'not improved' or 'not resolved'. The threshold corticosteroid dose was significantly higher in pediatric centers than in adult or combined programs (P = 0.003). ATG was used routinely for treatment of steroid-refractory GVHD by 67% of the respondents. Horse ATG was used more frequently than rabbit ATG overall (50% vs 24%, P < 0.001), and predominance of horse ATG was most evident in the western hemisphere, in small- to medium-sized centers, and in pediatric centers. A wide variety of dose schedules for both drugs was reported. We conclude that there is some degree of variation in the definition of steroid refractoriness, especially between pediatric and nonpediatric programs, and no consensus has emerged in identifying the optimal ATG dose schedule in this setting.