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

Comparison of rabbit ATLG and ATG for GVHD prophylaxis in hematological malignancies with haploidentical hematopoietic stem cell transplantation

Rabbit anti-human T lymphocyte globulin (ATLG) and anti-thymocyte globulin (ATG) are commonly used for graft-versus-host disease (GVHD) prophylaxis in allogeneic hematopoietic stem cell transplantation (HSCT). Yet, their efficacy and safety have seldom been compared in hematological malignancies with haploidentical HSCT. A retrospective analysis with 28 ATLG (total dosage, 20-30 mg/kg) and 18 ATG (total dosage, 8-10 mg/kg) patients were performed. The cumulative incidences of chronic GVHD and relapse were comparable between both groups. ATLG showed a trend towards a lower acute GVHD incidence (28.6% vs. 44.4%, P = 0.242) and 3-year non-relapse mortality (10.7% vs. 27.8%, P = 0.160), and had a significantly higher 3-year overall survival (OS, 64.3% vs. 33.3%, P = 0.033) and GVHD-free and relapse-free survival (GRFS, 32.1% vs. 11.1%, P = 0.045) compared with ATG. Multivariate Cox regression analysis demonstrated ATLG was independently associated with a favorable OS (hazard ratio [HR] = 0.37, 95% confidence interval [CI]: 0.16-0.86, P = 0.020) and GRFS (HR = 0.51, 95%CI: 0.26-1.00, P = 0.051). Furthermore, ATLG had a lower risk of fever (25.0% vs. 61.1%, P = 0.014) and hemorrhage cystitis (7.1% vs. 38.9%, P = 0.008) than ATG-T. In conclusion, ATLG confers more survival benefit and a better safety profile than ATG and can be used in hematological malignancies with haploidentical HSCT. Prospective designed trials with a larger sample size are warranted to confirm the results in the future.

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.

A Proposal for Early Dosing Regimens in Heart Transplant Patients Receiving Thymoglobulin and Calcineurin Inhibition

There is currently no consensus regarding the dose or duration of rabbit antithymocyte globulin (rATG) induction in different types of heart transplant patients, or the timing and intensity of initial calcineurin inhibitor (CNI) therapy in rATG-treated individuals. Based on limited data and personal experience, the authors propose an approach to rATG dosing and initial CNI administration. Usually rATG is initiated immediately after exclusion of primary graft failure, although intraoperative initiation may be appropriate in specific cases. A total rATG dose of 4.5 to 7.5 mg/kg is advisable, tailored within that range according to immunologic risk and adjusted according to immune monitoring. Lower doses (eg, 3.0 mg/kg) of rATG can be used in patients at low immunological risk, or 1.5 to 2.5 mg/kg for patients with infection on mechanical circulatory support. The timing of CNI introduction is dictated by renal recovery, varying between day 3 and day 0 after heart transplantation, and the initial target exposure is influenced by immunological risk and presence of infection. Rabbit antithymocyte globulin and CNI dosing should not overlap except in high-risk cases. There is a clear need for more studies to define the optimal dosing regimens for rATG and early CNI exposure according to risk profile in heart transplantation.

Comparing Two Types of Rabbit ATG prior to Reduced Intensity Conditioning Allogeneic Hematopoietic SCT for Hematologic Malignancies

Different rabbit polyclonal antilymphocyte globulins (ATGs) are used in allogeneic hematopoietic stem cell transplantation (alloHSCT) to prevent graft-versus-host disease (GvHD). We compared 2 different ATGs in alloHSCT after reduced intensity conditioning (RIC) for hematological malignancies. We reviewed 30 alloHSCT for hematologic malignancies performed between 2007 and 2010 with fludarabine and i.v. busulfan as conditioning regimen. Patients alternatingly received Thymoglobulin or ATG-F. Median followup was 3.3 (2.5-4.5) years. Adverse events appeared to occur more frequently during Thymoglobulin infusion than during ATG-F infusion but without statistical significance (P = 0.14). There were also no differences in 3-year overall survival (OS), disease-free survival (DFS), relapse incidence, and transplant related mortality (TRM) in the Thymoglobulin versus ATG-F group: 45.7% versus 46.7%, 40% versus 33.7%, 40% versus 33.3%, and 20% versus 33.3%. The same held for graft failure, rejection, infectious complications, immune reconstitution, and acute or chronic GvHD. In patients transplanted for hematologic malignancies after RIC, the use of Thymoglobulin is comparable to that of ATG-F in all the aspects evaluated in the study. However due to the small number of patients in each group we cannot exclude a possible difference that may exist.

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.

Early graft failure after heart transplant: risk factors and implications for improved donor-recipient matching

Early graft failure (EGF) is a dreaded complication after heart transplantation (HT). Despite several improvements, no effective therapy has been developed and the prognosis is poor. We evaluated the risk factors and clinical impact of EGF. In a consecutive series of 317 HTs performed at a single institution between January 1999 and December 2008, variables associated significantly with EGF were sought in bivariate and multivariable discriminant analyses. The deriving propensity score was used to stratify the study sample in to three groups (low, intermediate and high risk for EGF). Comparisons were performed between the higher-risk group and the remaining population in terms of preoperative features and outcomes. EGF occurred in 10.1% of the overall population (2.9, 3.8 and 23.6%, respectively, in the three groups). Overall, EGF-related mortality was 56.3% (100, 75 and 48%, respectively, in the three groups). Determinants of EGF in the highest-risk group were: redo procedure, valvular cardiomyopathy, status one at transplant, recipient male sex, donor-recipient (D/R) weight mismatch, high inotropic donor support, ischaemic time and first day troponin I release. In conclusion, several donor and recipient features predicted EGF. Since such characteristics are not readily modifiable but synergistically determine the occurrence of EGF, optimization of D/R matching is crucial to prevent it.

Report from a consensus conference on antibody-mediated rejection in heart transplantation

BACKGROUND

The problem of AMR remains unsolved because standardized schemes for diagnosis and treatment remains contentious. Therefore, a consensus conference was organized to discuss the current status of antibody-mediated rejection (AMR) in heart transplantation.

METHODS

The conference included 83 participants (transplant cardiologists, surgeons, immunologists and pathologists) representing 67 heart transplant centers from North America, Europe, and Asia who all participated in smaller break-out sessions to discuss the various topics of AMR and attempt to achieve consensus.

RESULTS

A tentative pathology diagnosis of AMR was established, however, the pathologist felt that further discussion was needed prior to a formal recommendation for AMR diagnosis. One of the most important outcomes of this conference was that a clinical definition for AMR (cardiac dysfunction and/or circulating donor-specific antibody) was no longer believed to be required due to recent publications demonstrating that asymptomatic (no cardiac dysfunction) biopsy-proven AMR is associated with subsequent greater mortality and greater development of cardiac allograft vasculopathy. It was also noted that donor-specific antibody is not always detected during AMR episodes as the antibody may be adhered to the donor heart. Finally, recommendations were made for the timing for specific staining of endomyocardial biopsy specimens and the frequency by which circulating antibodies should be assessed. Recommendations for management and future clinical trials were also provided.

CONCLUSIONS

The AMR Consensus Conference brought together clinicians, pathologists and immunologists to further the understanding of AMR. Progress was made toward a pathology AMR grading scale and consensus was accomplished regarding several clinical issues.

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.

Choice of antibody immunotherapy influences cytomegalovirus viremia in simultaneous pancreas-kidney transplant recipients

OBJECTIVE

Simultaneous pancreas-kidney (SPK) transplantation in type 1 diabetic patients requires immunotherapy against allo- and autoreactive T-cells. Cytomegalovirus (CMV) infection is a major cause for morbidity after transplantation and is possibly related to recurrent autoimmunity. In this study, we assessed the pattern of CMV viremia in SPK transplant recipients receiving either antithymocyte globulin (ATG) or anti-CD25 (daclizumab) immunosuppressive induction therapy.

RESEARCH DESIGN AND METHODS

We evaluated 36 SPK transplant recipients from a randomized cohort that received either ATG or daclizumab as induction therapy. Patients at risk for CMV infection received oral prophylactic ganciclovir therapy. The CMV DNA level in plasma was measured for at least 180 days using a quantitative real-time PCR. Recipient peripheral blood mononuclear cells were cross-sectionally HLA tetramer-stained for CMV-specific CD8(+) T-cells.

RESULTS

Positive CMV serostatus in donors was correlated with a higher incidence of CMV viremia than negative serostatus. In patients at risk, daclizumab induction therapy significantly prolonged CMV-free survival. CMV viremia occurred earlier and was more severe in patients with rejection episodes than in patients without rejection episodes. CMV-specific CD8(+) T-cell counts were significantly lower in patients developing CMV viremia than in those who did not.

CONCLUSIONS

Despite their comparable immunosuppressive potential, daclizumab is safer than ATG regarding CMV infection risk in SPK transplantation. ATG-treated rejection episodes are associated with earlier and more severe infection. Furthermore, high CMV-specific tetramer counts reflect antiviral immunity rather than concurrent viremia because they imply low viremic activity. These findings may prove valuable in the discussion on both safety of induction therapy and recurrent autoimmunity in SPK and islet transplantation.

Incidence of cancer after immunosuppressive treatment for heart transplantation

Prolonged or intensive immunosuppressive therapy used after organ transplantation is complicated by an increased incidence of cancer. Striking differences in incidence are observed in heart and heart-lung transplant recipients when compared with renal transplant patients. The most significant increase was in the incidence of lymphomas in cardiac versus renal patients. Moreover, a two-fold greater increase of all neoplasms was found in cardiac recipients, with nearly a six-fold increase in visceral tumors. Several factors may account for these differences. In cardiac allograft recipients, intensive immunosuppression is frequently used to reverse acute rejection and the highest number of cardiac transplants was performed in the era of polypharmacy, usually consisting of triple therapy.

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.