A 10-year experience with intravenous thymoglobuline in induction of immunosuppression following heart transplantation

Rabbit Antithymocyte Globulin Induction in Heart Transplant Recipients at High Risk for Rejection

Background: Induction with lymphocyte-depleting antibodies may improve allograft outcomes in heart transplant recipients who are at high immunologic risk for rejection.

Methods: We conducted a single-center retrospective cohort study that compared outcomes between adult patients receiving rabbit antithymocyte globulin (rATG) induction vs no induction from 2011 through 2017. Key exclusion criteria were patients who did not receive tacrolimus and mycophenolate and patients who did not meet high immunologic risk criteria.

Results: A total of 50 patients were included in the analysis. At 1 year, the composite primary outcome of ≥2R rejection as defined by the International Society for Heart and Lung Transplantation, any treated rejection, development of cardiac allograft vasculopathy, or graft loss was not different between groups (P=0.474). Serious infections were also similar between groups (P=0.963). In accordance with institutional guidelines, prednisone exposure was decreased in the rATG induction group at 1 month (24.04 mg ± 13.74 vs 35.18 mg ± 16.95; P=0.014).

Conclusion: These results suggest that while rATG induction does not improve heart allograft outcomes, it may enable reducing early corticosteroid exposure in patients at high immunologic risk.

Cell Therapy in Solid Organ Transplantation

Transplantation is the only cure for end-stage organ failure. Current immunosuppressive drugs have two major limitations: 1) non antigen specificity, which increases the risk of cancer and infection diseases, and 2) chronic toxicity. Cell therapy appears to be an innovative and promising strategy to minimize the use of immunosuppression in transplantation and to improve long-term graft survival. Preclinical studies have shown efficacy and safety of using various suppressor cells, such as regulatory T cells, regulatory B cells and tolerogenic dendritic cells. Recent clinical trials using cellbased therapies in solid organ transplantation also hold out the promise of improving efficacy. In this review, we will briefly go over the rejection process, current immunosuppressive drugs, and the potential therapeutic use of regulatory cells in transplantation.

Outcomes of Induction Therapy with Rabbit Anti-Thymocyte Globulin in Heart Transplant Recipients: A Single Center Retrospective Cohort Study

Background

Induction immunosuppression is used in transplantation to prevent early acute rejection. The survival benefit of rabbit anti-thymocyte globulin (rATG) induction has not been established yet. We sought to determine the role of rATG in preventing rejection and improving overall survival.

Material/Methods

A retrospective cohort study was conducted from 2005 to 2009 and data of consecutive 268 heart transplant recipients were reviewed.

Results

The data of 144 patients who received induction with rATG were compared to 124 patients who did not. Although overall survival was not different between the 2 groups (P=0.12), there was a significant difference in restricted mean survival time (RMST) at 5 years (RMST=4.8 months; 95% CI: 1.0–8.6, P=0.01) and 10 years (RMST=10.4 months; 95% CI: 1.6–19.3, P=0.02) in favor of the non-induced patients. No difference was observed between induced and non-induced patients who developed de novo donor specific antibodies. There was a significant difference in median days to first rejection in favor of the induced group (P<0.001).

Conclusions

Induction with rATG adds no survival benefit in heart transplant recipients. Patients who did not receive induction therapy had higher life expectancy at 5 years and 10 years. Although there was significant delay in the first rejection episode in favor of the rATG induced group, no difference was observed in donor specific antibodies. This study indicates a need for separate analysis of peri-transplantation co-morbidities and mainly the incidence of acute kidney injury, which could affect long-term survival.

Use of Anti-Thymocyte Globulin for Induction Therapy in Cardiac Transplantation: A Review

The most common causes of death after heart transplantation (HTx) include acute rejection and multi-organ failure in the early period and malignancy and cardiac allograft vasculopathy (CAV) in the late period. Polyclonal antibody preparations such as rabbit anti-thymocyte globulin (ATG) may reduce early acute rejection and the later occurrence of CAV after HTx. ATG therapy depletes T cells, modulates adhesion and cell-signaling molecules, interferes with dendritic cell function, and induces B-cell apoptosis and regulatory and natural killer T-cell expansion. Evidence from animal studies and from retrospective clinical studies in humans indicates that ATG can be used to delay calcineurin inhibitor (CNI) exposure after HTx, thus benefiting renal function, and to reduce the incidence of CAV and ischemia-reperfusion injury in the transplanted heart. ATG may reduce de novo antibody production after HTx. ATG does not appear to increase cytomegalovirus infection rates with longer prophylaxis (6-12 months). In addition, ATG may reduce the risk of lymphoproliferative disease and does not appear to confer an additive effect on acquiring lymphoma after HTx. Randomized, controlled trials may provide stronger evidence of ATG association with patient survival, graft rejection, renal protection through delayed CNI initiation, as well as other benefits. It can also help establish optimal dosing and patient criteria to maximize treatment benefits.

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.

New directions for rabbit antithymocyte globulin (Thymoglobulin(®)) in solid organ transplants, stem cell transplants and autoimmunity

In the 30 years since the rabbit antithymocyte globulin (rATG) Thymoglobulin^® was first licensed, its use in solid organ transplantation and hematology has expanded progressively. Although the evidence base is incomplete, specific roles for rATG in organ transplant recipients using contemporary dosing strategies are now relatively well-identified. The addition of rATG induction to a standard triple or dual regimen reduces acute cellular rejection, and possibly humoral rejection. It is an appropriate first choice in patients with moderate or high immunological risk, and may be used in low-risk patients receiving a calcineurin inhibitor (CNI)-sparing regimen from time of transplant, or if early steroid withdrawal is planned. Kidney transplant patients at risk of delayed graft function may also benefit from the use of rATG to facilitate delayed CNI introduction. In hematopoietic stem cell transplantation, rATG has become an important component of conventional myeloablative conditioning regimens, following demonstration of reduced acute and chronic graft-versus-host disease. More recently, a role for rATG has also been established in reduced-intensity conditioning regimens. In autoimmunity, rATG contributes to the treatment of severe aplastic anemia, and has been incorporated in autograft projects for the management of conditions such as multiple sclerosis, Crohn’s disease, and systemic sclerosis. Finally, research is underway for the induction of tolerance exploiting the ability of rATG to induce immunosuppresive cells such as regulatory T-cells. Despite its long history, rATG remains a key component of the immunosuppressive armamentarium, and its complex immunological properties indicate that its use will expand to a wider range of disease conditions in the future.

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.

Influence of polyclonal antithymocyte globulins on the expression of adhesion molecules of isolated human umbilical vein endothelial cells

OBJECTIVES

Polyclonal antithymocyte globulins (ATGs) are immunosuppressive agents applied for the treatment and prevention of organ rejection after transplantation. ATGs induce complement-mediated cell death in T lymphocytes and decrease leukocyte adhesion. However, little is known about the effects of ATGs on endothelial cells (EC). Our aim was to study the influence of ATGs upon the expression of adhesion molecules on human umbilical vein endothelial cells (HUVECs) after stimulation with tumor necrosis factor (TNF)-alpha.

MATERIAL AND METHODS

HUVECs obtained from umbilical cords were incubated with ATGs before and after 6-hour stimulation with TNF-alpha. The group incubated without ATG served as the controls. Another group was not stimulated with TNF-alpha. By flow cytometry, we analyzed the expression of several adhesion molecules: intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM), platelet EC adhesion molecule (PECAM), and CD62E. Statistical analysis used analysis of variance.

RESULTS

After TNF-alpha stimulation, the EC surface expression of ICAM-1 and CD62E was reduced, although not significantly, in treated as compared with untreated cells. The expression of ICAM-1 and CD62E was similar in the unstimulated groups. The expression of VCAM, PECAM, CD55, and CD58 was not modified by ATG treatment.

CONCLUSION

Our results demonstrated that ATGs insignificantly reduced the expression of adhesion molecules in HUVECs. The effect of ATGs on stimulated HUVECs remains unclear, probably due to the lack of effector cells.

Impact of polyclonal anti-thymocyte globulins on the expression of adhesion and inflammation molecules after ischemia-reperfusion injury

BACKGROUND

Polyclonal anti-thymocyte globulins (ATGs) are immunosuppressive agents used for the treatment and prevention of acute organ rejection after transplantation. ATGs induce apoptosis and complement-mediated cell death in peripheral T-lymphocytes and have shown a reduction of leukocyte adhesion after ischemia-reperfusion (IRI). We analyzed the impact of different ATGs upon the expression of adhesion and inflammation molecules after IRI.

MATERIALS AND METHODS

The major arteries and veins of the extremities of cynomolgus monkeys were surgically isolated and flushed with Ringer's lactate at 4 degrees C. After 60 min of ischemia the limbs were reperfused with matching human blood. ATGs were added to the blood 30 min prior to the reperfusion, forming four groups: Tecelac-ATG group (n=16), Fresenius(S)-ATG group (n=16), Thymoglobulin-ATG group (n=12) and a control group (n=16). Biopsies from muscular tissue were obtained after the experiments. The expression of adhesion (ICAM-1, VCAM, PECAM, CD11b, CD62E) and inflammation (IL-1, IL-6, TNF-alpha) molecules on endothelium, leukocytes, and reperfused tissue was analyzed by means of immunohistochemistry.

RESULTS

The expression of the studied adhesion molecules (ICAM-1, VCAM, PECAM, CD11b, and CD62E) was significantly increased in the control group when compared with the treated groups. The expression of IL-1, IL-6, and TNF-alpha was reduced in the ATG-groups in comparison to the control group.

DISCUSSION

Our results showed that ATGs caused a reduction of the expression of adhesion and inflammation molecules both in endothelium and reperfused tissue. The inhibition of the expression of molecules required for firm cellular adhesion, may contribute to decreasing cellular graft infiltration after post-ischemic reperfusion.

The changing face of heart transplantation

It has been 40 years since the first human-to-human heart transplant performed in South Africa by Christiaan Barnard in December 1967. This achievement did not come as a surprise to the medical community but was the result of many years of early pioneering experimental work by Alexis Carrel, Frank Mann, Norman Shumway, and Richard Lower. Since then, refinement of donor and recipient selection methods, better donor heart management, and advances in immunosuppression have significantly improved survival. In this article, we hope to give a perspective on the changing face of heart transplantation. Topics that will be covered in this review include the changing patient population as well as recent advances in transplantation immunology, organ preservation, allograft vasculopathy, and immune tolerance.

Basiliximab and Rabbit Anti-thymocyte Globulin for Prophylaxis of Acute Rejection After Heart Transplantation: A Non-inferiority Trial

BACKGROUND

Induction of immunosuppression with antibodies after heart transplantation decreases early acute rejection rate compared with placebo. We tested the non-inferiority of basiliximab vs rabbit anti-thymocyte globulin (RATG) on the incidence of acute rejection 6 months after transplantation.

METHODS

From July 2002 to April 2004, 35 patients were enrolled in a multicenter, parallel group, open-label, non-inferiority trial. Patients were randomized to receive induction treatment with basiliximab (20 mg on Day 0 and 4) or RATG (125 mg on Day 0, 1, and 2). Standard maintenance therapy with cyclosporine, mycophenolate mofetil, and prednisone was used.

RESULTS

Seventeen patients (aged 54 +/- 9 years old) received basiliximab, and 18 patients (aged 54 +/- 12 years old) received RATG. The freedom rate of rejection at 6 months (grade 3A or more) averaged 65% (11/17) with basiliximab and 83% (15/18) with RATG. The upper limit of the 1-sided 90% confidence interval for the difference RATG-basiliximab was 37.2%, exceeding the 22.5% non-inferiority margin. CD3 and CD4 levels were higher (p < 0.0001 for both), whereas CD25/CD4 and CD25/CD8 levels were lower (p < 0.0001 and p = 0.0462, respectively) in patients treated with basiliximab. One of the 14 basiliximab patients showed detectable cytomegalovirus viral load during the first 3 months after transplantation, whereas cytomegalovirus was detected by quantitative polymerase chain reaction in the plasma of 5 of the 13 RATG patients (p = 0.0505).

CONCLUSION

Non-inferiority of basiliximab treatment for prophylaxis of acute rejection after heart transplantation could not be shown. RATG administration is associated with a higher rate of asymptomatic cytomegalovirus viral load detection in the plasma.

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.

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.

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.

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.

Induction therapy after cardiac transplantation: A comparison of anti-thymocyte globulin and daclizumab in the prevention of acute rejection

BACKGROUND

Induction therapy with antibodies decreases and delays early allograft rejection. We compared the safety and efficacy of daclizumab and anti-thymocyte globulin (ATG) with respect to the frequency and severity of acute cardiac allograft rejection in heart transplant recipients.

METHODS

Forty sequential adult patients were retrospectively studied. In the first 20 patients ATG (2.5 mg/kg daily for 3 to 5 days peri-/and post-operatively) was used as induction therapy and, in the remaining 20 patients, daclizumab (1 mg/kg peri-operatively and every 2 weeks thereafter for a total of 5 doses) was used. A standard triple-drug immunosuppression regimen was administered to all patients.

RESULTS

Baseline characteristics and trough levels of cyclosporine in the 2 groups were similar. During the induction period, defined as the first 3 months, 12 acute rejection episodes requiring treatment (ISHLT Grade > or =2) occurred in the ATG group and 9 in the daclizumab group (p > 0.05). However, the number of biopsies with Grade 1 rejection was increased >2-fold in the daclizumab group (n = 35) compared with the ATG group (n = 17; p = 0.04). The total number of biopsies performed within the first 3 months increased by 26% in the daclizumab group. The number and severity of rejection episodes after 3 months was similar in the 2 groups. The overall occurrence of bacterial infections was significantly higher in the ATG group than in the daclizumab group (p = 0.05).

CONCLUSIONS

ATG and daclizumab are equally effective in preventing acute rejections requiring treatment (ISHLT Grade > or =2). Due to the significantly greater frequency of Grade 1 rejections, daclizumab was found to be associated with an increased number of additional biopsies for monitoring rejection status. This implies additional costs to the transplant program, and the long-term implications of the increased number of low-grade rejection episodes remains to be determined.

Use of basiliximab and cyclosporine in heart transplant patients with pre-operative renal dysfunction

BACKGROUND

The combined use of basiliximab and cyclosporine in heart transplantation is under investigation. In this study we sought to evaluate the safety and efficacy of basiliximab and delayed initiation of cyclosporine in patients with renal dysfunction undergoing heart transplantation.

METHODS

Seven patients (Group A) with renal dysfunction (creatinine > or =200 micromol/liter) received induction therapy with basiliximab. Seven patients (Group B) with renal dysfunction comprised the control group and received induction therapy with rabbit anti-thymocyte serum. Cyclosporine was initiated 5 days post-transplant in Group A and within 5 days post-transplant in Group B.

RESULTS

All patients were alive at the end of the 6-month follow-up. In Group A, mean pre-transplant creatinine was 243 +/- 48 micromol/liter, at 1 week post-transplant was 180 +/- 39 micromol/liter (p = 0.02), at 1 month was 166 +/- 57 micromol/liter (p = 0.019), at 3 months was 182 +/- 25 micromol/liter (p = 0.01) and at 6 months was 179 +/- 45 micromol/liter (p = 0.024). In Group B, mean pre-transplant creatinine was 242 +/- 41 micromol/liter, at 1 week was 140 +/- 35 micromol/liter (p = 0.0003), at 1 month was 143 +/- 38 mumol/liter (p = 0.0005), at 3 months was 138 +/- 37 micromol/liter (p = 0.0003) and at 6 months was 154 +/- 30 micromol/liter (p = 0.0006). There were no differences in renal dysfunction between both groups at 1 week (p = 0.069), 1 month (p = 0.39) or 6 months (p = 0.24) post-HT. Fewer episodes of cellular rejection were identified in Group B within the 6-month follow-up period.

CONCLUSIONS

The use of induction therapy either with basiliximab or rabbit anti-thymocyte serum in patients with pre-operative renal dysfunction confers renal protection early and up to 6 months post-transplant. Delayed initiation of cyclosporine might be considered to provide additional renal protection.

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.

The promise of C2, simulect, and certican in heart transplantation

Immunosuppressive therapy in clinical transplantation has evolved from general nonspecific suppression of the immune system to selective blockade of intracellular immune events, maximizing graft tolerance while minimizing toxicity. Cyclosporine 2-hour postdose level monitoring has been recommended as the single most sensitive sampling point for assessment of the area under the curve, and predictor of clinical outcomes in heart transplantation. Strategies for monitoring immunosuppressive drugs to improve efficacy without increased toxicity are critical as we move into the 21st century. Everolimus, a derivative of rapamycin, is a macrocyclic immunosuppressive agent with antiproliferative activity that is efficacious in preventing graft vasculopathy. Agents that increase the armamentarium against rejection allowing individualized therapy tailored to minimize complications, and prevent graft vasculopathy will improve our flexibility and may translate into improved long-term outcomes.

Bacterial mediastinitis after heart transplantation: clinical presentation, risk factors and treatment

BACKGROUND

The incidence of mediastinitis after heart transplantation has been reported to be between 2.5% and 7.5%. Most previous reports from the transplant literature have assessed patients who had not received induction therapy.

METHODS

From December 1996 to January 2002, a total of 230 heart transplants were performed using induction therapy with rabbit anti-thymocyte globulin at La Pitié Salpêtrière Hospital (Paris, France). Mediastinitis developed in 15 patients (6.5%). A case-control study was performed to characterize the clinical presentation, microbiology, risk factors and therapy of mediastinitis after heart transplantation.

RESULTS

Only 4 patients (26%) had a temperature of >38 degrees C and 6 patients (40%) had a white blood cell count of >10,000 cells/mm(3). Septicemia (46%) and positive temporary epicardial pacing wires culture (60%) were frequently observed. Staphylococcus aureus (5 of 15), Staphylococcus epidermidis (5 of 15) and gram-negative bacteria (5 of 15) were the causative organisms cultured intra-operatively. Mean duration of mechanical ventilation (2.4 vs 1.6 days; p < 0.03) and use of ventricular assistance (20% vs 0%; p < 0.04) were different between cases and controls. The mortality rate at hospital discharge was 6.7% (1 of 15).

CONCLUSIONS

In the context of immunosuppression after heart transplantation, a high degree of suspicion is necessary to make the diagnosis of mediastinitis. Positive blood and temporary epicardial pacing wires cultures can be helpful in suggesting the presence of mediastinitis. Using vancomycin and an aminoglycoside as prophylaxis has to be considered because of the high prevalence of methilcilin-resistant S epidermidis and gram-negative bacteria. Conservative therapy (sternal debridement without muscle flap closure, and closed-chest drainage) showed excellent results in this series.

Calcineurin inhibitor-associated early renal insufficiency in cardiac transplant recipients: risk factors and strategies for prevention and treatment

Cardiac transplantation is the definitive treatment for eligible patients with end-stage cardiac failure. Techniques have evolved to reduce surgical mortality to under 5%. Immediate and subsequent long-term survival is more dependent on acute and chronic rejection and the complications of immunosuppressive therapy. Ten-year survival is greater than 50%.The success of transplantation over the last 20 years has been largely due to the advances in immunosuppression. The most notable and dramatic milestone was the introduction of cyclosporine in the early 1980s, which resulted in a significant improvement in allograft and patient survival. Cyclosporine is a peptide that inhibits the immune system by suppressing T-helper cell activation via inhibition of calcineurin, a critical intracellular enzyme. Tacrolimus has a similar (but not identical) mechanism of action, and was introduced in the 1990s. Drugs such as cyclosporine and tacrolimus, generically referred to as calcineurin inhibitors, have become the cornerstones of immunosuppressive protocols. As a group, calcineurin inhibitors have adverse effects, including neurotoxicity, hypertension, and nephrotoxicity, which complicate their use. Early renal insufficiency manifests as postoperative oliguria (<50 mL/h urine output) or rising serum creatinine levels. There are a variety of postulated causes for calcineurin inhibitor-associated early renal insufficiency including direct calcineurin inhibitor-mediated renal arteriolar vasoconstriction, increased levels of endothelin-1 (a potent vasoconstrictor), as well as decreased nitric oxide production and alterations in the kidney's ability to adjust to changes in serum tonicity. Once early renal insufficiency occurs, no single treatment has been shown to be effective. Approaches discussed in this paper include reduction in calcineurin inhibitor dosages, as well as various drugs to promote increased renal perfusion such as misoprostol and dopamine. In addition, the paper emphasizes the importance of ruling out other causes of renal insufficiency in the early postoperative period, including volume depletion, depressed cardiac output, and mechanical obstruction to urine flow. Given that there is no highly efficacious treatment for this syndrome, ways to avoid its occurrence are desirable. One paper is referenced that suggests that avoidance of rapid changes in tacrolimus level during the first three days of therapy is associated with a low occurrence of early renal insufficiency.

Drug immunosuppression therapy for adult heart transplantation. Part 2: clinical applications and results

This review describes the clinical application of classical immunosuppressive drugs as well as that of more recent drugs. All current immunosuppressive drugs target T-cell activation, and cytokine production and clonal expansion, or both. Immunosuppressive protocols can be broadly divided into induction therapy, maintenance immunosuppression, and treatment of acute rejection episodes.

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.

Rabbit antithymocyte globulin as induction immunotherapy in pediatric heart transplantation

BACKGROUND

There is little published data on the use of antithymocyte globulins in children. This retrospective study describes the use of Thymoglobulin (Imtix, SangStat, Lyon, France) in pediatric cardiac transplantation over a 13-year period in a single center that adjusted the dose of Thymoglobulin according to platelet count monitoring and examines the short-term hematological effects as well as longer-term outcomes.

METHODS

Data for all children who received a heart transplant at the Hôpital Cardiologique at Lyon from 1984 to 2001 and who were given Thymoglobulin as part of their immunosuppressive protocol were extracted. The dose of Thymoglobulin given depended on baseline platelet count and was 2, 1.5, or 1 mg/kg per day over 5 days for the following platelet count groups: greater than 150,000/mm (normal group), 100 to 150,000/mm (mild thrombocytopenia group), and 50 to 100,000/mm (moderate thrombocytopenia group).

RESULTS

Thirty children of median age 14.2 years were given a median cumulative dose of Thymoglobulin of 8 mg/kg per patient; the moderate thrombocytopenia subgroup was given significantly less (6.4 mg/kg) ( P=0.032). Immediate tolerability of Thymoglobulin was good, with no cases of first-dose syndrome, anaphylaxis, or serum sickness. The platelet count decreased at the start of therapy, but recovered after discontinuation, and did not give rise to clinical concern. Patients were followed up for a median of 6.3 years (7 days-15.5 years); actuarial survival was 90%, 86%, and 74.5%, respectively, at 1, 5, and 10 years. In the first year, 50% of patients suffered an episode of rejection. The overall incidence of infection in the month following transplantation was 40%. One lymphoma occurred at 5 months.

CONCLUSIONS

The use of Thymoglobulin in pediatric heart-transplant patients as part of an immunosuppressive protocol, with dose adjustment according to platelet levels, has been shown to be effective in terms of rejection rate and patient survival and safe in terms of the incidence of infections and malignancy.

CD3 monitoring of antithymocyte globulin therapy in thoracic organ transplantation

BACKGROUND

Antithymocyte globulin is frequently used as a component of induction therapy in thoracic organ transplantation. This study evaluates the utility of monitoring peripheral CD3 lymphocytes to rationally adjust antithymocyte globulin therapy in this patient population.

METHODS

A total of 17 heart and 19 lung transplant recipients received antithymocyte globulin (ATGAM or thymoglobulin) as induction therapy or to treat steroid-resistant acute or chronic rejection. Absolute CD3 counts were maintained between 50 and 100 cells/microl.

RESULTS

With CD3 monitoring, the doses of antithymocyte globulin were reduced from 10-15 mg/kg to 1-5 mg/kg during the course of therapy. The total amount of antithymocyte globulin given to each CD3 monitored patient was reduced by 48%. Dose reduction did not alter the number of acute rejection or infectious episodes, and hematological side effects were infrequent.

CONCLUSION

CD3 monitoring of antithymocyte globulin therapy in thoracic organ recipients reduced the amount of drug received by each patient, while maintaining CD3 counts less than 100 cells/microl.

Immunologic events and long-term survival after combined heart and kidney transplantation: a 12-year single-center experience

BACKGROUND

In this study we compare the incidence of cardiac rejection and long-term survival after combined heart and kidney transplantation (HK) and single heart transplantation (H). Combined HK transplantation is a surgical option for patients with irreversible cardiac and renal failure. However, long-term results of combined HK transplantation on immunologic events and patient survival remain unknown.

METHODS

Between 1988 and 1997, 12 consecutive patients underwent combined HK transplantation (HK group) at a single institution. A control group (H group) of 24 single heart transplant recipients operated on within the same period was matched for age, pre-operative pulmonary vascular resistance, hepatic insufficiency and gender mismatch. Recipients and donors were ABO compatible without HLA antigen matching. All patients received immediate triple immunosuppression that included cyclosporine. Because of early renal dysfunction, cyclosporine was switched to anti-thymocyte globulin in 5 patients from the HK group and in 1 patient from the H group (p = 0.01).

RESULTS

Actuarial freedom from heart rejection at 6 months and at 1 year following transplantation averaged 90 +/- 9% and 70 +/- 14% in the HK group, and 65 +/- 10% and 49 +/- 11% in the H group, respectively (p = 0.023). Actuarial survival at 1, 5 and 12 years was not significantly different between groups, at 66%, 55% and 28% in the HK group, and 66%, 44% and 32% in the H group, respectively (p = 0.66).

CONCLUSION

The incidence of cardiac rejection was significantly lower. Long-term survival in the HK group was similar to that in the H group. Putative mechanisms of decreased cardiac rejection in the HK group include allogeneic stimulation, donor-derived dendritic cells and induction by anti-thymocyte globulins. The need for long-term immunosuppression may be reduced after combined heart and kidney transplantation.

Sternal wound infection after heart transplantation: incidence and results with aggressive surgical treatment

BACKGROUND

Sternal wound infection remains a significant complication. We reviewed the incidence and the treatment of sternal wound infection after heart transplantation.

METHODS

Of 226 patients who had a heart transplantation, 20 (8.8%) underwent postoperative wound debridement for superficial or deep sternal wound infection. The incidence and the survival of patients with sternal wound infection were analyzed.

RESULTS

The incidence of sternal wound infection was similar among patients treated with four protocols of immunosuppressive drugs: cyclosporine and prednisone (0 of 22; 0%); cyclosporine, prednisone, and azathioprine (2 of 24; 8.3%); cyclosporine, prednisone, azathioprine, and antithymocyte globulin (15 of 139; 10.8%); and cyclosporine, prednisone, mycophenolate mofetil, and antithymocyte globulin (3 of 41; 7.3%) (p = 0.4). Six-month and 5-year survival of patients with sternal wound infection averaged 85% +/- 8% and 74% +/- 10% compared with 92% +/- 2% and 82% +/- 3% in patients without wound infection (p = 0.15). Patients with deep sternal wound infection, debridement, and reconstruction had a 5-year survival averaging 80% +/- 10%.

CONCLUSIONS

The incidence of sternal wound infection remains similar between patients treated with the triple drug therapy. Surgical debridement and reconstruction can result in long-term survival after heart transplantation.

Immunosuppressive agents in transplantation: mechanisms of action and current anti-rejection strategies

Over the past century, the concept of interfering with the immune response at various sites by blocking the formation, stimulation, proliferation, and differentiation of lymphocytes has led to relentless development of new immunosuppressive drugs. These agents are associated with reduced risk of short- and long-term toxicity and have dramatically improved allograft and patient survival, especially in recipients of solid organ transplants. Current protocols in such patients are nearly all calcineurin-inhibitor based, using cyclosporine or tacrolimus, as part of dual, triple, or sequential therapy. This review focuses on agents currently in clinical use at transplant centers in United States. The drugs are described in terms of their basic mechanisms of action, therapeutic uses, clinical studies, and adverse effects. In addition, the efficacy and toxicity of a few promising new therapeutic approaches are examined. Finally, important challenges regarding pharmacological immunosuppression as it relates to solid organ and composite tissue allotransplantation are discussed.