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

Assessment of immunosuppression induction with basiliximab compared to antithymocyte-globulin in adult heart transplant patients

BACKGROUND

Patients undergoing heart transplants are at risk of rejection which can have significant morbidity and mortality. Induction immunosuppression at the time of transplant reduces the early risk and has additional benefits. The induction agent of choice within our program was changed from rabbit antithymocyte-globulin (rATG) to basiliximab, so it was necessary to evaluate whether this had any impact on patient outcomes.

OBJECTIVES

Our primary objective was to describe rejection, infection, and other outcomes in adult heart transplant patients at the University of Alberta Hospital in Edmonton, Canada.

METHODS

This study was a nonrandomized, retrospective cohort study.

RESULTS

Sixty-three patients were included with median ages 50 years versus 54 years. More female patients received rATG (20% vs. 42.4%). The most common indication for transplant in both cohorts was ICM (63.3% vs. 57.6%). Patients who received rATG had significantly higher PRA (0% vs. 43%, p < .001). Acute rejection episodes were similar between basiliximab and rATG at 3 months (16.7% vs. 15.1%; p = 1.0) and 6-months (30.0% vs. 18.1%; p = .376). Infections were not statistically different with basiliximab compared to rATG at 3-months, 43.3% vs. 63.6% and at 6-months 60.0% vs. 66.7%). There were no fatalities in either group.

CONCLUSIONS

Our study did not demonstrate differences in rejection with basiliximab compared to rATG. Mortality did not differ, but basiliximab-treated patients had fewer infections and infection-related hospitalizations than those treated with rATG. Larger studies with longer durations are needed to more completely describe the differences in rejection and infectious outcomes.

Induction therapy in heart transplantation: A systematic review and network meta-analysis for developing evidence-based recommendations

INTRODUCTION

Induction therapy (IT) utility in heart transplantation (HT) remains contested. Commissioned by a clinical-practice guidelines panel to evaluate the effectiveness and safety of IT in adult HT patients, we conducted this systematic review and network meta-analysis (NMA).

METHODS

We searched for studies from January 2000 to October 2022, reporting on the use of any IT agent in adult HT patients. Based on patient-important outcomes, we performed frequentist NMAs separately for RCTs and observational studies with adjusted analyses, and assessed the certainty of evidence using the GRADE framework.

RESULTS

From 5156 publications identified, we included 7 RCTs and 12 observational studies, and report on two contemporarily-used IT agents-basiliximab and rATG. The RCTs provide only very low certainty evidence and was uninformative of the effect of the two agents versus no IT or one another. With low certainty in the evidence from observational studies, basiliximab may increase 30-day (OR 1.13; 95% CI 1.06-1.20) and 1-year (OR 1.11; 95% CI 1.02-1.22) mortality compared to no IT. With low certainty from observational studies, rATG may decrease 5-year cardiac allograft vasculopathy (OR .82; 95% CI .74-.90) compared to no IT, as well as 30-day (OR .85; 95% CI .80-.92), 1-year (OR .87; 95% CI .79-.96), and overall (HR .84; 95% CI .76-.93) mortality compared to basiliximab.

CONCLUSION

With low and very low certainty in the synthetized evidence, these NMAs suggest possible superiority of rATG compared to basiliximab, but do not provide compelling evidence for the routine use of these agents in HT recipients.

Detection and management of HLA sensitization in candidates for adult heart transplantation

Heart transplantation (HT) remains the preferred therapy for patients with advanced heart failure. However, for sensitized HT candidates who have antibodies to human leukocyte antigens , finding a suitable donor can be challenging and can lead to adverse waitlist outcomes. In recent years, the number of sensitized patients awaiting HT has increased likely due to the use of durable and mechanical circulatory support as well as increasing number of candidates with underlying congenital heart disease. This State-of-the-Art review discusses the assessment of human leukocyte antigens antibodies, potential desensitization strategies including mechanisms of action and specific protocols, the approach to a potential donor including the use of complement-dependent cytotoxicity, flow cytometry, and virtual crossmatches, and peritransplant induction management.

Cardiac Regeneration Using Pluripotent Stem Cells and Controlling Immune Responses

Pluripotent stem cell (PSC)-derived cardiomyocytes are a promising source of cells in myocardial regeneration therapy for end-stage heart failure. Because most previous reports have focussed on xenotransplantation models using immunocompromised animals, studies on immune rejection in allogeneic transplantation models are needed for preclinical and clinical applications. Human leukocyte antigen (HLA) plays an important role in allogeneic transplantation, and cell bank projects are currently underway worldwide to stock induced pluripotent stem cells (iPSCs) generated from healthy individuals with homozygous HLA haplotypes. However, it is difficult to stock iPSCs that match the entire population in these cell banks; thus, several groups have produced hypoimmunogenic PSCs by knocking out HLA. These HLA-knockout PSCs were able to avoid rejection by T cells but still suffered rejection by natural killer (NK) cells caused by 'missing self-recognition'. Recent studies have attempted to generate hypoimmunogenic PSCs with gene editing to inhibit NK cell activation. Regenerative medicine using autologous iPSCs can be an ideal transplantation therapy, but, currently, there are major hurdles to its practical application. Hopefully, further research will resolve these issues. This review provides an overview of the current understanding and progress in this field.

Impact of induction therapy on cytomegalovirus infection and post-transplant outcomes in pediatric heart transplant recipients receiving routine antiviral prophylaxis

OBJECTIVES

Induction therapy has been increasingly used in pediatric heart transplantation. This study evaluated the impact of anti-thymocyte globulin (ATG) versus basiliximab as induction therapy on post-transplant cytomegalovirus (CMV) infection, rejection at 1 year, coronary allograft vasculopathy (CAV), and mortality in pediatric heart transplant recipients receiving antiviral prophylaxis.

RESULTS

Of the 96 patients (age < 18 years) analyzed, 46 (47.9%) patients received basiliximab, and 50 (52.1%) received ATG. Median follow-up was 3.0 (IQR, 1.7-4.9) years with 32.3% reporting CMV infection. The ATG group, as compared with the basiliximab group, had similar incidences of CMV infection (36% vs. 28.3%, p = .418), CMV viremia (22% vs. 19.6%, p = .769), and CMV-positive tissue biopsy (30% vs. 22%, p = .486). The ATG group had lower incidences of rejection at 1 year (16% vs. 36.9%, p = .022) and CAV (4% vs. 23.9%, p = .006) with no difference in mortality (8% vs. 15.2%, p = .343), compared with the basiliximab group. Multivariate analysis showed that induction with ATG was associated with a lower risk of rejection at 1 year (OR, .31; 95% CI, .09-.94; p = .039) with no impact on the incidences of CMV infection (HR, 2.06; 95% CI, .54-7.89; p = .292), CAV (HR, .30; 95% CI, .04-2.58; p = .275), and mortality (HR, .39; 95% CI, .09-1.82; p = .233) compared to basiliximab induction.

DISCUSSION AND CONCLUSIONS

In conclusion, induction with ATG was associated with reduction in risk of rejection at 1 year with no effects on CMV infection, CAV, and mortality in pediatric heart transplant recipients with universal antiviral prophylaxis compared with basiliximab induction therapy.

Retrospective Evaluation of Rabbit Antithymocyte Globulin Induction in Heart Transplant Patients

The dosing intensity of antithymocyte globulin as induction therapy in heart transplantation remains controversial. We sought to evaluate the efficacy and safety of rabbit antithymocyte globulin at a total dose of 4.5 mg/kg compared with <4.5 mg/kg.

Simultaneous glutamine metabolism and PD-L1 inhibition to enhance suppression of triple-negative breast cancer

Blockade of programmed cell death 1 ligand (PD-L1) has been used to treat triple-negative breast cancer (TNBC), and various strategies are under investigation to improve the treatment response rate. Inhibition of glutamine metabolism can reduce the massive consumption of glutamine by tumor cells and meet the demand for glutamine by lymphocytes in tumors, thereby improving the anti-tumor effect on the PD-L1 blockade therapy. Here, molybdenum disulfide (MoS2) was employed to simultaneously deliver anti-PDL1 antibody (aPDL1) and V9302 to boost the anti-tumor immune response in TNBC cells. The characterization results show that MoS2 has a dispersed lamellar structure with a size of about 181 nm and a size of 232 nm after poly (L-lysine) (PLL) modification, with high stability and biocompatibility. The loading capacity of aPDL1 and V9302 are 3.84% and 24.76%, respectively. V9302 loaded MoS2 (MoS2-V9302) can effectively kill 4T1 cells and significantly reduce glutamine uptake of tumor cells. It slightly increases CD8+ cells in the tumor and promotes CD8+ cells from the tumor edge into the tumor core. In vivo studies demonstrate that the combination of aPDL1 and V9302 (MoS2-aPDL1-V9302) can strongly inhibit the growth of TNBC 4T1 tumors. Interestingly, after the treatment of MoS2-aPDL1-V9302, glutamine levels in tumor interstitial fluid increased. Subsequently, subtypes of cytotoxic T cells (CD8+) in the tumors were analyzed according to two markers of T cell activation, CD69, and CD25, and the results reveal a marked increase in the proportion of activated T cells. The levels of cytokines in the corresponding tumor interstitial fluid are also significantly increased. Additionally, during the treatment, the body weights of the mice remain stable, the main indicators of liver and kidney function in the blood do not increase significantly, and there are no obvious lesions in the main organs, indicating low systemic toxicity. In conclusion, our study provides new insights into glutamine metabolism in the tumor microenvironment affects immune checkpoint blockade therapy in TNBC, and highlights the potential clinical implications of combining glutamine metabolism inhibition with immune checkpoint blockade in the treatment of TNBC.

Induction Therapy and Therapeutic Antibodies

Prevention of allograft rejection is one of the crucial goals in solid organ transplantation to ensure durability of the graft and is chiefly mediated by cellular and humoral pathways targeting cell surface alloantigens. The risk of rejection is highest in the first post-transplant year and wanes with time albeit the risk always exists and varies with the type of organ transplanted. Induction therapies refer to the use of high-intensity immunosuppression in the immediate post-operative period to mitigate the highest risk of rejection. This term encompasses chiefly the use of antibody therapies directed against one of the key pathways in T-cell activation or abrogating effects of circulating alloantibodies. These antibodies carry more potent immunomodulatory effect than maintenance immunosuppressive therapy alone and many of them lead to durable immune cell depletion. A variety of monoclonal and polyclonal antibodies have been utilized for use not only for induction therapy, but also for treatment of allograft rejection when it occurs and as components of desensitization therapy before and after transplantation to modulate circulating alloantibodies.

Influence of Induction Therapy Using Basiliximab With Delayed Tacrolimus Administration in Heart Transplant Recipients - Comparison With Standard Tacrolimus-Based Triple Immunosuppression

BACKGROUND

Appropriate indications and protocols for induction therapy using basiliximab have not been fully established in heart transplant (HTx) recipients. This study elucidated the influence of induction therapy using basiliximab along with delayed tacrolimus (Tac) initiation on the outcomes of high-risk HTx recipients.Methods and Results:A total of 86 HTx recipients treated with Tac-based immunosuppression were retrospectively reviewed. Induction therapy was administered to 46 recipients (53.5%) with impaired renal function, pre-transplant sensitization, and recipient- and donor-related risk factors (Induction group). Tac administration was delayed in the Induction group. Induction group subjects showed a lower cumulative incidence of acute cellular rejection grade ≥1R after propensity score adjustment, but this was not significantly different (hazard ratio [HR]: 0.63, 95% confidence interval [CI]: 0.37-1.08, P=0.093). Renal dysfunction in the Induction group significantly improved 6 months post-transplantation (P=0.029). The cumulative incidence of bacterial or fungal infections was significantly higher in the Induction group (HR: 10.6, 95% CI: 1.28-88.2, P=0.029).

CONCLUSIONS

These results suggest that basiliximab-based induction therapy with delayed Tac initiation may suppress mild acute cellular rejection and improve renal function in recipients with renal dysfunction, resulting in its non-inferior outcome, even in high-risk patients, when applied to the appropriate recipients. However, it should be carefully considered in recipients at a high risk of bacterial and fungal infections.

Cytomegalovirus myocarditis in solid organ transplant recipients: A case series and review of literature

Cytomegalovirus (CMV) is a DNA virus of the Herpesviridae family and is estimated to affect 15%-30% of high-risk solid organ transplant recipients. Typical manifestations of CMV end-organ disease in this population include colitis, esophagitis, and pneumonitis, and myocarditis is a rarely reported manifestation. We describe two cases of CMV myocarditis in solid organ transplant recipients and review the literature regarding previously published cases of CMV myocarditis.

A Single-Center Experience of the Optimal Initial Immunosuppressive Strategy for Preventing Early Acute Cellular Rejection in Orthotopic Heart Transplantation Associated With Renal Dysfunction

BACKGROUND

Renal dysfunction is a common complication following heart transplantation that may be worsened by the early initiation of calcineurin inhibitors. Antithymocyte globulin (ATG) or basiliximab has been used to delay or avoid calcineurin inhibitors. The most effective strategy for preventing early acute cellular rejection in this context is uncertain.

METHODS

We retrospectively reviewed all heart transplant cases between January 2012 and June 2017. The standard therapy consisted of mycophenolate mofetil, prednisolone, and tacrolimus. In patients at high risk of post-transplant renal dysfunction, an early calcineurin inhibitor-free regimen with basiliximab and/or ATG was used. Patients were assigned to cohorts based on the initial immunosuppressive strategy. The primary end point was the freedom rate of acute cellular rejection within 4 weeks post-transplant.

RESULTS

Of 93 cases, 21 patients received standard therapy, 64 patients received an initial calcineurin inhibitor-free regimen with basiliximab, and 8 patients received ATG and basiliximab. Freedom from acute rejection was greater in the ATG plus basiliximab group (all rejection free), compared to 40 (63%) of 64 patients treated with basiliximab and 10 (48%) of 21 patients treated with standard therapy (P < .05, log rank test). In patients treated with basiliximab, early administration (<24 hours) was associated with a higher freedom from acute rejection compared to ≥24 hours, (72% vs 29%, P < .05).

CONCLUSIONS

The combination of ATG and basiliximab was more effective in preventing acute cellular rejection. In those patients treated with basiliximab, rejection rates were no worse than standard therapy; however, it was only effective when administered within 24 hours.

Impact of induction immunosuppression on patient survival in heart transplant recipients treated with tacrolimus and mycophenolic acid in the current allocation era

BACKGROUND

The practice of induction therapy with either rabbit anti-thymocyte globulin (r-ATG) or interleukin-2 receptor antagonists (IL-2RA) is common among heart transplant recipients. However, its benefits in the setting of contemporary maintenance immunosuppression with tacrolimus/mycophenolic acid (TAC/MPA) are unknown.

METHODS

We compared post-transplant mortality among three induction therapy strategies (r-ATG vs IL2-RA vs no induction) in a retrospective cohort analysis of heart transplant recipients maintained on TAC/MPA in the Organ Procurement Transplant Network (OPTN) database between the years 2006 and 2015. We used a multivariable model adjusting for clinically important co-morbidities, and a propensity score analysis using the inverse probability weighted (IPW) method in the final analysis.

RESULTS

In multivariable IPW analysis, r-ATG (HR = 1.23; 95% CI = 1.05-1.46, P = 0.01) remained significantly associated with a higher mortality. There was a trend toward having a higher mortality in the IL2-RA (HR = 1.11; 95% CI = 1.00-1.24, P = 0.06) group. Subgroup analyses failed to show a patient survival benefit in using either r-ATG or IL2-RA among any of the subgroups analyzed.

CONCLUSION

In this contemporary cohort of heart transplant recipients receiving TAC/MPA, neither r-ATG nor IL2-RA were associated with a survival benefit. On the contrary, adjusted analyses showed a significantly higher mortality in the r-ATG group and a trend toward higher mortality in the IL2-RA group. While caution is needed in interpreting treatment effects in an observational cohort, these data call into question the benefit of induction therapy as a common practice and highlight the need for more studies.

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.

Induction regimen and survival in simultaneous heart-kidney transplant recipients

BACKGROUND

Induction therapy in simultaneous heart-kidney transplantation (SHKT) is not well studied in the setting of contemporary maintenance immunosuppression consisting of tacrolimus (TAC), mycophenolic acid (MPA), and prednisone (PRED).

METHODS

We analyzed the Organ Procurement and Transplant Network registry from January 1, 2000, to March 3, 2015, for recipients of SHKT (N = 623) maintained on TAC/MPA/PRED at hospital discharge. The study cohort was further stratified into 3 groups by induction choice: induction (n = 232), rabbit anti-thymoglobulin (r-ATG; n = 204), and interleukin-2 receptor-α (n = 187) antagonists. Survival rates were estimated using the Kaplan-Meier estimator. Multivariable inverse probability weighted Cox proportional hazard regression models were used to assess hazard ratios associated with post-transplant mortality as the primary outcome. The study cohort was censored on March 4, 2016, to allow at least 1-year of follow-up.

RESULTS

During the study period, the number of SHKTs increased nearly 5-fold. The Kaplan-Meier survival curve showed superior outcomes with r-ATG compared with no induction or interleukin-2 receptor-α induction. Compared with the no-induction group, an inverse probability weighted Cox proportional hazard model showed no independent association of induction therapy with the primary outcome. In sub-group analysis, r-ATG appeared to lower mortality in sensitized patients with panel reactive antibody of 10% or higher (hazard ratio, 0.19; 95% confidence interval, 0.05-0.71).

CONCLUSION

r-ATG may provide a survival benefit in SHKT, especially in sensitized patients maintained on TAC/MPA/PRED at hospital discharge.

Low-dose basiliximab induction therapy in heart transplantation

We prospectively studied efficacy and safety outcomes of two 10-mg doses of intravenous basiliximab on day 0 and day 4 for induction therapy in 17 consecutive de novo heart transplant recipients. By the 2-week assessment post-transplant, there were no deaths, graft failures, or acute cellular rejections (ACRs) ISHLT grade ≥ 2R. By the 1-year assessment post-transplant, there were 1 (6%) infectious death, no graft failures, 2 (12%) grade 2R ACRs, 6 (35%) asymptomatic cytomegalovirus (CMV) infections, and 4 (25%) treated infections. Our study was the first to show that low-dose basiliximab induction in heart transplant resulted in favorable efficacy and safety outcomes. Additionally, calcineurin inhibitor (CNI) initiation in a low-risk population could be safely delayed using the strategy of modified low-dose postoperative basiliximab. This strategy also appears to allow subsequent early corticosteroid wean, although with the concomitant maintenance of higher CNI levels and higher dosing of mycophenolate.

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.

Effects of anti-human T lymphocyte immune globulins in patients: new or old

Multiple studies demonstrated that anti‐human T lymphocyte immune globulins (ATG) can decrease the incidence of acute and chronic graft rejection in cell or organ transplants. However, further in‐depth study indicates that different subgroups may benefit from either different regimes or alteration of them. Studies among renal transplant patients indicate that low immunological risk patients may not gain the same amount of benefit and thus tilt the risk versus benefit consideration. This may hold true for low immunological risk patients receiving other organ transplants and would be worth further investigation. The recovery time of T cells and natural killer (NK) cells also bears consideration and the impact that it has on the severity and incidence of opportunistic infections closely correlated with the dosage of ATG. The use of lower doses of ATG in combination with other induction medications may offer a solution. The finding that ATG may lose efficacy in cases of multiple transplants or re‐transplants in the case of heart transplants may hold true for other transplantations. This may lead to reconsideration of which induction therapies would be most beneficial in the clinical setting. These studies on ATG done on different patient groups will naturally not be applicable to all, but the evidence accrued from them as a whole may offer us new and different perspectives on how to approach and potentially solve the clinical question of how to best reduce the mortality associated with chronic host‐versus‐graft disease.

Comparison of Basiliximab and Anti-Thymocyte Globulin as Induction Therapy in Pediatric Heart Transplantation: A Survival Analysis

Background

Basiliximab and anti‐thymocyte globulin are widely used drugs for induction therapy after pediatric heart transplantation. The aim of this study was to determine whether any differences could be observed between basiliximab and anti‐thymocyte globulin, with respect to long‐term mortality, in a population of pediatric cardiac transplant recipients.

Methods and Results

An analysis of pediatric heart transplant patients (aged <18 years) from the United Network for Organ Sharing database was conducted that compared patients receiving basiliximab with those that received anti‐thymocyte globulin for the risk of all‐cause mortality. Secondary endpoints included death attributable to graft failure, cardiovascular causes, infection, or malignancy. Of the 2275 patients, 685 received basiliximab and 1590 anti‐thymocyte globulin. One‐year survival was similar for both groups; however, at 5 and 10 years, basiliximab was associated with poorer long‐term survival (68% versus 76% at 5 years [P<0.001] and 49% versus 65% at 10 years [P<0.001], respectively). Basiliximab was associated with higher risk of death attributable to graft failure (P=0.013), but not death attributable to cardiovascular causes (P=0.444), infection (P=0.095), or malignancy (P=0.392). After multivariate analysis, use of basiliximab (versus use of anti‐thymocyte globulin) remained significantly associated with all‐cause mortality (hazard ratio, 1.27; 95% confidence interval, 1.02–1.57; P=0.030).

Conclusions

In pediatric heart transplant patients, use of basiliximab for induction therapy was associated with an increased risk of mortality, when compared with those receiving anti‐thymocyte globulin.

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.

Thymoglobulin induction in heart transplantation: patient selection and implications for maintenance immunosuppression

Clinical data relating to rabbit antithymocyte globulin (rATG) induction in heart transplantation are far less extensive than for other immunosuppressants, or indeed for rATG in other indications. This was highlighted by the low grade of evidence and the lack of detailed recommendations for prescribing rATG in the International Society for Heart and Lung Transplantation (ISHLT) guidelines. The heart transplant population includes an increasing frequency of patients on mechanical circulatory support (MCS), often with ongoing infection and/or presensitization, who are at high immunological risk but also vulnerable to infectious complications. The number of patients with renal impairment is also growing due to lengthening waiting times, intensifying the need for strategies that minimize calcineurin inhibitor (CNI) toxicity. Additionally, the importance of donor-specific antibodies (DSA) in predicting graft failure is influencing immunosuppressive regimens. In light of these developments, and in view of the lack of evidence-based prescribing criteria, experts from Germany, Austria, and Switzerland convened to identify indications for rATG induction in heart transplantation and to develop an algorithm for its use based on patient characteristics.

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.

Basiliximab: efficacy and safety evaluation in kidney transplantation

INTRODUCTION

Basiliximab is a chimeric monoclonal antibody directed against the alpha chain of interleukin-2 receptor (IL-2R). When administered intravenously at a dosage of 20 mg at the time of transplantation and 4 days later, basiliximab saturates the alpha chain of IL-2R for 4 weeks.

AREAS COVERED

This review evaluates the efficacy and safety of basiliximab in kidney transplantation. Randomized controlled trials showed that basiliximab can significantly reduce the incidence of acute rejection without increasing the risk of adverse events. When compared with other antibodies used for induction, basiliximab showed efficacy and safety profiles similar to daclizumab, another monoclonal antibody directed against the alpha chain of IL-2R. In comparison with rabbit anti-thymocyte globulins (rATG), basiliximab showed a similar efficacy. However, in patients at higher risk of rejection, rATG proved to be more effective. No serious safety problems related to basiliximab have been reported.

EXPERT OPINION

There is a solid evidence that basiliximab can significantly decrease the risk of acute rejection in kidney transplant recipients without increasing adverse events. This can allow decreased dosage or avoidance of glucocorticoids and reduced dosage of calcineurin inhibitors. On the basis of efficacy, tolerability, ease of administration, and cost effectiveness, basiliximab may be considered the drug of choice for the prophylaxis of acute rejection in standard renal transplant recipients.

Current strategies and future trends in immunosuppression after heart transplantation

PURPOSE OF REVIEW

Current immunosuppressive drugs have provided excellent outcomes after heart transplantation. However, more patients suffer from long-term complications of these drugs. A series of prospective randomized trials has been conducted and has offered disparate results. This report reviews the challenges of immunosuppressive therapy during the past decade, describes recent reports and explores potential future trends in immunosuppressive protocols in heart transplantation.

RECENT FINDINGS

The traditional combination of cyclosporine, azathioprine and steroids has been changed to tacrolimus (Tac) or cyclosporine in combination with mycophenolate mofetil (MMF) and steroids due to the results of several trials. The use of mammalian target of rapamycin inhibitors in combination with Tac or cyclosporine A has not shown a clear benefit compared with MMF. All different combinations have shown some positive effects counteracted by side-effects and negative synergism of combinations. Future protocols need to be adapted according to individual patient's needs and risks.

SUMMARY

The changing population of heart transplantation patients has become older and sicker. Immunosuppression strategies should be developed for each patient based on their risk for rejection and their risk for developing important complications of immunosuppressive therapy.

Antibody immunosuppressive therapy in solid-organ transplant: Part I

Currently, a wide variety of both polyclonal and monoclonal antibodies are being routinely utilized to prevent and treat solid organ rejection. More commonly, these agents are also administered in order to delay introduction of calcineurin inhibitors, especially in patients with already compromised renal function. While these antibody therapies dramatically reduced the incidence of acute rejection episodes and improved both short and long-term graft survival, they are also associated with an increased incidence of opportunistic infections and neoplastic complications. Therefore, effective patient management must necessarily balance these risks against the potential benefits of the therapy.

Induction treatment with monoclonal antibodies for heart transplantation

Individualization of induction therapy for heart transplantation (HT) is needed, given that only patients at significant risk for fatal rejection seem to present a favorable risk-benefit ratio. The question whether monoclonal interleukin 2 antagonists or antilymphocyte antibodies should be recommended remains unanswered. As most studies suggest that they have similar efficacy in preventing acute rejection, other variables related to safety or management costs should be taken into account. The cytokine release syndrome, associated with the use of OKT3, complicates management of HT patient. The experience in our center with 2 consecutive cohorts, treated with basiliximab (BAS) and OKT3, respectively, suggests that the use of BAS is associated, in addition to similar immunosuppressive efficacy and better safety profile than OKT3, with simpler patient management during the initial hospital stay, which could be associated with a reduction in posttransplant costs. Because few centers continue to use OKT3 as induction therapy in HT, more studies comparing cost-effectiveness of BAS vs polyclonal antilymphocyte antibodies (ATG) are needed.

Induction therapy: why, when, and which agent?

The long-term outcome of paediatric transplantation has improved over the last decade with an increase in the armamentarium of immunosuppressive agents. However, the battle against the hostile immune response at the time of and after transplantation continues. Induction therapy can reduce early injury, to optimize the long-term allograft survival. The goal of induction immunosuppression in paediatric transplantation is to permit the use of lower doses of maintenance immunosuppressive agents without increased rates of acute allograft rejection and chronic allograft damage. The aim of this review is to summarize the current literature relating to the use of antibody agents for induction in paediatric solid organ transplantation.

Induction Immunosuppression for Orthotopic Heart Transplantation: A Review

Objectives

To describe the appropriateness and safety of induction immunosuppression for patients at risk for fatal rejection, and to describe the safety and effectiveness profiles of the induction regimens available in the United States.

Data Sources

MEDLINE/PubMed database, EMBASE database, Google Scholar; references from pertinent articles were also reviewed to identify additional data.

Study Selection

A systematic literature review from January 1, 1980, through June 30, 2008, was performed. Included articles ranged from case series to prospective randomized controlled double-blind placebo-controlled trials that detailed the following topics with respect to induction immunosuppression: risk of fatal rejection, renal sparing, malignancy, OKT3, rabbit or equine antithymocyte globulin, daclizumab, basiliximab, and alemtuzumab.

Results

Patients at highest risk for fatal rejection experienced a survival benefit from induction immunosuppression, whereas all other patients experienced no benefit or harm. Most of the early data detail positive experiences with polyclonal antibody regimens. Several newer trials compare the use of polyclonal strategies with the use of anti-CD25 targeted monoclonal antibodies. Few researchers have assessed the usefulness of an anti-CD52 approach. Overall, induction therapy remains a poorly studied and widely variable practice among the major US heart transplant centers.

Conclusion

At present, the unrestricted use of induction for all patients does not seem prudent. Induction should be individualized for each patient on the basis of a well-designed protocol, careful analysis of the transplant center's demographics, and the effectiveness and safety profiles of the regimens used.