Induction with anti-thymocyte globulin in heart transplantation is associated with better long-term survival compared with basiliximab

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.

A heart transplant center experience with basiliximab induction strategies: A double edged sword?

BACKGROUND

The use of induction immunosuppression for heart transplantation (HT) is debated given the uncertain benefit and potential risks of infection and malignancy.

METHODS

This is a retrospective single-center analysis of 475 consecutive HT recipients from 2003 to 2020 grouped by use of induction with basiliximab group (BG) and the no basiliximab group (NBG). Subgroup analysis by era compared pre-2016 standard-basiliximab (BX) induction and 2016-2020 with selective-BX use as part of a calcineurin-inhibitor-sparing regimen.

RESULTS

When adjusted for confounders (sex, age, PRA, eGFR), the BG was less likely to have acute cellular rejection (ACR) (OR.42, p < .001), but had more antibody mediated rejection (AMR) (OR 11.7, p < .001) and more cardiac allograft vasculopathy (CAV) (OR 3.8, p = .04). There was no difference between BG and NBG in the incidence of malignancies or infections. When stratified by era (pre-2016 vs. 2016-2020), ACR remained less common in the BG than the NBG (36% vs. 50%, p = .045) groups, while AMR remained more common (9.7 vs. 0% p = .005). There was no significant difference in conditional survival comparing pre-and post-2016 NBG (HR 2.20 (95% CI.75-6.43); however, both pre-2016 BG and post-2016 BG have significantly higher mortality (HR 2.37 [95% CI 1.02-5.50) and HR 2.69 (95% CI 1.08-6.71), p = .045 and.03, respectively].

CONCLUSION

Basiliximab reduces the incidence of ACR but increases the risk of AMR, CAV, and may be associated with increased mortality. Mechanistic studies are needed to describe a potential T-cell-escape mechanism with enhanced humoral immunity.

Does the induction immunotherapy (basiliximab) influence the early acute cellular rejection index after orthotopic heart transplantation?- Preliminary assessment report

The study aimed to determine the influence of induction therapy on the acute cellular rejection (ACR) index in adult heart transplant recipients during the one-year observation. The study population consisted of 256 consecutive adult patients (pts), aged 51.5 (±11.9) years, 199 (77%) men treated with orthotopic heart transplantation (OHT) in the period between 2015 and 2020 in a single high-volume heart transplant center. The endomyocardial biopsies (EMBs) were performed according to the protocol consisting of 7 protocolary EMBs for up to 3 months and 10 EMBs for up to one year after OHT. The rejection index (ACRI) was calculated as the number of scheduled EMBs with the ACR ≥ 2 divided by the total number of protocolary EMBs. The study population was divided into two groups according to the application of basiliximab. The total number of pts. who received basiliximab was 10 (3.9%). The main indications for the usage of the induction therapy were heart retransplantation, mechanical circulatory support (MCS), severe renal insufficiency (eGFR <30 mL/min/1.73 m2), and a panel of reactive antibody (PRA) > 10%. In the group with induction, the mean age was 49 (±14) years; 3 (30%) patients had the MCS prior to OHT, and 3 (30%) patients had heart retransplantation. Four (40%) patients had diabetes mellitus, and 4 (40%) patients had severe renal insufficiency. As maintenance therapy during the observation period, tacrolimus was given to 10 (100%) patients, everolimus to 2 (20%) patients, and MPA to 9 (90%) patients. In the group with no induction, the mean age was 51.8 (±12) years, MCS was used in 56 (23%) patients, 2 (0.8%) patients were retransplanted; 10 (4%) patients had eGFR <30 mL/min/1.73 m2 and 58 (24%) patients had diabetes. Tacrolimus was administered to 243 (99%) patients, cyclosporine to 3 (1%), everolimus to 40 (16%), and mycophenolate to 245 (99.6%) heart recipients. The median one-year ACRI was 0.0, IQR:0.0-0.08 in the group with induction vs. 0.077, IQR: 0.0-0.154 with no induction; p = 0.11. ACRI up to three months was significantly higher in the entire cohort in comparison to up to one year (P < 0.01). The multivariate analysis showed that only everolimus implementation and younger age at the time of transplant influenced patients' mortality rate (P < 0.01). Significant graft rejections (≥ 2R ISHLT) are most common in the first three months after OHT. Patients who are initially at high risk of significant cellular rejection may benefit from induction therapy.

The effectiveness and safety of antibody induction immunosuppression in a large cohort of United States pediatric liver transplant recipients

Data on the potential benefits and risks of induction therapy in pediatric liver transplantation (LT) are limited. This was a retrospective cohort study of 2748 pediatric LT recipients at 26 children's hospitals between January 1, 2006 to May 31, 2017 using data from the pediatric health information system linked to the United Network for Organ Sharing database. The induction regimen was obtained from the pediatric health information system day-by-day pharmacy resource utilization. Cox proportional hazards evaluated the association of induction regimen (none/corticosteroid-only, nondepleting, and depleting) on patient and graft survival. Additional outcomes, including opportunistic infections and posttransplant lymphoproliferative disorder, were studied using multivariable logistic regression. Overall, 64.9% received none/corticosteroid-only induction, whereas 28.1% received nondepleting, 8.3% received depleting, and 2.5% other antibody regimens. Differences in patient characteristics were small, but center practices were heterogeneous. Compared with none/corticosteroid-only induction, nondepleting induction was associated with reduced acute rejection (odd ratio [OR], 0.53; P <.001) but with the increased posttransplant lymphoproliferative disorder (OR, 1.75; P =.021). Depleting induction was associated with improved graft survival (hazard ratio [HR], 0.64; P =.028) but with increased noncytomegalovirus opportunistic infections (OR, 1.46; P =.046). Depleting induction is underused yet may offer long-term benefits in this large multicenter cohort. Greater consensus guidance in this aspect of pediatric LT care is warranted.

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.

Impact of the United Network for Organ Sharing policy change on induction immunosuppression practice patterns and outcomes in adult heart transplant recipients

OBJECTIVE

We evaluated whether the new allocation system altered induction practice patterns and affected outcomes in adult HT recipients.

DESIGN

Retrospective, observational, cohort study.

DATA SOURCE

This study used data from the United Network for Organ Sharing (UNOS) database.

PATIENTS

We included adults (18+ years of age) who had undergone HT and received induction immunosuppression and were stratified based on surgery being before (January 1, 2015-May 31, 2018) and after (May 1, 2018-December 31, 2021) the UNOS allocation policy change.

MEASUREMENTS

Outcomes of 30-day mortality, 1-year mortality, and 1-year graft failure were compared between those transplanted before and after the policy change through risk-adjusted Cox proportional hazards models while drug-treated rejection in the first year was compared using multiple logistic regression.

RESULTS

Of the 7845 HT recipients who received induction therapy, 5070 (64.6%) were transplanted before and 2775 (35.4%) after the UNOS policy change. The most used induction agents were basiliximab (56.0%) and thymoglobulin (39.3%), with thymoglobulin used more often in the new (43.1%) than old system (37.2%; p < 0.001). Among adult HT recipients who received induction, risk-adjusted hazards of 30-day mortality (HR 0.89, 95% CI 0.67-1.18), 1-year mortality (HR 1.00, 95% CI 0.84-1.19), and 1-year graft failure (HR 0.83, 95% CI 0.60-1.15) were similar between the old and new systems. Conversely, the adjusted odds of drug-treated rejection in the first year was lower in the new system (OR 0.52, 95% CI 0.38-0.72).

CONCLUSIONS

HT recipients in the new allocation system were more likely to receive thymoglobulin induction, which may be associated with a reduced risk of drug-treated rejection.

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.

Review of Postoperative Care for Heart Transplant Recipients

The early postoperative management strategies after heart transplantation include optimizing the function of the denervated heart, correcting the causes of hemodynamic instability, and initiating and maintaining immunosuppressive therapy, allograft rejection surveillance, and prophylaxis against infections caused by immunosuppression. The course of postoperative support is influenced by the quality of allograft myocardial protection prior to implantation and reperfusion, donor-recipient heart size matching, surgical technique of orthotopic heart transplantation, and patient factors (eg, preoperative condition, immunologic compatibility, postoperative vasomotor tone, severity and reversibility of pulmonary vascular hypertension, pulmonary function, mediastinal blood loss, and end-organ perfusion). This review provides an overview of the early postoperative care of recipients and includes a brief description of the surgical techniques for orthotopic heart transplantation.

Racial and socioeconomic disparities in pediatric heart transplant outcomes in the era of anti-thymocyte globulin induction

BACKGROUND

Black race is associated with worse outcomes across solid organ transplantation. Augmenting immunosuppression through antithymocyte globulin (ATG) induction may mitigate organ rejection and graft loss. We investigated whether racial and socioeconomic outcome disparities persist in children receiving ATG induction.

METHODS

Using the Pediatric Heart Transplant Society registry, we compared outcomes in Black and White children who underwent heart transplant with ATG induction between 2000 and 2020. The primary outcomes of treated rejection, rejection with hemodynamic compromise (HC), and graft loss (death or re-transplant). We explored the association of these outcomes with race and socioeconomic disparity, assessed using a neighborhood deprivation index [NDI] score at 1-year post-transplant (high NDI score implies more socioeconomic disadvantage).

RESULTS

The study cohort included 1,719 ATG-induced pediatric heart transplant recipients (22% Black, 78% White). There was no difference in first year treated rejection (Black 24.5%, White 28.1%, p = 0.2). During 10 year follow up, the risk of treated rejection was similar; however, Black recipients were at higher risk of HC rejection (p = 0.009) and graft loss (p = 0.02). Black recipients had a higher mean NDI score (p < 0.001). Graft loss conditional on 1-year survival was associated with high NDI score in both White and Black recipients (p < 0.0001). In a multivariable Cox model, both high NDI score (HR 1.97, 95% CI 1.23-3.17) and Black race (HR 2.22, 95% CI 1.40-3.53) were associated with graft loss.

CONCLUSION

Black race and socioeconomic disadvantage remain associated with late HC rejection and graft loss in children with ATG induction. These disparities represent important opportunities to improve long term transplant outcomes.

Characteristics and outcomes of heart transplant recipients with a pretransplant history of malignancy

We aimed to investigate the characteristics and outcomes of HTx recipients with a history of pretransplant malignancy (PTM). Among 1062 HTx recipients between 1997 and 2013, 73 (7.1%) patients had PTMs (77 cancer cases). We analyzed post-HTx outcome, recurrence of PTM, and development of de novo malignancies. Post-HTx outcome included overall survival, 10-year survival, 10-year freedom from cardiac allograft vasculopathy (CAV), non-fatal major adverse cardiac events (NF-MACE), any treated rejection (ATR), acute cellular rejection (ACR), and antibody-mediated rejection (AMR). Four most common PTMs were lymphoproliferative disorders (18.2%), prostate cancers (18.2%), non-melanoma skin cancers (18.2%), and breast cancers (13.0%). Median time from PTM and HTx was 9.0 years. During a median follow-up of 8.6 years after HTx, patients with PTM, compared to those without, showed significantly higher incidence of posttransplant malignancies (43.8% vs. 20.8%, p < .001) including 9.6% (n = 7) of PTM recurrences. However, patients with PTM, compared to those without, showed comparable overall survival, 10-year survival, 10-year freedom from CAV, NF-MACE, ATR, ACR, and AMR. Therefore, a history of PTM should not disqualify patients from HTx listing, while further research is necessary for early detection of posttransplant malignancies in these patients.

Novel Immunosuppression in Solid Organ Transplantation

Solid organ transplantation and survival has improved tremendously in the last few decades, much of the success has been attributed to the advancements in immunosuppression. While steroids are being replaced and much of the immunosuppressive strategies focus on steroid free regimens, novel agents have introduced in the induction, maintenance, and treatment of acute rejection phase. MTOR inhibitors have helped with the renal sparing side effect from the calcineurin inhibitors, newer agents such as rituximab have decreased the incidence of donor-specific antibodies which led to decreased incidence of acute rejection reactions. In this chapter we discuss the newer therapies directed specifically for solid organ transplantation.

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.

Adverse Effects of Immunosuppression: Infections

Immunosuppressive therapies are currently indicated for a wide range of diseases. As new agents emerge and indications evolve the landscape grows increasingly complex. Therapies can target pathologic immune system over-activation in rheumatologic or autoimmune disease, or conditioning and graft versus host disease (GVHD) prophylactic regimens may eliminate or inhibit host immune function to improve graft survival and risk of complication in solid organ transplantation (SOT) or hematopoietic stem cell transplantation (HSCT). With immunosuppressive therapy, infections occur. Complex disease states, host factors, and concomitant therapies contribute to a "net state" of immunosuppression that must be considered and may confound perceived increased infection risks in patients receiving treatment.

Antithymocyte globulin induction therapy and myocardial complement deposition in pediatric heart transplantation

BACKGROUND

Antithymocyte globulin (ATG) consists of polyclonal antibodies directed primarily against human T lymphocytes but may contain antibodies with affinity for other tissues in the transplanted organ, resulting in complement (C4d) deposition. This phenomenon has been demonstrated in endomyocardial biopsies (EMBs) of adult cardiac transplants. We examined the relationship of induction immunosuppression with ATG and C4d deposition in EMB of pediatric cardiac transplants.

METHODS

Results of C4d immunohistochemistry were available from all EMB of patients transplanted at our center between June 2012 and April 2018 (n = 48) who received induction immunosuppression with either ATG (n = 20) or basiliximab (n = 28) as the standard of care.

RESULTS

C4d deposition in the first year post-heart transplant was more commonly seen among patients who received ATG induction (20% of EMBs in ATG group vs 1% of EMBs in basiliximab group; p < .0001). C4d deposition related to ATG was observed early post-transplant (50% ATG vs 0% basiliximab on first EMB; p < .0001 and 35% ATG vs 0% basiliximab on the second EMB; p = .0012). While this difference waned by the third EMB (5% ATG vs 0% basiliximab; p = .41), positive C4d staining persisted to the sixth EMB in the ATG group only (6%).

CONCLUSION

C4d deposition is common on EMB up to 1 year post-pediatric cardiac transplant following ATG induction. This high rate of positive C4d staining in the absence of histologic AMR after ATG induction therapy must be accounted for in making clinical decisions regarding cardiac allograft rejection diagnosis and treatment.

Impact of induction strategy change on first-year rejection in pediatric heart transplantation at a single center-From postoperative basiliximab to either postoperative anti-thymocyte globulin or preoperative basiliximab

BACKGROUND

Our pediatric heart transplant center transitioned from post-bypass basiliximab (BAS) induction to either anti-thymocyte globulin (ATG) or pre-bypass BAS. The purpose of this study was to compare first-year rejection rates before and after this change.

METHODS

A single-center retrospective analysis was conducted of pediatric heart transplant recipients from 2010 to 2019. Primary outcome was first-year rejection. Bivariate analysis, Kaplan-Meier curves, and multivariable regression were performed across eras.

RESULTS

Forty-three early era patients (55%) received post-bypass BAS, and 35 late era patients (45%) received pre-bypass BAS (n = 17) or ATG (n = 18). First-year rejection decreased in the late era (31% vs 53%, p = .05). This finding was more pronounced after excluding infants (38% vs 73%, p = .006). Late era was associated with a decreased likelihood of rejection (all cohort OR 0.19, 95% CI 0.05-0.66; infants excluded OR 0.17, 95% CI 0.04-0.61). No differences in post-transplant lymphoproliferative disease, donor-specific antibody, or infection were observed.

CONCLUSIONS

Fewer late era patients receiving ATG or pre-bypass BAS induction had first-year rejection compared to the early era patients receiving standard post-bypass BAS induction. This programmatic shift in induction strategy was readily achievable and potentially effective in reducing first-year rejection.

Post-transplant absolute lymphocyte count predicts early cytomegalovirus infection after heart transplantation

Immunosuppressive therapy can decrease rejection episodes and increase the risk of severe and fatal infections in heart transplantation (HT) recipients. Immunosuppressive therapy can also decrease the absolute lymphocyte count (ALC), but the relationship between early post-transplant ALC and early cytomegalovirus (CMV) infection is largely unknown, especially in HT. We retrospectively analyzed 58 HT recipients who tested positive for CMV IgG antibody and received basiliximab induction therapy. We collected preoperative and 2-month postoperative data on ALC and CMV load. The CMV load > 1200 IU/mL was used as the cutoff value to define early CMV infection. Post-transplant lymphopenia was defined as an ALC of < 500 cells/μL at postoperative day (POD) #7. On POD #7, 29 (50.0%) patients had post-transplant lymphopenia and 29 (50.0%) patients did not. The incidence of CMV infection within 1 or 2 months of HT was higher in the post-transplant lymphopenia group than in the non-lymphopenia group (82.8% vs. 48.3%, P = 0.013; 89.7% vs. 65.5%, P = 0.028, respectively). ALC < 500 cells/μL on POD #7 was an independent risk factor for early CMV infection within 1 month of HT (odds ratio, 4.14; 95% confidence interval, 1.16-14.77; P = 0.029). A low ALC after HT was associated with a high risk of early CMV infection. Post-transplant ALC monitoring is simple and inexpensive and can help identify patients at high risk of early CMV infection.

Heart Transplant Immunosuppression Strategies at Cedars-Sinai Medical Center

Heart transplant is the optimal treatment for selected patients with end-stage heart failure. Immunosuppression after heart transplantation has significantly reduced the incidence of rejection and improved patient outcomes with the routine use of calcineurin inhibitors. Antimetabolites and proliferation signal inhibitors add to the improvement in patient outcomes as well. The goal of induction therapy is to provide intense immunosuppression when the risk of allograft rejection is highest. Most maintenance immunosuppressive protocols employ a 3-drug regimen consisting of a calcineurin inhibitor, an antimetabolite agent and glucocorticoids. The management of rejection proceeds in a stepwise fashion based on the severity of rejection detected on biopsy and the patient's clinical presentation. This review will cover induction, maintenance, rejection therapy and some special considerations including sensitization, renal sparing protocol, and corticosteroid weaning. It will end in consideration of potential future directions in immunosuppressive strategies to promote patient and graft survival.

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.

Mechanisms and clinical applications of immunosuppressive medications

Immunosuppressive medications and regimens have evolved with significant advancements in the understanding of the immunologic process after solid organ transplantation. Medications can block the communication between antigen-presenting cells and T-cells, the activation and proliferation of T-cells, antibody production by plasma cells, and the activation of the complement system by antibodies. T-cell depleting antibodies and interleukin-2 receptor blockers are commonly used during induction therapy. Calcineurin inhibitors, antimetabolites, antiproliferative agents, and corticosteroids are commonly used in maintenance therapy regimens. These medications decrease the rates of rejection episodes and markedly increase the survival rates of short-term grafts. However, in terms of the survival rate of long-term grafts, there is still room for improvement. Opportunistic infections, development of cancer, metabolic diseases, and calcineurin inhibitor toxicity are hurdles in the improvement in survival rates of long-term grafts. Therefore, many efforts are being taken to overcome these hurdles, such as the development of new drugs, individualization of immunosuppression, and induction of immune tolerance.

The use of induction therapy in liver transplantation is highly variable and is associated with posttransplant outcomes

The use of induction immunosuppression in liver transplantation (LT) remains controversial. This was a retrospective cohort study of adult, first-time liver-alone recipients (N = 69 349) at 114 US centers between 2005 and 2018 using data from the United Network for Organ Sharing. The comparative effectiveness of nondepleting and depleting induction (NDI and DI) was assessed. Overall, 27% of recipients received induction with 65.7% of the variance in the receipt of induction being attributed to transplant center alone. NDI and DI were associated with a lower risk of death/graft failure compared to no induction (adjusted hazard ratio 0.90 [95% confidence interval (CI): 0.86-0.95] and 0.91 [95% CI: 0.85-0.97], respectively; P < .001). In nondialysis recipients at the mean transplant estimated glomerular filtration rate (eGFR), NDI was associated with an adjusted gain in eGFR by 6 months of +3.8 mL/min per 1.73 m² and DI of +3.33 mL/min per 1.73 m² compared to no induction (P < .001). Recipients with lower eGFR at LT had greater predicted improvement in eGFR (interaction P < .001). Only NDI was associated with a reduced risk of acute rejection in the first year post-LT (odds ratio 0.87, 95% CI: 0.8-0.94). Significant variability in induction practices exists, with center being a major determinant. The absolute incremental benefits of NDI and DI over no induction were small.

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.

Five decades of pediatric heart transplantation: challenges overcome, challenges remaining

PURPOSE OF REVIEW

Pediatric heart transplants continue to be the therapy of choice for children with end stage heart failure. The interplay of limited donor supply, improvement in ventricular assist device (VAD) technology and utilization, and a focus on optimizing long-term outcomes make it critically important for practitioners to be aware of an evolving diagnostic and therapeutic arsenal.

RECENT FINDINGS

Data suitable to define best practices for pediatric heart transplantation consist of an amalgam of small single center series, registry reviews and judicious inference from adult studies. Large-scale prospective pediatric studies are essentially nonexistent; the pediatric heart transplant study group continues to be highly productive while new collaboratives are emerging.

SUMMARY

Outcomes for pediatric transplants continue to improve. Technology and innovation continue to drive shifts in management. Improvements in VAD support along with refinement of solid-phase assays require clinicians to develop a deeper understanding of pre and post transplant management of donor-specific antibodies and antibody-mediated rejection. Expertise in retransplantation and the care of adults with congenital heart disease will be critical in the future.

Comparison of basiliximab vs antithymocyte globulin for induction in pediatric heart transplant recipients: An analysis of the International Society for Heart and Lung Transplantation database

This study aims to compare 2 common induction strategies, basiliximab and ATG. Analysis of the ISHLT transplant registry was performed. The database was queried for pediatric heart transplants from January 1, 2000, to June 30, 2015, who had received induction with basiliximab or ATG. Primary end-point was graft survival. Secondary end-points included 1-year survival and 1-year conditional survival. There were 3158 heart transplants who received induction with basiliximab or ATG. The ATG cohort was younger, more likely to have congenital heart disease or be a retransplant, have a higher PRA, longer ischemic time, and been transplanted earlier in the study period (all P<.01). There was no difference in graft loss in the basiliximab cohort compared to the ATG cohort (HR 1.18 P=.06). On conditional 1-year survival analysis, basiliximab induction was associated with graft loss (HR=1.35 95% CI 1.1-1.7, P<.01), and in the propensity-matched cohort, the basiliximab cohort was more likely to experience rejection prior to discharge (P=.04). Infection prior to discharge was more common in the antithymocyte cohort. Induction with ATG is associated with improved late graft survival compared to basiliximab.

A Review of Induction with Rabbit Antithymocyte Globulin in Pediatric Heart Transplant Recipients

Pediatric heart transplantation (pHTx) represents only a small proportion of cardiac transplants. Due to these low numbers, clinical data relating to induction therapy in this special population are far less extensive than for adults. Induction is used more widely in pHTx than in adults, mainly because of early steroid withdrawal or complete steroid avoidance. Antithymocyte globulin (ATG) is the most frequent choice for induction in pHTx, and rabbit antithymocyte globulin (rATG, Thymoglobulin^®) (Sanofi Genzyme) is the most widely-used ATG preparation. In the absence of large, prospective, blinded trials, we aimed to review the current literature and databases for evidence regarding the use, complications, and dosages of rATG. Analyses from registry databases suggest that, overall, ATG preparations are associated with improved graft survival compared to interleukin-2 receptor antagonists. Advantages for the use of rATG have been shown in low-risk patients given tacrolimus and mycophenolate mofetil in a steroid-free regimen, in sensitized patients with pre-formed alloantibodies and/or a positive donor-specific crossmatch, and in ABO-incompatible pHTx. Registry and clinical data have indicated no increased risk of infection or post-transplant lymphoproliferative disorder in children given rATG after pHTx. A total rATG dose in the range 3.5–7.5 mg/kg is advisable.

Combined Heart Lung Transplantation: An Updated Review of the Current Literature

Heart lung transplantation is a viable treatment option for patients with many end-stage heart and lung pathologies. However, given the complex nature of the procedure, it is imperative that patients are selected appropriately, and the clinician is aware of the many unique aspects in management of this population. This review seeks to describe updated organ selection policies, perioperative and postoperative management strategies, monitoring of graft function, and clinical outcomes for patients after combined heart-lung transplantation in the current era.

Postoperative management of heart transplantation patients

Heart transplant recipients are at risk for a number of post-transplantation complications such as graft dysfunction, rejection, and infection. The rates of many complications are decreasing over time, and prognosis is improving. However, these patients continue to experience significant morbidity and mortality. This review focuses on the optimal management of heart transplant recipients in the postoperative period, based on current knowledge. More information is needed about the best ways to predict, prevent, and treat primary graft dysfunction, right ventricular failure, and cellular and antibody-mediated rejection.

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.

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.

Desensitization Strategies Pre- and Post-Cardiac Transplantation

OPINION STATEMENT

Panel reactive antibody (PRA) testing has become standard in the evaluation of patients prior to cardiac transplant. Sensitizing events such as blood transfusions, which result in the accumulation of pre-transplant antibodies, should be avoided as clinically feasible. Desensitization therapy might be considered in sensitized patients with cPRA > 50 % although distinct cutoff PRA values for initiating therapy pre-transplant are patient and transplant program dependent. Post-cardiac transplant, quantitative antibodies should also be periodically analyzed, at intervals individualized to the patient. Donor-specific antibodies (DSA) after cardiac transplantation have been shown to be associated with worsened survival. It appears that complement fixing DSA confer the greatest risk for antibody-mediated rejection post-transplant. Desensitization strategies aim to reduce the number of clinically important antibodies prior to and after transplant, both by removal of antibodies and cessation of further production. Current desensitization regimens include pharmacologic, procedural, and surgical modalities, and must be individualized to the patient. Currently, most cardiac transplant programs tailor the post-transplant immunosuppressive regimen based on clinical factors and immunologic assays and may include the use of cytolytic induction and/or intravenous immune gammaglobulin in higher risk patients.

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.