Impact of induction immunosuppression on survival in heart transplant recipients: a contemporary analysis of agents

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.

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

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

Induction immunosuppression and post-transplant diabetes mellitus: a propensity-matched cohort study

Introduction

Post-transplant diabetes mellitus (PTDM) is a common complication among cardiac transplant recipients, causing diabetes-related complications and death. While certain maintenance immunosuppressive drugs increase PTDM risk, it is unclear whether induction immunosuppression can do the same. Therefore, we evaluated whether induction immunosuppression with IL-2 receptor antagonists, polyclonal anti-lymphocyte antibodies, or Alemtuzumab given in the peri-transplant period is associated with PTDM.

Methods

We used the Scientific Registry of Transplant Recipients database to conduct a cohort study of US adults who received cardiac transplants between January 2008-December 2018. We excluded patients with prior or multiple organ transplants and those with a history of diabetes, resulting in 17,142 recipients. We created propensity-matched cohorts (n=7,412) using predictors of induction immunosuppression and examined the association between post-transplant diabetes and induction immunosuppression by estimating hazard ratios using Cox proportional-hazards models.

Results

In the propensity-matched cohort, the average age was 52.5 (SD=13.2) years, 28.7% were female and 3,706 received induction immunosuppression. There were 867 incident cases of PTDM during 26,710 person-years of follow-up (32.5 cases/1,000 person-years). There was no association between induction immunosuppression and post-transplant diabetes (Hazard Ratio= 1.04, 95% confidence interval 0.91 - 1.19). Similarly, no associations were observed for each class of induction immunosuppression agents and post-transplant diabetes.

Conclusion

The use of contemporary induction immunosuppression in cardiac transplant patients was not associated with post-transplant diabetes.

Basiliximab induction versus no induction in adult heart transplantation

BACKGROUND

Induction immunosuppression in heart transplant recipients varies greatly by center. Basiliximab (BAS) is the most commonly used induction immunosuppressant but has not been shown to reduce rejection or improve survival. The objective of this retrospective study was to compare rejection, infection, and mortality within the first 12 months following heart transplant in patients who received BAS or no induction.

METHODS

This was a retrospective cohort study of adult heart transplant recipients given BAS or no induction from January 1, 2017 to May 31, 2021. The primary endpoint was incidence of treated acute cellular rejection (ACR) at 12-months post-transplant. Secondary endpoints included ACR at 90 days post-transplant, incidence of antibody-mediated rejection (AMR) at 90 days and 1 year, incidence of infection, and all-cause mortality at 1 year.

RESULTS

A total of 108 patients received BAS, and 26 patients received no induction within the specified timeframe. There was a lower incidence of ACR within the first year in the BAS group compared to the no induction group (27.7 vs. 68.2%, p < .002). BAS was independently associated with a lower probability of having a rejection event during the first 12-months post-transplant (hazard ratio (HR) .285, 95% confidence interval [CI] .142-.571, p < .001). There was no difference in the rate of infection and in mortality after hospital discharge at 1-year post-transplant (6% vs. 0%, p = .20).

CONCLUSION

BAS appears to be associated with greater freedom from rejection without an increase in infections. BAS may be a preferred to a no induction strategy in patients undergoing heart transplantation.

Post-transplant mortality and graft failure after induction immunosuppression among Black heart transplant recipients in the United States

Black heart transplant recipients are more likely to receive induction immunosuppression compared to other races because of higher rates of acute rejection, graft failure, and mortality. However, it is not known whether contemporary induction immunosuppression improves their post-transplant outcomes. To evaluate whether Black patients who were prescribed induction immunosuppression therapy have lower all-cause mortality or graft-failure rates compared to those who were not, we studied Black U.S. adult heart transplant recipients in the Scientific Registry of Transplant Recipients database (2008-2018). We used multivariable Cox proportional hazards regression analysis to compare the hazards of all-cause mortality or graft failure as a composite, for patients who were prescribed induction immunosuppression and those who were not. Among 5160 recipients, 2787 (54.0%) were prescribed induction immunosuppression and 2373 (46.0%) were not. There was no evidence of survival differences according to induction immunosuppression for the composite of all-cause mortality or graft failure (aHR = 1.13, 95% CI 0.96-1.32), mortality (aHR = 1.14, 95% CI 0.97-1.34), graft failure (aHR = 1.05, 95% CI 0.82-1.34) and acute rejection (aHR = 1.00, 95% CI 0.89-1.12). Given the side effects of treatment, future guidelines should reconsider the recommendation for induction immunosuppression among Black 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.

Use of induction therapy in pediatric heart transplant recipients in Switzerland - Analysis of the Swiss national database

BACKGROUND

Data on individualized immunosuppressive protocols for the pediatric heart recipients are missing in Europe. To contribute to this very small but specialized field, we describe the use of induction therapy (IT) in pediatric heart transplant patients in Switzerland and the retrospective outcomes.

METHOD

This is a retrospective national database analysis of children <19 years of age at time of heart transplantation (HT) from 05/2008-01/2018. Use of IT or no IT, use of steroids, calculated panel reactive antibodies (cPRA) and outcomes (Mortality, post-transplant lymphoproliferative disease (PTLD), rejection rates) were studied within a mean follow-up period of 2.9 years (0.2-8.1 years).

RESULTS

All 32 patients (12♂, 20♀), median age at HT of 6.4 years (24 days - 18 years) received IT using either polyclonal antibodies (ATG; 72%) or interleukin-2 receptor antagonist (anti-IL-2R mAb; 28%). Length of treatment was median of 4 (1-63) days. At time of HT all patients received steroids, while at discharge 32% and one year after HT 19%. Kaplan-Meier analysis of survival revealed a one-year survival of 86%. Three out of 7 patients with elevated cPRA (43%) died. Median time to first treated rejection was 19.4 months (±60.5 SD) without significant difference if treated with anti-IL-2R mAb or ATG (p:0.5). No development of PTLD, chronic renal failure needing ongoing renal replacement therapy or diabetes mellitus were recorded.

DISCUSSION

This is the first report of the national practice use of IT within Switzerland. It reveals a high use of IT, no development of PTLD and a low use of steroids at one-year post HT.

Impact of induction therapy on outcomes after heart transplantation

BACKGROUND

Approximately 50% of heart transplant (HT) programs utilize induction therapy (IT) with interleukin-2 receptor antagonists (IL2RA) or polyclonal anti-thymocyte antibodies (ATG).

METHODS

Adult HT recipients were identified in the UNOS Registry between 2010 and 2020. We compared mortality between IT strategies with competing risk analysis.

RESULTS

A total of 28 634 HT recipients were included in the study (50.1% no IT, 21.3% ATG, 27.9% IL2RA, .7% alemtuzumab, .01% OKT3). Adjusted all-cause, 30 day and 1 year mortality were lower among those treated with IT than no IT (sub-hazard ratio [SHR] .87, 95% CI .79-.96, SHR .86, .76-.97, SHR .76, .63-.93, P = .007, respectively). In propensity score matching analysis IT was associated with lower 30-day and 1-year mortality. IL2RA had higher all-cause and 1-year mortality than ATG (SHR 1.41, 95% CI 1.23-1.69 and 1.55, 95% CI 1.29-1.88, respectively). Utilization of IT was associated with significantly lower risk of treated rejection at 1 year after HT compared with no IT (relative risk ratio [RRR] .79) and similarly ATG compared with IL2RA (RRR .51).

CONCLUSION

IT was associated with lower mortality and treated rejection episodes than no IT. IL2RA is the most used IT approach but ATG has lower risk of treated rejection and mortality.

Outcomes Following ATG Therapy for Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) is the major factor limiting survival post lung transplantation (LTx) with limited effective therapeutic options. We report our 12-y experience of antithymocyte globulin (ATG) as second-line CLAD therapy.

Immunosuppression trends in solid organ transplantation: The future of individualization, monitoring, and management

Immunosuppression regimens used in solid organ transplant have evolved significantly over the past 70 years in the United States. Early immunosuppression and targets for allograft success were measured by incidence and severity of allograft rejection and 1-year patient survival. The limited number of agents, infancy of human leukocyte antigen (HLA) matching techniques and lack of understanding of immunoreactivity limited the early development of effective regimens. The 1980s and 1990s saw incredible advancements in these areas, with acute rejection rates halving in a short span of time. However, the constant struggle to achieve the optimal balance between under- and overimmunosuppression is weaved throughout the history of transplant immunosuppression. The aim of this paper is to discuss the different eras of immunosuppression and highlight the important milestones that were achieved while also discussing this in the context of rational agent selection and regimen design. This discussion sets the stage for how we can achieve optimal long-term outcomes during the next era of immunosuppression, which will move from universal protocols to patient-specific optimization.

Nationwide variability in the use of induction immunosuppression for adult heart transplantation

BACKGROUND

Institutional factors have been shown to impact outcomes following orthotopic heart transplantation (OHT). This study evaluated center variability in the utilization of induction therapy for OHT and its implications on clinical outcomes.

METHODS

Adult OHT patients between 2010 and 2018 were identified from the United Network for Organ Sharing registry. Transplant centers were stratified based on their rates of induction therapy utilization. Mixed-effects logistic regression models were created with drug-treated rejection within 1 year as primary endpoint and individual centers as a random parameter. Risk-adjusted Cox regression was used to evaluate patient-level mortality outcomes.

RESULTS

In 17,524 OHTs performed at 100 centers, induction therapy was utilized in 48.6% (n = 8411) with substantial variability between centers (interquartile range, 21.4%-79.1%). There were 36, 30, and 34 centers in the low (<29%), intermediate (29%-66%), and high (>67%) induction utilization terciles groups, respectively. Induction therapy did not account for the observed variability in the treated rejection rate at 1 year among centers after adjusting for donor and recipient factors (p = .20). No differences were observed in postoperative outcomes among induction utilization centers groups (all, p > .05). Furthermore, there was a weak correlation between the percentage of induction therapy utilization at the center-level and recipients found to have moderate (r = .03) or high (r = .04) baseline risks for acute rejection at 1 year.

CONCLUSIONS

This analysis demonstrates that there is substantial variability in the use of induction therapy among OHT centers. In addition, there was a minimal correlation with baseline recipient risk or 1-year rejection rates, suggesting a need for better-standardized practices for induction therapy use in OHT.

Impact of Induction Immunosuppression on Post-Transplant Outcomes of Patients Bridged with Contemporary Left Ventricular Assist Devices

For patients bridged to transplant (BTT) with left ventricular assist devices (LVAD), data regarding the use of induction immunosuppressive therapy remain limited. The objectives of the current study were to describe the current trends and clinical consequences of IT in patients BTT with LVAD. The United Network of Organ Sharing database was queried to identify adult, single-organ heart transplant recipients who were BTT with LVAD between 2008 and 2018. Propensity score matching was then used to balance clinical covariates between those patient who did and did not receive IT. The primary outcomes of interest were graft survival, hospitalization for rejection and infection, and freedom from transplant coronary artery disease (TCAD). In the overall cohort, 49.1% (n = 3,978) received IT, with basiliximab being the most commonly used agent followed by antithymocyte globulin. After propensity score matching, 4,388 patients (2,194 without induction and 2,194 with induction) were identified. Between those who did and did not receive IT, there was no significant difference in graft survival, freedom from hospitalization for rejection, and freedom from hospitalization for infection. Patients who received IT experienced increased freedom from TCAD (p = 0.004) with unadjusted hazard ratio of 0.81 (95% Cardiac Index: 0.70-0.93). For freedom from TCAD, antithymocyte globulin was associated with better outcomes than basiliximab (80.2% vs. 73.1% at 5 years, log rank p value = 0.004). In a sensitivity analysis, there was no significant increase in hospitalization for infection in those patients with an infected LVAD before transplant. Use of induction therapy in patients BTT with LVAD appears to be safe and feasible, without a significant increase in the risk of infection or rejection, even in those patients with pretransplant device-related infections. IT, particularly antithymocyte globulin, was associated with increased time to development of TCAD. Routine use of IT in patients BTT with LVAD may be considered, and further randomized control trials are warranted to further support these data.

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.

Incidence of cytomegalovirus in cardiac transplant recipients receiving induction immunosuppression with antithymocyte globulin

BACKGROUND

Cytomegalovirus (CMV) is a major cause of morbidity and mortality in cardiac transplant recipients. Use of induction immunosuppression in cardiac transplantation may have an impact on the incidence of CMV, but literature is limited.

METHODS

Single-center, retrospective cohort study comparing the risk of CMV infection and disease in cardiac transplant patients receiving antithymocyte globulin (ATG) induction therapy to those receiving no antibody induction.

RESULTS

A total of 75 patients were included in our analysis, 50 who received ATG induction and 25 who did not. CMV infection occurred in 10 (20%) and 5 (20%) patients in the ATG and No ATG groups, respectively (P > 0.99). CMV disease occurred in 10 (20%) and 4 (16%) patients in the ATG and No ATG groups, respectively (P = 0.763). The median time from transplant to CMV infection was 200.0 [142.5, 364.5] days in the ATG group vs 221.0 [192.0, 299.0] days in the No ATG group (P = 0.723). The median time from end of CMV prophylaxis to CMV infection was 94.5 [66.5, 151.0] days in the ATG group vs 53.0 [41.0,149.5] days in the No ATG group (P = 0.202). Freedom from CMV infection was highest in the D+/R+ group and lowest in the D+/R- group.

CONCLUSION

In cardiac transplant recipients, ATG induction was not associated with an increased incidence of CMV infection or disease in the setting of valganciclovir prophylaxis and an initial maintenance immunosuppression regimen of primarily steroids, mycophenolate mofetil, and tacrolimus.

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.

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.

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.