Outcomes Associated with Steroid Avoidance and Alemtuzumab among Kidney Transplant Recipients

The use of lymphocyte-depleting antibodies in specific populations of kidney transplant recipients: A systematic review and meta-analysis

BACKGROUND

Recommendations of the use of antibody induction treatments in kidney transplant recipients (KTR) are based on moderate quality and historical studies. This systematic review aims to reevaluate, based on actual studies, the effects of different antibody preparations when used in specific KTR subgroups.

METHODS

We searched MEDLINE and CENTRAL and selected randomized controlled trials (RCT) and observational studies looking at different antibody preparations used as induction in KTR. Comparisons were categorized into different KTR subgroups: standard, high risk of rejection, high risk of delayed graft function (DGF), living donor, and elderly KTR. Two authors independently assessed the risk of bias.

RESULTS

Thirty-seven RCT and 99 observational studies were finally included. Compared to anti-interleukin-2-receptor antibodies (IL2RA), anti-thymocyte globulin (ATG) reduced the risk of acute rejection at two years in standard KTR (RR 0.74, 95%CI 0.61-0.89) and high risk of rejection KTR (RR 0.55, 95%CI 0.43-0.72), but without decreasing the risk of graft loss. We did not find significant differences comparing ATG vs. alemtuzumab or different ATG dosages in any KTR group.

CONCLUSIONS

Despite many studies carried out on induction treatment in KTR, their heterogeneity and short follow-up preclude definitive conclusions to determine the optimal induction therapy. Compared with IL2RA, ATG reduced rejection in standard-risk, highly sensitized, and living donor graft recipients, but not in high DGF risk or elderly recipients. More studies are needed to demonstrate beneficial effects in other KTR subgroups and overall patient and graft survival.

Preoperative CD52 Level Predicts Graft Survival following Kidney Transplantation

Several factors have been reported to affect graft survival following kidney transplantation. CD52 molecules may increase T cell proliferation and activation, which may contribute to acute graft rejection and graft survival. In the current study, we studied the possible value of preoperative CD52 levels in predicting graft survival following renal transplantation. Ninety-six patients with end-stage renal disease who had kidney transplantation were included in the study from our prospective cohort. Blood samples were taken one day before surgery, and plasma CD52 levels were measured using ELISA (Cloud-Clone Corp., Houston, TX, USA). Acute rejection, acute tubular necrosis, delayed graft function, graft loss, BK infection, cytomegalovirus infection, and graft survival were evaluated. The mean age of recipients was $50.08\pm 12.82\text{years}$ , and 64.6% were male. The incidence of delayed graft function, acute rejection, graft loss ( $p<0.01$ ), BK virus infection, and serum creatinine levels were significantly higher in recipients with high preoperative CD52 levels six months after transplantation ( $p<0.05$ ). Kaplan–Meier analysis revealed that three-year graft survival was significantly higher in patients with low preoperative CD52 levels ( $p<0.0001$ ). Univariate and multivariate Cox regression analyses showed that serum creatinine levels ( $\text{hazard}\text{ratio}\left[\text{HR}\right]=1.7$ , $p<0.05$ ), acute rejection ( $\text{HR}=2.919$ , $p<0.05$ ), and preoperative CD52 levels ( $\text{HR}=3.114$ , $p<0.05$ ) were independent prognostic factors for graft survival after kidney transplantation. We showed that high preoperative CD52 levels are associated with higher rates of acute rejection, delayed graft function, and BK virus infection and lower rates of graft survival after kidney transplantation.

Steroid avoidance/withdrawal and maintenance immunosuppression in pediatric kidney transplantation

BACKGROUND

Corticosteroids have been an integral part of maintenance immunosuppression for pediatric kidney transplantation. However, prolonged steroid therapy is associated with significant toxicities resulting in several SW/avoidance strategies in recent years.

METHOD/OBJECTIVE

This comprehensive review aims to discuss steroid-related toxicities and the safety, efficacy, and benefit of steroid avoidance/withdrawal immunosuppression in pediatric kidney transplant recipients.

RESULTS

Initial studies of SW/avoidance conducted in the setting of CSA and AZA showed an increased incidence of AR but no increase in graft loss or mortality with SW/avoidance maintenance immunosuppression. Studies performed under modern immunosuppression (induction therapy, Tac, and MMF) show no significant increase in AR or graft loss with SW/avoidance immunosuppression. Furthermore, SW/avoidance immunosuppression is associated with significant improvement in growth, BMI, BP control, and lipid profile in pediatric kidney transplant recipients. Despite these data, SW/avoidance remains controversial, and only 40% of pediatric kidney transplant recipients in the United States are currently on SW/avoidance maintenance immunosuppression.

CONCLUSION

SW/avoidance maintenance immunosuppression is safe and associated with fewer side effects compared with steroid-inclusive maintenance immunosuppression in pediatric kidney transplant recipients.

Center practice drives variation in choice of US kidney transplant induction therapy: a retrospective analysis of contemporary practice

To assess factors that influence the choice of induction regimen in contemporary kidney transplantation, we examined center-identified, national transplant registry data for 166 776 US recipients (2005-2014). Bilevel hierarchical models were constructed, wherein use of each regimen was compared pairwise with use of interleukin-2 receptor blocking antibodies (IL2rAb). Overall, 82% of patients received induction, including thymoglobulin (TMG, 46%), IL2rAb (22%), alemtuzumab (ALEM, 13%), and other agents (1%). However, proportions of patients receiving induction varied widely across centers (0-100%). Recipients of living donor transplants and self-pay patients were less likely to receive induction treatment. Clinical factors associated with use of TMG or ALEM (vs. IL2rAb) included age, black race, sensitization, retransplant status, nonstandard deceased donor, and delayed graft function. However, these characteristics explained only 10-33% of observed variation. Based on intraclass correlation analysis, "center effect" explained most of the variation in TMG (58%), ALEM (66%), other (51%), and no induction (58%) use. Median odds ratios generated from case-factor adjusted models (7.66-11.19) also supported large differences in the likelihood of induction choices between centers. The wide variation in induction therapy choice across US transplant centers is not dominantly explained by differences in patient or donor characteristics; rather, it reflects center choice and practice.

Analysis of Risk Factors for Kidney Retransplant Outcomes Associated with Common Induction Regimens: A Study of over Twelve-Thousand Cases in the United States

We studied registry data of 12,944 adult kidney retransplant recipients categorized by induction regimen received into antithymocyte globulin (ATG) (N = 9120), alemtuzumab (N = 1687), and basiliximab (N = 2137) cohorts. We analyzed risk factors for 1-year acute rejection (AR) and 5-year death-censored graft loss (DCGL) and patient death. Compared with the reference, basiliximab: (1) one-year AR risk was lower with ATG in retransplant recipients of expanded criteria deceased-donor kidneys (HR = 0.56, 95% CI = 0.35-0.91 and HR = 0.54, 95% CI = 0.27-1.08, resp.), while AR risk was lower with alemtuzumab in retransplant recipients with >3 HLA mismatches before transplant (HR = 0.63, 95% CI = 0.44-0.93 and HR = 0.81, 95% CI = 0.63-1.06, resp.); (2) five-year DCGL risk was lower with alemtuzumab, not ATG, in retransplant recipients of African American race (HR = 0.54, 95% CI = 0.34-0.86 and HR = 0.73, 95% CI = 0.51-1.04, resp.) or with pretransplant glomerulonephritis (HR = 0.65, 95% CI = 0.43-0.98 and HR = 0.82, 95% CI = 0.60-1.12, resp.). Therefore, specific risk factor-induction regimen combinations may predict outcomes and this information may help in individualizing induction in retransplant recipients.

Comparing Outcomes between Antibody Induction Therapies in Kidney Transplantation

Kidney transplant recipients often receive antibody induction. Previous studies of induction therapy were often limited by short follow-up and/or absence of information about complications. After linking Organ Procurement and Transplantation Network data with Medicare claims, we compared outcomes between three induction therapies for kidney recipients. Using novel matching techniques developed on the basis of 15 clinical and demographic characteristics, we generated 1:1 pairs of alemtuzumab-rabbit antithymocyte globulin (rATG) (5330 pairs) and basiliximab-rATG (9378 pairs) recipients. We used paired Cox regression to analyze the primary outcomes of death and death or allograft failure. Secondary outcomes included death or sepsis, death or lymphoma, death or melanoma, and healthcare resource utilization within 1 year. Compared with rATG recipients, alemtuzumab recipients had higher risk of death (hazard ratio [HR], 1.14; 95% confidence interval [95% CI], 1.03 to 1.26; P<0.01) and death or allograft failure (HR, 1.18; 95% CI, 1.09 to 1.28; P<0.001). Results for death as well as death or allograft failure were generally consistent among elderly and nonelderly subgroups and among pairs receiving oral prednisone. Compared with rATG recipients, basiliximab recipients had higher risk of death (HR, 1.08; 95% CI, 1.01 to 1.16; P=0.03) and death or lymphoma (HR, 1.12; 95% CI, 1.01 to 1.23; P=0.03), although these differences were not confirmed in subgroup analyses. One-year resource utilization was slightly lower among alemtuzumab recipients than among rATG recipients, but did not differ between basiliximab and rATG recipients. This observational evidence indicates that, compared with alemtuzumab and basiliximab, rATG associates with lower risk of adverse outcomes, including mortality.