Age, exclusion criteria, and generalizability of randomized trials enrolling kidney transplant recipients

Assessing Long-Term Adverse Outcomes in Older Kidney Transplant Recipients: A Propensity Score-Matched Comparison of Early Steroid Withdrawal Versus Continuous Steroid Immunosuppression Using a Large Real-World Database

BACKGROUND

Steroids are widely used in maintenance immunosuppression treatment in kidney transplant recipients. Older individuals undergo age-related immunosenescence that consequently decreases their ability to process and evoke a response to foreign antigens. Thus, steroids may not be necessary in preventing allograft rejection and may consequently increase older recipients' risk of long-term steroid-related adverse effects.

OBJECTIVE

The objective of this study was to analyze the adverse outcomes of long-term steroid immunosuppression in older kidney transplant recipients using real-world electronic medical record data.

METHODS

The TriNetX database "US Collaborative Network" was utilized to perform a propensity score-matched case-control study comparing 1-year, 3-year, and 5-year adverse effects of steroid immunosuppression in older adults (aged ≥ 65 years) kidney transplant recipients who underwent either an early-steroid withdrawal (ESW) maintenance regimen or a steroid continuous immunosuppression (SCI) regimen between 31 December, 2010 and 31 December, 2020. Early-steroid withdrawal was defined as tacrolimus plus mycophenolate mofetil maintenance with no prednisone after the seventh day post-transplant. Steroid continuous immunosuppression was defined as tacrolimus plus mycophenolate mofetil plus prednisone maintenance. Cohorts were matched on age, race/ethnicity, and risk factors for adverse steroid-related outcomes and rejection. Outcomes included post-transplant diabetes mellitus, dyslipidemia osteoporosis/fractures, myocardial infarction, glaucoma/cataract, stroke, pulmonary embolism, and malignancy. Secondary outcomes analyzed incidences of infection-related outcomes, graft-related outcomes, and recipient mortality.

RESULTS

After matching, there were 304 recipients in each group (ESW, SCI). Mean age at the time of transplant was 69.2 ± 3.7 years (ESW) and 69.2 ± 3.4 years (SCI, p = 0.96). The Kaplan-Meier analysis showed recipients who underwent SCI had increased incidences of post-transplant diabetes mellitus at 1 year (22.36% vs 30.37%, p = 0.01) and 3 years (34.89% vs 44.29%, p = 0.01), but this became non-significant at 5 years post-transplant (41.97% vs 42.6%, p = 0.34). Incidences of acute pancreatitis were higher for the SCI cohort at 3 years (p = 0.02) as well as incidences of acute myocardial infarction at 5 years post-kidney transplant (6.75% vs 14.39%, p < 0.01). No difference was found for other adverse outcomes. Early-steroid withdrawal recipients experienced significantly fewer infection-related outcomes, such as cytomegalovirus, BK virus, sepsis/bacteremia, and fungal infections, compared with SCI recipients. Last, recipients who underwent ESW experienced fewer incidences of rejection and death-censored graft failure at 5 years post-transplant.

CONCLUSIONS

There is currently no standard maintenance immunosuppression protocol for older kidney transplant recipients. Death-censored graft survival, rejection, and patient survival were improved with ESW. Steroid minimization may be beneficial in this population given that it lowers the risk of drug-induced adverse effects.

Impact of Immunosenescence in Older Kidney Transplant Recipients: Associated Clinical Outcomes and Possible Risk Stratification for Immunosuppression Reduction

The number of older individuals receiving a kidney transplant as replacement therapy has significantly increased in the past decades and this increase is expected to continue. Older patients have a lower rate of acute rejection but an increased incidence of death with a functioning graft. Several factors, including an increased incidence of infections, post-transplant malignancy and cardiovascular comorbidity and mortality, contribute to this increased risk. Notwithstanding, kidney transplantation is still the best form of kidney replacement therapy in all patients with chronic kidney disease, including in older individuals. The best form of immunosuppression and the optimal dose of these medications in older recipients remains a topic of discussion. Pharmacological studies have usually excluded older patients and when included, patients were highly selected and their numbers insignificant to draw a reasonable conclusion. The reduced incidence of acute rejection in older recipients has largely been attributed to immunosenescence. Immunosenescence refers to the aging of the innate and adaptive immunity, accumulating in phenotypic and functional changes. These changes influences the response of the immune system to new challenges. In older individuals, immunosenescence is associated with increased susceptibility to infectious pathogens, a decreased response after vaccinations, increased risk of malignancies and cardiovascular morbidity and mortality. Chronic kidney disease is associated with premature immunosenescent changes, and these are independent of aging. The immunosenescent state is associated with low-grade sterile inflammation termed inflammaging. This chronic low-grade inflammation triggers a compensatory immunosuppressive state to avoid further tissue damage, leaving older individuals with chronic kidney disease in an immune-impaired state before kidney transplantation. Immunosuppression after transplantation may further enhance progression of this immunosenescent state. This review covers the role of immunosenescence in older kidney transplant recipients and it details present knowledge of the changes in chronic kidney disease and after transplantation. The impact of immunosuppression on the progression and complications of an immunosenescent state are discussed, and the future direction of a possible clinical implementation of immunosenescence to individualize/reduce immunosuppression in older recipients is laid out.

Treatment decision-making and care among older adults with kidney failure: protocol for a multicentre, prospective observational cohort study with nested substudies and linked qualitative research (the Elderly Advanced CKD Programme)

INTRODUCTION

Shared treatment decision-making and planning of care are fundamental in advanced chronic kidney disease (CKD) management. There are limited data on several key outcomes for the elderly population including survival, quality of life, symptom burden, changes in physical functioning and experienced burden of healthcare. Patients, caregivers and clinicians consequently face significant uncertainty when making life-impacting treatment decisions. The Elderly Advanced CKD Programme includes quantitative and qualitative studies to better address challenges in treatment decision-making and planning of care among this increasingly prevalent elderly cohort.

METHODS AND ANALYSIS

The primary component is OUTcomes of Older patients with Kidney failure (OUTLOOK), a multicentre prospective observational cohort study that will enrol 800 patients ≥75 years with kidney failure (estimated glomerular filtration rate ≤15 mL/min/1.73 m2) across a minimum of six sites in Australia. Patients entered are in the decision-making phase or have recently made a decision on preferred treatment (dialysis, conservative kidney management or undecided). Patients will be prospectively followed until death or a maximum of 4 years, with the primary outcome being survival. Secondary outcomes are receipt of short-term acute dialysis, receipt of long-term maintenance dialysis, changes in biochemistry and end-of-life care characteristics. Data will be used to formulate a risk prediction tool applicable for use in the decision-making phase. The nested substudies Treatment modalities for the InfirM ElderLY with end stage kidney disease (TIMELY) and Caregivers of The InfirM ElderLY with end stage kidney disease (Co-TIMELY) will longitudinally assess quality of life, symptom burden and caregiver burden among 150 patients and 100 caregivers, respectively. CONsumer views of Treatment options for Elderly patieNts with kiDney failure (CONTEND) is an additional qualitative study that will enrol a minimum of 20 patients and 20 caregivers to explore experiences of treatment decision-making and care.

ETHICS AND DISSEMINATION

Ethics approval was obtained through Sydney Local Health District Human Research Ethics Committee (2019/ETH07718, 2020/ETH02226, 2021/ETH01020, 2019/ETH07783). OUTLOOK is approved to have waiver of individual patient consent. TIMELY, Co-TIMELY and CONTEND participants will provide written informed consent. Final results will be disseminated through peer-reviewed journals and presented at scientific meetings.

Improving Cancer Care for Patients With CKD: The Need for Changes in Clinical Trials

Chemotherapeutic agents used to treat cancer generally have narrow therapeutic indices along with potentially serious adverse toxicities. Many cancer drugs are at least partially excreted through the kidney and, thus, the availability of accurate data on safe and effective dosing of these drugs in patients with chronic kidney disease (CKD) is essential to guide treatment decisions. Typically, during drug development, initial clinical studies only include patients with normal or only mildly impaired kidney function. In subsequent preregistration studies, a limited number of patients with more severe kidney dysfunction are included. Data obtained from patients with either severe kidney dysfunction (here defined as an estimated glomerular filtration rate [eGFR] < 30 ml/min or stage 4G CKD) or end-stage kidney disease (ESKD) requiring kidney replacement treatment are particularly limited before drug registration and only a minority of new drug applications to the US Food and Drug Administration (FDA) include data from this population. Unfortunately, limited data and/or other safety concerns may result in a manufacturer statement that the drug is contraindicated in patients with advanced kidney disease, which hinders access to potentially beneficial drugs for these patients. This systemic exclusion of patients with CKD from cancer drug trials remains an unsolved problem, which prevents provision of optimal clinical care for these patients, raises questions of inclusion, diversity, and equity. In addition, with the aging of the population, there are increasing numbers of patients with CKD and cancer who face these issues. In this review, we evaluate the scientific basis to exclude patients with CKD from cancer trials and propose a comprehensive strategy to address this problem.

Immunosuppression Considerations for Older Kidney Transplant Recipients

PURPOSE OF REVIEW

While kidney transplantation improves the long-term survival of the majority of patients with end-stage kidney disease (ESKD), age-related immune dysfunction and associated comorbidities make older transplant recipients more susceptible to complications related to immunosuppression. In this review, we discuss appropriate management of immunosuppressive agents in older adults to minimize adverse events, avoid acute rejection, and maximize patient and graft survival.

RECENT FINDINGS

Physiological changes associated with senescence can impact drug metabolism and increase the risk of posttransplant infection and malignancy. Clinical trials assessing the safety and efficacy of immunosuppressive agents in older adults are lacking. Recent findings from U.S. transplant registry-based studies suggest that risk-adjusted death-censored graft failure is higher among older patients who received antimetabolite avoidance, mammalian target of rapamycin inhibitor (mTORi)-based, and cyclosporine-based regimens. Observational data suggest that risk-adjusted mortality may be increased in older patients who receive mTORi-based and cyclosporine-based regimens but lower in those managed with T-cell induction and maintenance steroid avoidance/withdrawal.

SUMMARY

Tailored immunosuppression management to improve patient and graft survival in older transplant recipients is an important goal of personalized medicine. Lower intensity immunosuppression, such as steroid-sparing regimens, appear beneficial whereas mTORi- and cyclosporine-based maintenance are associated with greater potential for adverse effects. Prospective clinical trials to assess the safety and efficacy of immunosuppression agents in older recipients are urgently needed.

CTLA4-Ig prolongs graft survival specifically in young but not old mice

Elderly organ transplant recipients have remained underrepresented in clinical trials, despite representing a rapidly growing population. Here, we assessed age-specific effects of CTLA4-Ig (cytotoxic T-lymphocyte antigen 4-Ig), a fusion protein blocking costimulatory signaling between antigen-presenting cells and T cells through CD28. Cardiac allografts in young mice (2-3 months) treated with CTLA4-Ig survived indefinitely, whereas 80% of old recipients (18 months) had lost their graft after 100 days. CTLA4-Ig was also significantly less effective in older recipients of skin transplants. CTLA4-Ig reduced CD4⁺ central memory and effector memory T cells and diminished systemic interferon-gamma levels only in young recipients. These differences corresponded to a reduced expression of CD28 on antigen-experienced CD4⁺ T cells in old mice. In support, adoptive transfer of old CD4⁺ T cells that were transfected with a lentiviral vector inducing constant expression of CD28 accelerated the rejection of allogeneic skin grafts in young RAG2^-/- recipient mice. Regulatory T cells (Tregs), in contrast, demonstrated an increased expression of CD28 with aging and CTLA4-Ig treatment in old recipients resulted in reduced frequencies, compromised proliferation, and diminished suppressive capacity of Tregs. These findings may prove to have unique clinical consequences for immunosuppression in the growing population of elderly transplant recipients.

Predictive tools to determine risk of infection in kidney transplant recipients

Introduction: Infection represents a major complication after kidney transplantation (KT). Therapeutic drug monitoring is essentially the only approach for the adjustment of immunosuppression in current practice, with suboptimal results. The implementation of immune monitoring strategies may contribute to minimizing the risk of adverse events attributable to over-immunosuppression without compromising graft outcomes.Areas covered: The present review (based on PubMed/MEDLINE searches from database inception to November 2019) is focused on immune biomarkers with no antigen specificity (non-pathogen-specific), including serum levels of immunoglobulins and complement factors, peripheral blood lymphocyte subpopulations, soluble CD30, intracellular ATP production by stimulated CD4⁺ T-cells, and other cell-based immune assays. We also summarized recent advances in the use of replication kinetics of latent viruses to assess the functionality of T-cell immunity, with focus on the nonpathogenic anelloviruses. Finally, the composite risk scores reported in the literature are critically discussed.Expert opinion: Notable efforts have been made to develop an enlarging repertoire of immune biomarkers and prediction models, although most of them still lack technical standardization and external validation. Preventive interventions based on these tools (prolongation of prophylaxis, tapering of immunosuppression, or immunoglobulin replacement therapy in hypogammaglobulinemic patients) remain to be defined, ideally in the context of controlled trials.

Representativeness of Randomized Clinical Trial Cohorts in End-stage Kidney Disease: A Meta-analysis

IMPORTANCE

Systematic differences between patients included in randomized clinical trials (RCTs) and the general patient population may influence the generalizability of RCT findings. Comprehensive national registries of patients with end-stage kidney disease who are undergoing dialysis provide a unique opportunity to compare trial and real-world patient cohorts.

OBJECTIVE

To determine if participants in large, multicenter dialysis trials were similar to the general population undergoing dialysis in terms of age, comorbidities, and mortality rate.

DATA SOURCES

MEDLINE, PubMed, and the Cochrane Central Register of Controlled Trials were systematically searched on January 6, 2017, for studies published from January 1, 2007, to December 31, 2016. Data sources were published manuscripts, supplementary material, and trial registration information. Data on the general population undergoing dialysis were derived from the US Renal Data System (USRDS). Data were analyzed from March 17 to July 22, 2018.

STUDY SELECTION

Randomized clinical trials enrolling only participants undergoing dialysis for end-stage kidney disease with 100 or more adult participants from 2 or more sites.

DATA EXTRACTION AND SYNTHESIS

Abstract screening and data extraction were performed independently by 2 researchers. Data were pooled using a random-effects model.

MAIN OUTCOMES AND MEASURES

The primary outcome was difference in mean age between the RCT and USRDS populations. Secondary outcomes included differences in mortality rate and comorbidities.

RESULTS

The search identified 186 RCTs, enrolling 79 104 participants. Compared with the 2011 USRDS population, RCT participants were younger (mean age, 58.9 years; 95% CI, 58.3-59.5 years vs 61.2 years; P < .001), more likely to be male (58.9%; 95% CI, 57.6%-60.1% vs 55.7%; P < .001), and have coronary artery disease (26.9%; 95% CI, 22.2%-31.7% vs 17.7%; P < .001) and less likely to have diabetes (40.2%; 95% CI, 36.7%-43.6% vs 44.2%; P = .03) or heart failure (19.6%; 95% CI, 15.1%-24.0% vs 29.8%; P < .001). The mortality rate per 100 patient-years during trial participation was less than half that of the USRDS population (8.9; 95% CI, 7.8-10.0 vs 18.6; P < .001). The differences in age, mortality, and coronary artery disease remained when studies recruiting only from the United States were considered. Diabetes was more common in RCT participants from the United States than in the registry population.

CONCLUSIONS AND RELEVANCE

Participants in large, multicenter RCTs of patients with end-stage kidney disease undergoing dialysis are younger, have a different pattern of comorbidities, and have a lower mortality rate than the general population of patients undergoing dialysis. This finding has implications for the generalization of trial results to the broader patient population and for future trial design.

Outcomes of sirolimus regimens in 65-year-old and older kidney transplant recipients: a registry-based observational study

PURPOSE

In large observational studies of adult kidney transplant recipients (KTRs) where older adults (65 years old and older) were not well represented, the mammalian target of rapamycin inhibitors (mTOR inhibitors) has poorer outcomes than the standard tacrolimus-mycophenolate-steroids (TAC-MPA-S) regimen. We conducted this study to compare the outcomes of regimens containing the common mTOR inhibitor, sirolimus (SRL) against TAC-MPA-S in older adult KTRs.

METHODS

Using the 2000-2016 Scientific Registry of Transplant Recipients, Cox multivariable regression models were conducted to analyze the patient and graft outcomes associated with regimens containing SRL, steroids (S) and cyclosporine (CSA), tacrolimus (TAC), or mycophenolate (MPA) vs. the standard (TAC-MPA-S) regimen in older adult KTRs.

RESULTS

Included in the analysis were 15,008 (95.19%) older adult KTRs on standard (TAC-MPA-S) regimen, 242 (1.53%) on SRL-MPA-S, 300 (1.90%) on SRL-TAC-S, and 217 (1.38%) on SRL-CSA-S. Compared with the standard regimen, the adjusted risks of all-cause death and overall graft loss over a maximum 5-year follow-up were highest with SRL-MPA-S, intermediate with SRL-TAC-S and not significantly different with SRL-CSA-S. The adjusted risks of all-cause death and overall graft loss were modified by a pre-transplant history of malignancy in older adult KTRs on SRL-TAC-S, not in those on SRL-MPA-S or SRL-CSA-S.

CONCLUSIONS

In older adult kidney transplant recipients, SRL-TAC-S or SRL-MPA-S, but not SRL-CSA-S is associated with higher risks of death and allograft loss than standard TAC-MPA-S regimen and a pre-transplant malignancy history worsens these risks in patients on SRL-TAC-S. Confirmation of our findings by a prospective randomized trial is needed before translation into clinical practice can be recommended.

Induction Therapy in Elderly Kidney Transplant Recipients With Low Immunological Risk

BACKGROUND

In nonimmunized patients, similar rejection rates are observed for patients who have undergone thymoglobulin (antithymocyte globulins [ATG]) or basiliximab (BSX) therapy. While ATG may improve delayed graft function, it may also be associated with higher infection rates and malignancy risk. We compared survival and clinical outcomes in elderly recipients with low immunological risk according to their induction therapy.

METHODS

We conducted a multicentric study on nonimmunized patients ≥65 years of age receiving a first kidney transplant between 2010 and 2017. The principal outcome was patient and graft survival. Secondary outcomes were cumulative probabilities of infection, first acute rejection episode, malignancy, de novo donor specific antibody, posttransplant diabetes (PTD), cardiac complications, estimated glomerular filtration rate, and occurrence of delayed graft function. Cox, logistic, or linear statistical models were used depending on the outcome studied, and models were weighted on the propensity scores.

RESULTS

Two hundred and four patients were included in the BSX group and 179 in the ATG group with the average age of 71.0 and 70.5 years, respectively. Patient and graft survival at 3 years posttransplantation were 74% (95% CI, 65%-84%) and 68% (95% CI, 60%-78%) in ATG and BSX group, respectively, without significant difference. Occurrence of PTD was significatively higher in BSX group (23% versus 15%, P = 0.04) due to higher trough levels of Tacrolimus on month 3 (9.48 versus 7.30 ng/mL, P = 0.023). There was no difference in other evaluated outcomes.

CONCLUSIONS

In elderly recipients, ATG does not lead to poorer outcomes compared with BSX and could permit lower trough levels of Tacrolimus, thus reducing occurrence of PTD.

Risk Factors for Early Graft Failure and Death After Kidney Transplantation in Recipients Older Than 70 Years

INTRODUCTION

Although kidney transplantation carries a survival benefit compared with dialysis, mortality, especially the first year after transplantation, is high in recipients older than 70. The aim of this study was to evaluate early death and graft failure, and to determine the risk factors associated with these events in this specific population.

METHODS

All patients older than 70 years who received a kidney transplant between January 2000 and December 2014 in the North-West of France were included (n = 171). Baseline characteristics and outcomes after transplantation were studied. Kaplan-Meier analysis was performed to assess patient and graft survival, and Cox regression analysis to evaluate risk factors for graft failure and patient death.

RESULTS

The mean recipient age was 73.3 ± 2.5 years. Death-censored graft survival at 1, 3, and 5 years were 82.6%, 78.7%, and 75.4%, respectively. Patient survival at 1, 3, and 5 years was 90.1%, 82.5%, and 68.1%, respectively. One year after transplantation, 17 patients (9.9%) were dead, mainly from infectious (58.5%) or cardiovascular disease (29.4%). According to the Cox multivariate analysis, the independent risk factors for death or graft failure during the first year were arrhythmia (odds ratio [OR] 2.26; 95% confidence interval [CI] 1.08-4.8), left-ventricular ejection fraction (LVEF) under 56% (OR 2.38; 95% CI 1.18-4.83), human leucocyte antigen (HLA) antibodies (OR 2.1; 95% CI 1.04-4.2), deceased donor from cardiovascular cause (OR 5.18; 95% CI 1.22-6.3), and acute rejection (OR 2.77; 95% CI 1.2-6.3).

CONCLUSION

In kidney transplant recipients older than 70 years, cardiac evaluation and immunosuppression optimization seem to be crucial to improve short-term patient and graft survival.

Rapamycin Prolongs Graft Survival and Induces CD4+IFN-γ+IL-10+ Regulatory Type 1 Cells in Old Recipient Mice

BACKGROUND

Although the elderly represents a rapidly growing population among transplant recipients, age-specific aspects have not been considered sufficiently in clinical trials. Moreover, age-specific effects of immunosuppressive therapies remain poorly understood.

METHODS

Here, we assessed the impact of rapamycin on alloimmune responses in old recipients using a fully major histocompatibility complex-mismatched murine transplantation model.

RESULTS

Old untreated recipients displayed a prolonged skin graft survival compared to their young counterparts, an observation that confirmed data of our previous experiments. Rapamycin led to a significant prolongation of graft survival in both young and old recipients. However, graft survival was age-dependent and extended in old versus young recipients (19 days vs 12 days, P = 0.004). This age-specific effect was not linked to changes in frequencies or subset composition of either cluster of differentiation (CD)8 or CD4 T cells. Moreover, antiproliferative effects of rapamycin on CD8 and CD4 T cells as assessed by in vivo bromdesoxyuridine incorporation were comparable and age-independent. In contrast, the systemic production of IL-10 was markedly elevated in old recipients treated with rapamycin. In parallel to this shift in cytokine balance, IFN-γ/IL-10 double-positive regulatory type 1 cells emerged during T helper type 1 differentiation of old T helper cells in presence of rapamycin. Similarly, CD4IFN-γIL-10 cells expanded among Foxp3-negative cells after in vivo treatment of old recipients with rapamycin.

CONCLUSIONS

Our results highlight novel aspects of age-dependent immunosuppressive effects of rapamycin, with relevance for age-specific immunosuppressive regimens.

Do clinical trials reflect reality? A systematic review of inclusion/exclusion criteria in trials of renal transplant immunosuppression

Renal transplant recipients and donors are becoming increasingly more marginal, with more expanded criteria (ECD) and donation after circulatory death (DCD) donors and older recipients. Despite this, high-risk donors and recipients are often excluded from clinical trials, leading to uncertainty about the generalizability of findings. We extracted data regarding inclusion/exclusion criteria from 174 trials of immunosuppression in renal transplant recipients published over a 5-year period and compared criteria with those specified in published trial registries. Frequently reported donor exclusion criteria were age (16.1%), donor type and cold ischaemic time (22.4%). Common recipient exclusion criteria included upper age limit (38.5%), high panel reactive antibody (PRA) (42.5%) and previous transplantation (39.7%). Inclusion/exclusion criteria recorded in trial registries matched those reported in the manuscript in only 6 (7.8%) trials. Of registered trials, 51 (66.2%) trials included additional criteria in the manuscript, 51 (66.2%) were missing criteria in the manuscript specified in the protocol, and in 19 (24.7%) key criteria changed from the protocol to the manuscript. Our findings suggest many recent immunosuppression trials have restrictive inclusion criteria which may not be reflective of current renal transplant populations. Discrepancies between trial protocols and published reports raise the possibility of selection bias.

[Focusing on kidney transplantation in the elderly]

Due to the increase in life expectancy and the ageing of end-stage renal disease patients, the number of patients older than 65 years receiving a kidney transplant has been continuously growing over the last fifteen years. The benefits of renal transplantation compared to dialysis in terms of survival and quality of life have been shown in selected recipients over 65, or 70 years. However, the age remains the main limiting factor for the access to the waiting list, and the reluctance of the clinicians can be explained by the multiple comorbidities of these candidates, their limited life expectancy or the shortage of grafts. The challenge is to select the candidates who can benefit from renal transplantation, thanks to rigorous cardiovascular and neoplastic evaluation before enrolment and by taking into account the specific characteristics of elderly patients. The living donor appears to be the ideal option for elderly recipients, the alternative being the extended criteria donor, allowing waiting times to be limited. The choice of immunosuppressive therapy is also crucial in these patients at high risk of infectious and cardiovascular complications in whom the occurrence of acute rejection can have severe consequences. There are currently no specific recommendations for immunosuppression in elderly recipients, and we would need large-scale randomized studies to improve the prognosis of renal transplantation in this population.

Results of ASERTAA, a Randomized Prospective Crossover Pharmacogenetic Study of Immediate-Release Versus Extended-Release Tacrolimus in African American Kidney Transplant Recipients

BACKGROUND

Differences in tacrolimus dosing across ancestries is partly attributable to polymorphisms in CYP3A5 genes that encode tacrolimus-metabolizing cytochrome P450 3A5 enzymes. The CYP3A5*1 allele, preponderant in African Americans, is associated with rapid metabolism, subtherapeutic concentrations, and higher dose requirements for tacrolimus, all contributing to worse outcomes. Little is known about the relationship between CYP3A5 genotype and the tacrolimus pharmacokinetic area under the curve (AUC) profile in African Americans or whether pharmacogenetic differences exist between conventional twice-daily, rapidly absorbed, immediate-release tacrolimus (IR-Tac) and once-daily extended-release tacrolimus (LifeCycle Pharma Tac [LCPT]) with a delayed absorption profile.

STUDY DESIGN

Randomized prospective crossover study.

SETTING & PARTICIPANTS

50 African American maintenance kidney recipients on stable IR-Tac dosing.

INTERVENTION

Recipients were randomly assigned to continue IR-Tac on days 1 to 7 and then switch to LCPT on day 8 or receive LCPT on days 1 to 7 and then switch to IR-Tac on day 8. The LCPT dose was 85% of the IR-Tac total daily dose.

OUTCOMES

Tacrolimus 24-hour AUC (AUC_0-24), peak and trough concentrations (C_max and C_min), time to peak concentration, and bioavailability of LCPT versus IR-Tac, according to CYP3A5 genotype.

MEASUREMENTS

CYP3A5 genotype, 24-hour tacrolimus pharmacokinetic profiles.

RESULTS

∼80% of participants carried the CYP3A5*1 allele (CYP3A5 expressers). There were no significant differences in AUC_0-24 or C_min between CYP3A5 expressers and nonexpressers during administration of either IR-Tac or LCPT. With IR-Tac, tacrolimus C_max was 33% higher in CYP3A5 expressers compared with nonexpressers (P=0.04): With LCPT, this difference was 11% (P=0.4).

LIMITATIONS

This was primarily a pharmacogenetic study rather than an efficacy study; the follow-up period was too short to capture clinical outcomes.

CONCLUSIONS

Achieving therapeutic tacrolimus trough concentrations with IR-Tac in most African Americans results in significantly higher peak concentrations, potentially magnifying the risk for toxicity and adverse outcomes. This pharmacogenetic effect is attenuated by delayed tacrolimus absorption with LCPT.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov, with study number NCT01962922.

A Review of the Impact of Exclusion Criteria on the Generalizability of Schizophrenia Treatment Research

Treatment research studies employ criteria that determine which patients are eligible to participate and which are not. When such exclusion criteria produce a treatment research sample that is a small and unrepresentative subset of all patients with a particular disease, clinicians may be hesitant to apply the research results in front-line clinical practice. Accordingly, the present paper reviews the English-language literature on exclusion criteria in schizophrenia treatment research and draws initial conclusions about their impact. Empirically derived estimates of the rate of exclusion vary widely (31.0-98.2%), but the best available evidence suggests that about 4 in 5 patients with schizophrenia would be ineligible to enroll in a typical treatment research study. Women are particularly likely to be excluded from schizophrenia treatment research, which is problematic from both a clinical and social justice viewpoint. Excluded patients also tend to be older than eligible patients, and, though it has been examined in only a few studies, they also tend to have more severe problems at baseline and different outcomes over time than patients who are allowed to participate in research. More limited use of exclusion criteria in schizophrenia treatment research would be beneficial in terms of increasing generalizability, but would also potentially involve costs, particularly a need for larger samples. More modest steps that would improve treatment outcome research reports include requiring a full description of the rationale for, and nature of, any exclusion criteria, and, having a designated place in the discussion section which draws attention to the proper scope of generalization.

Age-Dependent Metabolic and Immunosuppressive Effects of Tacrolimus

Immunosuppression in elderly recipients has been underappreciated in clinical trials. Here, we assessed age-specific effects of the calcineurin inhibitor tacrolimus (TAC) in a murine transplant model and assessed its clinical relevance on human T cells. Old recipient mice exhibited prolonged skin graft survival compared with young animals after TAC administration. More important, half of the TAC dose was sufficient in old mice to achieve comparable systemic trough levels. TAC administration was able to reduce proinflammatory interferon-γ cytokine production and promote interleukin-10 production in old CD4⁺ T cells. In addition, TAC administration decreased interleukin-2 secretion in old CD4⁺ T cells more effectively while inhibiting the proliferation of CD4⁺ T cells in old mice. Both TAC-treated murine and human CD4⁺ T cells demonstrated an age-specific suppression of intracellular calcineurin levels and Ca²⁺ influx, two critical pathways in T cell activation. Of note, depletion of CD8⁺ T cells did not alter allograft survival outcome in old TAC-treated mice, suggesting that TAC age-specific effects were mainly CD4⁺ T cell mediated. Collectively, our study demonstrates age-specific immunosuppressive capacities of TAC that are CD4⁺ T cell mediated. The suppression of calcineurin levels and Ca²⁺ influx in both old murine and human T cells emphasizes the clinical relevance of age-specific effects when using TAC.

Immunosuppression in the elderly renal allograft recipient: a systematic review

BACKGROUND

The Elderly are the fastest growing part of kidney transplant recipients. The best immunosuppressive strategy is unknown.

METHODS

We performed a systematic search of randomized controlled trials and observational studies focused on safety and efficacy of different immunosuppression strategies in elderly kidney recipients. Data extraction and risk of bias evaluation were systematically performed.

RESULTS

Ten studies were included: 2 randomized clinical trials and 8 observational. A marginal benefit was found for early renal function with delayed tacrolimus or complete tacrolimus avoidance using mycophenolate mofetil (MMF). Observational cohort studies looked at different antibody induction strategies, calcineurin-inhibitors based maintenance immunosuppression, calcineurin-inhibitor-free sirolimus-based therapy and use of MMF versus azathioprine. Treatment with interleukin-2 receptor antibody induction, calcineurin-inhibitor minimization with MMF and steroid minimization is advisable in the low immunologic risk elderly recipient, considering the increased risk of toxicities, infection and malignancies. In the high immunologic risk elderly recipient, taking into account the morbid consequences of acute rejection in the elderly, observational studies support antibody induction with depletive antibodies, calcineurin-inhibitor, MMF and steroids; calcineurin-inhibitor-minimization is not recommended.

CONCLUSIONS

There is very limited evidence for the benefits and harms of different immunosuppression strategies in the elderly. Most of the published literature are observational studies, and randomized controlled trials are urgently needed.

Trial design and endpoints in clinical transplant research

The number of clinical trials in solid organ transplantation is progressively increasing year on year, but the quality of design and reporting still varies considerably. The constraints on organ availability, improving short-term outcomes, ethics and timescales involved in organ transplantation present unique challenges for trials in this field. An understanding of the methodology and potential pitfalls in clinical research is essential both to interpret trial results and to design robust studies. This review summarizes the scope and quality of reporting in existing transplant clinical trials and details aspects of clinical trial methodology with particular relevance to transplantation. We highlight initiatives designed to improve the quality of this process to ensure that the results of clinical trials are robust, well reported and of use in everyday clinical practice.

A Rationale for Age-Adapted Immunosuppression in Organ Transplantation

Demographic changes are associated with a steady increase of older patients with end-stage organ failure in need for transplantation. As a result, the majority of transplant recipients are currently older than 50 years, and organs from elderly donors are more frequently used. Nevertheless, the benefit of transplantation in older patients is well recognized, whereas the most frequent causes of death among older recipients are potentially linked to side effects of their immunosuppressants.Immunosenescence is a physiological part of aging linked to higher rates of diabetes, bacterial infections, and malignancies representing the major causes of death in older patients. These age-related changes impact older transplant candidates and may have significant implications for an age-adapted immunosuppression. For instance, immunosenescence is linked to lower rates of acute rejections in older recipients, whereas the engraftment of older organs has been associated with higher rejection rates. Moreover, new-onset diabetes mellitus after transplantation is more frequent in the elderly, potentially related to corticosteroids, calcineurin inhibitors, and mechanistic target of rapamycin inhibitors.This review presents current knowledge for an age-adapted immunosuppression based on both, experimental and clinical studies in and beyond transplantation. Recommendations of maintenance and induction therapy may help to improve graft function and to design future clinical trials in the elderly.

Understanding alterations in drug handling with aging: a focus on the pharmacokinetics of maintenance immunosuppressants in the elderly

PURPOSE OF REVIEW

This review presents current knowledge of the impact of age on the pharmacokinetics of maintenance immunosuppressants.

RECENT FINDINGS

Over the past decade, there has been a steady increase in older patients on organ transplant waiting lists. As a result, the average age of transplant recipients has significantly increased. The survival and quality-of-life benefits of transplantation in the elderly population have been demonstrated. Advancing age is associated with changes in immune responses, as well as changes in drug handling. Immunosenescence is a physiological part of aging and is linked to reduced rejection rates, but also higher rates of diabetes, infections and malignancies. Physiologic changes associated with age can have a significant impact on the pharmacokinetics of the maintenance immunosuppressive agents. Taken together, these age-related changes impact older transplant candidates and may have significant implications for managing immunosuppression in the elderly.

SUMMARY

Despite the lack of formal efficacy, safety and pharmacokinetic studies of individual immunosuppressants in the elderly transplant population, there are enough data available for practitioners to be able to adequately manage their older patients. A proficient understanding of the factors that impact the pharmacokinetics of the immunosuppressants in the elderly is essential to managing these patients successfully.

Clinical outcomes in Asian elderly kidney transplant recipients: a multicenter cohort study

BACKGROUND

The kidney transplantation rate in elderly patients is increasing rapidly. However, the clinical outcomes of kidney transplantation in elderly patients have not yet been thoroughly evaluated.

METHODS

This multicenter cohort study included adult kidney transplant recipients (KTRs) admitted to five major tertiary hospitals in Korea between 1997 and 2012. A total of 3,565 adult participants were enrolled. Patient survival, allograft survival, and biopsy-proven acute rejection (BPAR) of 242 elderly recipients (≥ 60 years) were assessed and compared with those of a younger population.

RESULTS

Patients were divided into five groups according to age at time of transplantation. The proportion of elderly patients was 6.7 % (mean age, 63.1 ± 2.7 years; n = 242). The numbers of male patients (69.4%), those with diabetes mellitus history (36.3%), and those with pretransplantation ischemic heart disease history (17.7%) were significantly higher in the elderly group than in the younger age groups. Elderly patients were more likely to receive a cadaveric kidney, and overall mortality rates were significantly higher in the elderly patients (1-year survival 93.3%, 5-year survival 91.3%). However, death-censored allograft survival rate and BPAR were not affected by patient age (P = .104 and .501, respectively). Among the elderly, BPAR and female donors were independent risk factors for allograft loss.

CONCLUSION

The overall survival rate of the elderly KTRs was significantly lower than that of younger KTRs. However, the death-censored allograft survival rate did not differ between groups. Kidney transplantation should not be stagnated especially in elderly patients with end-stage renal disease.

Managing transplant rejection in the elderly: the benefits of less aggressive immunosuppressive regimens

Organ transplantation is increasingly common in the older population, particularly among end-stage renal disease patients. The outcomes of transplantation are often inferior in older people compared with younger recipients, partly because of the side effects of immunosuppressive medication used after organ transplantation. In this paper, we explore treatment considerations for older transplant patients. The current commonly used immunosuppressive protocols have not been validated sufficiently in older organ recipients. The primary objective for the management of transplant recipients of all ages is to prevent rejection without increasing the risk of infection or other long-term complications. To avoid serious side effects related to immunosuppressive treatment, the clinician should consider modifying and tailoring the long-term regimen for individual patients. Modifications for older recipients include reduction in the dosage or avoidance of calcineurin inhibitors, with or without the introduction of a mammalian target of rapamycin inhibitor and discontinuing the use of corticosteroids. Such modifications must consider the individual risks and needs of each recipient. Treatment of an acute rejection episode should follow the same protocol as for younger recipients, but special attention is needed to ensure reduction in the total immunosuppressive load. One way to achieve this is to avoid anti-thymocyte globulin (ATG) induction and to use on-demand ATG treatment of rejection on the basis of the patient's CD3 T cell count.

Representativeness of patients enrolled in influential clinical trials: a comparison of substance dependence with other medical disorders

OBJECTIVE

The purpose of this study was to determine whether randomized trials of treatments for substance dependence differ from those for other medical disorders on quality of enrollment information reporting and sample representativeness.

METHOD

Twenty highly cited clinical trials (publication date 2002-2010) of treatments for each of 14 prevalent disorders were identified by structured literature search. The disorders were alcohol dependence, drug dependence, nicotine dependence, Alzheimer's disease, breast cancer, colorectal cancer, chronic obstructive pulmonary disease, depression, diabetes, HIV/AIDS, hypertension, ischemic heart disease, lung cancer, and schizophrenia. The 280 clinical trials were coded for number of individuals screened for eligibility, number of screened individuals meeting eligibility criteria, and number of eligible individuals refusing to participate.

RESULTS

Substance-dependence treatment trials were significantly more likely to track and report enrollment information (75% vs. 45% of clinical trials for other disorders, p < .001). Substance-dependence trials did not differ from trials focused on other disorders on mean rate of non-enrollment. Across disorders, the primary driver of non-enrollment appeared to be clinical trial exclusion criteria rather than eligible patients refusing to enroll.

CONCLUSIONS

Relative to other disorders, trials in the substance-dependence field do a better (although imperfect) job of tracking and reporting enrollment information. Low enrollment rates and unrepresentative samples are not challenges unique to treatment outcome studies in the substance-dependence field. Across a range of disorders, clinical trials that use eligibility criteria judiciously are more likely to produce findings that generalize to front-line clinical practice than are trials that restrict enrollment to a small and unrepresentative subset of patients.

Treatment dynamics of newly marketed drugs and implications for comparative effectiveness research

OBJECTIVES

Clinicians and payers require rapid comparative effectiveness (CE) evidence generation to inform decisions for new drugs. We empirically assessed treatment dynamics of newly marked drugs and their implications for conducting CE research.

METHODS

We used claims data to evaluate five drug-outcome pairs: 1) raloxifene (vs. alendronate) and fracture; 2) risedronate (vs. alendronate) and fracture; 3) simvastatin plus ezetimibe fixed-dose combination (simvastatin + ezetimibe) (vs. simvastatin alone) and cardiovascular events; 4) rofecoxib (vs. nonselective nonsteroidal anti-inflammatory drugs [ns-NSAIDs]) and myocardial infarction; and 5) rofecoxib (vs. ns-NSAIDS) and gastrointestinal bleed. We examined utilization dynamics in the early marketing period, including evolving utilization patterns, outcome risk among those treated with new versus established drugs, and prior treatment patterns that may indicate treatment resistance or intolerance. We addressed these challenges by replicating active CE monitoring with sequential matched cohort analysis.

RESULTS

Patients initiating new drugs were more likely to have used other drugs for the same indication in the past, but the majority of patients in all new drug cohorts were treatment naive (82.0% overall). Patients initiating rofecoxib had higher predicted baseline risk of gastrointestinal bleed than did patients initiating ns-NSAIDs. Patients initiating risedronate and alendronate had similar predicted baseline risks of fracture, while those initiating raloxifene and simvastatin + ezetimibe had lower risks of outcomes of interest relative to their comparators. Prospective monitoring yielded results consistent with expectation for each example.

CONCLUSIONS

Many challenges to assessing the CE of new drugs are borne out in empirical data. Attention to these challenges can yield valid CE results.

Kidney transplantation in the older adult

The end-stage renal disease population is aging. Nearly half of all new patients are older than 65 years and one third are older than 70 years. Assessing the possibility of transplantation for older patients with end-stage renal disease often involves contemplating more complex issues, including cognitive impairment, decreased functional status, and frailty, which makes selecting appropriate candidates more difficult. Older transplant recipients have decreased patient and transplant survival compared with younger recipients. For example, 75% of deceased donor transplant recipients aged 30-49 years are alive after 5 years compared to only 61% for those older than 65 years. Despite poorer outcomes compared with younger recipients, older transplant recipients have a significant improvement in survival compared with similar patients who remain on the wait list, with decreases in mortality of 41%-61% depending on the study. Use of living donors, even older living donors, provides significantly better outcomes for elderly recipients compared with the use of deceased donors. However, in the absence of a living donor, survival is improved significantly by accepting an expanded criteria donor organ rather than waiting for a standard criteria deceased donor. Older transplant recipients experience more infectious complications and less acute rejection, but the risk of transplant loss from rejection is increased compared with younger patients. These immunologic issues, along with the fact that older patients often are excluded from transplant trials, have made selecting an ideal immunosuppressive regimen challenging. Prospective comparative trials of different agents in the elderly population are warranted to better define the risk-benefit profile. This review discusses transplantation outcomes, including patient and transplant survival, different donor types, quality of life, and immunosuppression for older dialysis patients.

Lower calcineurin inhibitor doses in older compared to younger kidney transplant recipients yield similar troughs

The number of older adults undergoing kidney transplantation has increased, yet little is known about calcineurin inhibitor (CNI) metabolism in this group. We studied CNI troughs and doses to determine if there were age-related differences in metabolism and dose requirements. We studied 348 young (18-34 years), 1831 middle (35-64 years) and 374 older (65-84 years) adult kidney transplant recipients enrolled in a seven-center prospective study. Troughs were obtained from each patient 2×/week in weeks 1-8 and 2×/month in months 3-6. A multivariable linear-mixed model examined the effect of age on log dose and weight normalized troughs. Older recipients had higher normalized tacrolimus troughs than middle or young age adults despite receiving doses a median of 1-2 mg/day lower. Age and CYP3A5*1 genotype had the largest effect on tacrolimus troughs. Older recipients also had higher normalized cyclosporine troughs than middle or young adults despite receiving median doses 100 mg/day lower. After normalization for dose and weight, CNI troughs were more than 50% higher in older adults than young adults. These data support age-related changes in CNI metabolism. Further studies are needed to determine optimal dosing of CNIs in the elderly.