Infliximab Induction Lacks Efficacy and Increases BK Virus Infection in Deceased Donor Kidney Transplant Recipients: Results of the CTOT-19 Trial

BACKGROUND

Ischemia-reperfusion (IR) of a kidney transplant (KTx) upregulates TNF α production that amplifies allograft inflammation and may negatively affect transplant outcomes.

METHODS

We tested the effects of blocking TNF peri-KTx via a randomized, double-blind, placebo-controlled, 15-center, phase 2 clinical trial. A total of 225 primary transplant recipients of deceased-donor kidneys (KTx; 38.2% Black/African American, 44% White) were randomized to receive intravenous infliximab (IFX) 3 mg/kg or saline placebo (PLBO) initiated before kidney reperfusion. All patients received rabbit anti-thymocyte globulin induction and maintenance immunosuppression (IS) with tacrolimus, mycophenolate mofetil, and prednisone. The primary end point was the difference between groups in mean 24-month eGFR.

RESULTS

There was no difference in the primary end point of 24-month eGFR between IFX (52.45 ml/min per 1.73 m 2 ; 95% CI, 48.38 to 56.52) versus PLBO (57.35 ml/min per 1.73 m 2 ; 95% CI, 53.18 to 61.52; P =0.1). There were no significant differences between groups in rates of delayed graft function, biopsy-proven acute rejection (BPAR), development of de novo donor-specific antibodies, or graft loss/death. Immunosuppression did not differ, and day 7 post-KTx plasma analyses showed approximately ten-fold lower TNF ( P <0.001) in IFX versus PLBO. BK viremia requiring IS change occurred more frequently in IFX (28.9%) versus PLBO (13.4%; P =0.004), with a strong trend toward higher rates of BKV nephropathy in IFX (13.3%) versus PLBO (4.9%; P =0.06).

CONCLUSIONS

IFX induction therapy does not benefit recipients of kidney transplants from deceased donors on this IS regimen. Because the intervention unexpectedly increased rates of BK virus infections, our findings underscore the complexities of targeting peritransplant inflammation as a strategy to improve KTx outcomes.Clinical Trial registry name and registration number:clinicaltrials.gov (NCT02495077).

Prostate Cancer, Kidney Transplant Wait Time, and Mortality in Maintenance Dialysis Patients: A Cohort Study Using Linked United States Renal Data System Data

RATIONALE & OBJECTIVE

The impact of prostate cancer on mortality in patients with end-stage kidney disease may be different from the general population. Prostate cancer may also delay the kidney transplant but has not been studied in a population-based cohort. We examined how prostate cancer influenced time to kidney transplant and death in a dialysis population.

STUDY DESIGN

Retrospective population-based, risk-set propensity score-matched cohort study.

SETTING & PARTICIPANTS

Men, 40-79 years old, who were dialysis-dependent Medicare beneficiaries without prior documented prostate cancer, from the United States Renal Data System.

EXPOSURES

Incident prostate cancer, identified using International Classification of Disease, Ninth Revision, Clinical Modification system diagnosis code 185.

OUTCOMES

Time to kidney transplant and death.

ANALYTICAL APPROACH

Propensity-based risk-set matching to reduce bias between cases and controls. Cox proportional hazards model for time to death, and Fine-Gray competing risk model for time to kidney transplant.

RESULTS

Among a total of 588,478 male dialysis patients who met the eligibility criteria, 18,162 had claims for prostate cancer. After propensity-based risk-set matching, 15,554 pairs of prostate cancer cases and controls were identified. Among the matched pairs, survival rates were 76%, 48%, and 30% at 1, 3, and 5 years in the prostate cancer group, compared with 80%, 51%, and 33% in the control group, with relative mortality of 95%, 94%, and 91% respectively (log-rank test P < 0.001). Prostate cancer was associated with a 22% lower likelihood of kidney transplant (HR: 0.78; 95% CI: 0.72-0.85) and 11% higher likelihood of death (HR: 1.11; 95% CI: 1.08-1.14) compared with controls. Kidney transplant was associated with a 4-fold improvement in overall survival, both in patients with and without prostate cancer (HR: 0.20; 95% CI: 0.18-0.21).

LIMITATIONS

Retrospective registry study.

CONCLUSIONS

Prostate cancer is associated with a modest increase in the risk of death and time to transplant in patients with end-stage kidney disease. Kidney transplant is associated with the same degree of survival benefit among those with pretransplant prostate cancer as those without.

Securing the future of kidney transplantation by addressing the challenges of transplant nephrology

Kidney transplant is a life-changing procedure, and transplant nephrologists, as part of a larger transplant team, play an important role in the field by managing the complex medical needs of transplant patients. The subspecialty of transplant nephrology, however, faces structural challenges related to its workforce, reporting structures, compensation, research and innovation, and health care information technology. The position of transplant nephrology at the academic and operational intersection of medicine and surgery may limit its access to critical resources, hinder academic promotion, and contribute to physician burnout. The authors provide an overview of the subspecialty transplant nephrology and propose solutions. Collaborative efforts that fortify the subspecialty of transplant nephrology will ultimately improve the lives of patients suffering from kidney disease.

Peritransplant eculizumab does not prevent delayed graft function in deceased donor kidney transplant recipients: Results of two randomized controlled pilot trials

Animal models and observational human data indicate that complement, including C5a, pathogenically participates in ischemia reperfusion (IR) injury that manifests as delayed graft function (DGF) following deceased donor kidney transplantation. We report on the safety/efficacy of anti-C5 monoclonal antibody eculizumab (Ecu) administered in the operating room prior to reperfusion, to prevent DGF in recipients of deceased donor kidney transplants in two related, investigator-sponsored, randomized controlled trials. Eight recipients from a single center were enrolled in a pilot study that led to a 19-subject multicenter trial. Together, 27 deceased donor kidney transplant recipients, 16 Ecu-treated and 11 controls, were treated with rabbit antithymocyte globulin, tacrolimus, mycophenolate mofetil with or without glucocorticoids, and followed for 6 months. Data analysis showed no epidemiological or transplant-related differences between study arms. Ecu was well tolerated with a similar severe adverse event incidence between groups. The DGF rate did not differ between Ecu-treated (44%) and control (45%, P = 1.0) subjects. Serum creatinine reduction in the first week after transplantation, and graft function up to 180-days post-transplant, were also similar. Ecu administration was safe but did not reduce the rate of DGF in a high-risk population of deceased donor recipients.

Analysis of Biomarkers Within the Initial 2 Years Posttransplant and 5-Year Kidney Transplant Outcomes: Results From Clinical Trials in Organ Transplantation-17

BACKGROUND

An early posttransplant biomarker/surrogate marker for kidney allograft loss has the potential to guide targeted interventions. Previously published findings, including results from the Clinical Trials in Organ Transplantation (CTOT)-01 study, showed that elevated urinary chemokine CXCL9 levels and elevated frequencies of donor-reactive interferon gamma (IFNγ)-producing T cells by enzyme-linked immunosorbent spot (ELISPOT) assay associated with acute cellular rejection within the first year and with lower 1-year posttransplant estimated glomerular filtration rate (eGFR). How well these biomarkers correlate with late outcomes, including graft loss, is unclear.

METHODS

In CTOT-17, we obtained 5-year outcomes in the CTOT-01 cohort and correlated them with (a) biomarker results and (b) changes in eGFR (Chronic Kidney Disease Epidemiology Collaboration formula) over the initial 2 years posttransplant using univariable analysis and multivariable logistic regression.

RESULTS

Graft loss occurred in 14 (7.6%) of 184 subjects 2 to 5 years posttransplant. Neither IFNγ ELISPOTs nor urinary CXCL9 were informative. In contrast, a 40% or greater decline in eGFR from 6 months to 2 years posttransplant independently correlated with 13-fold odds of 5-year graft loss (adjusted odds ratio, 13.1; 95% confidence interval, 3.0-56.6), a result that was validated in the independent Genomics of Chronic Allograft Rejection cohort (n = 165; adjusted odds ratio, 11.2).

CONCLUSIONS

We conclude that although pretransplant and early posttransplant ELISPOT and chemokine measurements associate with outcomes within 2 years posttransplant, changes in eGFR between 3 or 6 months and 24 months are better surrogates for 5-year outcomes, including graft loss.

Costimulatory Blockade and Use of Mammalian Target of Rapamycin Inhibitors: Avoiding Injury Part 1

Although calcineurin inhibitor drugs have been the mostly used therapy in modern immunosuppression in kidney transplantation, their effect on kidney allograft dysfunction has been suboptimal as far as preservation of kidney function is concerned. Additionally, there are metabolic and other nonmetabolic effects including increased risk of malignancy that has necessitated the use of mammalian target of rapamycin inhibitors to reduce exposure to calcineurin inhibitors. Mammalian target of rapamycin inhibitors, both sirolimus and everolimus, have been studied in several trials to facilitate preservation of kidney function with variable effects on kidney allograft function and immunogenicity. Preservation of kidney function is increasingly becoming the mainstay of immunosuppression not only in kidney transplantation, but also in extrakidney transplantation. The best kidney outcomes have been reported in calcineurin inhibitor withdrawal studies using mammalian target of rapamycin inhibitors, in kidney transplant recipients with stable kidney function. This review article summarizes data from several studies in which mammalian target of rapamycin inhibitors have been used to reduce exposure to or withdraw calcineurin inhibitors in an attempt to preserve kidney function.

Interferon Gamma ELISPOT Testing as a Risk-Stratifying Biomarker for Kidney Transplant Injury: Results From the CTOT-01 Multicenter Study

Previous studies suggest that quantifying donor-reactive memory T cells prior to kidney transplantation by interferon gamma enzyme-linked immunosorbent spot assay (IFNγELISPOT) can assist in assessing risk of posttransplant allograft injury. Herein, we report an analysis of IFNγELISPOT results from the multicenter, Clinical Trials in Organ Transplantation-01 observational study of primary kidney transplant recipients treated with heterogeneous immunosuppression. Within the subset of 176 subjects with available IFNγELISPOT results, pretransplant IFNγELISPOT positivity surprisingly did not correlate with either the incidence of acute rejection (AR) or estimated glomerular filtration rate (eGFR) at 6- or 12-month. These unanticipated results prompted us to examine potential effect modifiers, including the use of T cell-depleting, rabbit anti-thymocyte globulin (ATG). Within the no-ATG subset, IFNγELISPOT(neg) subjects had higher 6- and 12-month eGFRs than IFNγELISPOT(pos) subjects, independent of biopsy-proven AR, peak PRA, human leukocyte antigen mismatches, African-American race, donor source, and recipient age or gender. In contrast, IFNγELISPOT status did not correlate with posttransplant eGFR in subjects given ATG. Our data confirm an association between pretransplant IFNγELISPOT positivity and lower posttransplant eGFR, but only in patients who do not receive ATG induction. Controlled studies are needed to test the hypothesis that ATG induction is preferentially beneficial to transplant candidates with high frequencies of donor-reactive memory T cells.

Adverse Outcomes of Tacrolimus Withdrawal in Immune-Quiescent Kidney Transplant Recipients

Concerns about adverse effects of calcineurin inhibitors (CNIs) have prompted development of protocols that minimize their use. Whereas previous CNI withdrawal trials in heterogeneous cohorts showed unacceptable rates of acute rejection (AR), we hypothesized that we could identify individuals capable of tolerating CNI withdrawal by targeting immunologically quiescent kidney transplant recipients. The Clinical Trials in Organ Transplantation-09 Trial was a randomized, prospective study of nonsensitized primary recipients of living donor kidney transplants. Subjects received rabbit antithymocyte globulin, tacrolimus, mycophenolate mofetil, and prednisone. Six months post-transplantation, subjects without de novo donor-specific antibodies (DSAs), AR, or inflammation at protocol biopsy were randomized to wean off or remain on tacrolimus. The intended primary end point was the change in interstitial fibrosis/tubular atrophy score between implantation and 24-month protocol biopsies. Serially collected urine CXCL9 ELISA results were correlated with outcomes. The study was terminated prematurely because of unacceptable rates of AR (4 of 14) and/or de novo DSAs (5 of 14) in the tacrolimus withdrawal arm. Positive urinary CXCL9 predated clinical detection of AR by a median of 15 days. Analyses showed that >16 HLA-DQ epitope mismatches and pretransplant, peripheral blood, donor-reactive IFN-γ ELISPOT assay results correlated with development of DSAs and/or AR on tacrolimus withdrawal. Although data indicate that urinary CXCL9 monitoring, epitope mismatches, and ELISPOT assays are potentially informative, complete CNI withdrawal must be strongly discouraged in kidney transplant recipients who are receiving standard-of-care immunosuppression, including those who are deemed to be immunologically quiescent on the basis of current clinical and laboratory criteria.

Urinary-cell mRNA profile and acute cellular rejection in kidney allografts

BACKGROUND

The standard test for the diagnosis of acute rejection in kidney transplants is the renal biopsy. Noninvasive tests would be preferable.

METHODS

We prospectively collected 4300 urine specimens from 485 kidney-graft recipients from day 3 through month 12 after transplantation. Messenger RNA (mRNA) levels were measured in urinary cells and correlated with allograft-rejection status with the use of logistic regression.

RESULTS

A three-gene signature of 18S ribosomal (rRNA)-normalized measures of CD3ε mRNA and interferon-inducible protein 10 (IP-10) mRNA, and 18S rRNA discriminated between biopsy specimens showing acute cellular rejection and those not showing rejection (area under the curve [AUC], 0.85; 95% confidence interval [CI], 0.78 to 0.91; P<0.001 by receiver-operating-characteristic curve analysis). The cross-validation estimate of the AUC was 0.83 by bootstrap resampling, and the Hosmer-Lemeshow test indicated good fit (P=0.77). In an external-validation data set, the AUC was 0.74 (95% CI, 0.61 to 0.86; P<0.001) and did not differ significantly from the AUC in our primary data set (P=0.13). The signature distinguished acute cellular rejection from acute antibody-mediated rejection and borderline rejection (AUC, 0.78; 95% CI, 0.68 to 0.89; P<0.001). It also distinguished patients who received anti-interleukin-2 receptor antibodies from those who received T-cell-depleting antibodies (P<0.001) and was diagnostic of acute cellular rejection in both groups. Urinary tract infection did not affect the signature (P=0.69). The average trajectory of the signature in repeated urine samples remained below the diagnostic threshold for acute cellular rejection in the group of patients with no rejection, but in the group with rejection, there was a sharp rise during the weeks before the biopsy showing rejection (P<0.001).

CONCLUSIONS

A molecular signature of CD3ε mRNA, IP-10 mRNA, and 18S rRNA levels in urinary cells appears to be diagnostic and prognostic of acute cellular rejection in kidney allografts. (Funded by the National Institutes of Health and others.).

Impact of navigators on completion of steps in the kidney transplant process: a randomized, controlled trial

BACKGROUND AND OBJECTIVES

Many patients with ESRD, particularly minorities and women, face barriers in completing the steps required to obtain a transplant. These eight sequential steps are as follows: medical suitability, interest in transplant, referral to a transplant center, first visit to center, transplant workup, successful candidate, waiting list or identify living donor, and receive transplant. This study sought to determine the effect of navigators on completion of steps.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Cluster randomized, controlled trial at 23 Ohio hemodialysis facilities. One hundred sixty-seven patients were recruited between January 2009 and August 2009 and were followed for up to 24 months or until study end in February 2011. Trained kidney transplant recipients met monthly with intervention participants (n=92), determined their step in the transplant process, and provided tailored information and assistance in completing the step. Control participants (n=75) continued to receive usual care. The primary outcome was the number of transplant process steps completed.

RESULTS

Starting step did not significantly differ between the two groups. By the end of the trial, intervention participants completed more than twice as many steps as control participants (3.5 versus 1.6 steps; difference, 1.9 steps; 95% confidence interval, 1.3-2.5 steps). The effect of the intervention on step completion was similar across race and sex subgroups.

CONCLUSIONS

Use of trained transplant recipients as navigators resulted in increased completion of transplant process steps.

Nephrology quiz and questionnaire: transplantation

Presentation of the Nephrology Quiz and Questionnaire (NQQ) has become an annual "tradition" at the meetings of the American Society of Nephrology. It is a very popular session judged by consistently large attendance. Members of the audience test their knowledge and judgment on a series of case-oriented questions prepared and discussed by experts. They can also compare their answers in real time, using audience response devices, to those of program directors of nephrology training programs in the United States, acquired through an Internet-based questionnaire. Topics presented here include transplantation issues. These cases, along with single best answer questions, were prepared by Dr. Hricik. After the audience responses, the "correct" and "incorrect" answers were then briefly discussed and the results of the questionnaire were displayed. This article aims to recapitulate the session and reproduce its educational value for a larger audience-that of the readers of the Clinical Journal of the American Society of Nephrology. Have fun.

T-cell immune monitoring by the ELISPOT assay for interferon gamma

The enzyme-linked immunosorbent spot (ELISPOT) assay for interferon gamma has been available for more than twenty years and has been used for a number of applications, including the monitoring of T cell immunity in solid organ transplant recipients. Studies from single centers indicate that heightened T cell alloreactivity measured with this assay correlates with acute and chronic rejection and with poor long-term allograft function. The assay has been used not only to assess T cell reactivity after transplantation, but also as a tool for assessing immune risk prior to transplantation. Additional work is needed to validate the assay in larger multicenter clinical trials.

Immune factors influencing ethnic disparities in kidney transplantation outcomes

An influence of ethnicity on the outcomes of kidney transplant recipients has been recognized for several decades. Both immune and nonimmune factors have been explored as potential explanations. Most studies have focused on the inferior outcomes of African-Americans. As a group, African-Americans differ from Caucasians with respect to a number of measurable components of the alloimmune response, including the T-cell repertoire and the expression and function of costimulatory molecules and various cytokines and chemokines. In general, these differences suggest that African-Americans may be high immune responders. However, no single difference in any of these components of alloimmunity satisfactorily explains the disparities in outcomes. It seems probable that some combination of immune factors interacts with nonimmune factors, such as socioeconomic resources, to influence transplant outcomes in a complex manner.

The 2010 nephrology quiz and questionnaire: part 1

Presentation of the Nephrology Quiz and Questionnaire (NQQ) has become an annual "tradition" at the meetings of the American Society of Nephrology. It is a very popular session judged by consistently large attendance. Members of the audience test their knowledge and judgment on a series of case-oriented questions prepared and discussed by experts. They can also compare their answers in real time, using audience response devices, to those of program directors of nephrology training programs in the United States, acquired through an Internet-based questionnaire. As in the past, the topics covered were transplantation, fluid and electrolyte disorders, end-stage renal disease and dialysis, and glomerular disorders. Two challenging cases representing each of these categories along with single best answer questions were prepared by a panel of experts (Drs. Hricik, Palmer, Bargman, and Fervenza, respectively). The "correct" and "incorrect" answers then were briefly discussed, after the audience responses and the results of the questionnaire were displayed. The 2010 version of the NQQ was exceptionally challenging, and the audience, for the first time, gained a better overall correct answer score than the program directors, but the margin was small. In this issue we present the transplantation and fluid and electrolyte cases; the remaining end-stage renal disease and dialysis, and glomerular disorder cases will be presented next month. These articles try to recapitulate the session and reproduce its educational value for a larger audience--the readers of the Clinical Journal of the American Society of Nephrology. Have fun.

Donor phosphorus levels and recipient outcomes in living-donor kidney transplantation

BACKGROUND AND OBJECTIVES

In living-donor kidney transplantation, various donor factors, including gender, age, and baseline kidney function, predict allograft function and recipient outcomes after transplantation. Because higher phosphorus is predictive of vascular injury in healthy adults, the effect of donor phosphorus levels on recipient renal function after transplantation was investigated.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Phosphorus levels in 241 living donors were analyzed from a 7-year period, and recipient renal function and acute rejection at 1 year posttransplantation were examined controlling for other influencing factors, including multiple donor variables, HLA matching, and acute rejection.

RESULTS

Female and African-American donors had significantly higher phosphorus levels predonation. By multivariable analysis, higher donor phosphorus correlated with higher recipient serum creatinine (slope=0.087, 95% confidence interval [CI]: 0.004 to 0.169, P=0.041) and lower recipient estimated GFR (slope=-4.321, 95% CI: -8.165 to -0.476, P=0.028) at 12 months. Higher donor phosphorus also displayed an independent correlation with biopsy-proven acute rejection and delayed or slow graft function after transplantation.

CONCLUSIONS

In a cohort of living kidney donors, higher donor phosphorus correlated with female gender and African-American ethnicity and was an independent risk factor for early allograft dysfunction after living-donor kidney transplantation.

Clinical predictors of proteinuria after conversion to sirolimus in kidney transplant recipients

Proteinuria is an increasingly recognized effect of sirolimus (SRL) therapy in kidney transplant recipients. Predictors of proteinuria after conversion to SRL are not well described, and in particular the risk in African-American (AA) kidney recipients is unknown. We sought to analyze risk factors for proteinuria with SRL therapy in a cohort of 39 patients (44% AA) converted from tacrolimus to SRL at a mean time of 4 months posttransplantation. Patients were maintained on therapy with mycophenolate mofetil while most patients underwent early steroid withdrawal. Urinary protein to creatinine ratio (Up/cr) at a mean of 14 months postconversion increased to > or =500 mg/g in 65% of AAs versus 14% of non-AAs (p = 0.001). Mean arterial blood pressure at the time of conversion and pretransplant proteinuric kidney disease were also predictors of proteinuria after SRL conversion. In conclusion, AAs appear to be at high risk for proteinuria and should be monitored closely after conversion to SRL in calcineurin inhibitor sparing protocols.

New-onset diabetes mellitus after solid organ transplantation

New-onset diabetes mellitus is a common complication of solid organ transplantation and is likely to become even more common with the current epidemic of obesity in some countries. It has become clear that both new-onset diabetes and prediabetic states (impaired fasting glucose and impaired glucose tolerance) negatively influence graft and patient survival after transplantation. This observation forms the basis for recommending meticulous screening for glucose intolerance before and after transplantation. Although a number of clinical factors including age, weight, ethnicity, family history, and infection with hepatitis C are closely associated with the new-onset diabetes mellitus, immunosuppression with corticosteroids, calcineurin inhibitors and possibly sirolimus plays a dominant role in its pathogenesis. Management of new-onset diabetes after transplantation generally conforms to the guidelines for treatment of type 2 diabetes mellitus in the general population. However, further studies are needed to determine the optimal immunosuppressive regimens for patients with this disorder.

Pretransplant cellular alloimmunity as assessed by a panel of reactive T cells assay correlates with acute renal graft rejection

BACKGROUND

The panel reactive antibody test (PRA) is an established method for assessing posttransplant risk of immune-mediated graft injury. The panel of reactive T cell assay (PRT) in which transplant candidates' peripheral blood mononuclear cells are tested for reactivity to a panel of allogenic stimulator cells by the IFN-gamma enzyme-linked immunosorbent spot assay analogously assesses the strength of the pretransplant effector-memory alloreactive T cell repertoire.

METHODS

PRT assays were performed in 30 kidney transplant candidates and results were correlated with acute rejection (AR). A positive PRT assay was defined as a response to at least 75% of the stimulators tested.

RESULTS

A positive pretransplant PRT test was observed in 11 of 30 (37%) patients, and AR within 1 year posttransplantation was seen in 7 of 30 (23%) subjects. Six of the seven (86%) patients with AR were PRT-positive (P=0.01) whereas only one of seven (14%) patients with a PRA greater than 15% had AR. The mean pretransplant PRT percentage was 40% for patients with no AR versus 81% for patients with AR (P=0.01). Estimated glomerular filtration rate (mL/min/1.73 m2) showed a trend towards a lower value in PRT-positive (48+/-15) versus PRT-negative (55+/-13) individuals.

CONCLUSIONS

The data suggest that pretransplant PRT screening can identify patients at risk for posttransplant cellular immune mediated graft injury despite the absence of humoral allosensitization. Once confirmed by larger prospective trials, PRT screening could be used to guide clinical decision-making with regard to choosing donor organs and individualizing immunosuppression regimens.

Use of sirolimus in solid organ transplantation

Sirolimus is a mammalian target of rapamycin (mTOR) inhibitor that inhibits cell cycle progression and has proven to be a potent immunosuppressive agent for use in solid organ transplant recipients. The drug was initially studied as an adjunct to ciclosporin (cyclosporine) to prevent acute rejection in kidney transplant recipients. Subsequent studies have shown efficacy when combined with a variety of other immunosuppressive agents. The most common adverse effects of sirolimus are hyperlipidaemia and myelosuppression. The drug has unique antiatherogenic and antineoplastic properties, and may promote immunological tolerance and reduce the incidence of chronic allograft nephropathy. Although sirolimus is relatively non-nephrotoxic when administered as monotherapy, it pharmacodynamically enhances the toxicity of calcineurin inhibitors. Ironically, the drug has been used to facilitate calcineurin inhibitor-free protocols designed to preserve renal function after solid organ transplantation. Whether sirolimus can be used safely over the long term with low doses of calcineurin inhibitors requires further study. The use of sirolimus as a corticosteroid-sparing agent also remains to be proven in controlled trials. Postmarketing studies have revealed a number of unforeseen adverse effects including impaired wound healing and possibly proteinuria, oedema, pneumonitis and thrombotic microangiopathy. Overall, sirolimus is a powerful agent when used judiciously with other available immunosuppressants. As is true for all immunosuppressive drugs available for treatment of solid organ transplant recipients, the efficacy of the drug must be balanced against its considerable adverse effects.

Hemodialysis vintage, black ethnicity, and pretransplantation antidonor cellular immunity in kidney transplant recipients

Prolonged exposure to dialysis before transplantation and black ethnicity are known risk factors for acute rejection and graft loss in kidney transplant recipients. Because the strength of the primed antidonor T cell repertoire before transplantation also is associated with rejection and graft dysfunction, this study sought to determine whether hemodialysis (HD) vintage and/or black ethnicity affected donor-directed T cell immunity. An enzyme-linked immunosorbent spot (ELISPOT) assay was used to measure the frequency of peripheral T cells that expressed IFN-gamma in response to donor stimulator cells before transplantation in 100 kidney recipients. Acute rejection occurred in 38% of ELISPOT (+) patients versus 14% of ELISPOT (-) patients (P = 0.008). The median (HD) vintage was 46 mo (0 to 125 mo) in ELISPOT (+) patients versus 24 mo (0 to 276 mo) in ELISPOT (-) patients (P = 0.009). Black recipients had a greater median HD vintage (55 versus 14 mo in nonblack recipients; P < 0.001). Black recipients with less HD exposure had a low incidence of an ELISPOT (+) test, similar to nonblack recipients. Among variables examined, only HD vintage remained a significant positive correlate with an ELISPOT (+) result (odds ratio per year of HD 1.3; P = 0.003). These data suggest that the risk for developing cross-reactive antidonor T cell immunity increases with longer HD vintage, providing an explanation for the previously observed relationship between increased dialysis exposure and worse posttransplantation outcome. Longer HD vintage may also explain the increased T cell alloreactivity that previously was observed in black kidney recipients.

Long-term graft outcomes after steroid withdrawal in African American kidney transplant recipients receiving sirolimus and tacrolimus

BACKGROUND

We previously reported excellent short-term outcomes in African American kidney transplant patients receiving tacrolimus/sirolimus and withdrawn from corticosteroid therapy three months after transplantation. We now report the long-term outcomes of patients subjected to this protocol.

METHODS

In all, 47 African American kidney transplant recipients were enrolled in an uncontrolled trial in which they were initially treated with sirolimus, tacrolimus, and corticosteroids, without antibody induction therapy. Eligible patients were withdrawn from prednisone between three and five months posttransplant, and followed for acute rejection and changes in renal function. Outcomes (group 1, n=32) were compared to those of patients deemed not to be candidates for steroid withdrawal (group 2, n=15).

RESULTS

After a mean follow-up of 48.5 months, 13 of 32 patients (41%) in group 1 developed acute rejection; only 13 patients (41%) remain steroid-free. Nine of 13 rejection episodes were associated with noncompliance. Graft loss occurred in 8 of 32 patients (25%) in group 1 and in 5 of 15 patients (33%) in group 2 (P=NS). Serum creatinine rose from 1.4+/-0.41 to 2.45+/-1.7 mg/dL in group 1 (P=0.004) and from 2.1+/-0.45 to 2.62+/-1.2 mg/dL (P=NS) in group 2. Among 13 patients in group 1 who remain steroid-free, creatinine concentration has risen from 1.28+/-.0.37 prior to steroid withdrawal to 1.64+0.54 at last follow-up (P=0.027).

CONCLUSIONS

Late noncompliance and/or rejection in African Americans withdrawn from steroids have a negative impact on long-term graft function and survival. Steroid withdrawal may be associated with long-term deterioration of renal function, even in the absence of overt acute rejection.

Differential Pharmacokinetic Interaction of Tacrolimus and Cyclosporine on Everolimus

OBJECTIVE

We characterized the pharmacokinetics of tacrolimus and everolimus in a combined immunosuppressive regimen.

METHODS

This was an open-label exploratory trial in eight maintenance renal transplant patients with calcineurin inhibitor intolerance initially receiving mycophenolate mofetil (MMF) and tacrolimus. At enrollment, MMF was discontinued and replaced with everolimus 1.5 mg twice a day in study period 1 (days 1 to 10). In period 2 (day 11 to month 3), tacrolimus dose was reduced by half.

RESULTS

At study entry tacrolimus trough level (C0) was 7.9 +/- 3.9 ng/mL and area under the curve over a dosing interval (AUC) was 132 +/- 56 ng x h/mL. The addition of everolimus in period 1 did not change tacrolimus exposure: C0 8.4 +/- 4.0 ng/mL, AUC 134 +/- 70 ng x h/mL. Everolimus pharmacokinetics in the presence of tacrolimus in period 1 were: C0 3.3 +/- 1.2 ng/mL, Cmax 10.4 +/- 5.1 ng/mL, AUC 58 +/- 20 ng x h/mL. When compared to pharmacokinetic data from a previous study in 47 renal transplant patients receiving everolimus at the same fixed dose (1.5 mg twice a day) with cyclosporine, everolimus exposure was 2.5-fold higher with cyclosporine relative to the data in this study with tacrolimus. After tacrolimus dose reduction in period 2, there was no clinically relevant change in everolimus exposure: C0 3.0 +/- 1.1 ng/mL, Cmax 8.2 +/- 1.3 ng/mL, AUC 49 +/- 10 ng x h/mL.

CONCLUSIONS

Tacrolimus appears to have a minimal effect on everolimus blood levels compared with the influence of cyclosporine. The dose of everolimus when combined with tacrolimus needs to be higher than when combined with cyclosporine in order to reach a given everolimus blood level.

Differences in proteinuria and graft function in de novo sirolimus-based vs. calcineurin inhibitor-based immunosuppression in live donor kidney transplantation

BACKGROUND

Calcineurin inhibitor(CNI)-free protocols using sirolimus (SRL) in kidney transplantation have proven effective, although reports have linked SRL to proteinuria. We sought to investigate this link and its impact on graft function.

METHODS

We retrospectively analyzed 184 live donor kidney transplant recipients who exclusively received de novo CNI-based (n = 106) or SRL-based (n = 78) regimens. Estimated glomerular filtration rate (GFR) and semi-quantitative dipstick proteinuria measurements were obtained at one, six, 12, and 24 months and six and 12 months, respectively.

RESULTS

SRL-treated patients had higher frequencies of proteinuria (> or =1+) at 6 months (40.8% vs. 21.4%, P = 0.006) and 12 months (37.8% vs. 18.4%, P = 0.004) than those treated with CNI. Independent predictors of proteinuria at 12 months were GFR at one month (OR 0.62 per 10 ml/min/1.73 m, P<0.001), delayed graft function (OR 11.5, P = 0.02), and a SRL-based regimen (OR 4.18, P=0.002). By univariable analysis, SRL vs. CNI patients had higher GFR at each point. SRL-treated patients without proteinuria had higher GFR at 12 months compared to CNI-treated patients with and without proteinuria (66 vs. 50 or 56 ml/min/1.73 m, P < 0.05). No difference in GFR was seen between SRL-treated patients with proteinuria vs. CNI-treated patients without proteinuria (57 vs. 56 ml/min/1.73 m, P > 0.05). Absence of proteinuria and a SRL-based regimen remained independently associated FS with higher GFR at 12 months by multivariable analyses.

CONCLUSIONS

De novo SRL-based immunosuppression is associated with a higher frequency of semi-quantitative proteinuria, however, estimated graft function at 1 year posttransplant remains superior to that of CNI-treated patients. Nevertheless, the long-term implications of these findings need to be determined.

Steroid Sparing in Kidney Transplantation: Changing Paradigms, Improving Outcomes, and Remaining Questions

The widely known adverse effects of long-term therapy with corticosteroids have motivated increasing interest in steroid-free immunosuppression for kidney transplant recipients. Results from recent trials that used newer immunosuppressants to facilitate elimination of steroids suggest better short-term results than were achieved in an earlier era. However, the best results have been reported in uncontrolled trials of low-risk patients or in randomized trials with relatively short periods of follow-up. Increasingly, the therapeutic paradigm has shifted from late withdrawal of steroids to very early withdrawal after transplantation or even complete avoidance. Induction antibody therapy has been used routinely in the most successful trials that involved early steroid withdrawal or avoidance. Although the outcomes of kidney transplant recipients who are treated with steroid-free immunosuppression are improving steadily, there still is room for concern in recommending this strategy as a standard of practice.

Improved Renal Function after Conversion from Tacrolimus/Sirolimus to Tacrolimus/Mycophenolate Mofetil in Kidney Transplant Recipients

BACKGROUND

There is limited data on the potential nephrotoxicity of sirolimus (SRL) and tacrolimus (TAC) in combination.

METHODS

We reviewed the course of 97 kidney transplant patients treated with SRL and reduced-dose TAC. Conversion from SRL to mycophenolate mofetil (MMF) was prescribed in a minority (n = 19) for various nonrenal side effects. We compared outcomes of converted patients to those remaining on TAC/SRL (n = 78).

RESULTS

TAC levels were increased in converters (P = 0.009). Rejection rates were similar between groups over 18 months (21% vs. 16%, p = ns). Serum creatinine (Cr) and MDRD glomerular filtration rate (GFR) were similar between groups at nadir and six-months, but at 18 months the percent change from six-month Cr was +17% in non-converters vs. -10% in converters (P = 0.004 for the difference). The difference in GFR between groups at 18 months was also significant (P = 0.01). By multivariate analysis, only conversion to MMF was associated with a greater percent change in Cr from 6 to 18 months (P = 0.015). Conversion to MMF also correlated with higher GFR at 18 months independent of rejection, delayed graft function, and ethnicity.

CONCLUSIONS

Conversion from TAC/SRL to TAC/MMF led to improved renal function despite increased TAC exposure after conversion.

Panel of reactive T cells as a measurement of primed cellular alloimmunity in kidney transplant candidates

Pretransplantation panel reactive antibody (PRA) testing assesses posttransplantation risk for antibody-mediated graft injury. It was postulated analogously that screening for effector/memory alloreactive T cells by "panel of reactive T cells" (PRT) using IFN-gamma enzyme-linked immunosorbent spot assays would evaluate independently cellular alloimmunity in transplant candidates. Peripheral blood lymphocytes from 41 hemodialysis patients who were awaiting first renal transplants were tested against a panel of allogeneic stimulator cells. Positive assays were defined arbitrarily as >25 spots/300,000 peripheral blood lymphocytes, and positive PRT was defined as when the responder reacted to 40 or 75% (PRT-75) of the stimulators. Seventeen percent of patients were PRT-75+, whereas 32% were PRA+. Twelve percent of the cohort was PRT-75+/PRA-, and only 5% of the patients were PRA+/PRT-75+, indicating that T cell alloreactivity did not routinely imply B cell sensitization and vice versa. PRT-75+ patients were more likely to be younger (<55 yr) and black. In contrast, a positive PRA was significantly associated with female gender but not race or age. Pretransplantation screening of cellular alloimmunity by enzyme-linked immunosorbent spot-based PRT detects a subset of hemodialysis patients who differ from those that are PRA+. Preliminary correlations with posttransplantation outcome in seven recipients suggest that PRT screening has the potential to aid in risk assessment in renal transplant candidates.

Analysis of Immune Markers in Human Cardiac Allograft Recipients and Association With Coronary Artery Vasculopathy

BACKGROUND

Because coronary artery vasculopathy (CAV) is a common cause of late cardiac allograft loss in humans, there is a need to develop and test non-invasive surrogate markers capable of detecting and predicting this disease entity.

METHODS

We performed a cross-sectional analysis of immune-based surrogate markers in 65 primary cardiac allograft recipients with or without angiographically documented CAV. Anti-donor cellular immunity was determined by interferon gamma (IFN)-gamma enzyme-linked immunosorbent spot (ELISPOT) assays using donor HLA-derived peptides (indirect pathway), and anti-donor alloantibodies were detected by flow cytometry using HLA-coated beads.

RESULTS

Anti-donor cellular and humoral immunity were detected more frequently in patients with CAV (17 of 32, 53.1%) than in controls (4 of 33, 12.1%) (p < 0.001). Anti-donor cellular and humoral immunity were detected in different sub-groups of CAV patients; peripheral blood lymphocytes (PBLs) from only 1 of 32 CAV patients reacted to donor peptides with simultaneous detection of peripheral anti-donor alloantibodies.

CONCLUSIONS

Immune reactivity in cardiac transplant recipients with CAV differs significantly from those without CAV and the detected responses are heterogeneous in nature. Serial assessments of anti-donor immunity using different methods will be required to detect and possibly predict outcome in cardiac transplant recipients.

Pre-transplant IFN-gamma ELISPOTs are associated with post-transplant renal function in African American renal transplant recipients

Final crossmatch testing is routinely used to assess the risk of antibody-mediated graft injury/rejection post-transplant. Analogously, we postulated that quantitative measurements of anti-donor effector/memory T cells pre-transplant would independently assess post-transplant risk. To address this hypothesis, we determined the frequencies of pre-transplant, donor-specific interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spots (ELISPOTs) and correlated the results with post-transplant outcomes in 37 African American recipients of deceased donor kidney transplants treated with tacrolimus- and sirolimus-based immunosuppression. A positive ELISPOT test (>25 spots/300,000 cells) was detected in 14 (38%) of 37 patients. The incidence of biopsy-proven acute rejection was 50% (7/14) in ELISPOT-positive versus 17% (4/23) in ELISPOT-negative patients (p=0.036). Calculated glomerular filtration rate (MDRD) at 12 months was 37+/-16 mL/min in ELISPOT-positive versus 55+/-20 mL/min in ELISPOT-negative patients (p=0.01). ELISPOT status remained a correlate of allograft function at 12 months by linear regression analysis (p=0.001), independent of rejection and other contributing variables. Pre-transplant donor-directed IFN-gamma ELISPOT assessment of anti-donor cellular immunity may function as a 'cellular crossmatch' and independently correlates with renal allograft function in African Americans receiving tacrolimus- and sirolimus-based immunosuppression.

Heterogeneous Alterations in Human Alloimmunity Associated with Immunization

BACKGROUND

The presence of alloantibodies and/or alloreactive T cells in a patient prior to a transplant can impact graft outcome. Environmental factors, including therapeutic vaccinations, may influence the strength and/or specificity of alloimmunity.

METHODS

To address this issue, we prospectively evaluated the effects of two different immunization protocols in human subjects on cellular alloimmunity using an IFNgamma ELISPOT assay and on alloantibody reactivity by flow cytometric analysis of HLA-coated beads.

RESULTS

Vaccination/immunization was associated with augmentation of cellular and/or humoral alloimmune reactivity in >50% of the test subjects. The effects were heterogeneous in that some detected increases were transient, peaking 30-60 days postimmunization, whereas others persisted for the length of the study. Antibodies reactive to the immunizing agent did not cross react with the detected alloantibodies, suggesting that the augmentation of alloimmune reactivity was most likely due to a nonspecific adjuvant effect from the vaccine.

CONCLUSIONS

Therapeutic vaccinations can alter the strength of cellular and humoral alloimmunity in humans. The results suggest that serial immune monitoring of alloreactivity might be beneficial when immunizations are administered to potential transplant recipients.

Comparative effects of sirolimus and mycophenolate mofetil on erythropoiesis in kidney transplant patients

Anemia and erythrocytosis (PTE) are common after kidney transplantation. We sought to determine the influence of sirolimus compared to mycophenolate mofetil (MMF) on post-transplant erythropoiesis. A total of 214 patients with recent kidney or kidney-pancreas transplants were treated with either sirolimus-based (n = 87) or MMF-based (n = 127) therapy. At 12 months, the prevalence of anemia was 31% with MMF and 57% with sirolimus (p < 0.001). Linear regression was used to examine the independent influence of sirolimus on hemoglobin at 12 months, controlling for multiple factors including gender and renal function. Sirolimus remained a significant correlate of lower hemoglobin in all patients (slope =-1.060, 95% CI: -1.76 to -0.362, p = 0.003), and in patients without PTE (slope =-0.671, 95% CI: -1.32 to -0.028, p = 0.041). PTE, defined as a persistent hematocrit above 51%, occurred in 19% with MMF and 7% with sirolimus (p = 0.013). PTE was examined using logistic regression analysis. Sirolimus use correlated negatively with PTE (odds ratio with sirolimus = 0.33, 95% CI: 0.12 to 0.89, p = 0.028). Our results indicate that, compared to treatment with MMF, treatment of kidney or kidney-pancreas recipients with sirolimus is associated with a higher prevalence of anemia, lower hemoglobin levels and lower incidence of PTE.

Comparative effects of sirolimus and mycophenolate mofetil on erythropoiesis in kidney transplant patients

Anemia and erythrocytosis (PTE) are common after kidney transplantation. We sought to determine the influence of sirolimus compared to mycophenolate mofetil (MMF) on post-transplant erythropoiesis. A total of 214 patients with recent kidney or kidney-pancreas transplants were treated with either sirolimus-based (n = 87) or MMF-based (n = 127) therapy. At 12 months, the prevalence of anemia was 31% with MMF and 57% with sirolimus (p < 0.001). Linear regression was used to examine the independent influence of sirolimus on hemoglobin at 12 months, controlling for multiple factors including gender and renal function. Sirolimus remained a significant correlate of lower hemoglobin in all patients (slope =-1.060, 95% CI: -1.76 to -0.362, p = 0.003), and in patients without PTE (slope =-0.671, 95% CI: -1.32 to -0.028, p = 0.041). PTE, defined as a persistent hematocrit above 51%, occurred in 19% with MMF and 7% with sirolimus (p = 0.013). PTE was examined using logistic regression analysis. Sirolimus use correlated negatively with PTE (odds ratio with sirolimus = 0.33, 95% CI: 0.12 to 0.89, p = 0.028). Our results indicate that, compared to treatment with MMF, treatment of kidney or kidney-pancreas recipients with sirolimus is associated with a higher prevalence of anemia, lower hemoglobin levels and lower incidence of PTE.

Alloreactivity in Renal Transplant Recipients with and without Chronic Allograft Nephropathy

The pathogenesis of chronic allograft nephropathy (CAN) involves both immunologic (antigen-dependent) and nonimmunologic (antigen-independent) mechanisms. In order to provide further insight into the immunologic basis of this disease, a cross-sectional analysis of cellular and humoral immunity in human renal allograft recipients with or without deteriorating renal function and biopsy proven CAN was performed. Interferon-gamma enzyme-linked immunosorbent spot assays were used to assess cellular immunity to donor, or fully mismatched third-party stimulator cells (direct pathway), and to synthetic peptides derived from donor HLA molecules (indirect pathway). Anti-HLA antibodies were evaluated by flow cytometry using HLA-coated beads. Both the mean frequencies of donor-reactive peripheral blood lymphocytes and the number of individuals who responded to donor antigens per group were statistically higher in CAN patients versus control subjects (P < 0.02). Calculated ratios of donor/third-party enzyme-linked immunosorbent spot responses showed mean values of 2.61 +/- 3.0 in the CAN group, with ratios of 0.50 to 0.72 +/- 0.42 in control subjects (P < 0.001), confirming that direct, donor-specific cellular immunity predominated in patients with CAN. Fifty percent of CAN patients studied exhibited donor peptide reactivity compared with only 28.6% in control subjects. Finally, 33% of patients in the CAN group developed new posttransplantation anti-HLA antibodies compared with only 4% in the control group (P < 0.05). Overall, the results suggest that persistent cell-mediated and humoral alloimmunity contribute to the development of CAN and further demonstrate that anti-donor immunity in patients with CAN is heterogeneous. Immune monitoring to predict long-term outcome should include multiple measures of cellular and humoral immunity.