Tacrolimus dose, blood concentrations and acute nephrotoxicity, but not CYP3A5/ABCB1 genetics, are associated with allograft tacrolimus concentrations in renal transplant recipients.

AIMS: Long-term use of the immunosuppressant tacrolimus is limited by nephrotoxicity. Following renal transplantation, the risk of nephrotoxicity may be determined more by allograft than by blood tacrolimus concentrations, and thus may be affected by donor CYP3A5 and ABCB1 genetics. Little is known regarding factors that determine tacrolimus intrarenal exposure. METHODS: This study investigated the relationship between trough blood (C0Blood ) and allograft (CGraft ) tacrolimus concentrations and tacrolimus dose, haematocrit, genetics, acute nephrotoxicity, rejection status, delayed graft function, and time post-transplant. C0Blood and CGraft were quantified in 132 renal transplant recipients together with recipient and donor CYP3A5 (rs776746) and ABCB1 3435 (rs1045642) genotypes. RESULTS: C0Blood ranged from 2.6 to 52.3 ng/mL and CGraft from 33 to 828 pg/mg tissue. Adjusting for dose, recipients who were CYP3A5 expressors had lower C0Blood compared to nonexpressors, whilst delayed graft function was associated with higher C0Blood . Linear regression showed that the significant predictors of CGraft were C0Blood (point-wise P = 7 × 10-10 ), dose (P = .004) acute nephrotoxicity (P = .002) and an interaction between C0Blood and acute tacrolimus nephrotoxicity (P = .0002), with an adjusted r2  = 0.35 and no contribution from donor or recipient CYP3A5 or ABCB1 genotype. The association between CGraft and acute nephrotoxicity depended on one very high CGraft (828 pg/mg tissue). CONCLUSIONS: Recipient and donor CYP3A5 and ABCB1 3435C>T genotypes are not determinants of allograft tacrolimus exposure in kidney transplant recipients. However, tacrolimus dose and C0Blood were significant predictors of CGraft , and the relationship between C0Blood and CGraft appeared to differ in the presence or absence of acute nephrotoxicity.

Effect of the proton-pump Inhibitor pantoprazole on MycoPhenolic ACid exposure in kidney and liver transplant recipienTs (IMPACT study): a randomized trial.

BACKGROUND: Mycophenolic acid (MPA) is widely utilized as an immunosuppressant in kidney and liver transplantation, with reports suggesting an independent relationship between MPA concentrations and adverse allograft outcome. Proton-pump inhibitors (PPIs) may have variable effects on the absorption of different MPA formulations leading to differences in MPA exposure. METHODS: A multicentre, randomized, prospective, double-blind placebo-controlled cross-over study was conducted to determine the effect of the PPI pantoprazole on the MPA and its metabolite MPA-glucuronide (MPA-G) area under the curve (AUC) >12 h (MPA-AUC12 h) in recipients maintained on mycophenolate mofetil (MMF) or enteric-coated mycophenolate sodium (EC-MPS). We planned a priori to examine separately recipients maintained on MMF and EC-MPS for each pharmacokinetic parameter. The trial (and protocol) was registered with the Australian New Zealand Clinical Trials Registry on 24 March 2011, with the registration number of ACTRN12611000316909 ('IMPACT' study). RESULTS: Of the 45 recipients screened, 40 (19 MMF and 21 EC-MPS) were randomized. The mean (standard deviation) recipient age was 58 (11) years with a median (interquartile range) time post-transplant of 43 (20-132) months. For recipients on MMF, there was a significant reduction in the MPA-AUC12 h [geometric mean (95% confidence interval) placebo: 53.9 (44.0-65.9) mg*h/L versus pantoprazole: 43.8 (35.6-53.4) mg*h/L; P = 0.004] when pantoprazole was co-administered compared with placebo. In contrast, co-administration with pantoprazole significantly increased MPA-AUC12 h [placebo: 36.1 (26.5-49.2) mg*h/L versus pantoprazole: 45.9 (35.5-59.3) mg*h/L; P = 0.023] in those receiving EC-MPS. Pantoprazole had no effect on the pharmacokinetic profiles of MPA-G for either group. CONCLUSIONS: The co-administration of pantoprazole substantially reduced the bioavailability of MPA in patients maintained on MMF and had the opposite effect in patients maintained on EC-MPS, and therefore, clinicians should be cognizant of this drug interaction when prescribing the different MPA formulations.

Long-Term Outcomes after Acute Rejection in Kidney Transplant Recipients: An ANZDATA Analysis.

BACKGROUND: Declining rates of acute rejection (AR) and the high rate of 1-year graft survival among patients with AR have prompted re-examination of AR as an outcome in the clinic and in trials. Yet AR and its treatment may directly or indirectly affect longer-term outcomes for kidney transplant recipients. METHODS: To understand the long-term effect of AR on outcomes, we analyzed data from the Australia and New Zealand Dialysis and Transplant Registry, including 13,614 recipients of a primary kidney-only transplant between 1997 and 2017 with at least 6 months of graft function. The associations between AR within 6 months post-transplant and subsequent cause-specific graft loss and death were determined using Cox models adjusted for baseline donor, recipient, and transplant characteristics. RESULTS: AR occurred in 2906 recipients (21.4%) and was associated with graft loss attributed to chronic allograft nephropathy (hazard ratio [HR], 1.39; 95% confidence interval [95% CI], 1.23 to 1.56) and recurrent AR beyond month 6 (HR, 1.85; 95% CI, 1.39 to 2.46). Early AR was also associated with death with a functioning graft (HR, 1.22; 95% CI, 1.08 to 1.36), and with death due to cardiovascular disease (HR, 1.30; 95% CI, 1.11 to 1.53) and cancer (HR, 1.35; 95% CI, 1.12 to 1.64). Sensitivity analyses restricted to subgroups with either biopsy-proven, antibody-mediated, or vascular rejection, or stratified by treatment response produced similar results. CONCLUSIONS: AR is associated with increased risks of longer-term graft failure and death, particularly death from cardiovascular disease and cancer. The results suggest AR remains an important short-term outcome to monitor in kidney transplantation and clinical trials.

Safety and efficacy of eculizumab for the prevention of antibody-mediated rejection after deceased-donor kidney transplantation in patients with preformed donor-specific antibodies.

The presence of preformed donor-specific antibodies in transplant recipients increases the risk of acute antibody-mediated rejection (AMR). Results of an open-label single-arm trial to evaluate the safety and efficacy of eculizumab in preventing acute AMR in recipients of deceased-donor kidney transplants with preformed donor-specific antibodies are reported. Participants received eculizumab as follows: 1200 mg immediately before reperfusion; 900 mg on posttransplant days 1, 7, 14, 21, and 28; and 1200 mg at weeks 5, 7, and 9. All patients received thymoglobulin induction therapy and standard maintenance immunosuppression including steroids. The primary end point was treatment failure rate, a composite of biopsy-proved grade II/III AMR (Banff 2007 criteria), graft loss, death, or loss to follow-up, within 9 weeks posttransplant. Eighty patients received transplants (48 women); the median age was 52 years (range 24-70 years). Observed treatment failure rate (8.8%) was significantly lower than expected for standard care (40%; P < .001). By 9 weeks, 3 of 80 patients had experienced AMR, and 4 of 80 had experienced graft loss. At 36 months, graft and patient survival rates were 83.4% and 91.5%, respectively. Eculizumab was well tolerated and no new safety concerns were identified. Eculizumab has the potential to provide prophylaxis against injury caused by acute AMR in such patients (EudraCT 2010-019631-35).

Relationship between allograft cyclosporin concentrations and P-glycoprotein expression in the 1st month following renal transplantation.

The immunosuppressant cyclosporin is a P-glycoprotein (P-gp) substrate whose impaired function has been associated with an increased risk of cyclosporin-induced nephrotoxicity following renal transplantation. This study investigated the relationship between blood and allograft cyclosporin concentration, and the effect of P-gp expression. Fifty biopsy samples were obtained from 39 renal transplant recipients who received cyclosporin as part of maintenance immunosuppression. Blood cyclosporin concentrations (2 hours postdose) were obtained from clinical records, matching allograft cyclosporin concentrations were measured in frozen biopsy tissue by liquid chromatography-tandem mass spectrometry, and allograft P-gp expression was assessed by immunohistochemistry. Blood and allograft cyclosporin concentrations in the 1st month post-transplantation ranged from 505-2005 µg/L and 0.01-16.7 ng/mg tissue, respectively. Dose was the only significant predictor of allograft cyclosporin concentrations (adjusted R2  = .24, F-statistic = 11.52, P = .0019), with no effect of P-gp expression or blood cyclosporin concentrations. P-gp expression is not the major determinant of allograft cyclosporin concentrations.

Weekend effect on early allograft outcome after kidney transplantation- a multi-centre cohort study.

Weekend surgery may be associated with a higher risk of early complications, but the effect of the timing of kidney transplant surgery on early allograft outcome remains uncertain. The aim of this study is to evaluate whether the association between weekend transplant surgery and allograft failure was modified by prevalent vascular disease. Using data from the Australia and New Zealand Dialysis and Transplant registry, we examined the association between weekend status and 90-day and 1-year allograft failure in deceased donor transplant recipients between 1994-2012. Two-way interaction between vascular disease and weekend status was examined. Of 6622 recipients, 1868 (28.2%) received transplants during weekends. Compared with weekday transplants, weekend transplants were associated with an adjusted hazard ratio (HR) for 90-day and 1-year allograft failure of 0.99 (0.78-1.25; P = 0.917) and 0.93 (0.76-1.13, P = 0.468), respectively. There was a significant interaction between prevalent vascular disease and weekend status for 90-day allograft failure (Pinteraction = 0.008) but not at 1-year, such that patients with vascular disease were more likely to experience 90-day allograft failure if transplanted on weekend (versus weekdays), particularly failures secondary to vascular complications. Timing of transplantation does not impact on allograft outcome, although those with vascular disease may benefit from more intensive post-transplant follow-up for potential vascular complications.

Kidney transplant graft outcomes in 379 257 recipients on 3 continents.

Kidney transplant outcomes that vary by program or geopolitical unit may result from variability in practice patterns or health care delivery systems. In this collaborative study, we compared kidney graft outcomes among 4 countries (United States, United Kingdom, Australia, and New Zealand) on 3 continents. We analyzed transplant and follow-up registry data from 1988-2014 for 379 257 recipients of first kidney-only transplants using Cox regression. Compared to the United States, 1-year adjusted graft failure risk was significantly higher in the United Kingdom (hazard ratio [HR] 1.22, 95% confidence interval [CI] 1.18-1.26, P < .001) and New Zealand (hazard ratio [HR] 1.29, 95% confidence interval [CI] 1.14-1.46, P < .001), but lower in Australia (HR 0.90, 95% CI 0.84-0.96, P = .001). In contrast, long-term adjusted graft failure risk (conditional on 1-year function) was significantly higher in the United States compared to Australia, New Zealand, and the United Kingdom (HR 0.74, 0.75, and 0.74, respectively; each P < .001). Thus long-term kidney graft outcomes are approximately 25% worse in the United States than in 3 other countries with well-developed kidney transplant systems. Case mix differences and residual confounding from unmeasured factors were found to be unlikely explanations. These findings suggest that identification of potentially modifiable country-specific differences in care delivery and/or practice patterns should be sought.

De novo or early conversion to everolimus and long-term cancer outcomes in kidney transplant recipients: A trial-based linkage study.

Choice of immunosuppression may modify the risk of cancer after kidney transplantation, however, long-term data are lacking. Using the Australian and New Zealand Dialysis and Transplant Registry, we compared the 9-year risk of incident cancer, non-melanoma skin cancer (NMSC), and death attributed to cancer among participants from Australia and New Zealand in four randomized-controlled trials which compared de novo or early switch to an everolimus-containing regimen with calcineurin-inhibitor-based triple therapy. An adjusted Cox-model with random effects was used to determine such risks. Two hundred seventy-nine patients (192 everolimus, 87 control) were followed for a median of 9 years (IQR 6.7, 11.2). Compared with control, everolimus use was not associated with a reduction in the risk of incident cancer, NMSC, or cancer-related death (unadjusted HR [95% CI] 0.86 [0.49-1.48], 0.58 [0.30-1.12], and 1.18 [0.32-4.38], respectively). Subgroup analyses showed a 56% reduction for NMSC in patients randomized to everolimus + reduced-dose calcineurin-inhibitor versus control (unadjusted HR 0.44 [0.21-0.92]), which remained significant after adjusting for age, gender and smoking (adjusted HR 0.45 [0.21-0.96]). Although de novo or early switch to everolimus did not alter the 9-year risk of incident cancer or cancer-related death, everolimus with reduced-dose calcineurin-inhibitor strategy may reduce the long-term risk of NMSC.

The risk of cancer in kidney transplant recipients may be reduced in those maintained on everolimus and reduced cyclosporine.

Kidney transplant recipients are at a high risk of developing cancers after transplantation. Switching from calcineurin inhibitors to sirolimus has been shown to prevent secondary nonmelanoma skin cancer but whether everolimus with reduced exposure to calcineurin inhibitors has similar anti-cancer effects remains unknown. Therefore, we compared the risk of incident cancer over seven years of follow-up among kidney transplant recipients randomized to everolimus plus reduced exposure cyclosporine versus mycophenolate sodium and standard exposure cyclosporine. Using the Australian and New Zealand Dialysis and Transplant Registry (ANZDATA), we assessed the seven-year risk of incident cancer and other graft outcomes among a subgroup of recipients who had participated in the A2309 study using adjusted Cox proportional hazard models. Of 95 recipients, 66 were randomized to everolimus (1.5 mg or 3 mg) with reduced cyclosporine and 29 received mycophenolate sodium and standard exposure cyclosporine. Compared to mycophenolate sodium and standard exposure cyclosporine, everolimus treatment was associated with unadjusted hazard ratios of 0.28 (95% confidence interval 0.11-0.74), 0.39 (0.16-0.98) and 0.41 (0.23-0.71), respectively for nonmelanoma skin cancer, non-skin cancers and any cancers. Interestingly, the adjusted hazard ratios were 0.34 (0.13-0.91), 0.35 (0.09-1.25) and 0.32 (0.15-0.71), respectively. There was no association between treatment groups and rejection, graft loss or death. Compared to standard-exposure cyclosporine, everolimus with reduced exposure to cyclosporine may be associated with a reduced risk of cancer, particularly for non-melanoma skin cancer. Thus, if confirmed in larger patient cohorts, de novo use of everolimus with reduced exposure to calcineurin inhibitors may enable a reduction in cancer burden after transplantation.

Maternal compared with paternal donor kidneys are associated with poorer graft outcomes after kidney transplantation.

Noninherited maternal human leukocyte antigens may be less detrimental on allograft outcomes after kidney transplantation compared with noninherited paternal antigens, but this association in the era of modern immunosuppression remains unknown. Here we determine the association between parental donor kidneys, acute rejection, and graft failure in primary live-donor parental kidney transplant recipients using data from the Australia and New Zealand Dialysis and Transplant Registry between 1997 and 2012. Of the 1139 recipients followed for a median of 7.2 years (8588 person-years), 652 received kidneys from maternal donors. Compared with paternal donor kidneys, maternal donor kidneys were associated with a significantly increased risk of acute rejection (adjusted odds ratio 1.54; 95% confidence interval [CI], 1.14-2.07) and significant overall graft loss. The latter was confined to recipients who have experienced acute rejection (adjusted hazard ratio 1.60; 95%CI, 1.05-2.43) but not in those who did not experience acute rejection. Thus, our study suggests that recipients of maternal donor kidneys have a greater risk of rejection and graft loss. Hence, clinicians and patients should be cognizant of this association when determining which of the 2 parental donors is most suitable for transplantation.