Pharmacodynamic assessment of mycophenolic acid in resting and activated target cell population during the first year after renal transplantation.

AIMS: To explore the pharmacodynamics of mycophenolic acid (MPA) through inosine monophosphate dehydrogenase (IMPDH) capacity measurement and purine levels in peripheral blood mononuclear cells (PBMC) longitudinally during the first year after renal transplantation (TX). METHODS: PBMC were isolated from renal recipients 0-4 days prior to and 6-9 days, 5-7 weeks and 1 year after TX (before and 1.5 hours after dose). IMPDH capacity and purine (guanine and adenine) levels were measured in stimulated and nonstimulated PBMC. RESULTS: Twenty-nine patients completed the follow-up period, of whom 24 received MPA. In stimulated PBMC, the IMPDH capacity (pmol 10-6 cells min-1 ) was median (interquartile range) 127 (95.8-147) before TX and thereafter 44.9 (19.2-93.2) predose and 12.1 (4.64-23.6) 1.5 hours postdose across study days after TX. The corresponding IMPDH capacity in nonstimulated PBMC was 5.71 (3.79-6.93), 3.35 (2.31-5.62) and 2.71 (1.38-4.08), respectively. Predose IMPDH capacity in nonstimulated PBMC increased with time, reaching pre-TX values at 1 year. In stimulated PBMC, both purines were reduced before (median 39% reduction across days after TX) and after (69% reduction) dose compared to before TX. No alteration in the purine levels was observed in nonstimulated PBMC. Patients needing dose reductions during the first year had lower pre-dose IMPDH capacity in nonstimulated PBMC (1.87 vs 3.00 pmol 10-6 cells min-1 , P = .049) at 6-9 days. CONCLUSION: The inhibitory effect of MPA was stronger in stimulated PBMC. Nonstimulated PBMC became less sensitive to MPA during the first year after TX. Early IMPDH capacity appeared to be predictive of dose reductions.

Cardiovascular rEmodelling in living kidNey donorS with reduced glomerular filtration rate: rationale and design of the CENS study.

Purpose: Until recently, it has been believed that donating a kidney not represents any risk for development of cardiovascular disease. However, a recent Norwegian epidemiological study suggests that kidney donors have an increased long-term risk of cardiovascular mortality. The pathophysiological mechanisms linking reduced kidney function to cardiovascular disease are not known. Living kidney donors are screened for cardiovascular morbidity before unilateral nephrectomy, and are left with mildly reduced glomerular filtration rate (GFR) after donation. Therefore, they represent an unique model for investigating the pathogenesis linking reduced GFR to cardiovascular disease and cardiovascular remodelling. We present the study design of Cardiovascular rEmodelling in living kidNey donorS with reduced glomerular filtration rate (CENS), which is an investigator-initiated prospective observational study on living kidney donors. The hypothesis is that living kidney donors develop cardiovascular remodelling due to a reduction of GFR.Materials and methods: 60 living kidney donors and 60 age and sex matched healthy controls will be recruited. The controls will be evaluated to fulfil the Norwegian transplantation protocol for living kidney donors. Investigations will be performed at baseline and after 1, 3, 6 and 10 years in both groups. The investigations include cardiac magnetic resonance imaging, echocardiography, bone density scan, flow mediated dilatation, laser Doppler flowmetry, nailfold capillaroscopy, office blood pressure, 24-h ambulatory blood pressure, heart rate variability and investigation of microbiota and biomarkers for inflammation, cardiovascular risk and the calcium-phosphate metabolism.Conclusions: The present study seeks to provide new insight in the pathophysiological mechanisms linking reduced kidney function to cardiovascular disease. In addition, we aim to enlighten predictors of adverse cardiovascular outcome in living kidney donors. The study is registered at Clinical-Trials.gov (identifier: NCT03729557).

Longitudinal Study of Tacrolimus in Lymphocytes During the First Year After Kidney Transplantation.

INTRODUCTION: Tacrolimus (TAC) is an immunosuppressive drug used after organ transplantation. Dosing is adjusted using whole blood (WB-TAC) measurements. Patients within the therapeutic WB-TAC window still experience rejections and adverse effects. Alternative monitoring methods are therefore warranted. The authors developed a method for measuring TAC in peripheral blood mononuclear cell (PBMC) isolates (PBMC-TAC) and performed a pharmacokinetic study in a cohort of kidney transplant patients during the first year after transplantation. METHODS: PBMCs were isolated from whole blood by gradient centrifugation. After methanol-based extraction, liquid chromatography with tandem mass spectrometry was used to determine TAC in the extract. PBMC-TAC was normalized to the number of cells and alternatively to the protein amount in cells. Predose and postdose (1.5 hours) samples from kidney transplant patients were collected at 1 week, 6 weeks, and 1 year after transplantation. WB-TAC was measured using immunoassay. RESULTS: The PBMC-TAC assay fulfilled the validation criteria of the European Medicines Agency guidelines. Twenty-nine patients completed the study. Predose PBMC-TAC was (median) 23 (1 week), 33 (6 weeks), and 27 pg/10 cells (1 year). Postdose PBMC-TAC was 44, 30, and 27 pg/10 cells at 1 week, 6 weeks, and 1 year after transplantation, respectively. Predose WB-TAC (median) was 5.0, 6.0, and 5.4 mcg/L, and postdose WB-TAC was 10.5, 8.3, and 9.1 mcg/L, respectively, at 1 week, 6 weeks, and 1 year after transplantation. Whole blood and PBMC-TAC correlated at all timepoints (rho 0.40-0.82, P < 0.05) except before dosage at 6 weeks. PBMC-TAC normalized to the number of cells, and the amount of protein was modestly correlated (rho 0.36-0.81, P < 0.056). CONCLUSIONS: The correlation between WB-TAC and PBMC-TAC is modest during the first-year posttransplantation. Normalization of PBMC-TAC to cells or protein may yield different results. PBMC-TAC is increased 1.5 hours after dose at 1 week after transplantation, but not after 6 weeks or 1 year, indicating altered distribution kinetics.

Determination of Tacrolimus Concentration and Protein Expression of P-Glycoprotein in Single Human Renal Core Biopsies.

BACKGROUND: Tacrolimus (TAC) is currently the cornerstone of immunosuppressive protocols for renal transplant recipients. Despite therapeutic whole blood monitoring, TAC is associated with nephrotoxicity, and it has been hypothesized that intrarenal accumulation of TAC and/or its metabolites are involved. As TAC is a substrate of P-glycoprotein (P-gp), the expression and activity of this efflux transporter could influence the levels of TAC in renal tissue. The primary aim of this study was to develop and validate a method for quantification of TAC in tissue homogenates from single human renal core biopsies. The secondary aim was to provide measures of P-gp expression and of the demethylated metabolites of TAC in the same renal biopsy. METHODS: Human renal tissue, with and without clinical TAC exposure, was used for method development and validation. Homogenates were prepared with bead-beating, and concentrations of TAC and its demethylated metabolites were analyzed with liquid chromatography tandem mass spectrometry after protein precipitation. A Western blot method was used for semiquantification of P-gp expression in the homogenates. The final methods were applied to renal core biopsies from 2 transplant patients. RESULTS: The TAC assay showed within- and between-run mean accuracy between 99.7% and 107% and coefficients of variation ≤6.7%. Matrix effects were nonsignificant, and samples were stable for 3 months preanalytically when stored at -80°C. TAC concentrations in the renal core biopsies were 62.6 and 43.7 pg/mg tissue. The methods for measurement of desmethyl-TAC and P-gp expression were suitable for semiquantification in homogenates from renal core biopsies. CONCLUSIONS: These methods may be valuable for the elucidation of the pharmacokinetic mechanisms behind TAC-induced nephrotoxicity in renal transplant recipients.

NFAT-regulated cytokine gene expression during tacrolimus therapy early after renal transplantation.

AIMS: Despite pharmacokinetic monitoring of calcineurin inhibitors, the long-term outcome after transplantation (Tx) is still hampered by the side effects of these drugs. The aim of the present study was to characterize nuclear factor of activated T cells (NFAT)-regulated gene expression as a potential pharmacodynamic biomarker for further individualization of tacrolimus (Tac) therapy. METHODS: In 29 renal allograft recipients, samples were drawn once pre-Tx, and before and 1.5 h after Tac dosing at approximately 1 week, 6 weeks and 1 year post-Tx. Tac concentrations were measured by immunoassay, while the expression of genes encoding NFAT-regulated cytokines [interleukin 2 (IL2), interferon gamma (IFNG), colony stimulating factor 2 (CSF2)] and cytochrome P450 3A5 (CYP3A5) genotyping were determined by real-time polymerase chain reaction. RESULTS: The cytokine response after Tac dosing varied up to 46-fold between patients and changed significantly with time post-engraftment. Tac concentrations 1.5 h postdose (C1.5 ) >15 µg l-1 were associated with strong cytokine inhibition and residual gene expression (RGE) ≤10%, while lower Tac C1.5 resulted in more variable responses (RGE 2.5-68.7%). Patients with ongoing subclinical acute rejection (n = 5) demonstrated limited cytokine inhibition (RGE 39.7-72.6%), while patients with polyoma virus viraemia (n = 3) had relatively strong inhibition of cytokines (RGE 2.5-32.5%). By contrast, there was no association between Tac exposure and rejection or viraemia. CONCLUSIONS: The findings of our study support the potential of NFAT-regulated gene expression measurements as a pharmacodynamic tool for additional monitoring of Tac therapy, especially in the context of overimmunosuppression and viraemia.

Low-target tacrolimus in de novo standard risk renal transplant recipients: A single-centre experience.

AIM: Optimal tacrolimus exposure in transplant recipients is not well established. The results from the Symphony study indicated that low-target tacrolimus (trough concentrations 3-7 µg/L) in de novo standard risk renal transplant recipients should be appropriate. The aim of this study was to evaluate real-life outcomes when applying a similar strategy in a clinical setting. METHODS: A single-centre analysis was conducted in standard risk renal transplant recipients receiving low-target tacrolimus, mycophenolate mofetil, glucocorticoids and basiliximab induction. One-year estimated glomerular filtration rate (eGFR, Cockcroft-Gault), one-year biopsy-proven acute rejection rate and graft- and patient survival up to 3 years post-transplant were compared with the outcomes in the Symphony study. RESULTS: From 1 January 2009 to 31 March 2013, we included 406 patients. One year after transplantation, the mean ± SD eGFR was 76.8 ± 28.3 mL/min (Symphony: 65.4 ± 27.0 mL/min, P < 0.001). Biopsy-proven acute rejections were seen in 14.5% of the patients (Symphony: 12.3%, P = 0.35). Kaplan-Meier estimates [95% confidence interval] of three-year death-censored graft- and patient survival were 96.6% [94.2-99.0%] (Symphony: 93%) and 95.0% [92.6-97.3%] (Symphony: 95%), respectively. CONCLUSION: Low-target tacrolimus-based immunosuppression is safe and effective also in a standard clinical setting in de novo standard risk renal transplant recipients.

Laparoscopic repair of incisional hernia in solid organ-transplanted patients: the method of choice?

Due to immunosuppressive (IS) therapy, incisional hernias are overrepresented in the organ-transplanted (Tx) population with larger defects, a high rate of recurrence, and a tendency toward more seromas and infectious problems. Thirty-one Tx/IS patients with a control group of 70 non-IS patients with incisional hernia (6/7 recurrences) were included in a prospective interventional study. Both cohorts were treated with laparoscopic ventral hernia repair (LVHR). Follow-up time and rate was 37 months and 95%. One hundred LVHR's were completed as there was one conversion in the Tx/IS group. No late infections or mesh removals occurred. Recurrence rates were 9.7% vs. 4.2% (P = 0.37) and the overall complication rates were 19% vs. 27% (P = 0.80). The Tx/IS group had a higher mesh-protrusion rate (29% vs. 13%, P = 0.09), but also larger hernias. Polycystic kidney disease was overrepresented in the Tx cohort (44% of kidney-Tx). Incisional hernias in Tx/IS patients may be treated by LVHR with the same low complication rate and recurrence rate as non-IS patients. By LVHR, the highly problematic seroma/infection problems encountered in Tx/IS patients treated by conventional open technique seem almost eliminated. The minimally invasive procedure seems particularly rational in the Tx/Is population and should be the method of choice. (ClinicalTrials.gov number: NCT00455299, date: 5 May 2006).

Long-term Outcomes After Kidney Transplantation From DBD Donors Aged 70 y and Older.

Background: Transplantation of kidneys from elderly donations after brain death (DBD) donors has increased owing to organ shortages. We aimed to assess the impact on long-term kidney transplant outcomes from DBD donors aged 70 y and older compared with kidneys from younger donors. Methods: From 2007 to 2022, 2274 first single kidney transplantations from DBD donors were performed at our center. Data from 1417 kidney transplant recipients receiving a DBD organ were included and categorized into 3 groups according to donor age: 70 y and older (n = 444, median age 74 y), 60-69 y (n = 527, median age 64 y), and a reference group consisting of donors aged 45-54 y (n = 446, median age 50 y). Kaplan-Meier plots and multivariate Cox regression with correction for recipient, donor, and transplant characteristics were used to investigate patient and kidney graft survival outcomes. Results: The median patient follow-up time was 9.3 y (interquartile range, 5.3-13.1). The adjusted hazard ratios for patient death in recipients of kidneys from DBD donors aged 70 y and older compared with 60-69 y and 45-54 y were 1.12 (95% confidence interval [CI], 0.92-1.36; P = 0.26) and 1.62 (95% CI, 1.26-2.07; P < 0.001), respectively. Compared with recipients of donors aged 60-69 y and 45-54 y, the adjusted hazard ratios for kidney graft loss in recipients of donors aged 70 y and older were 1.23 (95% CI, 1.02-1.48; P = 0.029) and 1.94 (95% CI, 1.54-2.45; P < 0.001), respectively. Conclusions: Transplantation of kidneys from DBD donors aged 70 y and older resulted in acceptable long-term outcomes and is encouraging.

Renal Cell Carcinoma and Kidney Transplantation: A Narrative Review.

Kidney transplant recipients (KTRs) are at increased risk of developing renal cell carcinoma (RCC). The cancer can be encountered at different steps in the transplant process. RCC found during work-up of a transplant candidate needs treatment and to limit the risk of recurrence usually a mandatory observation period before transplantation is recommended. An observation period may be omitted for candidates with incidentally discovered and excised small RCCs (<3 cm). Likewise, RCC in the donor organ may not always preclude usage if tumor is small (<2 to 4 cm) and removed with clear margins before transplantation. After transplantation, 90% of RCCs are detected in the native kidneys, particularly if acquired cystic kidney disease has developed during prolonged dialysis. Screening for RCC after transplantation has not been found cost-effective. Treatment of RCC in KTRs poses challenges with adjustments of immunosuppression and oncologic treatments. For localized RCC, excision or nephrectomy is often curative. For metastatic RCC, recent landmark trials in the nontransplanted population demonstrate that immunotherapy combinations improve survival. Dedicated trials in KTRs are lacking. Case series on immune checkpoint inhibitors in solid organ recipients with a range of cancer types indicate partial or complete tumor response in approximately one-third of the patients at the cost of rejection developing in ~40%.

Improved Tacrolimus Target Concentration Achievement Using Computerized Dosing in Renal Transplant Recipients--A Prospective, Randomized Study.

BACKGROUND: Early after renal transplantation, it is often challenging to achieve and maintain tacrolimus concentrations within the target range. Computerized dose individualization using population pharmacokinetic models may be helpful. The objective of this study was to prospectively evaluate the target concentration achievement of tacrolimus using computerized dosing compared with conventional dosing performed by experienced transplant physicians. METHODS: A single-center, prospective study was conducted. Renal transplant recipients were randomized to receive either computerized or conventional tacrolimus dosing during the first 8 weeks after transplantation. The median proportion of tacrolimus trough concentrations within the target range was compared between the groups. Standard risk (target, 3-7 µg/L) and high-risk (8-12 µg/L) recipients were analyzed separately. RESULTS: Eighty renal transplant recipients were randomized, and 78 were included in the analysis (computerized dosing (n = 39): 32 standard risk/7 high-risk, conventional dosing (n = 39): 35 standard risk/4 high-risk). A total of 1711 tacrolimus whole blood concentrations were evaluated. The proportion of concentrations per patient within the target range was significantly higher with computerized dosing than with conventional dosing, both in standard risk patients (medians, 90% [95% confidence interval {95% CI}, 84-95%] vs 78% [95% CI, 76-82%], respectively, P < 0.001) and in high-risk patients (medians, 77% [95% CI, 71-80%] vs 59% [95% CI, 40-74%], respectively, P = 0.04). CONCLUSIONS: Computerized dose individualization improves target concentration achievement of tacrolimus after renal transplantation. The computer software is applicable as a clinical dosing tool to optimize tacrolimus exposure and may potentially improve long-term outcome.

Presensitization revisited: pitfalls of vascular allografts in transplant candidates.

Vascular allografts in end-stage renal disease (ESRD) patients represent a particular immunological challenge. A broad HLA immunization led us to study in depth the history of two patients with vascular allografts. In Case 1 the allograft was added to a Gore-Tex graft used for haemodialysis access and no immunosuppression was administered. In Case 2 the allograft was used to prolong a renal artery from living donor and immunosuppression was suboptimal. In vascular surgery, immunosuppression is mainly used to improve graft patency. ESRD patients are potential organ recipients and immunosuppression should therefore be tailored to reduce HLA immunization.

Kidney transplantation with and without simultaneous bilateral native nephrectomy in patients with polycystic kidney disease: a comparative retrospective study.

BACKGROUND: Patients with autosomal dominant polycystic kidney disease (ADPKD) often need to undergo native nephrectomy and are candidates for kidney transplantation. The necessity and timing of nephrectomy are controversial. Some authors recommend simultaneous bilateral native nephrectomy (SBN) as the preferred option in living-donor kidney transplantation (LDKT). These recommendations are based on small study populations. We therefore set out to study outcomes of LDKT with SBN, compared with LDKT alone in a larger single-center cohort. METHODS: A consecutive series of 159 patients with ADPKD undergoing LDKT were included in the study. Of the 159 patients, 2 were excluded because of missing data, 79 underwent LDKT alone (group A), and 78 underwent LDKT with SBN (group B). Demographic data and intraoperative and postoperative data were collected from patient charts and the national kidney registry. RESULTS: There were no differences regarding background data. Group B experienced significantly longer operating times (183.7 vs. 319.3 min, P<0.001), a greater need for blood transfusions (0.1 vs. 1.6 units, P<0.001) and plasma products (35.1 vs. 438.3 mL, P<0.001), and longer hospital stays (11.8 vs. 15.4 days, P<0.001). It also experienced more intraoperative events and postoperative complications but fewer reoperations/reinterventions. There were no differences in patient and graft survival rates. CONCLUSIONS: SBN in patients undergoing LDKT for ADPKD does not have a significant negative impact on patient and graft survival rates. It obviates a separate surgical procedure but requires longer hospital stay. It may be associated with more postoperative complications and risk of graft loss. These considerations should be communicated to the recipient and the donor.