Safety and long-term effects of renal denervation: Rationale and design of the Dutch registry.

BACKGROUND: Percutaneous renal denervation (RDN) has recently been introduced as a treatment for therapy-resistant hypertension. Also, it has been suggested that RDN may be beneficial for other conditions characterised by increased sympathetic nerve activity. There are still many uncertainties with regard to efficacy, safety, predictors for success and long-term effects. To answer these important questions, we initiated a Dutch RDN registry aiming to collect data from all RDN procedures performed in the Netherlands. METHODS: The Dutch RDN registry is an ongoing investigator-initiated, prospective, multicentre cohort study. Twenty-six Dutch hospitals agreed to participate in this registry. All patients who undergo RDN, regardless of the clinical indication or device that is used, will be included. Data are currently being collected on eligibility and screening, treatment and follow-up. RESULTS: Procedures have been performed since August 2010. At present, data from 306 patients have been entered into the database. The main indication for RDN was hypertension (n = 302, 99%). Patients had a mean office blood pressure of 177/100 (±29/16) mmHg with a median use of three (range 0-8) blood pressure lowering drugs. Mean 24-hour blood pressure before RDN was 157/93 (±18/13) mmHg. RDN was performed with different devices, with the Simplicity™ catheter currently used most frequently. CONCLUSION: Here we report on the rationale and design of the Dutch RDN registry. Enrolment in this investigator-initiated study is ongoing. We present baseline characteristics of the first 306 participants.

Cinacalcet for secondary hyperparathyroidism: from improved mineral levels to improved mortality?

Secondary hyperparathyroidism is an almost inevitable complication of advanced kidney failure. The introduction of the calcimimetic cinacalcet for the treatment of secondary hyperparathyroidism in patients on dialysis was based on its ability to reduce elevated levels of parathyroid hormone (PTH). Subsequent clinical studies confirmed the beneficial effects of cinacalcet on biochemical parameters reflecting mineral disturbances and bone disease. In this review we summarise the impact of cinacalcet on biochemical, intermediate and clinical outcomes. We also present previously unpublished mineral metabolism data from 144 Dutch dialysis patients treated with cinacalcet who participated in the pan-European ECHO observational study. Although secondary hyperparathyroidism tended to be more severe in our Dutch cohort, compared with the entire ECHO cohort, cinacalcet was nevertheless effective in reducing PTH in these patients. Two recent clinical studies evaluated, respectively, the efficacy of cinacalcet in improving the intermediate endpoint of cardiovascular calcifications (ADVANCE trial), and its impact on clinical outcomes, including all-cause mortality and cardiovascular events (EVOLVE trial). The ADVANCE trial provided evidence that cinacalcet may indeed improve calcification in both large arteries and cardiac valves. The EVOLVE trial, however, did not meet its clinical primary endpoint (time to all-cause mortality, myocardial infarction, hospitalisation for unstable angina, heart failure or a peripheral vascular event), although secondary and sensitivity analysis suggested a beneficial effect. The clinical implications of these important studies are also addressed in this review.

The relative importance of cyclosporine exposure in heart, kidney or liver transplant recipients on maintenance therapy.

We investigated the relationship between cyclosporine exposure and the presence of cyclosporine-related side effects and assessed the advantage of the cyclosporine concentration 2 h post-dose (C(2)) over pre-dose concentration (C(0)) monitoring. Cyclosporine area-under-the-concentration-time curves were measured during the absorption phase (AUC(0-4 h)) in 49 liver, 28 heart and 26 kidney transplant recipients (time since transplantation >6 years) with or without cyclosporine-related side effects on maintenance therapy. The cyclosporine C(0) correlated well with AUC(0-4) (r=0.77), whereas C(2) levels correlated strongly with AUC(0-4) (r=0.92). Although we observed a trend towards higher CsA concentrations in transplant recipients with side effects than in patients without CsA toxicity, the large majority of those differences were not statistically significant. Thus, as cyclosporine exposure was not clearly related to the presence of side effects, and C(0) correlated fairly with AUC(0-4), the advantage of monitoring cyclosporine treatment using C(2) rather than C(0), may be limited for patients on cyclosporine maintenance therapy.

The use of cyclosporine in renal transplantation.

The introduction of cyclosporine (CsA) into clinical practice resulted in a dramatic reduction in the incidence and severity of acute rejection. As a result, short-term and medium-term kidney allograft survival increased greatly. However, the long-term patient and graft survival have not improved to a similar degree. This can partly be attributed to the side effects of CsA and partly to the fact that the use of CsA has not led to a reduced incidence of chronic allograft nephropathy. Thus, there has been a continuing search for strategies that minimize CsA toxicity but maintain adequate immunosuppression. This has resulted in the development of the CsA microemulsion formulation and improved methods for therapeutic drug monitoring. With the introduction of newer immunosuppressive drugs, early CsA withdrawal and CsA-free immunosuppressive therapy have become feasible. However, CsA weaning or complete avoidance is associated with a slightly higher risk of acute rejection, and the long-term efficacy and safety of such strategies remain to be established. Therefore, it is to be expected that in the near future CsA will remain part of the standard immunosuppressive regimen in many transplant centers.

Unusual presentation of herpes virus infections in renal transplant recipients exposed to high mycophenolic acid plasma concentrations.

Viral infections constitute an important problem for transplant recipients and their physicians. Often the balance between adequate and over-immunosuppression is hard to find and therapeutic drug monitoring might be a welcome adjunct in the management of transplant patients. We report four renal transplant recipients with extra-ordinary presentations of viral disease who were all treated with mycophenolate mofetil and in whom high mycophenolic acid (MPA) trough levels were found. High MPA levels may reflect over-immunosuppression resulting in infectious complications.

Immunosuppression should be stopped in patients with renal allograft failure.

Patients returning to haemodialysis or peritoneal dialysis after a failed kidney transplantation sometimes have a renal allograft left in situ for some urine production. Low-dose immunosuppressive medication is often continued in such patients. To evaluate the morbidity and mortality between patients in time periods with (group A) or without (group B) low-dose maintenance immunosuppression, the present study was initiated. In a multi-centre cohort study we analysed data from patient files, which showed failure after at least 3 months graft function between 10 August 1972 and 4 April 1996, including 197 kidney transplantations. A total of 1.7 versus 0.51 infections per patient year was found in groups A and B, respectively (odds ratio [OR]: 3.4, 95% confidence interval [CI]: 2.5-4.5). There was an increased mortality in group A compared to group B (OR 3.4, 95% CI: 1.8-6.3), both from infectious disease (OR 2.8, 95% CI: 1.1-7.0), and cardiovascular disease (OR 4.9, 95% CI: 1.8-13.5). Continuation of immunosuppressive medication did not lead to fewer rejections (defined as a painful, tender graft and/or haematuria and/or low-grade non-infectious fever). Transplantectomy-related morbidity and mortality were acceptable. The increase in morbidity and mortality associated with low-dose maintenance immunosuppression argues in favour of stopping these medicaments when failed renal allograft patients return to dialysis.

Mycophenolate mofetil, Cellcept, a new immunosuppressive drug with great potential in internal medicine.

Mycophenolate mofetil is a new immunosuppressive drug, exhibiting its effect through inhibition of proliferation of T- and B-lymphocytes. Superior efficacy of mycophenolate mofetil compared to azathioprine, in combination with cyclosporine and prednisone, in the prevention of acute rejection in organ transplantation has made mycophenolate mofetil one of the standard immunosuppressive drugs after transplantation. Mycophenolate mofetil also is an interesting candidate drug for many other, mainly auto-immune mediated diseases. The use of mycophenolate mofetil in several of these diseases is discussed. The definitive place of mycophenolate mofetil will depend on the results of randomised trials currently under way.

Mycophenolic acid trough levels after kidney transplantation in a cyclosporine-free protocol.

Twenty-seven stable kidney transplant recipients treated with cyclosporine and prednisone were converted to mycophenolate mofetil (MMF) and prednisone 1 year after transplantation. After conversion the patients were treated with a standard daily dose of 1 g MMF b.i.d. and 10 mg prednisone for 4 months. Thereafter, two MMF dose reductions were performed with a 4-month interval. Mycophenolic acid (MPA) trough levels were measured at regular intervals. A relation was found between MPA trough levels and MMF dose. The median MPA trough level for patients treated with 1 g MMF b.i.d. was 4.3 microg/ml (0.95-15.5) and 3.0 microg/ml (0.73-7.8) for patients treated with 750 mg b.i.d. (P = 0.0002). The MPA trough levels further decreased from 3.0 to 2.3 microg/ml (0.6-6.63) in patients treated with 500 mg MMF b.i.d. (P = 0.01). Dose reduction of MMF from 1 g to 750 mg b.i.d. could be performed without acute rejections. A further dose reduction to 500 mg b.i.d. elicited 3 rejections. Patients experiencing an acute rejection had a median MPA trough level of 2.3 microg/ml (1.26-3.38) compared to 3.8 microg/ml (1.48-6.52) in patients without an acute rejection (P = 0.25). We conclude that there is a significant relation between MPA trough levels and MMF dose. MPA trough levels were not predictive of rejection in the present study.

Donor-specific T-cell reactivity identifies kidney transplant patients in whom immunosuppressive therapy can be safely reduced.

BACKGROUND: To reduce the side effects of long-term immunosuppressive therapy, stable renal transplant patients were routinely converted from cyclosporine to either azathioprine or mycophenolate mofetil. Thereafter, the azathioprine and mycophenolate mofetil dose was reduced to 75% at 4 months and to 50% at 8 months after conversion. We questioned whether the T-cell reactivity before conversion was able to predict which patients could be safely converted and tapered in their immunosuppressive load, while remaining free from acute rejection. METHODS: Before conversion, the T-cell reactivity of peripheral blood mononuclear cells against donor and third-party spleen cells were tested in mixed lymphocyte cultures. We measured the frequency of donor and third-party reactive helper T-lymphocyte (HTLpf) and cytotoxic T-lymphocyte (CTLpf) precursors and their avidity for HLA class I antigens using limiting dilution analysis. Peripheral blood mononuclear cells were also stimulated with tetanus toxoid to test the general immune response. RESULTS: The tetanus toxoid response, reactivity to donor and third-party cells as measured in mixed lymphocyte cultures and HTLpf, and the avidity of cytotoxic T-lymphocyte precursors were not predictive for the development of acute rejection. However, significant differences were found in donor-specific CTLpf before conversion, between patients with and without acute rejection after conversion in immunosuppression. The donor-specific CTLpf was significantly lower in patients without compared to those with acute rejection (P=0.01). Additionally, when no CTLpf was detectable before conversion, acute rejection did not occur after conversion. Acute rejection was only diagnosed in patients with detectable CTLpf before conversion. CONCLUSION: The number of donor-specific cytotoxic T-lymphocytes identifies patients in whom the immunosuppressive load can be safely reduced.

Randomized study on the conversion of treatment with cyclosporine to azathioprine or mycophenolate mofetil followed by dose reduction.

BACKGROUND: The introduction of cyclosporine (CsA) in kidney transplantation has improved early graft survival. However, its long-term use is associated with impairment of renal function and increased cardiovascular risk factors. To avoid CsA-related long-term adverse effects, patients were converted to either azathioprine (AZA) or mycophenolate mofetil (MMF) 1 year after transplantation. METHODS: Between September 1995 and January 1997, 64 stable renal transplant recipients on CsA and prednisone treatment were included in a prospective, randomized study. Patients were randomized for conversion of CsA to 2 mg/kg AZA (n=30) or 1 g of MMF twice daily (n=34). All patients remained on low-dose steroids. To decrease the total immunosuppressive load, a dose reduction in MMF and AZA was performed at 4 and again at 8 months after conversion. Mycophenolic acid trough levels were measured at regular intervals. RESULTS: After conversion, a decrease in serum creatinine was found for both groups: for MMF, 132 to 109 micromol/L (P=0.016); and for AZA, 123 to 112 micromol/L (P<0.0001). After conversion, more acute rejections occurred in the AZA group (11/30) compared to the MMF group (4/34) (P=0.04). Dose reduction of MMF to 500 mg twice daily and of AZA to 1.0 mg/kg elicited three rejections in both groups. The incidence of side effects and infections were similar. CONCLUSION: Discontinuation of CsA spared renal function. In patients converted to MMF significantly less rejections occurred compared to patients converted to AZA. Furthermore, dose reduction of both AZA and MMF is possible in the majority (72%) of the patients.

Effect of mycophenolate mofetil on erythropoiesis in stable renal transplant patients is correlated with mycophenolic acid trough levels.

BACKGROUND: Both mycophenolate mofetil (MMF) and azathioprine (AZA) are immunosuppressive drugs that inhibit purine synthesis. In theory, MMF selectively inhibits lymphocyte proliferation, while AZA has well-known effects on red blood cells and thrombocytes as well. In renal transplant recipients we replaced CsA therapy by MMF in an attempt to reduce the immunosuppressive load 1 year after kidney transplantation. During this study we observed the effect of MMF on haematological parameters such as haemoglobin (Hb), leukocytes, and thrombocytes. METHODS: One year after kidney transplantation 26 stable patients were converted from cyclosporin A (CsA) to MMF (2 g/day). Thereafter, these patients were tapered twice in their MMF dose from 2 g to 1.5 g (4 months after conversion) and from 1.5 to 1 g (8 months after conversion) per day. The Hb levels, leukocyte and thrombocyte counts, and mycophenolic acid (MPA) trough levels were routinely measured. RESULTS: After conversion from CsA to MMF not only creatinine levels and the number of leukocytes, but also the haemoglobin (Hb) level significantly decreased in 21/26 patients (P=0.0004). In eight patients the Hb level dropped more than 1 mmol/l (=1.61 g/dl). Only in two of eight patients was an explanation for blood loss found. The effect on Hb level did not ameliorate after the first MMF dose reduction to 1.5 g/day. After tapering the MMF dose to 1 g/day, the Hb approached the pre-conversion level. Not only the MMF dose but also the mycophenolic acid (MPA) trough level correlated with the Hb level. CONCLUSIONS: After conversion from CsA to MMF 1 year after kidney transplantation, a decrease in Hb level and leukocyte count was observed. The MPA trough level correlated also with the Hb level. The effect on the Hb level was reversible after dose reduction. This finding suggests that MMF exerts a negative effect on erythropoietic cells.

Mycophenolic acid plasma concentrations in kidney allograft recipients with or without cyclosporin: a cross-sectional study.

BACKGROUND: Combining cyclosporin (CsA) and prednisone with mycophenolate mofetil (MMF) results in a significant reduction in the rate of biopsy-proven acute rejection after kidney transplantation. This is achieved with a standard daily MMF dosage of 2 or 3 g. Whether monitoring of the pharmacologically active metabolite mycophenolic acid (MPA) will lead to improved safety and efficacy is unclear. METHODS: We monitored MPA trough levels in 18 kidney transplant recipients treated with CsA, prednisone, and MMF (63 samples) and in 11 patients (31 samples) treated with prednisone and MMF only, in a cross-sectional study. All patients were at least 3 months after transplantation with stable graft function. All patients were treated with 2 g MMF for at least 3 months and 10 mg prednisone. RESULTS: The MPA trough levels in the CsA-treated patients were significantly lower (P<0.0001; Mann-Whitney) than those in patients on MMF and prednisone only (mean MPA levels 1.98+/-0.12 vs 4.38+/-0.40 mg/l respectively). CONCLUSIONS: Although all patients were treated with an identical MMF dose, a significant difference was found in the MPA trough levels between CsA- vs non-CsA-treated patients. This suggests that CsA influences the MPA trough level. The level at which CsA affects the MPA trough levels is unclear.

Fever and rigors as sole symptoms of azathioprine hypersensitivity.

The case history of a haemodialysis patient with fever and rigors is presented. This diagnostic problem turned out to be a hypersensitivity reaction to azathioprine, with identical complaints recurring after a rechallenge with azathioprine, findings which resolved on discontinuation of this drug. The more extended indications for use of azathioprine warrant attention to the possibility of side-effects like drug fever.