Effect of Ramipril on Urinary Protein Excretion in Maintenance Renal Transplant Patients Converted to Sirolimus

Surrogate Endpoints for Late Kidney Transplantation Failure

In kidney transplant recipients, late graft failure is often multifactorial. In addition, primary endpoints in kidney transplantation studies seek to demonstrate the short-term efficacy and safety of clinical interventions. Although such endpoints might demonstrate short-term improvement in specific aspects of graft function or incidence of rejection, such findings do not automatically translate into meaningful long-term graft survival benefits. Combining many factors into a well-validated model is therefore more likely to predict long-term outcome and better reflect the complexity of late graft failure than using single endpoints. If conditional marketing authorization could be considered for therapies that aim to improve long-term outcomes following kidney transplantation, then the surrogate endpoint for graft failure in clinical trial settings needs clearer definition. This Consensus Report considers the potential benefits and drawbacks of several candidate surrogate endpoints (including estimated glomerular filtration rate, proteinuria, histological lesions, and donor-specific anti-human leukocyte antigen antibodies) and composite scoring systems. The content was created from information prepared by a working group within the European Society for Organ Transplantation (ESOT). The group submitted a Broad Scientific Advice request to the European Medicines Agency (EMA), June 2020: the request focused on clinical trial design and endpoints in kidney transplantation. Following discussion and refinement, the EMA made final recommendations to ESOT in December 2020 regarding the potential to use surrogate endpoints in clinical studies that aim to improving late graft failure.

Interventions to Prevent Nonmelanoma Skin Cancers in Recipients of a Solid Organ Transplant: Systematic Review of Randomized Controlled Trials

BACKGROUND

Organ transplant recipients are at high risk of developing skin cancer. The benefits and harms of interventions to prevent nonmelanoma skin cancer in solid organ transplant recipients have not been summarized.

METHODS

We searched MEDLINE, Embase, and CENTRAL through April 2018. Risk of bias was assessed using the Cochrane tool, and evidence certainty was evaluated using the Grades of Recommendation, Assessment, Development, and Evaluation process. Prespecified outcomes were nonmelanoma skin cancer, clearance and prevention of keratotic skin lesions, and intervention-specific adverse events.

RESULTS

Ninety-two trials (20 012 participants) were included. The evaluated treatments were cancer-specific interventions (acitretin, imiquimod, photodynamic therapy, nicotinamide, topical diclofenac, and selenium) and immunosuppression regimes (azathioprine, mycophenolate mofetil, calcineurin inhibitors, mammalian target of rapamycin [mTOR] inhibitors, belatacept, induction agents, and withdrawal of calcineurin inhibitors or corticosteroids). Effects on nonmelanoma skin cancer were uncertain for photodynamic therapy (3 trials, 93 participants, risk ratio [RR] 1.42 [95% confidence interval (CI), 0.65-3.11]; low certainty evidence), nicotinamide (2 trials, 60 participants), acitretin (2 trials, 61 participants), and imiquimod (1 trial, 20 participants) compared to control. mTOR inhibitors probably reduced skin cancer compared to calcineurin inhibitors (12 trials, 2225 participants, RR 0.62 [95% CI, 0.45-0.85]; moderate certainty evidence). Photodynamic therapy may cause pain at the treatment site (4 trials, 95 patients, RR 17.09 [95% CI, 4.22-69.26]; low certainty evidence).

CONCLUSIONS

There is limited evidence for the efficacy and safety of specific treatments to prevent nonmelanoma skin cancers among solid organ transplant recipients.

Adverse Events and Discontinuation Rates Associated with Sirolimus Treatment in Adult Renal Transplant Patients in Latin America vs Non-Latin American Countries

BACKGROUND

Sirolimus is approved for prophylaxis of organ rejection following renal transplantation. Rates of treatment-emergent adverse events (TEAEs) leading to sirolimus discontinuation differ geographically.

METHODS

Rates of TEAEs, serious AEs (SAEs), and discontinuations were evaluated in 3 clinical trials of conversion from calcineurin inhibitors to sirolimus. Posttransplantation, patients were treated over 4 years (study 1), over 1 year (study 2), and over 2 years (study 3). TEAEs, SAEs, and discontinuation rates were compared between Latin America (LATAM) vs North America (NA) and Europe/rest of world (EU/ROW). Data from studies 2 and 3, with similar times to conversion, were pooled.

RESULTS

Study 1 comprised 551 patients (LATAM, n=189); studies 2/3 comprised 395 (LATAM, n=111). LATAM patients were significantly younger than NA or EU/ROW patients in study 1 and studies 2/3 (P < .0001), with a lower proportion of white patients and higher proportion of patients of other races in LATAM vs NA (P < .0001) and EU/ROW (P = .02) groups. Almost all patients reported TEAEs. Discontinuation because of medical events was significantly lower (P < .05) in LATAM vs NA or EU/ROW. Hypercholesterolemia and hypertriglyceridemia were more common, and anemia and peripheral edema less common in LATAM; diarrhea and proteinuria did not differ by region. Types of AEs leading to discontinuation did not differ by region.

CONCLUSION

LATAM renal transplant recipients converted to sirolimus were more likely to remain on therapy than patients in other regions.

Comparative effectiveness of different antihypertensive agents in kidney transplantation: a systematic review and meta-analysis

Background

We conducted a systematic review and meta-analysis to compare benefits and harms of different antihypertensive drug classes in kidney transplant recipients, as post-transplant hypertension (HTN) associates with increased cardiovascular (CV) morbidity and mortality.

Methods

The Ovid-MEDLINE, PubMed and CENTRAL databases were searched for randomized controlled trials (RCTs) comparing all main antihypertensive agents versus placebo/no treatment, routine treatment.

Results

The search identified 71 RCTs. Calcium channel blockers (CCBs) (26 trials) reduced the risk for graft loss {risk ratio [RR] 0.58 [95% confidence interval (CI) 0.38–0.89]}, increased glomerular filtration rate (GFR) [mean difference (MD) 3.08 mL/min (95% CI 0.38–5.78)] and reduced blood pressure (BP). Angiotensin-converting enzyme inhibitors (ACEIs) (13 trials) reduced the risk for graft loss [RR 0.62 (95% CI 0.40–0.96)] but decreased renal function and increased the risk for hyperkalaemia. Angiotensin receptor blockers (ARBs) (10 trials) did not modify the risk of death, graft loss and non-fatal CV events and increased the risk for hyperkalaemia. When pooling ACEI and ARB data, the risk for graft failure was lower in renin–angiotensin system (RAS) blockade as compared with control treatments. In direct comparison with ACEIs or ARBs (11 trials), CCBs increased GFR [MD 11.07 mL/min (95% CI 6.04–16.09)] and reduced potassium levels but were not more effective in reducing BP. There are few available data on mortality, graft loss and rejection. Very few studies performed comparisons with other active drugs.

Conclusions

CCBs could be the preferred first-step antihypertensive agents in kidney transplant patients, as they improve graft function and reduce graft loss. No definite patient or graft survival benefits were associated with RAS inhibitor use over conventional treatment.

Effect of renin-angiotensin system inhibitors on survival in kidney transplant recipients: A systematic review and meta-analysis

Renin-angiotensin system inhibitors, specifically angiotensin II converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), have confirmed renoprotective benefits in patients with proteinuria and hypertension. However, it remains controversial whether these agents are beneficial to kidney recipients. We conducted this meta-analysis to evaluate the effects of ACEI/ARB treatment on patient and allograft survival after kidney transplant. The PubMed, Embase and Cochrane Library databases were searched for eligible articles from before May 2016, and we included 24 articles (9 randomised controlled trials [RCTs] and 15 cohort studies with 54,096 patients), in which patient or graft survival was compared between an ACEI/ARB treatment arm and a control arm. Pooled results showed that ACEI/ARB was associated with decreased risks of patient death (relative risk [RR] = 0.64; 95% confidence interval [CI]:0.49-0.84) and graft loss (RR = 0.59; 95%CI:0.47-0.74). Subgroup analysis of the cohorts revealed significantly reduced patient death (RR = 0.61; 95%CI:0.50-0.74) and graft loss (RR = 0.58; 95%CI:0.46-0.73), but this was not seen in RCTs (patient survival: RR = 0.84, 95%CI:0.39-1.81; graft survival: RR = 0.70, 95%CI:0.17-2.79). Significantly less graft loss was noted among patients with biopsy-proved chronic allograft nephropathy (CAN) (RR = 0.26, 95%CI:0.16-0.44). Furthermore, the benefit of ACEI/ARB on patient survival (RR = 0.62; 95%CI:0.47-0.83) and graft survival (RR = 0.58, 95%CI:0.47-0.71) was limited to those with ≥3years' follow-up. ACEI/ARB decreased proteinuria (P < 0.001) and lowered haemoglobin (P = 0.002), but the haemoglobin change requires no additional treatment (from 119-131 g/L to 107-123 g/L). We therefore concluded that ACEI/ARB treatment may reduce patient death and graft loss, but additional well-designed prospective studies are needed to validate these findings.

The role of sirolimus in proteinuria in diabetic nephropathy rats

Objective(s):

The aim of this study was to observe the impact of sirolimus on proteinuria in streptozotocin (STZ) induced diabetic rats.

Materials and Methods:

Rats were given a single injection of STZ to induce diabetic rat model. Rats’ 24 hr urine was collected to test, urinary and the kidney tissues were harvested at the 8^th and 20^th weeks, respectively. Podocyte morphological changes were examined by electron microscopy and the ZO-1, podocin expressions in kidneys were detected by immunohistochemistry; the protein levels of Raptor and pS6 were measured by Western blot assay.

Results:

In the early stage of diabetic nephropathy (DN), sirolimus reduced the proteinuria significantly (P<0.05); but in the advanced stage of DN, sirolimus worsened proteinuria (P<0.05). Electron microscopy test suggested that sirolimus could reduce the injury of podocyte at the early DN, but increased the injury at the late DN podocyte. Immunohistochemistry results indicated that sirolimus increased the expressions of podocin and ZO-1 at the early DN (P<0.05), but reduced the expressions of ZO-1 and podocin (P<0.05) at the advanced DN. In the different periods of DN, the expression levels of Raptor and pS6 in sirolimus-treated groups were significantly lower than in the DN control groups (P<0.05).

Conclusion:

Sirolimus can reduce proteinuria and alleviate the early DN podocyte injury in diabetic rat model by inhibiting the activity of mTORC1; but in the advanced stage of DN, sirolimus can increase podocyte injury and urine protein level.

Roles of mTOR complexes in the kidney: implications for renal disease and transplantation

The mTOR pathway has a central role in the regulation of cell metabolism, growth and proliferation. Studies involving selective gene targeting of mTOR complexes (mTORC1 and mTORC2) in renal cell populations and/or pharmacologic mTOR inhibition have revealed important roles of mTOR in podocyte homeostasis and tubular transport. Important advances have also been made in understanding the role of mTOR in renal injury, polycystic kidney disease and glomerular diseases, including diabetic nephropathy. Novel insights into the roles of mTORC1 and mTORC2 in the regulation of immune cell homeostasis and function are helping to improve understanding of the complex effects of mTOR targeting on immune responses, including those that impact both de novo renal disease and renal allograft outcomes. Extensive experience in clinical renal transplantation has resulted in successful conversion of patients from calcineurin inhibitors to mTOR inhibitors at various times post-transplantation, with excellent long-term graft function. Widespread use of this practice has, however, been limited owing to mTOR-inhibitor- related toxicities. Unique attributes of mTOR inhibitors include reduced rates of squamous cell carcinoma and cytomegalovirus infection compared to other regimens. As understanding of the mechanisms by which mTORC1 and mTORC2 drive the pathogenesis of renal disease progresses, clinical studies of mTOR pathway targeting will enable testing of evolving hypotheses.

A high sodium intake reduces antiproteinuric response to renin-angiotensin-aldosterone system blockade in kidney transplant recipients

BACKGROUND

Post-transplant proteinuria is associated with lower graft and patient survival. Renin-angiotensin-aldosterone system blockers are used to reduce proteinuria and improve renal outcome. Although it is known that a high salt intake blunts the antiproteinuric effect of ACEI and ARB drugs in non-transplant patients, this effect has not been studied in kidney transplant recipients.

OBJECTIVE

To analyse the relationship between sodium intake and the antiproteinuric effect of ACEI/ARB drugs in kidney transplant recipients.

METHODS

We selected 103 kidney transplant recipients receiving ACEI/ARB drugs for more than 6 months due to proteinuria>1 g/day. Proteinuria was analysed at baseline and at 6 months after starting ACEI/ARB treatment. Salt intake was estimated by urinary sodium to creatinine ratio (uNa/Cr).

RESULTS

Proteinuria fell to less than 1g/day in 46 patients (44.7%). High uNa/Cr was associated with a smaller proteinuria decrease (r=-0.251, P=.011). The percentage proteinuria reduction was significantly lower in patients in the highest uNa/Cr tertile [63.9% (IQR 47.1%), 60.1% (IQR 55.4%), 38.9% (IQR 85.5%), P=.047]. High uNa/Cr independently relates (OR 2.406 per 100 mEq/g, 95% CI: 1.008-5.745, P=.048) to an antiproteinuric response <50% after renin-angiotensin-aldosterone system blockade.

CONCLUSIONS

A high salt intake results in a smaller proteinuria decrease in kidney transplant recipients with proteinuria treated with ACEI/ARB drugs.

Reviewing 15 years of experience with sirolimus

Here, we review 15 years of clinical use of sirolimus in our transplant center, in context with the developing immunosuppressive strategies use worldwide. The majority of studies were conducted in de novo kidney transplant recipients, using sirolimus (SRL) in combination with calcineurin inhibitors (CNIs). We also explored steroid (ST) or CNI-sparing therapies, including CNI minimization, elimination, or conversion strategies in combination with mycophenolate (MMF/MPS). Pooled long-term outcomes were comparable with those obtained with CNI and antimetabolite combination. Surprisingly, there are still several areas that need further investigation to improve the risk/benefit profile of SRL in kidney transplantation, including pharmacokinetic/pharmacodynamic drug-to-drug interaction with cyclosporine (CsA) or tacrolimus (TAC), mechanisms of SRL-associated adverse reactions and combinations with other drugs such as belatacept and once-daily TAC, possibly leading to improved long-term adherence. These studies, along with others investigating the benefits of SRL associated lower viral infections and malignancies, are essential as we do not expect the introduction of new immunosuppressive drugs in the near future.