Why Do Patients Develop Proteinuria With Sirolimus? Do We Have the Answer?

Mtor inhibitors associated with higher cardiovascular adverse events-A large population database analysis

There are limited real-world data available regarding adverse events (AEs) of immunosuppressants. We utilized the FDA Adverse Event Reporting System (FAERS) database from 2004 to 2018 to perform a retrospective database analysis. We analyzed AE reports due to the individual agents tacrolimus, sirolimus, or everolimus and compared reporting odds ratios of the mTOR inhibitors to tacrolimus. The mTOR inhibitors arm had 1282 reports with 4176 AEs, while the tacrolimus arm had a total of 7587 reports with 20 940 individual AEs. mTOR inhibitors had significantly higher incidences of cardiovascular (ROR 1.95, 95% CI 1.70, 2.23), dermatologic (ROR 1.34, 95% CI 1.04, 1.73), endocrine (ROR 1.52, 95% CI 1.26, 1.82), gastrointestinal (ROR 1.15, 95% CI 1.01, 1.30), infectious disease (ROR 1.35, 95% 1.20, 1.52), musculoskeletal (ROR 1.39, 95% CI 1.13, 1.70), pulmonary (ROR 3.46, 95% 2.97, 4.03), renal (ROR 1.27, 95% CI 1.10, 1.46), and vascular AEs (ROR 3.10, 95% CI 2.14, 4.49). Across every organ type, mTOR inhibitors had greater cardiovascular AEs compared to tacrolimus, specifically in arteriosclerosis, heart failure, hypotension, tachycardia, chest pain, edema, and pericardial disorders. mTOR inhibitors may be associated with higher cardiovascular AEs. Further investigation is required to determine the potential mechanism of this effect.

Combination of calcineurin and mTOR inhibitors in kidney transplantation: a propensity score analysis based on current clinical practice

INTRODUCTION

The TRANSFORM study demonstrated that an immunosuppression based on a combination of calcineurin inhibitors and de-novo mTOR inhibitors (mTORi) is safe and effective in kidney transplant recipients. However, data that validate this approach in clinical practice are currently missing.

MATERIALS AND METHODS

Analysis of 401 kidney transplant recipients transplanted from June 2013 to December 2016. All patients received tacrolimus with prednisone in combination with either mycophenolate (n = 186) or mTORi (either everolimus or sirolimus, n = 215). A propensity score to receive mTORi was calculated based on the inverse probability of treatment weighting (IPTW) from the following parameters: age and sex of donor and recipient, BMI, previous transplants, diabetes, cPRA, dialysis before transplantation, dialysis vintage, type of donor, ABO-incompatibility, HLA-mismatches, induction and ischemia time. Median follow-up was 2.6 [1.9; 3.7] years.

RESULTS

Cox-regression analysis suggests good results for mTORi versus MPA in terms of 1-year biopsy-proven acute rejection (BPAR, P = 0.063), 1-year graft loss (P = 0.025) and patient survival (P < 0.001). Results observed for BPAR and graft failure were largely attributed to those patients that would have been excluded by the TRANSFORM because of some exclusion criteria (52.9% of the population, P = 0.003 for 1-year BPAR and P = 0.040 for graft loss). In patients who met selection criteria for TRANSFORM, no effect of treatment for BPAR or graft failure was observed, while the beneficial effect on overall survival persisted.

CONCLUSIONS

In a real-life setting, a protocol based on de-novo mTORi with tacrolimus and prednisone could be employed as a standard immunosuppressive regimen and was associated with good outcomes.

Effect of Calcineurin Inhibitor-Free, Everolimus-Based Immunosuppressive Regimen on Albuminuria and Glomerular Filtration Rate After Heart Transplantation

BACKGROUND

Albuminuria in maintenance heart transplantation (HTx) is associated with poor renal response when switching to a calcineurin inhibitor (CNI)-lowered or CNI-free immunosuppressive regimen using everolimus (EVR), but the significance of albuminuria associated with EVR treatment after early CNI withdrawal in de novo HTx is unknown.

METHODS

We tested if measured glomerular filtration rate (mGFR, by chrome-ethylenediaminetetraacetic acid clearance) was associated with urine albumin/creatinine ratio (UACR) post-HTx in a subgroup of patients included in the Scandinavian Heart Transplant Everolimus De Novo Study With Early Calcineurin Inhibitor Avoidance trial, where de novo HTx patients (n = 115) were randomized to EVR with complete CNI elimination 7 to 11 weeks post-HTx or standard CNI immunosuppression.

RESULTS

In 66 patients, UACR measures were available at 1 year. In 7 patients in the EVR group, a CNI was reintroduced within 12 months. Median mGFR was significantly higher in the EVR group both 1 and 3 years post-HTx (P = 0.0004 and P = 0.03, respectively). Median UACR at 1 year was significantly higher in the EVR group (P = 0.002). There was no correlation between log(UACR) at 1 year and mGFR at 1 or 3 years (r = -0.01, P = 0.9 and r = 0.15, P = 0.26, respectively) and in the EVR group between log(UACR) at 1 year and change in mGFR (Δ1-3 years) (r = 0.27, P = 0.14). Excluding patients in the EVR group in whom a CNI was reintroduced did not significantly change the results.

CONCLUSIONS

The effects of EVR with early CNI withdrawal after HTx on albuminuria and renal function seem dissociated; hence, the clinical significance of albuminuria in this setting is uncertain and should not necessarily rule out EVR-based immunosuppression.

Effects of TORC1 Inhibition during the Early and Established Phases of Polycystic Kidney Disease

The disease-modifying effects of target of rapamycin complex 1 (TORC1) inhibitors during different stages of polycystic kidney disease (PKD) are not well defined. In this study, male Lewis Polycystic Kidney Disease (LPK) rats (a genetic ortholog of human NPHP9, phenotypically characterised by diffuse distal nephron cystic growth) and Lewis controls received either vehicle (V) or sirolimus (S, 0.2 mg/kg by intraperitoneal injection 5 days per week) during the early (postnatal weeks 3 to 10) or late stages of disease (weeks 10 to 20). In early-stage disease, sirolimus reduced kidney enlargement (by 63%), slowed the rate of increase in total kidney volume (TKV) in serial MRI by 78.2% (LPK+V: 132.3±59.7 vs. LPK+S: 28.8±12.0% per week) but only partly reduced the percentage renal cyst area (by 19%) and did not affect the decline in endogenous creatinine clearance (CrCl) in LPK rats. In late-stage disease, sirolimus reduced kidney enlargement (by 22%) and the rate of increase in TKV by 71.8% (LPK+V: 13.1±6.6 vs. LPK+S: 3.7±3.7% per week) but the percentage renal cyst area was unaltered, and the CrCl only marginally better. Sirolimus reduced renal TORC1 activation but not TORC2, NF-κB DNA binding activity, CCL2 or TNFα expression, and abnormalities in cilia ultrastructure, hypertension and cardiac disease were also not improved. Thus, the relative treatment efficacy of TORC1 inhibition on kidney enlargement was consistent at all disease stages, but the absolute effect was determined by the timing of drug initiation. Furthermore, cystic microarchitecture, renal function and cardiac disease remain abnormal with TORC1 inhibition, indicating that additional approaches to normalise cellular dedifferentiation, inflammation and hypertension are required to completely arrest the progression of PKDs.

mTOR inhibition with temsirolimus causes acute increases in glomerular permeability, but inhibits the dynamic permeability actions of puromycin aminonucleoside

Inhibitors of the mammalian target of rapamycin (mTORi) can produce de novo proteinuria in kidney transplant patients. On the other hand, mTORi has been shown to suppress disease progression in several animal models of kidney disease. In the present study, we investigated whether glomerular permeability can be acutely altered by the mTORi temsirolimus and whether mTORi can affect acute puromycin aminonucleoside (PAN) or angiotensin II (ANG II)-induced glomerular hyperpermeability. In anesthetized Wistar rats, the left ureter was cannulated for urine collection, while simultaneously blood access was achieved. Temsirolimus was administered as a single intravenous dose 30 min before the start of the experiments in animals infused with PAN or ANG II or in nonexposed animals. Polydispersed FITC-Ficoll-70/400 (molecular radius 10-80 Å) and (51)Cr-EDTA infusion was given during the whole experiment. Measurements of Ficoll in plasma and urine were performed sequentially before the temsirolimus injection (baseline) and at 5, 15, 30, 60, and 120 min after the start of the experiments. Urine and plasma samples were analyzed by high-performance size-exclusion chromatography (HPSEC) to assess glomerular sieving coefficients (θ) for Ficoll10-80Å. Temsirolimus per se increased baseline glomerular permeability to Ficoll50-80Å 45 min after its administration, a reactive oxygen species (ROS)-dependent phenomenon. PAN caused a rapid and reversible increase in glomerular permeability, peaking at 5 min, and again at 60-120 min, which could be blocked by the ROS scavenger tempol. mTORi abrogated the second permeability peak induced by PAN. However, it had no effect on the immediate ANG II- or PAN-induced increases in glomerular permeability.

Lipidomic assessment of plasma and placenta of women with early-onset preeclampsia

Introduction

Adipose tissue is responsible for triggering chronic systemic inflammatory response and these changes may be involved in the pathophysiology of preeclampsia.

Objective

To characterize the lipid profile in the placenta and plasma of patients with preeclampsia.

Methodology

Samples were collected from placenta and plasma of 10 pregnant women with preeclampsia and 10 controls. Lipids were extracted using the Bligh–Dyer protocol and were analysed by MALDI TOF-TOF mass spectrometry.

Results

Approximately 200 lipid signals were quantified. The most prevalent lipid present in plasma of patients with preeclampsia was the main class Glycerophosphoserines-GP03 (PS) representing 52.30% of the total lipid composition, followed by the main classes Glycerophosphoethanolamines-GP02 (PEt), Glycerophosphocholines-GP01 (PC) and Flavanoids-PK12 (FLV), with 24.03%, 9.47% and 8.39% respectively. When compared to the control group, plasma samples of patients with preeclampsia showed an increase of PS (p<0.0001), PC (p<0.0001) and FLV (p<0.0001). Placental analysis of patients with preeclampsia, revealed the PS as the most prevalent lipid representing 56.28%, followed by the main class Macrolides/polyketides-PK04 with 32.77%, both with increased levels when compared with patients control group, PS (p<0.0001) and PK04 (p<0.0001).

Conclusion

Lipids found in placenta and plasma from patients with preeclampsia differ from those of pregnant women in the control group. Further studies are needed to clarify if these changes are specific and a cause or consequence of preeclampsia.

Sirolimus reduces vasculopathy but exacerbates proteinuria in association with inhibition of VEGF and VEGFR in a rat kidney model of chronic allograft dysfunction

BACKGROUND

Use of the mTOR inhibitor (mTORi) sirolimus to replace calcineurin inhibitors in kidney transplantation has been associated with improved renal function but, in a proportion of cases, also with de novo or exacerbated proteinuria. Experimental deficiency of vascular endothelial growth factor (VEGF) induces proteinuria and mTOR is required for VEGF production and signalling. We therefore explored the impact of sirolimus on the development of chronic allograft dysfunction (CAD) in the rat, with a focus on VEGF biology.

METHODS

Lewis rats received F344 kidney allografts and were treated with 24 weeks of cyclosporine or sirolimus. Controls included allografts treated with cyclosporine for 10 days only and isografts treated with cyclosporine or sirolimus for 24 weeks. Kidney injury (proteinuria and histology) and expression of VEGF and VEGF-receptor (VEGFR; immunohistochemistry, laser capture micro-dissection and quantitative RT-PCR) were assessed.

RESULTS

Allograft controls developed proteinuria, tubulointerstitial fibrosis and atrophy, glomerulosclerosis, vasculopathy and leucocyte accumulation. Proteinuria was significantly reduced in both treatment groups but significantly more in cyclosporine treated animals. Tubulointerstitial damage, glomerulosclerosis and leucocyte accumulation were significantly attenuated in both treatment groups; however, vasculopathy was reduced only by sirolimus. Significantly diminished expression of VEGF and VEGFR mRNA and protein was evident in the sirolimus group. In vitro, sirolimus reduced VEGF production by podocytes (P < 0.05) and inhibited VEGF-induced proliferation of podocytes, endothelial and mesangial cells.

CONCLUSIONS

Cyclosporine and sirolimus retard development of CAD in this rat model. Sirolimus exhibits greater protection against vasculopathy but induces proteinuria; effects are likely to be related to inhibition of VEGF signalling.

An evaluation of sirolimus in renal transplantation

INTRODUCTION

Sirolimus is a powerful antiproliferative immunosuppressive drug approved for the prevention of kidney allograft rejection. By its unique mechanism of action, sirolimus provides a multitude of clinical potential and has been used effectively in different drug combinations. Extensive experience has been gained regarding the best timing of its application, side effect profile and potential benefits and limitations compared with other immunosuppressive drugs.

AREAS COVERED

The authors evaluate the recent experience with sirolimus in kidney transplantation. Pivotal randomized controlled trials were used to provide an overview with special attention to pharmacokinetic and dynamic aspects of sirolimus, its current clinical use as well as perspectives for its future role.

EXPERT OPINION

Sirolimus enriches the possibilities of immunosuppressive therapies after renal transplantation. Beneficial effects toward kidney function by allowing CNI sparing, lower incidence of malignancies and less viral infections have been suggested. Sirolimus should be used cautiously in de novo patients for reasons of wound healing. An early conversion to a sirolimus-based CNI-free regimen has shown promising results, whereas late conversion is more challenging. Finally, sirolimus-associated side effects are causing tolerability concerns and frequent discontinuations. Future research should aim to better define the therapeutic window and those patients most likely to benefit.

GSK3β inactivation in podocytes results in decreased phosphorylation of p70S6K accompanied by cytoskeletal rearrangements and inhibited motility

The inhibition of mTOR kinase after renal transplantation has been associated with podocyte injury and proteinuria; however, the signaling pathways regulating these effects are not well understood. We found that prolonged rapamycin treatment in podocytes leads to an increase in glycogen synthase kinase 3β (GSK3β) phosphorylation, resulting in inactivation of total GSK3β kinase activity. To investigate the cellular consequences of the inactivation of GSK3β, we used two inhibitors reducing kinase activity and studied the cross talk between GSK3 function and the Akt/mammalian target of rapamycin (mTOR) pathway. Both GSK3 inhibitors reduced the phosphorylation of the mTOR downstream target, p70(S6K), indicating that GSK3 inhibition in podocytes is able to cause similar effects as treatment with rapamycin. Moreover, GSK3 inhibition was accompanied by the reduced expression of slit diaphragm-associated proteins and resulted in an altered cytoskeletal structure and reduced motility of podocytes, suggesting that GSK3 kinase can modulate Akt/mTOR-dependent signaling in podocytes.

Sirolimus and kidney growth in autosomal dominant polycystic kidney disease

BACKGROUND

In autosomal dominant polycystic kidney disease (ADPKD), aberrant activation of the mammalian target of rapamycin (mTOR) pathway is associated with progressive kidney enlargement. The drug sirolimus suppresses mTOR signaling.

METHODS

In this 18-month, open-label, randomized, controlled trial, we sought to determine whether sirolimus halts the growth in kidney volume among patients with ADPKD. We randomly assigned 100 patients between the ages of 18 and 40 years to receive either sirolimus (target dose, 2 mg daily) or standard care. All patients had an estimated creatinine clearance of at least 70 ml per minute. Serial magnetic resonance imaging was performed to measure the volume of polycystic kidneys. The primary outcome was total kidney volume at 18 months on blinded assessment. Secondary outcomes were the glomerular filtration rate and urinary albumin excretion rate at 18 months.

RESULTS

At randomization, the median total kidney volume was 907 cm3 (interquartile range, 577 to 1330) in the sirolimus group and 1003 cm3 (interquartile range, 574 to 1422) in the control group. The median increase over the 18-month period was 99 cm3 (interquartile range, 43 to 173) in the sirolimus group and 97 cm3 (interquartile range, 37 to 181) in the control group. At 18 months, the median total kidney volume in the sirolimus group was 102% of that in the control group (95% confidence interval, 99 to 105; P=0.26). The glomerular filtration rate did not differ significantly between the two groups; however, the urinary albumin excretion rate was higher in the sirolimus group.

CONCLUSIONS

In adults with ADPKD and early chronic kidney disease, 18 months of treatment with sirolimus did not halt polycystic kidney growth. (Funded by Wyeth and others; ClinicalTrials.gov number, NCT00346918.)