Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42345 (mTOR)
 26,049 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proliferation signal or mammalian target-of-rapamycin inhibitors (PSI/mTOR inhibitors), everolimus and sirolimus, provide attractive options for use in heart transplantation because they are immunosuppressive and anti-proliferative. PSI/mTOR inhibitors work synergistically with calcineurin inhibitors (CNIs) and thus permit the minimization of CNIs without compromising efficacy. This approach is advantageous for the majority of heart transplant recipients and might provide particular benefit in specific cases, such as patients with cardiac allograft vasculopathy, malignancies and renal dysfunction, or in patients intolerant to other immunosuppressive agents. Drawing on the expertise of transplant cardiologists, cardiac surgeons and nephrologists, we addressed the assessment of renal function; management of adverse events associated with this class of drugs; and clinical guidance, specifically for the use of everolimus, including patient selection, indications for treatment and practicalities of drug initiation and monitoring.
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PMID:Multidisciplinary insights on clinical guidance for the use of proliferation signal inhibitors in heart transplantation. 1826 19

We examined the effect of cyclosporin A, tacrolimus, sirolimus and everolimus on the cell growth, viability, proliferation, expression of cellular adhesion molecules (CAM) and leukocyte (PBMC) binding of human macrovascular (coronary artery, saphenous vein) and microvascular endothelial cells (EC). Tacrolimus did not affect EC integrity, growth or expression of CAM. Exclusively, EC from the coronary arteries showed a reduced cellular growth (about 30%) under cyclosporin A and tacrolimus treatment. In contrast, treatment with mTOR inhibitors reduced EC proliferative activity by about 40%, independently of the EC origin. No induction of apoptosis (caspase-3/7 activity) or cytotoxicity (MTS test) was observed. Long-term treatment with high concentrations of sirolimus and everolimus did not enhance the expression of CAM. Stimulation with tumor necrosis factor significantly increased the expression of CAM, independently of the drugs used. None of the mTOR inhibitors influenced the tumor necrosis factor-induced expression of CAM, whereas adhesion of PBMC increased significantly, as described by other papers. In summary, neither calcineurin inhibitors nor mTOR inhibitors activate human micro- and macrovascular EC. Therefore, the investigated drugs are unlikely to contribute to EC activation during transplant-associated vasculopathy.
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PMID:mTOR inhibitors and calcineurin inhibitors do not affect adhesion molecule expression of human macro- and microvascular endothelial cells. 1831 92

Massive urinary protein excretion has been observed after conversion from calcineurin inhibitors to mammalian target of rapamycin (mToR) inhibitors, especially sirolimus, in renal transplant recipients with chronic allograft nephropathy. Because proteinuria is a major predictive factor of poor transplantation outcome, many studies focused on this adverse event during the past years. Whether proteinuria was due to sirolimus or only a consequence of calcineurin inhibitors withdrawal remained unsolved until high range proteinuria has been observed during sirolimus therapy in islet transplantation and in patients who received sirolimus de novo. Podocyte injury and focal segmental glomerulosclerosis have been related to mToR inhibition in some patients, but the pathways underlying these lesions remain hypothetic. We discuss herein the possible mechanisms and the significance of mToR blockade-induced proteinuria.
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PMID:mToR inhibitors-induced proteinuria: mechanisms, significance, and management. 1863 65

For patients with end-stage kidney failure, kidney transplantation improves both their quality of life and overall life expectancy compared with dialysis, but it is not without adverse effects. Cancer is second to cardiovascular disease as one of the major causes of morbidity and mortality in renal transplant recipients. Prolonged use of modern immunosuppression, which leads to alteration of immune function and immune surveillance, is associated with increased cancer risk. There is now convincing evidence from observational studies and registry data to confirm a 3- to 5-fold increase in overall cancer incidence, with viral-related neoplasia incurring the greatest risk when compare with the general population. Despite the increased risk, little is known about the overall cancer prognosis, screening, treatment strategies, and effectiveness in this population. Cancers can recur, occur de novo, and be transmitted from donor organs posttransplantation. Uncertainties exist as to how modern immunosuppressive agents impact on cancer management and outcomes in these patients, with some agents such as calcineurin inhibitors and azathioprine, being more carcinogenic than others. The newer agents, proliferation signal/mammalian target of rapamycin inhibitors and mycophenolate mofitil, may have some antiproliferative and antitumor activities demonstrated in preclinical and clinical studies, but long-term well-powered trial data are needed to determine whether they are either protective or curative for cancers in renal transplant recipients. In this review, the incidence, etiology, prognosis, and potential approaches to cancer screening and management post-renal transplantation are discussed.
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PMID:Cancers after renal transplantation. 1863 67

Inhibitors of mTOR (mammalian target of rapamycin) are immunosuppressants with less nephrotoxic potential than calcineurin inhibitors and antiproliferative effects, which are advantageous in the case of malignancy. However, a series of adverse events has been reported with the first-generation mTOR inhibitor sirolimus that includes hypersensitivity-like interstitial pneumonitis. To our knowledge, only one case of a pneumonitis associated with everolimus in a heart transplant patient has been reported, and it was related to elevated trough blood levels. We report herein the first case of a kidney graft recipient who developed everolimus-associated pneumonitis with normal trough blood levels that was completely reversed after drug withdrawal.
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PMID:Severe everolimus-associated pneumonitis in a renal transplant recipient. 1865 77

Interleukin-18 (IL-18), a product of dendritic cells (DC), is a pro-inflammatory cytokine involved in the pathogenesis of allograft rejection, vascular disease, arthritis and diabetes. Rapamycin (Rapa) is an immunosuppressant that inhibits T cell mTOR kinase activation. In contrast, Sanglifehrin A (SFA), is a cyclophilin-binding immunosuppressant that does not act on calcineurin phosphatases but appears to inhibit IL-2-dependent T cell proliferation. Rapa and SFA exert some immunosuppressive effects on DC by inhibiting IL-12 production, although their effects on DC have not been investigated as comprehensively as those on T cells. We aimed to determine the impact of these drugs on DC IL-18 synthesis in vivo and in vitro. We found in vivo that LPS-stimulated OX62(+) DC produced significantly more IL-18 mRNA, compared to OX62(+) DC depleted splenocytes (p<0.01) and non-LPS-stimulated OX62(+) DC (p<0.01). OX62(+)CD4(+) and OX62(+)CD4(-) cells produced similar amounts of IL-18 mRNA. Rapa and SFA, but not CsA, significantly inhibited IL-18 production from OX62(+) DC in vitro, in a dose-dependent manner (p<0.05). In vivo IL-18 production was also inhibited by Rapa and SFA in splenic OX62(+) DC (p<0.01). Finally, inhibition of IL-18 production by Rapa and SFA was independent of the FK506 or cyclophilin pathways, respectively. In conclusion, Rapa and SFA, but not CsA, block IL-18 production and this novel Rapa blockade effect on IL-18 may contribute to the ability of Rapa to inhibit chronic allograft nephropathy and restenosis.
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PMID:Dentritic cell derived IL-18 production is inhibited by rapamycin and sanglifehrin A, but not cyclosporine A. 1866 82

Sirolimus (SRL) is an mTOR inhibitor that has been shown, in contrast to calcineurin inhibitors (CNI), to inhibit cancers in experimental models. Since February 2005, we introduced SRL in liver transplant patients in group a, in whom the primary disease was hepatocellular carcinoma (HCC) associated with hepatitis B virus (HBV), hepatitis C virus (HCV), alcoholic or autoimmune liver cirrhosis, and group b, HCC-negative patients who developed posttransplantation cancers de novo. Of 18 patients in group a, 11 received SRL ab initio (subgroup a1), starting for 10 patients at 66.1+/-29.2 days after surgical healing and after 10 days in 1 case; the remaining 7 patients (subgroup a2) received SRL at 31.2+/-24.2 months. Three patients in group b, included 1 with Kaposi's sarcoma, 1 with bladder cancer, and 1 with thyroid cancer. In this group, SRL was introduced at 80.8+/-40.4 months. In all patients but one, who received a single 5 mg loading dose, SRL was started at 2 mg/d and adjusted to 6 to 8 ng/mL blood levels. CNI drugs, present as primary therapy, were gradually tapered to low levels and eventually stopped. The following observations were drawn from this initial experience: (1) 4/21 (19.0%) patients had to discontinue SRL because of early and late side effects: thrombocytopenia (n=2) and headache with leukopenia and leg edema associated with knee joint arthralgia (n=2); (2) 14 patients (11 in group a and 3 in group b) are still on SRL monotherapy; (3) 1 HCC recurrence and 1 de novo pancreatic adenocarcinoma were observed at 14 and 16 months, respectively (at the time of transplantation, both patients were beyond the MIlan HCC criteria), and (4) 1 patient, from subgroup a1, died after 99 days due to pneumonitis and possible relation to SRL lung toxicity. In conclusion, SRL appeared to be an effective immunosuppressant that could be used as monotherapy in liver transplant patients. Any conclusion on SRL anticancer effects can only come from randomized large studies after long follow-up.
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PMID:Sirolimus therapy in liver transplant patients: an initial experience at a single center. 1867 98

Sirolimus (SRL) is a recently available immunosuppressive agent. SRL, is a macrolide isolated from Streptomyces hydroscopicus that, in complex with its cellular receptor, FK binding protein, potently inhibits downstream signaling by the mammalian target of rapamycin (mTOR). It has been shown to reduce the incidence of acute rejection episode after renal transplantation. SRL by itself does not seem to cause significant nephrotoxicity in most animals and human studies in normal conditions. However, when combined with calcineurin inhibitors, serum creatinine levels often increase. The mechanisms for the synergism of this side-effect are still discussed. Furthermore, recent clinical data have shown that the administration of SRL immediately after renal transplant delay the recovery from delayed graft function. This effect may be secondary to the inhibition of the proliferation of the renal tubular cells which is a normal process for tubular repair. Some experimental data have confirmed this hypothesis. Finally, in the long-term, SRL use has been associated with a significant increase of proteinuria which may in the long-term increase the risk of graft loss of cardio-vascular morbio-mortality. For all these reasons, SRL nephrotoxicty has become an important issue after renal transplantation. The review will discuss the clinical and the experimental data regarding this complication, which has been underestimated.
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PMID:Sirolimus early graft nephrotoxicity: clinical and experimental data. 1869 Sep 29

The combination of synergistic drugs is the main strategy to prevent early acute rejection and to provide long-term effective rejection prophylaxis. Evaluation of drug concentrations to guide drug dosing is routinely established for calcineurin-inhibitors CNIs and mTOR inhibitors. Arguments in favour of therapeutic drug-monitoring TDM are the large inter-patient variability of many immunosuppressants with their potential for severe toxicity and drug-to-drug interactions. The manuscript discusses several confounding factors, which influence the appropriate therapeutic window. These include decreasing risk of rejection over time, cumulative risk for toxicity with time, and the synergistic potential of combination immunosuppressive therapy with respect to efficacy and shared toxicities. In addition, a long list of donor and recipient characteristics have a direct or indirect effect on the therapeutic window, but have not been evaluated in rigorous, prospective trials. Unfortunately, only a very small number of adequately powered, prospective randomized trials evaluate different therapeutic windows for immunosuppressants or even the utility of TDM at all. Other problems of TDM include the inherent variability of absorption and drug levels and a suboptimal correlation between pharmacokinetic surrogate parameters and drug exposure for most drugs. Drugs with a high intra-patient day-to-day variability may be less suited for TDM compared to drugs with a high inter-patient, but low intra-patient variability. Furthermore it is not known whether the same parameter is suitable for controlling efficacy as well toxicity. With cumulative overexposure the effect of time might be more far more important than a specific level at a given time point and provides another fundamental dimension. A new approach of TDM, classified as pharmacodynamic (PD) drug monitoring, which directly reflects the drug's biological effects has been proposed to better assess the individual state of immunosuppression, however difficult test systems and lack of prospective trials limit this approach currently. Future studies have to take these considerations into account in order to better guide immunosuppression towards a more individualized therapy, which remains an important goal in transplant medicine.
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PMID:Pharmacokinetic principles of immunosuppressive drugs. 1880 27

Nephrotoxicity-sparing protocols, using mycophenolate mofetil (MMF) and steroids without calcineurin inhibitors (CNIs) or mammalian target rapamycin (mTOR), could be used to treat maintenance renal transplant patients. However, the risk for acute rejection seems to be high. The aim of this pharmacodynamic study was to analyze T-cell function, T-cell activation, and T-cell proliferation among patients receiving MMF and steroids (n = 15) compared with patients receiving immunosuppression with CNI-based therapy including tacrolimus, MMF, and steroids. Our data suggested that among stable maintenance patients, dual therapy with MMF and steroids might provide a similar reduction in T-cell proliferation and T-cell activation as that observed among patients on standard immunosuppressive therapy. As expected, intralymphocytic interleukin-2 (IL-2) and tumor necrosis factor-alpha (TNF-alpha) expressions were higher in patients not receiving CNIs.
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PMID:T-cell function in maintenance renal transplant patients receiving mycophenolate mofetil and steroids with or without tacrolimus. 1910 Apr 3


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