Combination therapy with tacrolimus and mycophenolate mofetil: effects of early and late minimization of mycophenolate mofetil after renal transplant

The objectives of the study were: (i) to compare the efficacy and safety of minimizing mycophenolate mofetil (MMF) early (30 d) or late (90 d) after renal transplantation, when used in combination with tacrolimus; (ii) to retrospectively investigate factors associated with early, acute rejections and (iii) to investigate the pharmacokinetic interaction between tacrolimus and diltiazem. A prospective, randomized, multicenter, open-label study was conducted in 124 de novo kidney transplant recipients. Efficacy and safety outcomes were assessed for 180 d after transplantation and subjects were followed-up for a mean duration of 5.1 yr. The efficacy and safety outcomes were comparable whether the dose of MMF was minimized early or late. The incidence of early, acute rejection episodes was higher for recipients who were younger, received a graft from an unrelated donor or failed to achieve adequate tacrolimus concentrations (trough > 10 ng/mL) in the first seven d after transplant. Concomitant use of diltiazem had a tacrolimus-sparing effect in some subjects. Based on these results, we support the achievement of a high target tacrolimus concentration within the first week after renal transplant and suggest that early minimization of MMF can be achieved when used in combination with tacrolimus.     

Oral ulcers in kidney transplant recipients treated with sirolimus and mycophenolate mofetil

BACKGROUND: In an attempt to reduce calcineurin inhibitor toxicity, transplant patients treated with tacrolimus can be switched to maintenance treatment with sirolimus. METHODS: In a prospective, randomized, multicenter trial, 33 kidney transplant recipients on steroid-free maintenance treatment with tacrolimus and mycophenolate mofetil continued tacrolimus and mycophenolate mofetil (control group, n=18) or were converted from tacrolimus to sirolimus (study group, n=15) at 1 year after transplantation. RESULTS: The study was prematurely stopped as a result of a cluster of nine patients suffering from painful oral ulcerations in the study group. Oral ulcerations did not occur in the control group. The authors here report on the individual cases suffering from this side effect of the instituted immunosuppressive regimen. CONCLUSIONS: The authors review the literature with respect to the occurrence of oral ulcers associated with the use of sirolimus or mycophenolate mofetil and speculate on the causes of the high incidence of oral ulcers in their study group. Possible explanations are overimmunosuppression during the period of the conversion from tacrolimus to sirolimus without antiviral prophylaxis, the use of the oral emulsion instead of tablets, or the lack of corticosteroid co-administration.     

Conversion from calcineurin inhibitors to sirolimus in kidney transplant patients reduces the urinary transforming growth factor-beta1 concentration

INTRODUCTION: Chronic allograft dysfunction (CAD) is the main cause of late transplant failure. Although several etiologies have been postulated, toxicity for calcineurin inhibitors (CNIs) is one of the most important causes of CAD, characterized by arteriolar hyalinosis, luminal narrowing, increased glomerulosclerosis, and tubulointerstitial damage. It's known that in transplant patients with CAD, fibrogenic mediators such as transforming growth factor beta (TGF-beta) are increased. Sirolimus is an immunosuppressive agent with a distinct mechanism of action compared with CNI. AIM: This study assessed variations in levels of fibrogenic mediators among CAD patients treated with CNIs, before and after conversion to sirolimus. PATIENTS AND METHODS: We studied twelve renal transplant patients with CAD on CNI treatment. TGF-beta in plasma and urine, endothelin-1, and vascular endothelial growth factor (VEGF) were studied before and 8 months after conversion to sirolimus treatment. RESULTS: TGF-beta urine levels decreased from 24.7 +/- 11.2 to 12.8 +/- 5.1 ng/24 h (P = .049). In plasma, a similar decrease trend was observed (22.2 +/- 32 to 10.3 +/- 3 ng/mL), although it was not significant (P = .079). Endothelin-1 showed a decrease (8.1 +/- 3 to 5.2 +/- 1.1 pmol/L; P = .1) and VEGF in plasma increased from 34.3 +/- 37 to 92.2 +/- 86 pg/mL (P = .051). CONCLUSIONS: Patients undergoing conversion from CNI to sirolimus treatment for CAD presented a significant decrease in TGF-beta urine levels, representing a decreased mediator of the CAD fibrogenic process.     

Immunosuppression in pancreas transplantation: mycophenolate mofetil versus sirolimus

The use of mycophenolate mofetil (MMF) in pancreas transplantation has increased graft survival and decreased the incidence of acute rejections episodes (ARE), regardless of the choice of calcineurin inhibitor. The combination of MMF with tacrolimus (TAC) is the most common protocol, it is considered the gold standard for new protocols. In the last few years, there have been reports of a small number of patients treated with sirolimus (RAPA), usually combined with TAC. Patient and pancreas survival rates as well as the incidence of ARE were similar to protocols with TAC and MMF. Twenty simultaneous pancreas and kidney (SPK) transplantations were performed using an immunosuppressive protocol of TAC, RAPA, and steroids (STE) after 2000. The incidence of ARE was 25%; all episodes responded to STE. Only 2 patients (10%) displayed hypercholesterolemia requiring treatment with statins. The use of RAPA as an alternative to MMF is promising, although presently one with limited experience. The combination of MMF and RAPA with or without a calcineurin inhibitor is an option to be evaluated in the future.     

A prospective, randomized trial of tacrolimus in combination with sirolimus or mycophenolate mofetil in kidney transplantation: results at 1 year

BACKGROUND: This is the 1-year report of a randomized, multicenter, clinical trial comparing the combination of sirolimus or mycophenolate mofetil (MMF) with tacrolimus-based immunosuppression in kidney transplantation. METHODS: Prior to transplantation, recipients were randomized to receive tacrolimus plus corticosteroids with either sirolimus (n=185) or MMF (n=176). The incidence of biopsy-confirmed acute rejection at 6 months was the primary endpoint of the study. Patient and graft survival, renal function, study drug dosing and discontinuations were evaluated at 1 year. RESULTS: At 1 year, there was no difference in patient survival (95.7% sirolimus vs. 97.2% MMF; P=0.45) or graft survival (90.8% sirolimus vs. 94.3% MMF; P=0.22). Patients without delayed graft function (DGF) receiving MMF had significantly better graft survival (99% vs. 93%; P=0.01). Patients receiving a transplant from a live donor had a trend towards better graft survival with MMF as compared to sirolimus (98% vs. 91%; P=0.07). Patients receiving sirolimus had a significantly higher incidence of study drug discontinuation (26.5% vs. 14.8% MMF; P=0.006). Patients receiving MMF had significantly better renal function as shown by median serum creatinine levels (1.3 mg/dL vs. 1.5 mg/dL; P=0.03) and a trend towards higher calculated creatinine clearance (CrCl), (58.4 ml/min vs. 54.3 ml/min; P=0.06). More patients in the sirolimus group had a serum creatinine >2.0 mg/dL, (20.4% vs. 11.0%; P=0.02). CONCLUSIONS: Tacrolimus is safe and effective in live and deceased donor kidney transplantation when given in combination with sirolimus or MMF. Patient and graft survival were excellent in both arms. Renal function is superior for patients treated with tacrolimus + MMF combination.     

Randomized trial of tacrolimus in combination with sirolimus or mycophenolate mofetil in kidney transplantation: results at 6 months

BACKGROUND: This is the first report of a randomized, multicenter, clinical trial comparing the combination of sirolimus or mycophenolate mofetil (MMF) with tacrolimus-based immunosuppression in kidney transplantation. Results at 6 months of follow-up are presented. METHODS: Before transplantation, patients were randomized to receive tacrolimus plus corticosteroids with sirolimus (n=185) or MMF (n=176). The primary endpoint of the study was the incidence of biopsy-confirmed acute rejection. Patient and graft survival, renal function, and composite endpoints also were evaluated. Safety was assessed by monitoring laboratory parameters and adverse events. RESULTS: By 6 months of follow-up, the incidence of biopsy-confirmed acute rejection was similar in both treatment groups (13.0% tacrolimus+sirolimus vs. 11.4% tacrolimus+MMF; P=0.64 log-rank). Patient survival (97.3% tacrolimus+sirolimus vs. 97.7% tacrolimus+MMF) and graft survival (93.0% tacrolimus+sirolimus vs. 95.5% tacrolimus+MMF) were equivalent (P=0.53, overall survival log-rank). There was a significantly higher incidence of study drug discontinuation in patients receiving sirolimus (21.1% vs. 10.8%; P=0.008). Renal function was significantly better in the MMF-treatment group (serum creatinine 1.44+/-0.45 mg/dL vs. 1.77+/-1.42 mg/dL; P=0.018). Hyperlipidemia was significantly more prevalent in the sirolimus-treatment group. Diastolic blood pressure was significantly higher in sirolimus-treated patients. There were significantly more leukopenia and gastrointestinal adverse events in the MMF-treatment group. The incidence of posttransplant diabetes mellitus was 7.6% in the sirolimus group and 7.7% in the MMF group. CONCLUSION: Tacrolimus is equally effective in renal transplantation when combined with sirolimus or MMF. The tacrolimus-MMF combination may be superior in terms of improved renal function and improved cardiovascular risk factors including hyperlipidemia and hypertension.     

Combined mycophenolate mofetil and losartan therapy arrests established injury in the remnant kidney

Previously it was shown that early treatment with mycophenolate mofetil (MMF) attenuated renal inflammation, glomerulosclerosis (GS), and interstitial expansion in the 5/6 ablation (NX) model. Angiotensin II antagonists also mitigate renal injury in NX, presumably by lowering glomerular pressure (P(GC)). This study investigated: (1) whether combined MMF/angiotensin II antagonists treatment affords superior protection compared with the respective monotherapies; and (2) whether this association is effective even when instituted late in the course of the disease. Adult male Munich-Wistar rats underwent NX, remaining untreated for 30 d. BP, albuminuria, and the extent of GS, interstitial expansion, and macrophage infiltration were then determined in 17 rats. The remaining 118 rats received either inert vehicle or one of the following: MMF, 10 mg/kg by gavage once daily; losartan potassium (L), 20 mg/dl in drinking water; or combined MMF/L treatment. Sixty days after ablation, untreated NX rats exhibited marked glomerular hypertension, which was attenuated by MMF and, more effectively, by either L or combined MMF/L treatment. At 120 d, hypertension and albuminuria were worsened in untreated NX rats, which exhibited intense macrophage infiltration and severe glomerular and interstitial disease. L and, to a lesser extent, MMF monotherapies attenuated these abnormalities, without preventing their progression. In rats given combined MMF/L therapy, macrophage infiltration, GS, and interstitial expansion remained at pretreatment levels. By acting on two distinct pathogenic mechanisms, combined MMF/L treatment arrested established renal injury in the NX model. Further investigation is needed to determine whether this association can prevent renal scarring in other models and in human disease.     

Glucocorticoids interfere with mycophenolate mofetil bioavailability in kidney transplantation

BACKGROUND: Steroids have been shown to induce the hepatic glucuronyltransferase (GT) expression enhancing the activity of uridine diphosphate-GT, the enzyme responsible for mycophenolic acid (MPA) metabolism. The impact of steroids on MPA pharmacokinetics, however, has not been investigated to date. METHODS: As a part of a steroid-sparing clinical trial, we studied the effect of steroids on MPA bioavailability in 26 kidney transplant recipients. RESULTS: Despite that the MMF dose did not change significantly with time, dose-normalized MPA AUC0-12h was lower during the first month (triple therapy, high doses of steroids) than at month 6 post-surgery (triple therapy, low maintenance dose of steroids (32.94 +/- 10.98 vs. 50.87 +/- 22.37 microg/mL. h; P < 0.01). During the steroid tapering and withdrawal phase (from month 6 to 21 post-Tx), plasma MPA trough and peak concentration as well as AUC0-12h progressively increased, while plasma MPA clearance and MPAG (the major MPA metabolite) trough levels declined. Renal function was stable throughout. Since cyclosporine A (CsA) may interfere with MPA pharmacokinetics, MPA and CsA also were measured in an additional control group of 12 kidney transplant patients at month 21 post-Tx who were still on triple therapy (MMF, CsA and steroids). Despite a similar CsA exposure, the control group had a significantly lower MPA AUC0-12h and higher MPAG trough concentration than patients on dual therapy at month 21 post-Tx. CONCLUSION: These findings indicate that steroids interfere with MPA bioavailability, and that discontinuation of the drug results in higher MPA exposure, which may compensate at least in part for the lower immunosuppressive level achieved with the remaining dual therapy with CsA and MMF.     

Use of basiliximab with mycophenolate mofetil in kidney transplantation

INTRODUCTION: Randomized, placebo-controlled studies have determined that administration of basiliximab (chimeric IL-2 receptor antagonist) decreases the acute rejection rate in kidney transplantation when used in combination with cyclosporine, azathioprine, and steroids. We report our experience using basiliximab with mycophenolate mofetil, a calcineurin inhibitor, and steroids in kidney transplantation. METHODS: We retrospectively analyzed 127 patients who received their first kidney transplant between September 1, 1998, and December 30, 2000, including 59 who received basiliximab (22 living and 37 cadaveric donor recipients) and the 68 that did not receive this antibody (31 living and 37 cadaveric donor recipients). The groups were demographically comparable for risk factors such as race, peak of panel-reactive antibody, delayed graft function, donor age, and cold ischemia time. The analysis assessed serum creatinine levels, acute rejection, cytomegalovirus infection, and posttransplant lymphoproliferative disease incidence as well as patient and graft survival at 6 months. RESULTS: Serum creatinine levels were 3 +/- 3.1 and 2.6 +/- 2.5 mg/dL (P =.346) at discharge, 1.5 +/- 0.6 and 1.7 +/- 1.1 mg/dL (P =.098) at 1 month, and 1.5 +/- 0.7 and 1.6 +/- 0.7 mg/dL (P =.454) at 6 months posttransplantation for patients treated with versus without basiliximab, respectively. Only one episode of acute rejection was seen among patients treated with basiliximab within 1 month posttransplantation versus three episodes among patients treated without basiliximab (P =.382). Three patients (5.1%) treated with basiliximab and two patients (2.9%) treated without basiliximab developed acute rejection within 6 months posttransplantation (P =.536). Patient and graft survivals at 6 months posttransplantation were not significantly different between patients treated with versus without basiliximab (100% and 100% versus 100% and 98.3%, respectively). There was no increased incidence of cytomegalovirus infection with the use of basiliximab (5.1% vs 5.9%, P =.844). There was only one case of posttransplant lymphoproliferative disease within 6 months posttransplantation in a patient treated without basiliximab. CONCLUSION: These data suggest that the routine addition of basiliximab to a mycophenolate mofetil-based regimens does not appear to be warranted. A larger prospective randomized study with longer follow-up is needed to confirm these results.     

Gene transfer of transforming growth factor-beta1 to the rat peritoneum: effects on membrane function

Long-term peritoneal dialysis is limited by physiologic changes in the peritoneum that lead to ultrafiltration failure. To determine the role of profibrotic cytokines in the alteration of peritoneal transport, a rodent model of transforming growth factor-beta (TGF-beta)-mediated peritoneal fibrosis was established. An adenoviral vector driving the active form of TGF-beta1 (AdTGFbeta1) was administered intraperitoneally, and peritoneal structure and function were evaluated for 28 d after infection. Seven days after AdTGFbeta1 infection, thickening of the peritoneum, with cellular proliferation and increased vascularization, was noted. By day 28, there was persistent thickening and extensive collagen deposition. The mesenteric collagen content was significantly elevated, compared with control adenovirus-treated animals, 21 d after infection (2.9 versus 1.8 mg hydroxyproline/g tissue, P = 0.006). Blood vessel density, as measured using factor VIII immunohistochemical analyses, was significantly increased from day 4 to day 21 but decreased by day 28. Animals infected with AdTGFbeta1 demonstrated increased transport of solutes and decreased net ultrafiltration, which was maximal on day 7 and returned to baseline levels by day 28. It was demonstrated in vitro and in vivo that TGF-beta1 induced production of vascular endothelial growth factor. Overexpression of TGF-beta1 after adenovirus-mediated gene transfer causes peritoneal fibrosis, neoangiogenesis, and increased peritoneal membrane solute transport. This model should allow further delineation of the relative contributions of profibrotic and angiogenic cytokines to changes in peritoneal function and may lead to potential new interventions for peritoneal membrane failure.     

Blocking transforming growth factor-beta receptor signaling down-regulates transforming growth factor-beta1 autoproduction in keloid fibroblasts.

OBJECTIVE: To study transforming growth factor-beta1 (TGF-beta1) autoproduction in keloid fibroblasts and the regulation effect of blocking TGF-beta intracellular signaling on rhTGF-beta1 autoproduction. METHODS: Keloid fibroblasts cultured in vitro were treated with either rhTGF-beta1 (5 ng/ml) or recombinant adenovirus containing a truncated type II TGF-beta receptor gene (50 pfu/cell). Their effects of regulating gene expression of TGF-beta1 and its receptor I and II were observed with Northern blot. RESULTS: rhTGF-beta1 up-regulated the gene expression of TGF-beta1 and receptor I, but not receptor II. Over-expression of the truncated receptor II down-regulated the gene expression of TGF-beta1 and its receptor I, but not receptor II. CONCLUSIONS: TGF-beta1 autoproduction was observed in keloid fibroblasts. Over-expression of the truncated TGFbeta receptor II decreased TGF-beta1 autoproduction via blocking TGF-beta receptor signaling.     

霉酚酸酯对肾大部切除大鼠肾脏的保护作用

目的 观察霉酚酸酯在肾大部切除大鼠模型中对残肾的保护作用并探讨其可能的机制。方法 采用5/6肾大部切除模型,分别给予霉酚酸酯(MMF,15 mg·kg-1·d-1),福辛普利(25mg·kg-1·d-1)及两药合用。8周后观察大鼠24 h尿蛋白、BUN、Scr以及肾脏病理改变。并用免疫组化观察了胶原Ⅳ、纤连蛋白(FN)、增殖细胞核抗原(PCNA)和巨噬细胞趋化蛋白1(MCP-1)。用RT-PCR的方法测定了肾皮质中转化生长因子β1(TGF-β1)和组织性金属蛋白酶抑制剂1(TIMP-1)mRNA的表达。结果 两药均能减少尿蛋白,降低BUN和Scr,合用组减少最为明显。病理上,肾大部切除组可见基质增生,肾小球硬化,用药后病变减轻。其中应用MMF者可见PCNA和MCP-1明显减少。结论 在5/6肾大部切除模型中,MMF能通过抑制肾脏中的异常增殖、减少MCP-1的表达,下调TGF-β1和TIMP-1,减少细胞外基质,减少尿蛋白,从而明显减轻肾脏的损害。     

TGF-β1与腱病关系的研究进展

腱病是常见的软组织疾病,但其发病机制尚未阐明并缺乏有效治疗手段。组织纤维化改变是其最主要的病理学特点之一。转化生长因子β1(transforming growth factor-beta1,TGF-β1)是参与纤维化的重要因子,它在腱病组织中的表达并不一致,仍存在争议。但绝大多数研究显示TGF-β1有异常表达,且以升高为主,表明TGF-β1在腱病发病过程中起重要作用。在肌腱的损伤和修复过程中,TGF-β1增高的时间点并不一致,其在肌腱修复中发挥作用的时间目前尚无定论。因TGF-β1在肌腱腱病和肌腱修复这两个看似相反的过程中都有异常表达,所以推测它并非一种单向调节的因子,而是具有多效性的。目前研究认为TGF-β1的作用途径是TGF-β1与受体相结合,将信号传入细胞,现在发现其受体有3种。TGF-β1在细胞内信号传导的经典通路主要是通过激活Smad通路进行的,同时也存在一些非经典通路。TGF-β1可以打破细胞外基质的平衡,这可能是造成腱病的一个途径,但其对细胞外基质的调控是复杂且多样的,需要深入研究。现有研究显示,阻断TGF-β1的下游通路对改善腱病的作用不佳,因此可以尝试对TGF-β1产生的上游机制进行研究,从寻找TGF-β1产生源头出发,或许可以找到更好的抑制腱病发生发展的新靶点。