A pharmacoeconomic comparison of antithymocyte globulin and muromonab CD3 induction therapy in renal transplant recipients

Antithymocyte globulin (ATG) and muromonab CD3 (OKT3) are currently the only antilymphocyte preparations that are commercially available for induction immunosuppressive therapy for renal allograft transplantation in the US. ATG, in the usually prescribed doses, is more expensive than muromonab CD3, but muromonab CD3 is associated with more severe adverse effects that may affect clinical outcome and overall cost. We performed a retrospective study of all adult recipients of a first cadaveric renal allograft, who underwent transplantation between January 1991 and December 1994 who received either ATG (n = 92) or muromonab CD3 (n = 91) for induction therapy at our transplant centre. The average age of recipients was older (50 vs 44 yrs; p = 0.001) and extended donors were more commonly used in the ATG group (41 vs 13%; p = 0.0001) compared with the muromonab CD3 group. Nevertheless, at 1 year post-transplant, the incidence of rejection was lower (34 vs 47%) and graft survival was better (93 vs 85%; p = 0.03) in the ATG group. Patients who received ATG were discharged earlier (9.4 vs 13.3 days; p = 0.0001) and had similar serum creatinine levels on the day of discharge (2.4 +/- 1.5 vs 2.1 +/- 1.1 mg/dl; p = 0.25). Overall, the 1-year hospitalisation costs of transplantation and readmissions were similar [$US39,937 +/- 17,014 vs $US42,850 +/- 20,923 (currency year 1994); p = 0.22]. This is the first comparison of ATG and muromonab CD3 in renal transplant recipients to consider clinical as well as economic outcomes. For renal transplant patients in whom induction therapy is used at our centre, the initial expense of ATG can be justified by improved graft survival, fewer rejection episodes, and shorter hospital stays, which are associated with similar overall transplantation costs.     

The use of mycophenolate mofetil in transplant recipients

With the development of new immunosuppressive agents, the focus of anti-rejection therapy has shifted from prevention of acute allograft rejection to an emphasis on sufficient immunosuppression with minimal toxicity. Mycophenolate mofetil (MMF) is a recently developed immunosuppressive drug, which acts to inhibit T and B cell proliferation by blocking the production of guanosine nucleotides required for DNA synthesis. It also prevents the glycosylation of adhesion molecules that are involved in attachment of lymphocytes to endothelium and potentially in leukocyte infiltration of an allograft during an immune response. High-quality randomized clinical trials have demonstrated that MMF, when used with cyclosporine (CsA) and steroids, reduces the frequency and severity of acute rejection episodes in kidney and heart transplants, improves patient and graft survival in heart allograft recipients and increases renal allograft survival at 3 years. It has also been effective in reversing acute and resistant rejection episodes in heart, kidney and liver recipients. The ability of MMF to facilitate sparing of other immunosuppressive agents, particularly in CsA-related nephrotoxicity, is also promising. By permitting reduction in CsA doses, MMF may stabilize or improve renal graft function in patients with CsA-related nephrotoxicity or chronic allograft nephropathy. Early results of phase I and II trials evaluating MMF therapy in liver and combined pancreas/kidney transplant recipients are encouraging. The main adverse effects associated with oral or intravenous MMF are gastrointestinal and hematologic in nature. Although the direct costs of using MMF vs. azathioprine (AZA) are higher, the decreased incidence and treatment of acute rejection in patients treated with MMF supports its use as a cost-effective option during the first year following transplantation.Thus, MMF has become an important therapeutic tool in the transplant clinician's armamentarium. Ongoing issues to be resolved in clinical trials include the role of MMF in the absence of other potent agents, e.g., as monotherapy or with a steroid but without calcineurin inhibitor; whether MMF will have an impact on chronic allograft dysfunction; and the cost-effectiveness of treatment following the first year of transplantation.     

Basiliximab: a review of its use as induction therapy in renal transplantation

Basiliximab (Simulect), a chimeric (human/murine) monoclonal antibody, is indicated for the prevention of acute organ rejection in adult and paediatric renal transplant recipients in combination with other immunosuppressive agents.Basiliximab significantly reduced acute rejection compared with placebo in renal transplant recipients receiving dual- (cyclosporin microemulsion and corticosteroids) or triple-immunotherapy (azathioprine- or mycophenolate mofetil-based); graft and patient survival rates at 12 months were similar. Significantly more basiliximab than placebo recipients were free from the combined endpoint of death, graft loss or acute rejection 3 years, but not 5 years, after transplantation.The incidence of adverse events was similar in basiliximab and placebo recipients, with no increase in the incidence of infection, including cytomegalovirus (CMV) infection. Malignancies or post-transplant lymphoproliferative disorders after treatment with basiliximab were rare, with a similar incidence to that seen with placebo at 12 months or 5 years post-transplantation. Rare cases of hypersensitivity reactions to basiliximab have been reported.The efficacy of basiliximab was similar to that of equine antithymocyte globulin (ATG) and daclizumab, and similar to or greater than that of muromonab CD3. Basiliximab was as effective as rabbit antithymocyte globulin (RATG) in patients at relatively low risk of acute rejection, but less effective in high-risk patients. Numerically or significantly fewer patients receiving basiliximab experienced adverse events considered to be related to the study drug than ATG or RATG recipients. The incidence of infection, including CMV infection, was similar with basiliximab and ATG or RATG.Basiliximab plus baseline immunosuppression resulted in no significant differences in acute rejection rates compared with baseline immunosuppression with or without ATG or antilymphocyte globulin in retrospective analyses conducted for small numbers of paediatric patients. Limited data from paediatric renal transplant recipients suggest a similar tolerability profile to that in adults. Basiliximab appears to allow the withdrawal of corticosteroids or the use of corticosteroid-free or calcineurin inhibitor-sparing regimens in renal transplant recipients.Basiliximab did not increase the overall costs of therapy in pharmacoeconomic studies.CONCLUSION: Basiliximab reduces acute rejection without increasing the incidence of adverse events, including infection and malignancy, in renal transplant recipients when combined with standard dual- or triple-immunotherapy. The overall incidence of death, graft loss or acute rejection was significantly reduced at 3 years; there was no significant difference for this endpoint 5 years after transplantation. Malignancy was not increased at 5 years. The overall efficacy, tolerability, ease of administration and cost effectiveness of basiliximab make it an attractive option for the prophylaxis of acute renal transplant rejection.     

Tacrolimus: a further update of its use in the management of organ transplantation

Extensive clinical use has confirmed that tacrolimus (Prograf) is a key option for immunosuppression after transplantation. In large, prospective, randomised, multicentre trials in adults and children receiving solid organ transplants, tacrolimus was at least as effective or provided better efficacy than cyclosporin microemulsion in terms of patient and graft survival, treatment failure rates and the incidence of biopsy-proven acute and corticosteroid-resistant rejection episodes. Notably, the lower incidence of rejection episodes after renal transplantation in tacrolimus recipients was reflected in improved cost effectiveness. In bone marrow transplant (BMT) recipients, the incidence of tacrolimus grade II-IV graft-versus-host disease was significantly lower with tacrolimus than cyclosporin treatment. Efficacy was maintained in renal and liver transplant recipients after total withdrawal of corticosteroid therapy from tacrolimus-based immunosuppression, with the incidence of acute rejection episodes at up to 2 years' follow-up being similar with or without corticosteroids. Tacrolimus provided effective rescue therapy in transplant recipients with persistent acute or chronic allograft rejection or drug-related toxicity associated with cyclosporin treatment. Typically, conversion to tacrolimus reversed rejection episodes and/or improved the tolerability profile, particularly in terms of reduced hyperlipidaemia. In lung transplant recipients with obliterative bronchiolitis, conversion to tacrolimus reduced the decline in and/or improved lung function in terms of forced expiratory volume in 1 second. Tolerability issues may be a factor when choosing a calcineurin inhibitor. Cyclosporin tends to be associated with a higher incidence of significant hypertension, hyperlipidaemia, hirsutism, gingivitis and gum hyperplasia, whereas the incidence of some types of neurotoxicity, disturbances in glucose metabolism, diarrhoea, pruritus and alopecia may be higher with tacrolimus treatment. Renal function, as assessed by serum creatinine levels and glomerular filtration rates, was better in tacrolimus than cyclosporin recipients at up to 5 years' follow-up. CONCLUSION: Recent well designed trials have consolidated the place of tacrolimus as an important choice for primary immunosuppression in solid organ transplantation and in BMT. Notably, in adults and children receiving transplants, tacrolimus-based primary immunosuppression was at least as effective or provided better efficacy than cyclosporin microemulsion treatment in terms of patient and graft survival, treatment failure and the incidence of acute and corticosteroid-resistant rejection episodes. The reduced incidence of rejection episodes in renal transplant recipients receiving tacrolimus translated into a better cost effectiveness relative to cyclosporin microemulsion treatment. The optimal immunosuppression regimen is ultimately dependent on balancing such factors as the efficacy of the individual drugs, their tolerability, potential for drug interactions and pharmacoeconomic issues.     

Induction immunosuppression in kidney transplant recipients older than 60 years of age : safety and efficacy of ATGAM, OKT3 and Simulect

BACKGROUND: The choice of induction immunosuppression for kidney transplantation in elderly recipients is dictated by the consideration of the risk of infection as well as efficacy in the prevention of acute rejection, thus allowing a reduction in subsequent maintenance immunosuppression and its attendant long-term adverse effects. OBJECTIVE: To compare the efficacy and safety of the antibody induction immunosuppression strategies in elderly recipients of kidney transplants. PATIENTS AND METHODS: We present retrospective data analysis on 183 kidney transplant recipients > or = 60 years of age at Hahnemann University Hospital (Philadelphia, PA, USA) over a 12-year period. We compared four consecutive cohorts of kidney transplant recipients receiving lymphocyte immune globulin, equine antithymocyte globulin (ATGAM) [n = 29]; muromonab CD3 (OKT3) [n = 45]; basiliximab (Simulect) with corticosteroid maintenance [n = 40]; and Simulect without corticosteroid maintenance (n = 69). RESULTS: Delayed graft function (DGF) was observed in 48% of patients receiving ATGAM, 35.6% in the OKT3 group and 35% in the Simulect group with corticosteroid maintenance and 36.2% in the Simulect group without corticosteroid maintenance. The rejection rate within the first 3 months was 31% in the ATGAM and OKT3 groups, 17.5% in the Simulect group with corticosteroid maintenance and 14.5% in the Simulect group without corticosteroid maintenance. These differences for DGF and acute rejection were statistically significant between patients receiving ATGAM and OKT3, ATGAM or OKT3 and both groups of Simulect (all p < 0.05). Patients receiving Simulect were free of adverse effects typically encountered by patients receiving polyclonal and monoclonal antibodies for induction. Patients receiving Simulect had much shorter hospital stays and benefited from significant reduction of costs compared with other groups. CONCLUSION: Our data indicate that kidney transplant recipients > or = 60 years of age benefit from induction therapy with Simulect followed by corticosteroid-free maintenance immunosuppression.     

巴利昔单抗联合鼠抗人CD3单克隆抗体在高致敏受者肾移植中的临床应用

目的:探讨巴利昔单抗与鼠抗人CD3单克隆抗体(OKT3)联合诱导在高致敏受者肾移植临床应用中的有效性及安全性。方法:术前2个月内群体反应性抗体(PRA)检测值均>50%的尸体供肾肾移植受者20例,其中9例受者接受巴利昔单抗联合OKT3免疫诱导(联合诱导组),11例受者接受OKT3常规免疫诱导(OKT3诱导组),均以他克莫司(Tac)+吗替麦考酚酯(MMF)+泼尼松(Pred)为基础免疫抑制方案,评估术后移植肾功能恢复情况、3个月内急性排斥反应发生率、1年内肺部感染发生率、1年人/肾存活率及移植肾功能。结果:联合诱导组、OKT3诱导组肾移植术后3个月内急性排斥反应发生率及术后1年内肺部感染发生率分别为11.1%vs.36.4%(P=0.319),11.1%vs.63.6%(P=0.028);联合诱导组患者术后1周内移植肾功能恢复正常比例明显高于OKT3诱导组(88.9%vs.27.3%,P=0.010);联合诱导组术后1年人/肾存活率均为100%,与OKT3诱导组(分别为90.9%、81.8%)比较,差异不显著(P=1.00和P=0.100);术后1年联合诱导组、OKT3诱导组血肌酐值分别为(105±24)、(97±22)μmol·L-1(P=0.437)。结论:巴利昔单抗联合OKT3进行免疫诱导,在预防高致敏受者术后早期排斥反应的同时,缩短了移植肾功能的恢复时间,是一种安全、有效的防治策略。     

Combination treatment with sirolimus and ciclosporin in clinical renal transplantation: A comprehensive review

Sirolimus is a potent new immunosuppressive agent that has been shown to reduce the incidence of acute rejection episodes among renal transplant recipients as well as provide a unique approach to optimize treatment outcomes in difficult transplant situations. Owing to its properties as a critical-dose drug, therapeutic concentration monitoring of sirolimus readily compensates for intra- and interpatient variability and drug interactions with a variety of other agents such as ciclosporin. This review summarizes the results that demonstrate the efficacy of sirolimus in combination treatment with ciclosporin in human renal transplantation, as well as its potential in alternative therapeutic modalities in a broad range of transplant recipients. The clinical trials for SDZ-RAD, a macrocyclic lactone immunosuppressant structurally similar to sirolimus, also are reviewed herein. SDZ-RAD was developed in an attempt to improve the pharmacokinetic characteristics of sirolimus, particularly to increase the extent and reproducibility of its oral bioavailability and to reduce the extensive tissue distribution by virtue of its greater polarity. (c) 2001 Prous Science. All rights reserved.     

Immunosuppression for long-term maintenance of renal allograft function

The incidence and severity of acute rejection episodes was markedly reduced by the introduction of new immunosuppressive drug regimens for renal transplantation, resulting in improved graft survival at 1 year. However, only modest improvement has been shown in long-term graft function rates.This overview evaluates the efficacy of currently used immunosuppressive drugs and drug combinations for long-term maintenance therapy. Prospective controlled trials rarely extend beyond 5 years; therefore, registry data and retrospective reports have also been employed. From currently available data it may be concluded that the initial beneficial effect of ciclosporin (cyclosporin) is lost 10 years after transplantation. Tacrolimus is an alternative to ciclosporin with a different profile of adverse effects and a higher efficacy in acute rejection treatment. For long-term maintenance, projected half-lives of kidney graft function are in favour of tacrolimus. Mycophenolate mofetil (MMF) has been shown to significantly reduce the incidence of early rejections. However, the improved long-term graft survival reported in retrospective studies has still to be confirmed in controlled trials. There is no convincing evidence for superiority of triple therapy including prednisone (or prednisolone), calcineurin inhibitors and azathioprine/MMF over dual therapy without azathioprine/MMF with respect to long-term outcome. Withdrawal of corticosteroids or calcineurin inhibitors clearly reduces adverse drug effects but carries the risk of acute rejection episodes. Avoidance of corticosteroids by using new immunosuppressive drug combinations may be an option to minimise toxic adverse effects in the future.At present, it seems unjustified to convert renal transplant recipients with stable graft function and tolerable adverse effects from one drug to another solely in expectation of future benefits. Acute early or late rejection episodes and intolerable adverse effects are good reasons for conversions between calcineurin inhibitors or cytotoxic agents. Chronic allograft nephropathy with slowly deteriorating graft function remains an unresolved problem.     

Cyclosporin: an updated review of the pharmacokinetic properties, clinical efficacy and tolerability of a microemulsion-based formulation (neoral)1 in organ transplantation.

Cyclosporin is a lipophilic cyclic polypeptide immunosuppressant that interferes with the activity of T cells chiefly via calcineurin inhibition. The original oil-based oral formulation of this drug (Sandimmun)l was characterised by high intra- and interpatient pharmacokinetic variability, with poor bioavailability in many patients; a novel microemulsion formulation (Neoral)1 was therefore developed to circumvent these problems. Studies show increases, attributable chiefly to improved absorption in patients who absorb the drug only poorly from the original formulation, in mean systemic exposure to cyclosporin with the microemulsion, with no clinically significant differences in tolerability or drug interaction profiles. Cyclosporin microemulsion is at least as effective as the oil-based formulation in renal, liver and heart transplant recipients, with trends towards decreased incidence of acute rejection with the microemulsion formulation in some (statistically significant in a few) trials. Cyclosporin microemulsion and tacrolimus appear to have similar efficacy in preventing acute rejection episodes in most renal, pancreas-kidney, liver and heart transplant recipients. However, there are indications of superior efficacy for tacrolimus in some trials, particularly in the prevention of severe acute rejection and in Black transplant recipients. Current 12-month data also indicate equivalent efficacy of sirolimus in renal transplantation. Conversion from the oil-based to microemulsion formulation in stable renal, liver and heart transplant recipients is achievable with no change in acute rejection rates. The addition of an anti-interleukin-2 receptor monoclonal antibody and/or mycophenolate mofetil to cyclosporin microemulsion plus corticosteroids decreases rates of acute rejection; corticosteroid withdrawal without increased acute rejection rates was also achieved on the addition of these agents in some trials. Pharmacoeconomic analyses have shown savings in direct healthcare costs in kidney or liver transplantation when cyclosporin microemulsion is used in preference to the oil-based formulation, although studies incorporating indirect costs or expressing costs in terms of therapeutic outcomes are currently unavailable. CONCLUSIONS: The introduction of cyclosporin microemulsion has consolidated the place of the drug as a mainstay of therapy in all types of solid organ transplantation; research into optimisation of outcomes through more effective therapeutic monitoring in patients receiving this formulation is ongoing. Several novel immunosuppressants have been introduced in recent years: further clinical and pharmacoeconomic research will be needed to clarify the relative positioning of these agents, particularly with respect to specific patient groups. Other new drugs (basiliximab/daclizumab and mycophenolate mofetil) offer particular advantages when used in combination with cyclosporin.     

Anti-interleukin-2 receptor antibodies for the prevention of rejection in pediatric renal transplant patients: current status

The anti-interleukin-2 receptor (anti-IL-2R) antibody therapy is an exciting approach to the prevention of acute rejection after renal allograft transplantation whereby immunosuppression is exerted by a selective and competitive inhibition of IL-2-induced T cell proliferation, a critical pathway of allorecognition. The anti-IL-2R antibodies specifically block the alpha-subunit of the IL-2R on activated T cells, and prevent T cell proliferation and activation of the effector arms of the immune system. The anti-IL-2R antibodies are used as induction therapy, immediately after renal transplantation, for prevention of acute cellular rejection in children and adults. During acute rejection, the IL-2Ralpha chain is no longer expressed on T cells; thus, the antibodies cannot be used to treat an existing acute rejection. Two anti-IL-2R monoclonal antibodies are currently in clinical use: daclizumab and basiliximab. In placebo-controlled phase III clinical trials in adults, daclizumab and basiliximab in combination with calcineurin inhibitor-based immunosuppression, significantly reduced the incidence of acute rejection and corticosteroid-resistant acute rejection without increasing the risk of infectious or malignant complications, and neither antibody was associated with the cytokine-release syndrome. Children who receive calcineurin inhibitors and corticosteroids for maintenance immunosuppression, as well as children who receive augmented immunosuppression to treat acute rejection, are at increased risk of growth impairment, hypertension, hyperlipidemia, lymphoproliferative disorders, diabetes mellitus, and cosmetic changes. In older children, the cosmetic adverse effects frequently reduce compliance with the treatment, and subsequently increase the risk of allograft loss. Being effective and well tolerated in children, the anti-IL-2R antibodies reduce the need for calcineurin inhibitors while maintaining the overall efficacy of the regimen; thus, the anti-IL-2R antibodies increase the safety margin (less toxicity, fewer adverse effects) of the baseline immunosuppression. Secondly, the anti-IL-2R antibodies decrease the need for corticosteroids and muromonab CD3 (OKT3) in children as a result of decreased incidence of acute rejection. The recommended pediatric dose of daclizumab is 1 mg/kg intravenously every 14 days for five doses, with the first dose administered within 24 hours pre-transplantation. This administration regimen maintains daclizumab levels necessary to completely saturate the IL-2Ralpha (5-10 microg/mL) in children for at least 12 weeks.The recommended pediatric dose of basiliximab for recipients <35 kg is 10 mg, and 20 mg for recipients > or =35 kg, intravenously on days 0 and 4 post-transplantation. This administration regimen maintains basiliximab levels necessary to completely saturate the IL-2Ralpha (>0.2 microg/mL) in children for at least 3 weeks.     

巴利昔单抗对肾移植受者白细胞介素2和可溶性白介素2受体的影响

目的:分析巴利昔单抗和抗CD3单克隆抗体(OKT3)对肾移植受者白细胞介素2(IL2)和可溶性白细胞介素2受体(sIL2R)的影响,评价其治疗的有效性及安全性。方法:将74例肾移植受者随机分为巴利昔单抗组(n=39)和OKT3组(n=35)。所有病人均采用环孢素+霉酚酸酯+泼尼松三联免疫抑制维持治疗。巴利昔单抗组:分别于术前2h和术后d4使用巴利昔单抗20mg,静脉滴注;OKT3组:从术后d1开始,给OKT35mg静脉滴注,qd,共7～10d。检测术后2mo内IL2和sIL2R浓度,观察急性排斥反应(AR)、肌酐恢复时间、不良反应、受者和移植肾存活情况。结果:巴利昔单抗组IL2和sIL2R浓度明显低于OKT3组(P<0.05)。有12例病人发生AR,巴利昔单抗组3例,OKT3组9例(P<0.05)。巴利昔单抗组肌酐恢复时间(4.7±s2.1)d,明显短于OKT3组(9±5)d(P<0.05)。巴利昔单抗组感染7例,细胞因子释放综合征0例,过敏反应0例,明显低于OKT3组(P<0.05)。结论:巴利昔单抗明显降低IL2和sIL2R浓度和AR发生率,不良反应少,是一种强效安全的免疫抑制剂。     

Paradoxical cyclosporine A requirements in pediatric renal transplants receiving high-dose steroids

The potent immunosuppressant cyclosporine A (CyA) is a mainstay of treatment in the renal transplant population. During episodes of acute allograft rejection, therapy also includes the pulse administration of high-dose steroids such as prednisone or methylprednisolone. Both steroids and CyA are metabolized by the CYP3A4 isoenzyme of the cytochrome P450 catalytic system. On a theoretical basis, high steroid concentrations during a rejection episode could competitively inhibit CyA metabolism, increasing its systemic concentration and decreasing its dose requirements. A database was compiled consisting of pediatric patients who had undergone an acute renal rejection event during the years 1993 to 2003. The severity of rejection events, as well as the CyA and prednisone dosing regimens used during rejection, were assessed using a comprehensive chart analysis. The presence or absence of additional medications that could potentially interact with CyA was also examined. Although some patients responded in the predicted manner, the authors also found that a subgroup of pediatric patients placed on highdose pulse steroid therapy for acute graft rejection required increased amounts of CyA to maintain therapeutic concentrations. The authors recommend monitoring of patients on high-dose steroids for paradoxical CyA requirements intermittently during high-dose steroid treatment to individualize CyA therapy appropriately during renal allograft rejection and thereby maximize efficacy while minimizing potential toxic side effects of CyA such as under-immunosuppression and organ rejection.     

Administration of Antithymocyte Globulin (Rabbit) to Treat a Severe,Mixed Rejection Episode in a Pregnant Renal Transplant Recipient

Pregnancy in solid organ transplant recipients carries numerous risks to the mother such as increased risk of rejection, gestational diabetes mellitus, and preeclampsia. The developing fetus is subjected to risks such as birth defects, preterm delivery, and low birth weight. Typically, these risks can be managed through intensive, multidisciplinary prenatal care and a proper immunosuppressive regimen. In the setting of rejection, however, little data are available to suggest safe and effective treatment of acute cellular rejection, antibody‐mediated rejection, or mixed rejection episodes in the pregnant solid organ transplant recipient. We describe the first case, to our knowledge, in which antithymocyte globulin (rabbit) was used to successfully treat a pregnant renal transplant recipient who experienced a mixed rejection episode. A 22‐year‐old, African American woman with stage 6 chronic kidney disease received a deceased donor renal transplant after undergoing hemodialysis for 3 years. Her maintenance immunosuppressive regimen at the time of transplantation consisted of tacrolimus, prednisone, and mycophenolate mofetil. Despite counseling efforts on the importance of having a planned pregnancy after kidney transplantation so that her immunosuppressive medications could be optimized, the patient became pregnant 12 months later; her mycophenolate mofetil was changed to azathioprine to reduce the risk of fetal deformities or death. Three months later, the patient was admitted for biopsy of her transplanted kidney and was evaluated for possible kidney rejection. After confirmation of a mixed 1B acute cellular rejection and antibody‐mediated rejection episode, the patient decided to pursue resolution of her rejection episode and continue the pregnancy despite the potential risks to the fetus. She was treated with high‐dose corticosteroids, intravenous immunoglobulin, plasmapheresis, and antithymocyte globulin (rabbit). Twenty‐nine months after transplantation, the patient was induced and gave birth to a healthy baby boy. Our patient's case offers unique insight into the potential management of a rejection episode requiring aggressive immunosuppressive therapy. Although potent immunosuppressive therapies were successfully used in our patient, further studies are needed to make definitive recommendations regarding the use of such therapies for treatment of rejection episodes in pregnant solid organ transplant recipients. The risks and uncertainties of treating rejection episodes should always be discussed with and understood by the patient before an informed decision is made.     

Sirolimus: a comprehensive review

Sirolimus (Rapamune), Wyeth-Ayerst, Madison, NJ) is a new, potent, immunosuppressant that is emerging as a foundation for long-term immunosuppressive therapy in renal transplantation. The drug acts during both co-stimulatory activation and cytokine-driven pathways via a unique mechanism: inhibition of a multifunctional serine-threonine kinase, mammalian target of rapamycin (mTOR). Although there is no a priori reason to assume it, sirolimus displays a synergistic interaction to enhance the efficacy of cyclosporin A (CsA). In trials wherein the concentrations of CsA and sirolimus were tightly controlled, rates of acute rejection episodes were < 10%, despite markedly reduced exposures to each agent. In pivotal multi-centre blinded dose-controlled trials, the rates of acute rejection episodes within 12 months following administration of 2 or 5 mg/day sirolimus in combination with CsA and steroids were reduced to 19 and 14%, respectively. Since the inhibitory effect of sirolimus disables virtually all responses to cytokine mediators due to the widespread involvement of mTOR in multiple signalling pathways, the agent is likely also to retard proliferation of endothelial and vascular smooth muscle cells, an important component of the immuno-obliterative processes associated with chronic rejection. The advantages of this unique therapeutic action combined with an intrinsic lack of nephrotoxicity are counterbalanced by myelosuppressive and hyperlipidaemic side effects. Ongoing studies are assessing whether the long-term benefits of sirolimus to permit reduction in exposure to or elimination of calcineurin inhibitors ameliorate the progression of chronic nephropathy, the condition that erodes long-term renal transplant survival.     

Antibody-mediated rejection following renal transplantation

Antibody-mediated rejection (AMR) accounts for 20-30% of all acute rejection episodes following renal transplantation. AMR is generally less responsive to conventional anti-rejection therapy, resulting in poor allograft survival. Introduction of C4d immunostaining of renal allograft biopsies and the demonstration of donor-specific antibodies in the recipients have increased our ability to diagnose AMR. Therapeutic options are evolving and include plasmapheresis, intravenous immunoglobulin, immunoadsorption and rituximab, together with intensification of immunosuppression with a tacrolimus/mycophenolate mofetil combination. Future studies might further define optimal therapeutic approach in renal transplant recipients presenting with AMR.     

Review of the proliferation inhibitor everolimus

Everolimus (Certican^?) is being developed for prevention of acute and chronic rejection of solid organ transplants. A novel proliferation inhibitor, everolimus synergies with cyclosporine to prevent and reverse acute rejection in preclinical models of kidney, heart or lung transplantation. The manifestations of chronic rejection that may contribute to graft loss are also inhibited by everolimus in preclinical models. Although everolimus is metabolised by the cytochrome P450 CYP3A isoenzyme, coadministration with cyclosporine does not alter the pharmacokinetics of cyclosporine, but cyclosporine coadministration increases exposure to everolimus. Everolimus interacts with inhibitors and inducers of this system; its clearance is reduced in patients with hepatic impairment. In an immunosuppressive regimen with cyclosporine microemulsion formulation and corticosteroids, transplant recipients treated with everolimus show low rates of acute rejection and, in one heart and one renal trial, lower rates of cytomegalovirus infection. Acute rejection rates are lower than those seen with azathioprine in cardiac transplant recipients and similar to those seen with mycophenolate mofetil in renal transplant recipients. Low rates of acute rejection are maintained when everolimus is given as part of a quadruple immunosuppressive regimen with low-dose cyclosporine in renal transplant recipients, with the added benefit of better renal function compared with full-dose cyclosporine. Use of C₂ monitoring to optimise cyclosporine exposure and enhance efficacy and safety of everolimus is planned in future studies. Hypertriglyceridaemia and hypercholesterolaemia have been associated with everolimus, but these effects are not dose-limiting. There is no clear upper therapeutic limit of everolimus. However, thrombocytopenia occurs at a rate of 17% at everolimus trough serum concentrations above 7.8 ng/ml in renal transplant recipients. There are limited safety data available in patients with trough concentrations > 12 ng/ml. Studies suggest everolimus targets primary causes of chronic rejection by reducing acute rejection, allowing for cyclosporine dose reduction (which may lead to improved renal function relative to full-dose cyclosporine) and by reducing cytomegalovirus infection and inhibiting vascular remodelling.     

Review of the proliferation inhibitor everolimus

Everolimus (Certican) is being developed for prevention of acute and chronic rejection of solid organ transplants. A novel proliferation inhibitor, everolimus synergies with cyclosporine to prevent and reverse acute rejection in preclinical models of kidney, heart or lung transplantation. The manifestations of chronic rejection that may contribute to graft loss are also inhibited by everolimus in preclinical models. Although everolimus is metabolised by the cytochrome P450 CYP3A isoenzyme, coadministration with cyclosporine does not alter the pharmacokinetics of cyclosporine, but cyclosporine coadministration increases exposure to everolimus. Everolimus interacts with inhibitors and inducers of this system; its clearance is reduced in patients with hepatic impairment. In an immunosuppressive regimen with cyclosporine microemulsion formulation and corticosteroids, transplant recipients treated with everolimus show low rates of acute rejection and, in one heart and one renal trial, lower rates of cytomegalovirus infection. Acute rejection rates are lower than those seen with azathioprine in cardiac transplant recipients and similar to those seen with mycophenolate mofetil in renal transplant recipients. Low rates of acute rejection are maintained when everolimus is given as part of a quadruple immunosuppressive regimen with low-dose cyclosporine in renal transplant recipients, with the added benefit of better renal function compared with full-dose cyclosporine. Use of C(2) monitoring to optimise cyclosporine exposure and enhance efficacy and safety of everolimus is planned in future studies. Hypertriglyceridaemia and hypercholesterolaemia have been associated with everolimus, but these effects are not dose-limiting. There is no clear upper therapeutic limit of everolimus. However, thrombocytopenia occurs at a rate of 17% at everolimus trough serum concentrations above 7.8 ng/ml in renal transplant recipients. There are limited safety data available in patients with trough concentrations > 12 ng/ml. Studies suggest everolimus targets primary causes of chronic rejection by reducing acute rejection, allowing for cyclosporine dose reduction (which may lead to improved renal function relative to full-dose cyclosporine) and by reducing cytomegalovirus infection and inhibiting vascular remodelling.     

The role of therapeutic monitoring of everolimus in solid organ transplantation

Everolimus is a novel proliferation signal inhibitor used in immunosuppressive therapies for the prevention of acute and chronic rejection. A role for everolimus drug monitoring has been suggested because of the potential for improving efficacy and reducing adverse effects. Everolimus has proven efficacy for prevention of rejection in adult de novo renal and cardiac transplant recipients. Similar effects have been shown in pediatric renal transplant patients. Several analytic methods are available to quantify everolimus concentrations. A good relationship exists between everolimus concentration and pharmacological response. Mere clinical monitoring of efficacy is insufficient because clinical presentations of graft rejection vary for each patient and are nonspecific. Thus, the authors have used a previously published 9-step decision-making algorithm to evaluate the utility of therapeutic drug monitoring for everolimus. The recommended therapeutic range for everolimus is a trough concentration of 3 to 8 ng/mL, as concentrations over 3 ng/mL have been associated with a decreased incidence of rejection, and concentrations >8 ng/mL with increased toxicity. Everolimus exhibits interindividual pharmacokinetic variability. African American patients have higher apparent clearance, whereas patients with hepatic dysfunction or those on concomitant medications with potent cytochrome P450 (CYP) 3A4 inhibitor or inducer properties have lower or higher apparent clearance, respectively. Solid organ transplant recipients will likely be maintained on immunosuppressant therapy for the life of the graft and/or recipient and thus are likely to benefit from clinical pharmacokinetic monitoring. Based on the available evidence, therapeutic drug monitoring for everolimus may provide additional information on efficacy and safety than sound clinical judgment alone. Patients on everolimus who have problems with absorption, who take concurrent cytochrome P450 inhibitors or inducers, or are noncompliant will attain the greatest benefit from drug monitoring.     

雷帕霉素联合环孢素预防肾移植急性排斥反应的随机对照前瞻性研究

目的:评价雷帕霉素(RPM)口服液联合环孢素(CsA)预防肾移植术后早期急性排斥反应的疗效。方法:首次肾移植患者20例,随机分成RPM试验组和硫唑嘌呤(Aza)对照组,每组各10例,分别接受以CsA和类固醇激素为基础的免疫抑制治疗方案6mo,比较2组人/肾存活率、急性排斥反应发生、不良事件发生等指标的差异。结果:17例完成治疗者人/肾均存活;仅Aza组1例发生2次急性排斥反应;2组各发生2例严重不良事件。结论:RPM联合CsA可有效预防移植肾急性排斥反应,并维持肾功能于良好水平,但是也可能增强CsA的肝毒性。     

Radionuclide perfusion scans in the assessment of acute renal transplant rejection

Acute renal transplant rejection is a diagnostic and management problem. In the oliguric patient clinical evaluation and biochemical tests are less helpful than in those with a functioning graft. The perfusion index derived from a 99mTc-diethylenetriamine penta-acetic acid scan may be a more reliable marker of acute rejection. We studied 20 consecutive renal transplant recipients with serial radionuclide imaging to assess the usefulness of the perfusion index. Seventy-two of 74 episodes of acute rejection were evaluated. Thirty-three (46%) episodes were predicted or supported by a change in the perfusion index. In the non-functioning transplant, 12 of 15 (80%) acute rejection episodes were predicted or supported. A scan obtained the day after transplantation confirmed graft artery patency in all patients. The perfusion index is a useful diagnostic test for the diagnosis and management of acute rejection, particularly in the non-functioning transplanted kidney.