New trails in transplantation: how to exploit the potential of sirolimus in clinical transplantation

Target of rapamycin inhibitors (TOR-I; sirolimus and everolimus) for primary immunosuppression in kidney transplant recipients

BACKGROUND

Kidney transplantation is the therapy of choice for many patients with end-stage kidney disease (ESKD) with an improvement in survival rates and satisfactory short term graft survival. However, there has been little improvement in long-term survival. The place of target of rapamycin inhibitors (TOR-I) (sirolimus, everolimus), which have different modes of action from other commonly used immunosuppressive agents, in kidney transplantation remains uncertain. This is an update of a review first published in 2006.

OBJECTIVES

To evaluate the short and long-term benefits and harms of TOR-I (sirolimus and everolimus) when used in primary immunosuppressive regimens for kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 20 September 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register were identified through searches of CENTRAL, MEDLINE and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs in which drug regimens, containing TOR-I commenced within seven days of transplant, were compared to alternative drug regimens, were included without age restriction, dosage or language of report.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed study eligibility, risk of bias, and extracted data. Results were reported as risk ratios (RR) with 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) with 95% CI for continuous outcomes. Statistical analyses were performed using the random-effects model. The certainty of the evidence was assessed using GRADE MAIN RESULTS: Seventy studies (17,462 randomised participants) were included; eight studies included two comparisons to provide 78 comparisons. Outcomes were reported at six months to three years post transplant. Risk of bias was judged to be low for sequence generation in 25 studies, for allocation concealment in 23 studies, performance bias in four studies, detection bias in 65 studies, attrition bias in 45 studies, selective reporting bias in 48 studies, and for other potential bias in three studies. Risk of bias was judged to be at high risk of bias for sequence generation in two studies, allocation concealment in two studies, performance bias in 61 studies, detection bias in one study, attrition bias in four studies, for selective reporting bias in 11 studies and for other potential risk of bias in 46 studies. Compared with CNI and antimetabolite, TOR-I with antimetabolite probably makes little or no difference to death (RR 1.31, 95% CI 0.87 to 1.98; 19 studies) or malignancies (RR 0.86, 95% CI 0.50 to 1.48; 10 studies); probably increases graft loss censored for death (RR 1.32, 95% CI 0.96 to 1.81; 15 studies), biopsy-proven acute rejection (RR 1.60, 95% CI 1.25 to 2.04; 15 studies), need to change treatment (RR 2.42, 95% CI 1.88 to 3.11; 14 studies) and wound complications (RR 2.56, 95% CI 1.94 to 3.36; 12 studies) (moderate certainty evidence); but reduces CMV infection (RR 0.43, 95% CI 0.29 to 0.63; 13 studies) (high certainty evidence). Compared with antimetabolites and CNI, TOR-I with CNI probably makes little or no difference to death (RR 1.06, 95% CI 0.84 to 1.33; 31 studies), graft loss censored for death (RR 1.09, 95% CI 0.82 to 1.45; 26 studies), biopsy-proven acute rejection (RR 0.95, 95% CI 0.81 to 1.12; 24 studies); and malignancies (RR 0.83, 95% CI 0.64 to 1.07; 17 studies); probably increases the need to change treatment (RR 1.56, 95% CI 1.28 to 1.90; 25 studies), and wound complications (RR 1.56, 95% CI 1.28 to 1.91; 17 studies); but probably reduces CMV infection (RR 0.44, 95% CI 0.34 to 0.58; 25 studies) (moderate certainty evidence). Lower dose TOR-I and standard dose CNI compared with higher dose TOR-I and reduced dose CNI probably makes little or no difference to death (RR 1.07, 95% CI 0.64 to 1.78; 9 studies), graft loss censored for death (RR 1.09, 95% CI 0.54 to 2.20; 8 studies), biopsy-proven acute rejection (RR 0.87, 95% CI 0.67 to 1.13; 8 studies), and CMV infection (RR 1.42, 95% CI 0.78 to 2.60; 5 studies) (moderate certainty evidence); and may make little or no difference to wound complications (RR 0.95, 95% CI 0.53 to 1.71; 3 studies), malignancies (RR 1.04, 95% CI 0.36 to 3.04; 7 studies), and the need to change treatments (RR 1.18, 95% CI 0.58 to 2.42; 5 studies) (low certainty evidence). Lower dose of TOR-I compared with higher doses probably makes little or no difference to death (RR 0.84, 95% CI 0.67 to 1.06; 13 studies), graft loss censored for death (RR 0.92, 95% CI 0.71 to 1.19; 12 studies), biopsy-proven acute rejection (RR 1.26, 95% CI 1.10 to 1.43; 11 studies), CMV infection (RR 0.87, 95% CI 0.63 to 1.21; 9 studies), wound complications (RR 0.92, 95% CI 0.66 to 1.29; 7 studies), and malignancy (RR 0.84, 95% CI 0.54 to 1.32; 10 studies) (moderate certainty evidence); and may make little or no difference to the need to change treatments (RR 0.91, 95% CI 0.78 to 1.05; 10 studies) (low certainty evidence). It is uncertain whether sirolimus and everolimus differ in their effects on kidney function and lipid levels because the certainty of the evidence is very low based on a single small study with only three months of follow-up.

AUTHORS' CONCLUSIONS

In studies with follow-up to three years, TOR-I with an antimetabolite increases the risk of graft loss and acute rejection compared with CNI and an antimetabolite. TOR-I with CNI potentially offers an alternative to an antimetabolite with CNI as rates of graft loss and acute rejection are similar between interventions and TOR-I regimens are associated with a reduced risk of CMV infections. Wound complications and the need to change immunosuppressive medications are higher with TOR-I regimens. While further new studies are not required, longer-term follow-up data from participants in existing methodologically robust RCTs are needed to determine how useful immunosuppressive regimens, which include TOR-I, are in maintaining kidney transplant function and survival beyond three years.

Defining the role of sirolimus in the management of graft-versus-host disease: from prophylaxis to treatment

Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Measures developed that have significantly reduced GVHD were also frequently associated with an increased risk of relapse. GVHD and graft-versus-tumor (GVT) effects are tightly linked, and balance between both reactions is difficult to achieve. To have an impact on the outcome and quality of life after HSCT, improvements in current strategies to prevent and treat GVHD while preserving the GVT effect are clearly needed. Sirolimus (rapamycin) is a lipophilic macrocytic lactone with immunosuppressive, antitumor, and antiviral properties. Because of its multiple modes of activities, it is being increasingly used in the management of GVHD. This review aims to summarize its mechanisms of action and potential advantages over other immunosuppressors and to analyze the most relevant studies investigating its role in both prevention and treatment of GVHD.

Target of rapamycin inhibitors (sirolimus and everolimus) for primary immunosuppression of kidney transplant recipients: a systematic review and meta-analysis of randomized trials

BACKGROUND

Target of rapamycin inhibitors (TOR-I) have a novel mode of action but uncertain clinical role. We performed a systematic review of randomized trials where immunosuppressive regimens containing TOR-I were compared with other regimens as initial therapy for kidney transplant recipients.

METHODS

Databases (inception, June 2005) and conference proceedings (1996-2005) were searched. Two independent reviewers assessed trials for eligibility and quality. Results at 1 year, are expressed as relative risk (RR), where values<1 favor TOR-I, or lower dose of TOR-I, and for continuous outcomes are expressed as weighted mean difference (WMD), both expressed with 95% confidence intervals (CI).

RESULTS

Thirty-three trials (142 reports) were included (27 trials of sirolimus, 5 of everolimus, and 1 of head-to-head comparison). When TOR-I replaced calcineurin inhibitors (CNI) (8 trials with 750 participants), there was no difference in acute rejection (RR, 1.03; 95% CI, 0.74-1.44), but serum creatinine was lower (WMD, -18.31 micromol/L; 95% CI, -30.96 to -5.67) and bone marrow more suppressed (leukopenia: RR 2.02; 95% CI, 1.12-3.66; thrombocytopenia: RR, 6.97; 95% CI, 2.97-16.36; and anaemia: RR, 1.67; 95% CI, 1.27-2.20). When TOR-I replaced antimetabolites (11 trials with 3966 participants), acute rejection and cytomegalovirus infection (CMV) were reduced (RR, 0.84; 95% CI, 0.71-0.99; RR, 0.49; 95% CI, 0.37-0.65, respectively), but hypercholesterolemia was increased (RR, 1.65; 95% CI, 1.32-2.06). When low- was compared with high-dose TOR-I, with equal CNI dose (10 trials with 3,175 participants), rejection was increased (RR, 1.23; 95% CI, 1.06-1.43) but calculated glomerular filtration rate (GFR) higher (WMD, 4.27 mL/min; 95% CI, 1.12-7.41), and when lower-dose TOR-I and standard-dose CNI were compared with higher-dose TOR-I and reduced CNI, acute rejection was reduced (RR, 0.67; 95% CI, 0.52-0.88), but calculated GFR was also reduced (WMD, -9.46 mL/min; 95% CI, -12.16 to -6.76). There was no significant difference in mortality, graft loss, or malignancy risk for TOR-I in any comparison.

CONCLUSIONS

TOR-I have been evaluated in four different primary immunosuppressive algorithms: as replacement for CNI and antimetabolites, in combination with CNI at low and high doses, and with a variable dose of CNI. Generally, surrogate endpoints for graft survival favor TOR-I (lower risk of acute rejection and higher GFR), and surrogate endpoints for patient outcomes are worsened by TOR-I (bone marrow suppression and lipid disturbance). Long-term hard-endpoint data from methodologically robust randomized trials are still required.

Target of rapamycin inhibitors (TOR-I; sirolimus and everolimus) for primary immunosuppression in kidney transplant recipients

BACKGROUND

Target of rapamycin inhibitors (TOR-I) (sirolimus, everolimus) are immunosuppressive agents with a novel mode of action but an uncertain clinical role.

OBJECTIVES

To investigate the benefits and harms of immunosuppressive regimens containing TOR-I when compared to other regimens as initial therapy for kidney transplant recipients.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (in The Cochrane Library, issue 2, 2005), MEDLINE (1966-June 2005), EMBASE (1980-June 2005), the specialised register of the Cochrane Renal Group (June 2005)., and contacted authors and pharmaceutical companies to identify relevant studies.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs where drug regimens containing TOR-I were compared to alternative drug regimens in the immediate post-transplant period were included, without age restriction, dosage or language of report.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trials for eligibility and quality, and extracted data. Results are expressed as relative risk (RR) or weight mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

Thirty three trials (142 reports) were included (sirolimus (27), everolimus (5), head-to-head (1)). When TOR-I replaced CNI there was no difference in acute rejection, but serum creatinine was lower (MD -18.31 micromol/L, -30.96 to -5.67), and bone marrow more suppressed (leucopenia: RR 2.02 1.12 to 3.66; thrombocytopenia: RR 6.97 2.97 to 16.36; anaemia: RR 1.67, 1.27 to 2.20). When TOR-I replaced antimetabolites, acute rejection (RR 0.84, 0.71 to 0.99) and cytomegalovirus infection (CMV) (RR 0.49; 0.37 to 0.65) were reduced, but hypercholesterolaemia was increased (RR 1.65, 1.32 to 2.06). For low versus high-dose TOR-I, with equal CNI dose, rejection was increased (RR 1.23, 1.06 to 1.43) but calculated GFR higher (MD 4.27 mL/min, 1.12 to 7.41), and for low-dose TOR-I/standard-dose CNI versus higher-dose TOR-I/reduced CNI, acute rejection (RR 0.67, 0.52 to 0.88) and calculated GFR (MD -9.46 mL/min, -12.16 to -6.76) were reduced. There was no significant difference in mortality, graft loss or malignancy risk for TOR-I in any comparison.

AUTHORS' CONCLUSIONS

TOR-I have been evaluated in four different primary immunosuppressive algorithms; as replacement for CNI and for antimetabolites, in combination with CNI at low and high dose and with variable dose of CNI. Generally, surrogate endpoints for graft survival favour TOR-I (lower risk of acute rejection and higher GFR) and surrogate endpoints for patient outcomes are worsened by TOR-I (bone marrow suppression, lipid disturbance). Long-term hard-endpoint data from methodologically robust RCTs are still needed.

Sirolimus in combination with tacrolimus and corticosteroids for the treatment of resistant chronic graft-versus-host disease

Chronic graft-versus-host disease (cGVHD) remains a major cause of morbidity and mortality in haematopoietic transplant recipients. Sirolimus is a macrocyclic triene antibiotic with immunosuppressive, antifungal and antitumour properties, that has activity in the prevention and treatment of acute GVHD. We conducted a phase II trial of sirolimus combined with tacrolimus and methylprednisolone in patients with steroid-resistant cGVHD. Thirty-five patients who developed GVHD after day 100 post-transplant were studied. Six patients had a complete response and 16 a partial response with an overall response rate of 63%. Major adverse events related to the combination of tacrolimus and sirolimus were hyperlipidaemia, renal dysfunction and cytopenias. Four patients had thrombotic microangiopathy (TMA) and 27 (77%) had infectious complications. The median survival for the whole group was 15 months. A significantly better outcome was observed in patients with a platelet count > or = 100 x 10(9)/l, as well as in those with true chronic manifestations of GVHD compared to those with acute GVHD beyond day 100. Controlled trials comparing this approach with alternative strategies to determine which can best achieve the goal of GVHD-free survival are warranted.

Successful use in lung transplantation of an immunosuppressive regimen aimed at reducing target blood levels of sirolimus and tacrolimus

BACKGROUND

The primary aim of this study was to assess the safety and efficacy in lung transplantation of an immunosuppressive regimen aimed at achieving sirolimus and tacrolimus concentrations of 6 to 10 microg/ml and 5 to 7 ng/ml, respectively.

METHODS

We retrospectively identified 49 lung transplant recipients who were converted to an immunosuppressive regimen consisting of tacrolimus, sirolimus, and prednisone. Data collected included demographic information, laboratory work, episodes of rejection, bronchiolitis obliterans syndrome (BOS) grade, and adverse effects.

RESULTS

The most common reason for conversion to a sirolimus and tacrolimus regimen was BOS. The most common adverse effects were increased triglycerides (10%), leukopenia (8%), and skin rash (6%). Four patients (8%) experienced acute allograft rejection during the study period. We followed BOS grade for 1 year in 23 patients. Of these, BOS grade improved in 8, 13 patients remained unchanged, and 2 worsened. Eleven patients (22%) discontinued sirolimus because of adverse events.

CONCLUSION

An immunosuppressive regimen consisting of sirolimus and tacrolimus that aims to keep the trough drug concentrations at 6 to 10 microg/ml and 5 to 7 ng/ml, respectively, provides effective lung allograft protection while maintaining an acceptable side-effect profile. The use of this immunosuppressive combination may have a benefit with regard to BOS.

Immunosuppressive drugs in paediatric liver transplantation

Orthotopic liver transplantation is established treatment for children with acute and chronic liver failure. Despite advances in pre- and postoperative management, innovative surgical techniques and new immunosuppressive drugs, acute and chronic rejection remains a problem. In addition, well established adverse effects of commonly used immunosuppressive drugs are no longer accept able. More potent, but less toxic, immunosuppressive agents have been developed and some novel compounds are now entering routine practice. Cyclosporin was the cornerstone of immunosuppressive therapy until the introduction of its novel pharmaceutical form (Neoral) with improved bioavailability, lower inter- and intraindividual pharmacokinetic variability and improved graft survival. Recently, tacrolimus, a macrolide drug with a similar mode of action, but much higher potency, was introduced and, at present, is the only agent which can successfully replace cyclosporin as a first-line immunosuppressive drug. Mycophenolate mofetil has recently been approved for use in adult and paediatric renal transplant recipients. It has a similar mode of action to cyclosporin and tacrolimus, but acts at a later stage of the T cell activation pathway. Administration with standard immunosuppressive drugs reduces the incidence of acute rejection and enables cyclosporin and tacrolimus dose reduction, thus reducing the risk of associated toxic effects. Phase I and II trials with sirolimus (rapamycin), a macrolide antibiotic, have shown comparable immunosuppressive action, when administered in conjunction with standard immunosuppressants. Further clinical trials need to be carried out to establish efficacy, tolerability and pharmacokinetics in paediatric transplant recipients. Monoclonal antibody therapy (daclizumab and basiliximab) is an exciting new development whereby T cell proliferation is inhibited by selective blockade of interleukin (IL)-2 receptors. Preliminary results, when used in combination with a standard immunosuppressive regimen, are good with respect to incidence of acute graft rejection, host immune response and adverse effects. FTY720 is a novel synthetic immunosuppressive compound which induces a reduction in peripheral blood lymphocyte count through apoptotic T cell death or accelerated trafficking of T cells into lymphatic tissues. Experimental animal studies demonstrated synergistic action in combination with low dose cyclosporin or tacrolimus, potentiating their immunosuppressive effects. Further studies are being carried out to determine its potential for application in organ transplantation. Despite this rapid development of novel compounds, it will take many years before they may become part of standard protocols in paediatric transplantation medicine. Further development and research of efficacy and tolerability of existing drugs is, therefore, vital.