title: Target of rapamycin inhibitors (sirolimus and everolimus) for primary immunosuppression of kidney transplant recipients: a systematic review and meta-analysis of randomized trials.
abstract: 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.
authors.affiliation: Cochrane Renal Group, Children's Hospital at Westmead, Westmead, and School of Public Health, University of Sydney, Sydney, Australia. angela.webster@gmail.com
authors.forename: Angela C
authors.initials: AC
authors.lastname: Webster
authors.forename: Vincent W S
authors.initials: VW
authors.lastname: Lee
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Chapman
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Craig
mesh_terms: D003404:Creatinine / Q000097:blood; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D016030:Kidney Transplantation / Q000276:immunology* / Q000401:mortality; D016032:Randomized Controlled Trials as Topic; D020123:Sirolimus / Q000627:therapeutic use*; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D007166:Immunosuppressive Agents; D003404:Creatinine; D020123:Sirolimus