title: A Randomized 2x2 Factorial Clinical Trial of Renal Transplantation: Steroid-Free Maintenance Immunosuppression with Calcineurin Inhibitor Withdrawal after Six Months Associates with Improved Renal Function and Reduced Chronic Histopathology.
abstract: BACKGROUND
  The two most significant impediments to renal allograft survival are rejection and the direct nephrotoxicity of the immunosuppressant drugs required to prevent it. Calcineurin inhibitors (CNI), a mainstay of most immunosuppression regimens, are particularly nephrotoxic. Until less toxic antirejection agents become available, the only option is to optimize our use of those at hand.
  
  
  OBJECTIVE
  To determine whether intensive rabbit anti-thymocyte globulin (rATG) induction followed by CNI withdrawal would individually or combined improve graft function and reduce graft chronic histopathology-surrogates for graft and, therefore, patient survival. As previously reported, a single large rATG dose over 24 hours was well-tolerated and associated with better renal function, fewer infections, and improved patient survival. Here we report testing whether complete CNI discontinuation would improve renal function and decrease graft pathology.
  
  
  METHODS
  Between April 20, 2004 and 4-14-2009 we conducted a prospective, randomized, non-blinded renal transplantation trial of two rATG dosing protocols (single dose, 6 mg/kg vs. divided doses, 1.5 mg/kg every other day x 4; target enrollment = 180). Subsequent maintenance immunosuppression consisted of tacrolimus, a CNI, and sirolimus, a mammalian target of rapamycin inhibitor. We report here the outcome of converting patients after six months either to minimized tacrolimus/sirolimus or mycophenolate mofetil/sirolimus. Primary endpoints were graft function and chronic histopathology from protocol kidney biopsies at 12 and 24 months.
  
  
  RESULTS
  CNI withdrawal (on-treatment analysis) associated with better graft function (p <0.001) and lower chronic histopathology composite scores in protocol biopsies at 12 (p = 0.003) and 24 (p = 0.013) months, without affecting patient (p = 0.81) or graft (p = 0.93) survival, or rejection rate (p = 0.17).
  
  
  CONCLUSIONS
  CNI (tacrolimus) withdrawal at six months may provide a strategy for decreased nephrotoxicity and improved long-term function in steroid-free low immunological risk renal transplant patients.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT00556933.
authors.affiliation: Department of Surgery, Wright State University Boonshoft School of Medicine, Dayton, Ohio, United States of America.
authors.forename: R Brian
authors.initials: RB
authors.lastname: Stevens
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Kirk W
authors.initials: KW
authors.lastname: Foster
authors.affiliation: Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Clifford D
authors.initials: CD
authors.lastname: Miles
authors.affiliation: Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Andre C
authors.initials: AC
authors.lastname: Kalil
authors.affiliation: Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Diana F
authors.initials: DF
authors.lastname: Florescu
authors.affiliation: Department of Surgery, Wright State University Boonshoft School of Medicine, Dayton, Ohio, United States of America.
authors.forename: John P
authors.initials: JP
authors.lastname: Sandoz
authors.affiliation: Department of Surgery, Wright State University Boonshoft School of Medicine, Dayton, Ohio, United States of America.
authors.forename: Theodore H
authors.initials: TH
authors.lastname: Rigley
authors.affiliation: Department of Surgery, Wright State University Boonshoft School of Medicine, Dayton, Ohio, United States of America.
authors.forename: Tamer
authors.initials: T
authors.lastname: Malik
authors.affiliation: Department of Surgery, Wright State University Boonshoft School of Medicine, Dayton, Ohio, United States of America.
authors.forename: Lucile E
authors.initials: LE
authors.lastname: Wrenshall
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000961:Antilymphocyte Serum / Q000737:chemistry; D001706:Biopsy; D065095:Calcineurin Inhibitors / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D005260:Female; D006084:Graft Rejection / Q000517:prevention & control; D006801:Humans; D007165:Immunosuppression Therapy / Q000379:methods*; D007166:Immunosuppressive Agents / Q000008:administration & dosage*; D007668:Kidney / Q000187:drug effects*; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D009173:Mycophenolic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives; D011446:Prospective Studies; D011817:Rabbits; D020123:Sirolimus / Q000008:administration & dosage; D013256:Steroids / Q000008:administration & dosage*; D016559:Tacrolimus / Q000008:administration & dosage; D013997:Time Factors; D055815:Young Adult
chemical_list: D000961:Antilymphocyte Serum; D065095:Calcineurin Inhibitors; D007166:Immunosuppressive Agents; D013256:Steroids; D009173:Mycophenolic Acid; D020123:Sirolimus; D016559:Tacrolimus