title: Combination therapy of malononitrilamide FK778 with tacrolimus on cell proliferation assays and in rats receiving renal allografts.
abstract: BACKGROUND
  Malononitrilamide FK778, an analogue of leflunomide's active metabolite, is a promising novel small molecule with immunosuppressive and immunomodulatory properties. In this study, we evaluated the ability of combination therapy of FK778 with tacrolimus to inhibit lymphocyte proliferation and to prevent acute allograft rejection.
  
  
  METHODS
  Proliferation assay was used to evaluate the effect of FK778 plus tacrolimus on murine splenocytes, monkey lymphocytes, and human peripheral blood mononuclear cells, after activation with T or B cell-specific mitogens. A rat kidney transplantation model was used to evaluate the ability of FK778 combined with tacrolimus to prolong allograft survival. Median-effect principle and combination index (CI) were used to determine synergism, summation, or antagonism.
  
  
  RESULTS
  A total of 58 combinations of FK778 plus tacrolimus were evaluated. Of the combinations tested, 82.8% (24/29) produced additive to synergistic effects in B cells, whereas 79.3% (23/29) produced moderate antagonistic effects in T cells. A concomitant 14-day therapy of FK778 (10 mg/kg/day) and tacrolimus (1 mg/kg/day) synergistically prolonged renal allograft survival to 25.5+/-5.9 days (CI=0.458). However, when addition of FK778 to tacrolimus therapy was delayed to day 7 after transplantation, a strong synergism was obtained (mean survival time=74.9+/-14.8 days, CI<0.001).
  
  
  CONCLUSIONS
  This study demonstrates that the combination of FK778 with tacrolimus in vitro produces synergistic inhibition on B-cell proliferation but not on T cell proliferation in mice, nonhuman primates, and humans. When the addition of FK778 treatment was delayed to day 7 after transplantation, a strong synergism was produced in prolongation of renal allograft survival in the rat.
authors.affiliation: Laboratory of Experimental Surgery, Research Center of Centre Hospitalier de l'Université de Montreal, Notré-Dame Hospital, Quebec, Canada.
authors.forename: Minh Diem
authors.initials: MD
authors.lastname: Vu
authors.forename: Shijie
authors.initials: S
authors.lastname: Qi
authors.forename: Xiang
authors.initials: X
authors.lastname: Wang
authors.forename: Wenlei
authors.initials: W
authors.lastname: Jiang
authors.forename: Anlun
authors.initials: A
authors.lastname: Ma
authors.forename: Dasheng
authors.initials: D
authors.lastname: Xu
authors.forename: Ihor
authors.initials: I
authors.lastname: Bekersky
authors.forename: William E
authors.initials: WE
authors.lastname: Fitzsimmons
authors.forename: Jiangping
authors.initials: J
authors.lastname: Wu
authors.forename: Huifang
authors.initials: H
authors.lastname: Chen
mesh_terms: D000480:Alkynes; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D002455:Cell Division / Q000187:drug effects; D004359:Drug Therapy, Combination; D005260:Female; D006084:Graft Rejection / Q000517:prevention & control; D007166:Immunosuppressive Agents / Q000008:administration & dosage*; D007555:Isoxazoles / Q000008:administration & dosage*; D016030:Kidney Transplantation; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D009570:Nitriles; D051381:Rats; D011917:Rats, Inbred Lew; D013045:Species Specificity; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D016559:Tacrolimus / Q000008:administration & dosage*; D014184:Transplantation, Homologous
chemical_list: D000480:Alkynes; D007166:Immunosuppressive Agents; D007555:Isoxazoles; D009570:Nitriles; C115284:2-cyano-3-hydroxy-N-(4-(trifluoromethyl)phenyl)-2-hepten-6-ynamide; D016559:Tacrolimus