Nephrol Dial Transplant 2001) 16: 1756±1760 Anti-interleukin-2 receptor antibodies: basiliximab and daclizumab Julio Pascual, Roberto Marce Ân and Joaquõ Ân Ortun Äo Servicio de Nefrologõ Âa, Hospital Ramo Ân y Cajal, Universidad de Alcala Â, Madrid, Spain Keywords: basiliximab; daclizumab; monoclonal anti- bodies At present, classical induction therapy is inadvisable forlow-riskrenaltransplantationRT)recipients,given the ef®cacy of immunosuppressive regimens based onmicro-emulsi®edcyclosporin,tacrolimus,MMF,or sirolimus and the risk of infections and malignancies w1x.Theclassicalinductionismorequestionableforhigh immunological risk patients. Monoclonal antibodies against IL-2 receptor IL-2r) offer the possibility of more selective immunosuppression. Murineanti-IL-2rantibodiessigni®cantlyreducethe incidence of early acute rejection without any relevant associated toxicity w2x. However, they stimulate a potent immune response in the human recipient that limits their use at medium or long-term, exhibit a half-life and are inef®cient to destroy human cells. A chimeric anti-IL-2r antibody: basiliximab Basiliximab is a chimeric monoclonal antibody murineuhuman) with human IgG1 constant heavy chainregionsandkappalightchain.Itspeci®callybinds and blocks CD25 antigen, IL-2r a-chain, at the surface of activated T-lymphocytes w3x. This speci®c basiliximab binding to IL-2r competitively inhibits IL-2 mediated lymphocyte activation, a crucial phase in cellular immune response of allograft rejection. Three phase II studies are available in primary cadaveric RT recipients treated with basiliximab w3±5x. They showed i) absence of adverse reactions attributed to antibody infusion, ii) absence of anti-basiliximab immunization, iii) restricted initial distribution volume and slow clearance, with pro- longedhalf-life,iv)auniquepre-transplantdosebeing potentially adequate for acute rejection prophylaxis duringthe®rst4±6post-transplantweeks,v)noin¯u- enceofweightandsexonpharmacokineticparameters and vi) the requirement of basiliximab to be adminis- tered in association with cyclosporine starting in the the immediate post-transplant period. Two phase III multicentre, randomized, double- blind placebo-controlled trials have been undertaken inEuropeuCanadans380) w6x andtheUSns348) w7x with basiliximab induction. Therapy was double cyclosporin-steroids and basiliximab was administered atadoseof20mgpre-transplantand20mgatday4. The results were similar in both studies: reduction in the incidence of acute rejection and good patient and graft survivals Table 1). The incidence of major adverse events attributed to the study drug, namely infectionsandneoplasiaweresimilartothoseobserved with placebo. Correspondence and offprint requests to: Julio Pascual, Servicio de Nefrologõ Âa, Hospital Ramo Ân y Cajal, Universidad de Alcala Â, Carretera de Colmenar km 9, 100, E-28034 Madrid, Spain. 1756 Nephrol Dial Transplant 2001) 16: Editorial Comments # 2001 European Renal Association±European Dialysis and Transplant Association