TREATMENT WITH LO-TACT-1, A MONOCLONAL-ANTIBODY TO THE INTERLEUKIN-2 RECEPTOR, IN RENAL-TRANSPLANTATION

From May to August 1989 15 cadaver-donor renal transplant recipients were treated for 14 days with LO-Tact-1 (10 mg i.v. per day) in combination with cyclosporin (8 mg/kg/day from day -1), low-dose steroids (1/2 mg/kg/day from day 1, then reduced to 0.25 mg/kg at day 26 and 10 mg/day at day 45), and azathioprine (1 mg/kg/day) started at day 45. LO-Tact-1 is a rat monoclonal antibody which is directed to the interleukin-2 receptor. The control group consisted of 20 patients receiving cyclosporin, high-dose steroids (2 mg/day at day 1) and a 14-day course of polyclonal horse antilymphocyte globulins (ALG). Seven patients experienced 9 rejections during the first 3 months post-transplant between day 10 and day 67 (mean 0.6 per patient), comparable to the incidence of rejections in the control group: 8 rejections in 7 patients (mean 0.4 per patient). All rejections were reversed by steroid boluses and ATG. To date, all study patients have functioning grafts, and at 1-year post-transplant, the mean blood creatinine level is 161.2-mu-mol/l. In the control group, one patient died of CMV infection, and 2 other grafts failed due to rejection. No adverse effect of antibody administration was observed, and hematological changes remained of minor importance. Viral infections were not observed, except one case of herpes simplex. Comparatively, clinical CMV infections occurred in 3 patients receiving ALG (15 percent). Our data suggest that a combination anti-IL-2 monoclonal antibody, cyclosporin and low-dose steroids can safely be administered to allograft recipients, avoid severe viral infections, and, in our early experience, is as potent as the powerful combination ALG, cyclosporin and high-doses steroids in preventing allograft rejection.