Klin Wochenschr (1988) 66:1126-1137 Klinische Wochen- schdft © Springer-Verlag 1988 Cyclosporin A Treatment in Children with Minimal Change Nephrotic Syndrome and Focal Segmental Glomerulosclerosis J. Brodehl 1, M. Brandis 2, U. Helmchen 3, P.F. Hoyer 1, R. Burghard 2, J.H.H. Ehrich 1, R.B. Zimmerhackl 2, W. Klein 2, and K. Wonigeit 4 1 KinderklinikMedizinische ttochschuIe,Hannover z Universit/its-Kinderklinik, Marburg 3 PathologischesInstitut der Universit/it,G6ttingen 4 Klinik fiir Abdominal-und Transplantationschirurgie, Medizinische Hochschule,Hannover Summary. In a pilot study 23 children with neph- rotic syndrome were treated with cyclosporin A (Cs) for 6-45 months. 8 children suffered from steroid dependent minimal change nephrotic syn- drome (MCNS) and had experienced at least one course with cytotoxic drugs, but had relapsed thereafter. 2 children had diabetes mellitus type I with nephrotic syndrome and 13 children had ster- oid resistant focal segmental glomerulosclerosis (FSGS). Cs was started with 100 mg/m2/day in two doses and increased stepwise to obtain a Cs whole blood trough level of 200400 ng/ml. In ster- oid dependent MCNS treatment with Cs reduced relapse rate significantly, and prednisone therapy could be stopped completely. After discontinua- tion of Cs, relapses reoccurred as frequently as be- fore. Renal function remained unimpaired despite repeated Cs treatment courses up to 38 months. In cases of nephrotic syndrome with diabetes type I Cs treatment led to complete remission without changing the insulin requirement. However, after discontinuation of Cs relapses reoccurred. In ster- oid resistant FSGS 6 children benefited from Cs treatment: 4 went into complete remission, 2 into partial remission. The 2 children with complete re- mission relapsed but remained Cs responsive. The remaining 7 children with FSGS did not respond to Cs but continued the course of their disease, with two patients rapidly progressing to terminal renal failure. Side-effects of Cs treatment were mild. It is concluded that Cs is an effective agent in steroid dependent MCNS and can be used as an alternative drug in specific cases like steroid toxicity or diabetes mellitus. In steroid resistant FSGS a trial with Cs seems to be warranted since Abbreviations: MCNS=minimal change nephrotic syndrome; FSGS = focal segmental glomerulosclerosis; Cs = Cyclosporin A some cases do respond favorably. To avoid neph- rotoxicity treatment with Cs should always be monitored closely by determination of blood levels and renal function. Key words: Cyclosporin - minimal change neph- rotic syndrome - focal segmental glomerulosclero- sis - children Cyclosporin A (Cs) is a novel and potent immuno- suppressive drug, that has found widespread appli- cation in organ transplantation. It has an unique action on T helper/inducer lymphocytes without exhibiting any myelosuppressive side effects. Its mechanism of action is primarily by blocking the production of interleukin 2, a T-lymphocyte de- rived lymphokine, which plays an important role in the immune respone to foreign antigens [7, 8, 51]. Because of this specific action, it has been sug- gested to extend the indications for Cs treatment to therapy of autoimmunological diseases, especially to those which are thought to be T-cell mediated. Minimal change nephrotic syndrome (MCNS) and focal segmental glomerulosclerosis (FSGS) belong to this category [17, 18, 39, 43]. In 1983 we, therefore, initiated a pilot study to treat children with MCNS and FSGS with Cs. After a 4 years' experience we now assess prelimi- nary results [9-11, 23] and compare them to those reported by other investigators [15, 33, 34, 37, 44, 45, 49]. Patients and Methods The efficacy and tolerance of Cs treatment was assessed in children with steroid-dependent MCNS