ROLE OF RENAL-ALLOGRAFT BIOPSY IN MULTICENTER CLINICAL-TRIALS IN TRANSPLANTATION

There is current agreement that in the design of prospective clinical trials, patients should be assigned to various treatment groups based on histological diagnosis of acute renal allograft rejection. The Banf f schema is satisfactory in reporting and grading histology for patien t entry into clinical trials, particularly in multicenter studies beca use it standardizes the entry and randomization criteria and maintains reproducibility of the histological interpretation between the differ ent centers. It should be emphasized that for biopsy specimens to be e ffective tools for either clinical practice or clinical trials, they n eed to be obtained before therapeutic intervention and handled by expe rienced histopathology laboratory technicians. Adequate tissue samplin g is necessary for diagnosis and for proper grading of rejection. It i s recommended that a minimum of two cores of renal tissue are needed t o avoid underestimation of rejection grade. Banff classification consi ders a biopsy specimen to be adequate if it contains seven or more glo meruli and at least a single artery. Examination of serial step sectio ns through the tissue samples is crucial to identify focal lesions of toxicity and to properly score intimal arteritis and tubulitis, in add ition, fast interpretation of the biopsy by an experienced nephropatho logist or a transplant pathologist within 24 hours optimizes the utili zation of the biopsy-acquired information, At the present time, it is premature to decide on the role of graft histology as an endpoint in c linical trials, but posttreatment biopsies should be encouraged in lar ge, multicenter, prospective trials because they may be our only tools to study postrejection changes. Semiquantitative biopsy reporting sys tems should be routinely included in clinical databases to allow for t he prospective examination of structure-function relationships and lon g-term outcomes following acute rejection. (C) 1998 by the National Ki dney Foundation, Inc.