Spontaneous renal tumors in two rats from a thirteen week rodent feeding study with grain from molecular stacked...

A thirteen week feeding study was conducted by feeding young adult male and female Sprague Dawley [Crl:CD®(SD)] rats diets containing grain from genetically modified (GM) DP-ØØ4114-3 maize that was either untreated (4114) or treated in the field with glufosinate ammonium (4114GLU). Control rats were fed diets containing the same concentration of near isogenic, non-GM maize grain (091) or one of three types of commercially available non-GM maize grain. At the end of the in-life phase, renal tubule tumors were reported in two male rats consuming diets containing 4114 maize grain. An expert panel of pathologists was convened as a Pathology Working Group (PWG) to review coded kidney histology sections from control (091) and treated (4114 and 4114GLU) male rats. The objectives were for the panel to characterize the histopathologic findings and to interpret their relationship to consumption of the indicated diet. The PWG concluded unanimously that the kidney tumors were characteristic of amphophilic-vacuolar (AV) tumors and AV atypical tubular hyperplasia which represent a distinctive phenotype that has been reported to occur sporadically in young Sprague Dawley Rats. The PWG determined that the neoplasms and atypical tubular hyperplasias were multicentric and bilateral which typifies tumors of familial origin. Degenerative/regenerative or cytotoxic changes consistent with nephrotoxicity leading to tumor induction were not observed in these rats and thus supports the conclusion that tumors were unrelated to consumption of the test diet. It was the unanimous opinion of the PWG that the proliferative renal tubule cell lesions were spontaneous and not related to consumption of diets containing 4114 maize grain.