Spontaneous Findings in the Eyes of Cynomolgus Monkeys ( Macaca fascicularis) of Mauritian Origin.

Spontaneous findings noted in the eyes of Mauritian cynomolgus monkeys are described and descriptions are supplemented with illustrations. Findings observed after extensive histopathologic examinations (20 to 44 sections per eye) from 20 control, 17 treatment-naive stock monkeys, and 2 findings noted in drug-treated monkeys that were considered to be spontaneous are included. Also included are findings from 361 control monkeys of routine toxicity studies performed at our laboratories, for most of which a standard histopathological examination of 1 section per eye was conducted. Common observations in monkeys examined extensively and in historical controls were limited to lymphocytic or mononuclear cell infiltrations of the uvea and/or conjunctiva/sclera and, less commonly observed, melanocytoma of the ciliary body or iris. Findings noted only in monkeys examined extensively consisted of inflammation of the conjunctiva, ora serrata cysts, glial nodules, focal degeneration of the retina, cystoid degeneration of the central retina, ballooning degeneration of the ciliary epithelium, cyst of the ciliary body, and decreased pigmentation of the retinal pigment epithelium. Changes recorded only in historical controls included retinal atrophy and nuclear displacement in the retina. Lesions are discussed and compared with pertinent literature.

Regulatory Forum.

Revision of the International Council for Harmonization (ICH) S1 guidance for rat carcinogenicity studies to be more selective of compounds requiring a 2-year rat carcinogenicity study has been proposed following extensive evaluation of rat carcinogenicity and chronic toxicity studies by industry and drug regulatory authorities. To inform the ICH S1 expert working group in their potential revision of ICH S1, a prospective evaluation study was initiated in 2013, in which sponsors would assess the pharmacologic and toxicologic findings present in the chronic toxicity studies and predict a positive or negative carcinogenicity outcome using a weight of evidence argument (a carcinogenicity assessment document [CAD]). The Scientific and Regulatory Policy Committee was asked by the Society of Toxicology Pathology (STP) executive committee to track these changes with ICH S1 and inform the STP membership of status changes. This commentary is intended to provide a brief summary of recent changes to the CAD guidance and highlight the importance of STP membership participation in the process of CAD submissions.