Common spontaneous neoplastic findings in Tg.rasH2 mice used in nonclinical research studies

STP 2024 -- Historically, the use of two-year rodent (CD-1� mouse and Sprague Dawley� or Wistar Han� rat) studies has been the standard practice to assess the carcinogenic potential of pharmaceuticals. Currently, the use of 26-week Tg.rasH2� transgenic mouse models is generally accepted as a substitute for the standard two-year carcinogenicity mouse bioassay by several regulatory agencies and now widely used in the pharmaceutical industry. (Hickman, 2015). The use of this alternate mouse model can provide significant advantages with similar predictivity for human carcinogens. This retrospective analysis of the spontaneous tumor incidences in Tg.rasH2 mice from 26-week carcinogenicity studies is to serve as a reference source from a robust historical database for the types, incidence and range of background neoplastic findings in these types of studies. In addition, a comparison to the available published literature (Nambiar, 2014; Paranjpe, 2018) was made to determine if there has been a genetic shift over the years.