DECADES OF EXPERTISE.
IITRI has performed carcinogenicity studies in rodent models for over 40 years. We have been a major preclinical contractor to the National Cancer Institute for decades, and our scientists are known as leaders in carcinogenicity evaluation and in studies of mechanisms of carcinogenesis and the modulation of cancer induction by hormones, pharmaceuticals, and food components. In addition to numerous unpublished studies performed for commercial sponsors, studies performed by IITRI scientists have resulted in over 200 published papers and book chapters in the fields of carcinogenesis, cancer chemoprevention, and cancer chemotherapy.
6-MONTH vs 2-YEAR STUDIES
Advantages of replacing a two-year mouse carcinogenicity study with a six-month carcinogenicity study in rasH2 mice include:
• Accelerated study completion
• Reduced animal utilization (25 versus ≥50/sex/group)
• Substantially reduced study cost
2-YEAR RODENT BIOASSAYS
The two-year rodent bioassay is generally considered to be the “gold standard” for experimental assessment of carcinogenicity. These studies involve exposure of large (≥50 per sex) groups of rats or mice to a drug or chemical for two years, followed by a complete necropsy and comprehensive microscopic evaluation of tissues by a board-certified veterinary pathologist. Historical databases are available at IITRI for several rodent strains.
6-MONTH BIOASSAYS in GENETICALLY ENGINEERED MICE
The IITRI team has worked extensively with genetically engineered mouse models for carcinogenicity testing, including the p53+/– (p53 knockout) mouse and several models expressing or overexpressing ras oncogenes. The FDA and other regulatory agencies commonly accept data from a 6-month carcinogenicity study in the rasH2 mouse in lieu of data from a 2-year carcinogenicity study in mice. Carrying both the human homolog of the Hras oncogene and the murine Ha-ras oncogene, rasH2 mice are highly sensitive to tumor induction and offer a model suitable for accelerated evaluation of carcinogenicity. At study termination, tissues from 6-month carcinogenicity studies in rasH2 mice are also evaluated by a board-certified veterinary pathologist; an extensive historical control database is available.
ROUTES OF ADMINISTRATION
IITRI scientists and technicians are experienced in conducting single dose, subchronic, and chronic bioassays using the
following routes of exposure:
• Oral (gavage, diet, drinking water)
• Inhalation (nose only, whole body)
• Dermal
• Injection (subcutaneous)
• Implantation (subcutaneous)
EXPERIENCED AND STABLE TEAM
The experience of scientific and technical staff is a critical factor for the effective and accurate performance of in vivo bioassays. IITRI offers an exceptionally stable scientific team: the average tenure of our toxicologists and toxicology technicians exceeds 15 years. We can ensure that a coherent, experienced team performs your study from start to finish.
If you’d like to discuss further about how IITRI can best meet your needs, feel free to contact us anytime.
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