ABSTRACT
The heterogenous nature of human cancers, paired with their often complex polygenic pathobiologies and reliance on an intact immune system to regulate growth and progression, make human neoplasia exceedingly difficult to model in a laboratory setting. In 2003 the National Cancer Institute Comparative Oncology Program was founded, which currently forms a network of 24 academic veterinary oncology centers in the United States and Canada, providing infrastructure facilitating the design and execution of clinical trials of novel cancer therapeutics in canine patients. There are numerous published examples of comparative oncology studies that have advanced our understanding of cancer biology and/or that have contributed to the development of Federal Drug Administration (FDA)-approved oncology therapeutics. DNA topoisomerase 1 (TOP1) is an enzyme that induces single strand breaks in supercoiled DNA permitting relaxation and remodeling, which is essential for transcription, replication, and repair. Two TOP1 inhibitors, irinotecan and topotecan, have been FDA approved for use in ovarian, small cell-lung, cervical, colorectal, and/or gastric cancers.
