Think of O-PDX models as your personal mouse avatars — replicates of your unique form of cancer in immuno-compromised mice. To create an orthotopic PDX model, Certis scientists surgically implant fragments of expanded tumor tissue from your first-generation mice into the location of origin—the same anatomical location from which the original tumor came from in your body. For example, if your tumor biopsy came from your colon, we engraft tissue into your mouse avatars’ colon. This is important because we know from years of research that the microenvironment in which a tumor grows can greatly influence drug response, drug resistance and metastatic behavior.