Cancer and Mouse Models - The Pros and Cons
Since cultured cancer cell lines and genomic biomarkers have shortcomings as previously described, for the past half-century the cancer community has been using preclinical animal models where human cancers were transplanted into mice. Early mouse models were developed based on transplanting cancer cells into mice that were immune deficient, which allowed the human cancer cells from being rejected. However, these models failed. The reason for the failure was that the cancer pathology failed to reflect the original cancer pathology from a patient. Subsequently, a new type of mouse model was created called patient derived xenografts (PDX) in which a small fragment of the patient tumor is transplanted into mice. These models have been more valuable. The caner pathology in PDX models is similar to the patient's original pathology. Yet PDX models have shortcomings. First, over time the transplanted tumor becomes less similar with the original cancer. Second, the models are more challenging to test immunotherapies which is a major focus within the pharmaceutical industry. Third, the process is expensive and only half the time the process works in creating an animal model. Lastly, it takes too long to obtain personalized healthcare for patients. Thus, the PDX model is more suitable as a research tool than a diagnostic test.