Table 1.

Advantages and limitations of each cancer model.

	Advantages	Limitations	Recommendations to Overcome Limitations
Cell line (cultured in vitro)	·Maintained inexpensively ·Treated very easily ·Grow infinitely	·Completely lack the tumor microenvironment ·Can’t maintain original cell properties ⇒Very low predictive value	·Should be used in basic studies and very early stages of drug development ·Co-culture with cancer associated fibroblasts (CAFs) or immune cells will improve the predictive value
Cell line xenograft	·High take rates ·Slightly recapitulate tumor microenvironment ·Take short time to be established	·Can’t reproduce heterogeneity ·Can’t maintain the original cell properties ⇒Low predictive value	·Should be used in the relatively early stages of drug development with a large number of mice, which can reflect the inter-tumor heterogeneity
Genetically engineered mouse	·Recapitulate tumor initiation and early development process ·Gene of interest can be studied in detail ·Can be increased easily after establishment	·Can’t reproduce heterogeneity of human tumor ⇒Low predictive value ·Take long time to be established	·Should be used when investigating how a specific gene of interest could contribute to tumor initiation and relapse
PDX	·Partly recapitulate tumor microenvironment ·Maintain histologic and genetic features of origin ⇒High predictive value ·Can be used for metastatic model	·Low take rate ·Very expensive ·Take long time to be established	·Development of new immunodeficient mice and/or better methods of tumor transplantation will improve the take rates and the cost