TABLE 1.

Advantages and limitations of human and cell models

Clinical Studies	Cell Models
Advantages Most relevant study system Pharmacokinetic as well as pharmacodynamic testing possible Ability to analyze effects of interactions of multiple tissues Allows investigation of environmental factors and drug-drug interactions	Ease of experimental manipulation Controlled testing system free of in vivo confounders Ability to test drugs with narrow therapeutic index Genetic and expression data publicly available for hundreds of established cell lines Cost-effective Unlimited resource
Limitations Difficult to collect large cohorts of patients for discovery and replication Can be difficult to parse effects of environment from genetic effects Ethical issues with studying drugs with narrow therapeutic indices Not all cohorts will have detailed pharmacological data, especially retrospective cohorts	Phenotype may not recapitulate in vivo system Subject to in vitro confounders that may affect phenotype Cell lines can be generated from only a limited number of tissues Cells may not express important metabolic enzymes relevant to pharmacology, such as the cytochrome P450 family Establishing cell lines from tumor may alter characteristics of tumor