New cancer drugs must be thoroughly tested in preclinical models, often in mice, before they can be offered to cancer patients for the first time in phase I clinical trials. Key components of this process include pharmacokinetic and pharmacodynamic studies, which evaluate how the drug acts on a living organism. These studies measure the pharmacologic response and the duration and magnitude of response observed relative to the concentration of the drug at an active site in the organism. A new comparison of four different methodologies for pharmacokinetic and pharmacodynamic testing of the anti-melanoma agent carboplatin, demonstrates that genetically-engineered mouse models provide tumor delivery of drug most comparable to the response seen in melanoma patients.