In vitro pharmacology involves testing drugs on isolated cancer cells, tissues, or biomolecules in laboratory dishes to evaluate drug sensitivity, therapeutic responses, and resistance mechanisms outside of a living organism. Ex vivo pharmacology uses freshly obtained patient or mouse model-derived tumor tissue maintained in culture for a limited time to test drug effects while preserving the original tumor microenvironment and cellular architecture. In vivo pharmacology studies drug effects within living mouse models that replicate human disease conditions, allowing assessment of tumor response, drug metabolism, toxicity, efficacy, and complex biological interactions.