Various human samples (e.g., serum, plasma, whole blood, erythrocytes, urine, feces, bile, and/or saliva) will be collected from cancer patients enrolled on approved clinical trials, in accordance with the local protocol. These trials are being conducted at outside institutions, in collaboration with the National Cancer Institute (NCI) and the samples will be sent to the NCI for pharmacological analysis, involving determination of parent drug and/or metabolite concentrations and subsequent pharmacokinetics and statistical data analysis. This study aims to further characterize the clinical pharmacokinetic behavior of select cancer therapeutics. Future collaborators will be added via the protocol amendment procedure.