In vivo imaging as a pharmacodynamic marker.

Although numerous anticancer drugs are widely used in the clinic, many questions remain about pharmacokinetics, biodistribution, toxicities, and efficacy. Positron emission tomography (PET) using radiolabeled drugs is a promising method to further understand the clinical behavior of anticancer agents. In addition, it may contribute to better guided treatment planning in individual patients with cancer. Among the available anticancer drugs, considerable experience has been gained with radiolabeling taxanes. At present, two radiolabeled taxanes, paclitaxel and docetaxel, are available as PET tracers. In the present review, data available for the labeled taxanes [(18)F]paclitaxel and [(11)C]docetaxel are discussed and linked to clinical observations following paclitaxel and docetaxel therapy, respectively. In addition, the review discusses the applications and the future of PET using radiolabeled drugs. Experience gained with [(18)F]paclitaxel and [(11)C]docetaxel may be extrapolated to other taxanes and may provide a framework for the development and clinical implementation of other radiolabeled anticancer drugs, even outside the taxane era. See all articles in this CCR focus section, "Progress in pharmacodynamic endpoints."