Promise and limits of the CellSearch platform for evaluating pharmacodynamics in circulating tumor cells

<!-- START_ABSTRACT --> <p> Circulating tumor cells (CTCs), defined by capture from blood with anti-EpCAM antibodies, have established prognostic value in specific epithelial cancers, but less is known about their utility for assessing patient response to molecularly targeted agents via measurement of pharmacodynamic (PD) endpoints. We discuss the use of CellSearch CTC isolation technology for monitoring PD response in early phase trials. We present representative data from three clinical trials with the PARP inhibitor veliparib (ABT-888) suggesting that CTCs can be used to measure PD effects, but our experience points to the difficulty in obtaining sufficient EpCAM-expressing CTCs from patients with advanced disease to reach statistically significant conclusions about PD effects from each trial, instead often leading to hypothesis generating information. Overall, the level of phenotypic heterogeneity observed in specimens from patients with advanced carcinomas suggests caution in the use of cell-surface differentiation marker-based methods for isolating CTCs. </p> <!-- END_ABSTRACT --> <!-- START_TEMPLATE --> <ul> <li> Source: </li> <li> Tags: </li> </ul> <!-- END_TEMPLATE -->