Molecular Biomarkers for Patients with Castration-Resistant Prostate Cancer: Validating Assays Predictive of Tumor Response
Neoplastic Cells, Circulating
Tumor-specific markers, developed to select targeted therapies and to assess outcome in clinical trials and clinical practice, remain a significant unmet medical need for patients with metastatic prostate cancer. Currently, assessment of disease progression in these patients relies on the modest association between changes in prostate-specific antigen (PSA) levels and imaging of distant metastases, however limited the specificity of either metric. Circulating tumor cells (CTCs) are shed into the peripheral circulation from both the primary tumor and metastatic sites. Because they retain the intrinsic properties of the tumor, distinct from extent of disease, they have the same potential prognostic and predictive value of sensitivity to targeted therapies. The development of assays to robustly measure molecular biomarkers for metastatic prostate cancer within CTCs, which can be correlated to tissue markers, is necessary before clinical utility can be tested. Pathologic analysis of individual metastatic sites is limited by the difficulty of obtaining metastatic tissue, the lack of validated assays, the heterogeneity of the disease itself, and the lack of standards for recording and interpreting the results. This vignette focuses on the effort to qualify molecular biomarkers in CTCs from patients with prostate cancer. © 2013 Elsevier Inc. All rights reserved.
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