Sequential Monitoring Of Androgen Receptor Expression And Copy Number Variation In Castration-Resistant Prostate Cancer (Crpc)

11047 Background: The high-definition circulating tumor cell (HD-CTC) assay provides for an enrichment-free approach to identify and characterize CTCs. Here, we utilized the HD-CTC assay to study androgen receptor (AR) expression combined with single-nucleus sequencing for genome-wide analysis of copy number variation (CNV) in sequential samples obtained from patients with CRPC treated with abiraterone acetate (AA). Methods: Patients were approached for participation in a study to provide peripheral blood at baseline, at 2-5 weeks, and at 9-12 weeks (or at progression). In each sample, 106cells (defined with a DAPI-intact nucleus) were quantitatively examined for the presence of cytokeratin and AR (CTCs) and CD45 (leukocytes). Initial results are available from 9 subjects treated with AA as standard of care. Results: At baseline, the median (range) CTC was 7.8 (1.1-57.2) cells/ml. Using a definition of AR positive (AR+) as u003e6 standard deviations over mean signal observed in leukocytes, the median (range) ...