Glucocorticoid receptor (GR) expression in circulating tumor cells (CTCs) to prognosticate overall survival (OS) for metastatic castration-resistant prostate cancer (mCRPC) patients (pts) treated with androgen receptor signaling inhibitors (ARSi).

• DOI: 10.1200/jco.2017.35.6_suppl.194
• Publication Date: 2017-03-29T15:03:53Z
• Authors: David Wise; James Kelvin; Ryon Graf; Nicole A. Schreiber; Brigit McLaughlin; Luisa Fernandez; Normy Rivera; Bianca Petines; Melissa Harvey; Linda Nguyen; Aaron Oh; Lee Horiuchi; Ryan Vance Dittamore; Howard I. Scher
• Keywords: Enzalutamide; Circulating tumor cell; Abiraterone acetate

194 Background: Upregulation of GR protein expression in metastatic biopsies from pts with CRPC has previously been shown to correlate resistance enzalutamide and validated as a therapeutic target pre-clinical studies. We sought determine whether upregulated CTCs progressing mCRPC predicted clinical outcomes following treatment (E) or abiraterone (A). Methods: Pre-therapy blood samples 54 were subjected CTC analysis using the Epic Sciences platform. Samples examined identify CK+ (CK+, CD45- cells, intact nuclei, morph distinct) for expression. GR+ defined having greater than 95 th percentile negative LNCAP cell line. Kaplan-Meier was used test impact on OS A E. Cox proportional hazards model number positivity multivariate analysis. Results: 37 out (69%) had detectable viable CTCs. 28 (76%) staining median 6 GR+/CK+ cells/ml per patient (range 0.7 – 244 cells/ml). The patients treated ARSi significantly worse that without (11.4 mo. vs NA, p < 0.01), an effect independent additive presence CTCs, described prognostic biomarker (see Table). Conclusions: upregulation can be detected significant percentage predicts response ARSi. data supports reported proposing pathogenic role mediating therapy. Detection may useful predictive guide GR-directed therapies. [Table: see text]