673P Assessing bone health and osteoporotic risk in patients requiring anti androgen therapy for prostate cancer

Abstract

has been recently investigated. Hence, we explored the predictive value of ARV7, ARFL and PSMA combined expression on circulating tumor cells (CTCs) detected in mCRPC pts undergoing I line ARTA therapy (PRIMERA trial).Methods: Pts with mCRPC eligible for ARTA were prospectively enrolled. Twelve statuses were defined according to the combined expression of biomarkers (ARV7 and ARFL variants and PSMA) detection on CTCs at baseline. Multiple regression was performed to explore the correlation between status and treatment response features (overall PSA drop, 8 weeks PSA drop, PSA determined at 8 weeks, PSA nadir in CRPC status and time to CRPC).Results: Overall, cohort was composed of 28 pts. CTCs were detected in 15 (53.6 %) pts. PSMA, ARV7 and ARFL were expressed in 11, 2 and 9 pts, respectively. ARFL was significantly associated with increased PSA drop and overall PSA drop (P 0.02 and 0.04, respectively). ARFL-/PSMA+ status was significantly predictive for higher PSA at 8 weeks (P 0.01) and higher PSA nadir in CRPC status (P 0.01). Moreover, ARFL+/ PSMA-status was shown to be predictive for reduced time to CRPC development (P 0.02). ARV7-/ARFL+ status was shown to predict an increased PSA drop (P 0.01 and R2 0.2) and overall PSA drop (P 0.02). Conclusions:The combined expression of ARFL, PSMA and ARV7 may affect biochemical treatment response and may be related to biological aggressiveness of disease. Our data prompt further prospective evidence to confirm biological rationale and implication of these biomarkers on treatment sequencing for mCRPC.