Synaptophysin expression on circulating tumor cells in patients with castration resistant prostate cancer undergoing treatment with abiraterone acetate or enzalutamide

We have demonstrated that Syp can be quantified on CTCs and that Syp expression correlates with resistance to abiraterone and enzalutamide. Larger studies testing Syp as a biomarker of emergence of nonadenocarcinoma disease and as a marker of response to AR-targeted therapies are warranted.