(UroToday.com) Taxanes (docetaxel, cabazitaxel) and androgen-signaling-targeted inhibitors (abiraterone, enzalutamide) have shown survival benefits in metastatic castration resistant prostate cancer (mCRPC), however until recently the optimal sequence of these treatments was unclear. In clinical practice, many patients with prostate cancer often receive sequential androgen-signaling-targeted inhibitors. Patients who have progressed on an androgen-signaling-targeted inhibitor may not respond to a second alternative androgen-signaling-targeted inhibitor, possibly due to shared resistance mechanisms.