Predicting Response and Recognizing Resistance: Improving Outcomes in Patients With Castration-resistant Prostate Cancer.

Optimal sequencing strategies for approved agents in metastatic castration-resistant prostate cancer (mCRPC) are unclear. Retrospective clinical studies suggest cross-resistance between specific therapies. This review assesses treatment decisions for mCRPC. Increased use of chemohormonal therapy in castration-sensitive disease may affect subsequent treatment decisions in mCRPC. Initial abiraterone or enzalutamide treatment may result in cross-resistance for subsequent androgen receptor-targeted therapy. Clinical responses may be seen in both docetaxel- and cabazitaxel-treated patients progressing after treatment with abiraterone or enzalutamide. These observations are supported by proposed resistance mechanisms. In conclusion, small, retrospective studies suggest cross-resistance between specific therapies in mCRPC. Larger prospective studies are required.