Primary Objective~-Demonstrate detection of ARv7 splice variant transcripts from exosomes in the circulation of MCRPC patients pre and post treatment with selective Androgen pathway inhibitors (i.e. abiraterone and enzalutamide)~Secondary and Exploratory Objectives~Correlate ARv7 status with PSA response (>/=50% decline in PSA level from baseline, maintained for >/=4 weeks) at any time after the initiation of therapy.~Comparison of median progression free survival (PFS) and overall survival (OS).~Determine additional molecular lesions in exoRNA and cfDNA in MCRPC patients post-treatment with androgen pathway inhibitors.~Correlate other AR-variants (non ARv7) with clinical outcomes including PSA response.
Demonstrate detection of ARv7 splice variant transcripts from exosomes in the circulation of MCRPC patients pre and post treatment with selective Androgen pathway inhibitors (i.e. abiraterone and enzalutamide)