OHSU and KDL researches were able to demonstrate that AR amplification is conserved between CTCs and biopsies and that CTCs can serve as non-invasive surrogate to document AR amplification in mCRPC

Podolak J, Eilers K, Newby T, Slottke R, Erin Tucker, Olson S, Lue H, Small EJ, Graff JN, Alumkal J, Beer TM, Thomas GV. Androgen receptor amplification is concordant between circulating tumor cells and biopsies from men undergoing treatment for metastatic castration resistant prostate cancer; March 2017, Oncotarget, 2017 March 12: 8(42) 71447-71455. PMCID: PMC5641061

Androgen receptor amplification is concordant between circulating tumor cells and biopsies from men undergoing treatment for metastatic castration resistant prostate cancer