AR and neoplasm: In mCRPC prognostic and predictive biomarkers previously investigated include PSA,12 hemoglobin, lactate dehydrogenase and alkaline phosphatase levels,12 βIII-tubulin,13 CTCs,14,15AR-V7, AR-V9 splice variants,16-21 plasma tumor fraction (circulating tumor DNA-ctDNA),22-31 and plasma cell-free DNA (cfDNA),32-34 among others.