As ctDNA copy number alteration (CNA) analyses can be influenced by low tumor fraction, whole-exome sequencing (WES) of whole mCRPC tumor biopsies (n = 93) was also interrogated and demonstrated a similar pattern of RNASEH2B and RB1 deletion, with shallow deletion occurring in 55% of samples and deep deletion in 18% of samples (Figure 1B). This evidence concerns the gene RB1 and neoplasm.