In exploratory analyses in our full cohort, we observed an enrichment of cfDNA detectable AR amplification in samples from patients with limited PSA response (Figure 5A), with both cfDNA detectable AR amplification (Kaplan-Meier log-rank test, chi-square = 15.3, p < 0.0001; Figure 5B) and elevated cfDNA tumor content (Kaplan-Meier log-rank test, chi-square = 8.2, p < 0.0042; Figure 5C) showing a significant association with reduced time on therapy. Here, AR is linked to neoplasm.