PTEN and cancer: In the prototype cases of prostate cancer described here, leukopak-derived CTC analysis using WES reproduced the mutations identified by cancer gene mutation panels in either biopsied metastatic lesions or blood-based ctDNA sampling (e.g., PTEN and TP53), and also discovered additional potentially significant mutations in genes implicated in homologous recombination (HRR), cell cycle checkpoints and chromatin remodeling.