Analogous results in patients with metastatic melanoma receiving serine/threonine-protein kinase B-Raf (BRAF) inhibitors, colorectal cancers patients treated with anti-EGFR antibodies and patients with gastrointestinal stromal tumors during tyrosine-protein kinase Kit/alpha-type platelet-derived growth factor receptor (KIT/PDGFR)-targeting treatment [49-52] support performing real-time analysis of predictive biomarkers of response in cancer medicine, and minimally invasive CTC-based studies represent an advance compared with tumor biopsy samples for repetitive, real-time analysis. This evidence concerns the gene KIT and metastatic melanoma.