Blood-based genomics of triple-negative breast cancer progression in patients treated with neoadjuvant chemotherapy

•ctDNA was detected in 77% of early-stage TNBC patients undergoing neoadjuvant chemotherapy.•Patients with still detectable ctDNA after NAC were more than twice as likely to relapse as those with undetectable levels.•Detection of ctDNA during follow-up antedated clinical overt metastases up to 13 months.•ctDNA was undetectable in all but one non-recurrent patient with a temporary peak in only 1 of 8 samples tested.•CTCs of progressing cases lacked epithelial surface markers and showed therapeutically exploitable molecular features.