Chromosome 1q21.3 amplification is a trackable biomarker and actionable target for breast cancer recurrence

Amplification of chromosome 1q21.3 distinguishes cells with tumor-initiating capacity that drive tumor recurrence across different breast cancer subtypes. A droplet digital PCR assay in circulating free tumor DNA identifies patients with early-stage cancer at high risk of relapse and predicts response to therapy in the metastatic setting. Pharmacological blockade of targets within this amplicon using a clinically available compound prevents tumor recurrence, suggesting a potential therapeutic approach to improve the clinical management of patients harboring 1q21.3-amplified breast tumors.