Circulating tumor cells (CTCs) are considered to be precursors of metastasis in various cancer types and are found in the blood of cancer patients as single CTCs and CTC clusters, with the latter featuring a higher ability to seed metastasis.~CTC cluster share several properties that commonly feature stem cell biology which drive metastases formation. Preclinical data shows that CTC clusters can be disaggregated into single cells by the treatment with cardiac glycosides such as digoxin. This single arm therapeutic exploratory study of digoxin in patients with advanced or metastatic breast cancer investigates whether cardiac glycosides are able to disrupt CTC clusters in breast cancer patients.~Patients with advanced or metastatic breast cancer in whom CTC clusters could be identified will receive an individualized daily maintenance dose of digoxin adapted to their kidney function. Blood samples for analyses of digoxin serum level and mean CTC cluster size will be drawn at specified time points.
This single arm therapeutic exploratory study of digoxin in patients with advanced or metastatic breast cancer investigates whether cardiac glycosides are able to disrupt CTC clusters in breast cancer patients.