A Study for CTC Expression and cfDNA/RNA Assessment in Metastatic Breast Cancer Patients

CTC-EXPRESS: A Prospective Observational Study for CTC Expression and cfDNA/RNA Assessment in Metastatic Breast Cancer

The purpose of this research is to learn if the CellSearch Circulating Tumor Cells (CTC) test can help doctors in making decisions about treatment and monitoring of breast cancer. The test consists of diagnostic CTC counts (enumeration) and expression of biomarkers Human Epidermal growth factor Receptor 2 (HER2), Estrogen Receptor (ER), and programmed death-ligand 1 (PD-L1) and cell free DNA/RNA (cfDNA/RNA) analysis.

A prospective, multicenter, observational study of CellSearch CTC enumeration, CTC HER2, ER, and PD-L1 expression, and MSearch cfDNA/RNA results in subjects with histologically proven MBC. Treatment for MBC will be chosen and performed by treating physicians/providers. Eligible subjects will be enrolled after signing the ICF. Subjects will receive CTC enumeration, CTC HER2, ER, PD-L1 expression and, and MSearch cfDNA/RNA assessments at baseline and first restaging as part of Standard of Care (SoC). Subjects will receive any additional cfDNA/RNA assessments as part of research collection. For all subjects 4 to 6 tubes will be collected at baseline and minimally before the first restaging visit. For any subsequent restaging visits a total of 3 to 4 tubes will be collected.

Inclusion Criteria:

• Invasive breast cancer with radiographic and/or clinical evidence of advanced metastatic or unresectable disease.
• HR+/HER2 negative or triple negative (TN) subjects prior to starting first line therapy or beyond in the metastatic setting.

OR HER2+ subjects prior to starting second line therapy or beyond in the metastatic setting.

• Subject must have the CTC HER2, ER, PD-L1, and cfDNA/RNA tests ordered during routine patient care.
• Age > 18 years.

Exclusion Criteria:

• Participant is pregnant.
• Inability to provide blood samples based on the judgment of the treating physician.