Prevalence of Emerging Treatment-induced Mutations in Metastatic ER-positive Breast Cancer.

Inclusion Criteria12

• Cohort 1:
• BC patients, male and female, 18 years old and older, pre or post menopausal, with HR+ (ER and/or PR positive), Her-2 negative (confirmed centrally) locally advanced irresectable and/or metastatic disease
• Confirmation of HR and Her-2 status may be performed in the primary tumor or in the metastatic lesion (patients with discordant results may be included)
• Patients must be candidates to CDK4/6i therapy in combination with endocrine therapy in the first line setting (with or without ovarian suppression)
• Patients may have received one previous line of chemotherapy in the metastatic setting, but no endocrine therapy in the metastatic setting is allowed
• Patients may have received chemotherapy in the neo/adjuvant setting
• Patients may have received endocrine therapy (with or without ovarian suppression) in the neo/adjuvant setting
• Patients may have received a CDK4/6i in the adjuvant setting, provided they are still candidates for CDK4/6i therapy in the metastatic setting
• Patients must be able to undergo a liquid biopsy procedure before starting their first line treatment
• All patients must fill and sign an informed consent form.
• Cohort 2:
• BC patients, male and felame, 18 years old and older, pre or post menopausal, with HR+ (ER and/or PR positive), Her-2 negative (confirmed centrally) locally advanced irresectable and/or metastatic disease who have progressed on a CDK4/6i in combination with endocrine therapy (with or without ovarian suppression) in the first or second line setting