This study is being done to answer the following question: Can testing breast cancer for DNA abnormalities or "biomarkers" help predict which patients are most likely to be helped by certain treatments? The pre-study screening is being done to test a sample of blood (or tumour tissue) for biomarkers to see if patients can participate in the study
Patients must have histologically and/or cytologically confirmed, advanced / metastatic breast cancer, ER >10% and not HER2 overexpressing/amplified as per ASCO/CAP criteria. Patients with locally advanced or inflammatory disease without distant metastases that is potentially resectable or treatable with curative intent are not eligible
All patients must have a formalin fixed paraffin embedded tissue block (from primary or metastatic tumour) available and must have provided informed consent for the release of the block
Patients must have had objective disease progression demonstrated on (defined as while taking or within 8 weeks of the last dose) first line CDK4/6i + ET for MBC. Patients who discontinued CDK4/6i + ET without disease progression more than 8 weeks prior to objective disease progression (toxicity, patient request) are not eligible. Patients must have received at least 24 weeks of first line CDK4/6i + ET therapy
Presence of clinically and/or radiologically documented disease. All radiology studies must be performed within 21 days prior to enrollment (within 28 days if negative). All patients must have measurable disease as defined by RECIST 1.1.
Patients with a history of other malignancies, including Myelodysplastic syndrome (MDS) or Acute myeloid leukemia (AML) except: adequately treated non-melanoma skin cancer, curatively treated in-situ cancer of the cervix, or other malignancies curatively treated with no evidence of disease for ˃ 2 years and which do not require ongoing treatment.
Patients with active or uncontrolled infections or with serious illnesses or medical conditions which would not permit the patient to be managed according to protocol.
Infection includes but is not limited to active infection requiring systemic therapy and active or known human immunodeficiency virus (HIV) with detectable viral load, known hepatitis B surface antigen or positive hepatitis C antibody
Pneumonitis or any history of pneumonitis requiring steroids (any dose)
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Treatment groupsSee each treatment group below.