Gene-Guided chemo trial aims to improve survival in tough breast cancer

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Signed and dated written informed consent. * Subjects ≥ 18 years of age. * Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1. * Clinical stage IV invasive mammary carcinoma or unresectable locoregional recurrence of invasive mammary carcinoma that is: * ER (\>/=1%) and/or PR (\>/= 1%) by IHC and HER2 negative (by IHC or FISH) * Previously exposed to an aromatase inhibitor (AI) or a selective estrogenreceptor modulator/ downregulator (SERM; SERD) + a CDK4/6 inhibitor. * Prior radiation permitted (if completed at least 2 weeks prior to study entry. Patients who have received prior radiotherapy must have recovered from toxicity (≤ grade 1) induced by this treatment (except for alopecia) * Patients with brain metastasis secondary to breast cancer and clinically stable for more than 4 weeks from completion of radiation treatment and off steroids * Evaluable disease (measurable or non-measurable) * Measurable disease, ie, at least 1 measurable lesion as per RECIST 1.1 (a lesion at a previously irradiated site may only be counted as a target lesion if there is clear sign of progression since the irradiation) * Patients with bone only disease allowed if possible to evaluate on radiological exams (eg.bone scan, PET/CT, CT, MRI) even if lesions are non-measurable according to RECIST1.1. * Adequate organ function including: * Absolute neutrophil count (ANC) ≥ 1.5 × 10\^9/L * Platelets ≥ 100 × 10\^9/L * Hemoglobin ≥ 8/g/dL (may have been transfused) * Total serum bilirubin ≤ 1.5 times upper limit of normal (ULN) * Aspartate aminotransferase (AST/SGOT) and alanine aminotransferase (ALT/SGPT) ≤ 2.5 × ULN (or ≤ 5 × ULN if liver metastases are present) * Serum creatinine ≤ 1.5 x ULN or estimated creatinine clearance ≥ 50mL/min as calculated using the Cockcroft-Gault (CG) equation * For randomized patients only: tumors must be diagnosed as non-Luminal A using the Blueprint® and Mammaprint® tests Exclusion Criteria: * Prior chemotherapy in the metastatic setting * Previous malignant disease other than breast cancer within the last 2 years with associated competing risk, with the exception of basal or squamous cell carcinoma of the skin, cervical carcinoma in situ, or low-risk cancers considered curatively treated (i.e. complete remission achieved at least 2 years prior to first dose of study drugs AND additional therapy not required while receiving study treatment). * Persisting symptoms related to prior therapy that has not reduced to Grade 1 \[National Cancer Institute Common Toxicity Criteria for Adverse Events (NCI CTCAE) version 5.0\]; however, menopausal symptoms, alopecia, and sensory neuropathy Grade ≤ 2 is acceptable * Pregnant or breastfeeding females.