BettER: Biomarker Driven Early Therapeutic Selection in Patients With HR+ HER2- Metastatic or Unresectable Breast Cancer

Prior treatment

• Receipt of any prior cytotoxic chemotherapy line for metastatic disease. There will be no limit to chemotherapy use in the neoadjuvant or adjuvant setting.
• Prior or concurrent malignancy (unless that malignancy's natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen).
• Arms 1 and 2: Concurrent participation in any investigational therapeutic trial for treatment of metastatic breast cancer.
  • Eligibility Criteria - Physicians

Other illness

• Medical Oncologist at Siteman Cancer Center.
• Treating patients with metastatic or advanced unresectable breast cancer.

Other

• Willing to complete Physician Surveys during participation.

• Diagnosis of metastatic or advanced unresectable invasive breast cancer with MD intent to treat as HR-positive and HER2-negative, with the following arm-specific requirements:
  • Arm 1: Patient must be planning to initiate standard of care first-line therapy with FDA-approved endocrine therapy plus CDK4/6 inhibitor for the stated diagnosis at the time of study enrollment. Note: Ribociclib is the preferred CDK4/6 inhibitor, but alternative CDK4/6 inhibitors are allowed. Note: Initiation of endocrine therapy prior to ultimate plan for addition of CDK4/6 inhibitor is permitted prior to enrollment.
  • Arm 2: patient must be planning to initiate standard of care second-line therapy with FDA-approved endocrine therapy plus CDK4/6 inhibitor for the stated diagnosis at the time of study enrollment. Triplet regimens are permitted as long as they contain CDK4/6 inhibitor and endocrine therapy. Note: Initiation of endocrine therapy prior to ultimate plan for addition of CDK4/6 inhibitor is permitted prior to enrollment.
  • Arm 3: patient must be planning to initiate first- or second-line therapy for the stated diagnosis at the time of study enrollment with therapy other than endocrine therapy plus CDK4/6 inhibitor.
• Any prior therapy for early stage breast cancer is allowed, including endocrine therapy and chemotherapy.
• Prior receipt of adjuvant CDK 4/6 inhibitor therapy is permitted with the following arm-specific requirements:
  • Arm 1: CDK4/6 inhibitor may have been given only in the neoadjuvant/adjuvant setting (not metastatic setting), and the last dose must have been \> 12 months prior to study enrollment.
  • Arms 2 and 3: No restrictions on prior CDK4/6 inhibitors.
• Measurable or non-measurable disease per RECIST v1.1.
• At least 18 years of age.
• ECOG PS ≤ 2
• Post-menopausal status, defined as one of the following:
  • Age ≥ 60 years
  • Age \< 60 with intact uterus and amenorrhea for 12 consecutive months or more
  • Status post bilateral oophorectomy, total hysterectomy
  • Pre- or peri-menopausal with suppressed ovarian function by use of GnRH agonist/antagonist or surgical bilateral oophorectomy
• Ability to understand and willingness to sign an IRB approved written informed consent document (or that of legally authorized representative, if applicable).