Overview

The purpose of this study is to understand treatment adherence and patient-reported outcomes of switching to giredestrant due to prior aromatase inhibitor (AI) intolerance. Giredestrant will be administered as adjuvant endocrine therapy for participants with low-, medium-, and high-risk, Stage I-III, histologically confirmed, estrogen receptor positive (ER+), human epidermal growth factor receptor 2 negative (HER2-), early breast cancer (eBC), as defined by the investigator. Participants will enroll if considered to be intolerant to a prior adjuvant AI therapy.

Eligibility

Inclusion Criteria:

• Considered appropriate for treatment with endocrine therapy (ET)
• Histologically confirmed diagnosis of ER+/HER2-, Stage I-III (low-/medium-/high-risk) early breast cancer (eBC)
• Documented ER+ tumor according to American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP), defined as ≥1% of tumor cells stained positive
• Documented HER2- tumor according to ASCO/CAP
• Postmenopausal females at the time of signing the Informed Consent Form
• Documented use of a prior adjuvant aromatase inhibitor (AI) (i.e., anastrozole, exemestane, or letrozole) for a total of ≥6 months
• Documented use of an adjuvant AI (i.e., anastrozole, exemestane, or letrozole) for the consecutive ≥3 months immediately prior to consent
• Participant and investigator agree that current symptoms on AI are intolerable and warrant a switch in therapy to attempt sustained treatment
• Documented Grade 2 or 3 adverse events, per NCI CTCAE v6.0, determined by the investigator to be associated with AI therapy's intolerance
• Participant and investigator planning the first switch from an AI
• Has completed the following: (neo)adjuvant chemotherapy (if administered), definitive surgery of primary breast tumor(s) and/or axillary lymph nodes dissection (ALND) and/or sentinel lymph node biopsy (SLNB) and/or radiotherapy
• Eastern Cooperative Oncology Group Performance (ECOG) Performance Status 0 or 1

Exclusion Criteria:

• Participation within 6 months before enrollment in any other clinical study involving an investigational adjuvant treatment including anti-cancer agents
• Diagnosis of rheumatoid arthritis, psoriatic arthritis, or other inflammatory connective tissue disease
• Any prior fulvestrant or any oral selective estrogen receptor degraders (SERDs)
• Have active cardiac disease or history of cardiac dysfunction
• Have clinically significant liver disease consistent with Child-Pugh Class B or C, including active hepatitis (e.g., hepatitis B virus \[HBV\] or hepatitis C virus \[HCV\]), current alcohol abuse, cirrhosis, or positive test for viral hepatitis
• Treatment with strong CYP3A inhibitors or inducers within 14 days or 5 drug elimination half-lives (whichever is longer) prior to initiation of study treatment
• Have had any serious medical condition or abnormality in clinical laboratory tests that, in the investigator's judgment, precludes an individual's safe participation in and completion of the study