Overview
This study will evaluate the efficacy and safety of the combination of inavolisib plus a cyclin-dependent kinase 4 and 6 inhibitor (CDK4/6i) and letrozole versus placebo plus a CDK4/6i and letrozole in the first-line setting in participants with endocrine-sensitive PIK3CA-mutated hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), advanced breast cancer (ABC).
Eligibility
Inclusion Criteria:
- Women or men with histologically or cytologically confirmed carcinoma of the breast
- Documented ER-positive and/or progesterone receptor-positive tumor according to American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines
- Documented HER2-negative tumor according to ASCO/CAP guidelines
- De-novo HR+ , HER2- ABC, or, alternatively, relapsed HR+ , HER2- ABC after at least 2 years of standard neoadjuvant/adjuvant endocrine therapy without disease progression during that treatment and disease-free interval of at least 1 year since the completion of that treatment
- Participants who have bilateral breast cancers which are both HR-positive and HER2-negative
- Confirmation of biomarker eligibility
- Consent to provide fresh or archival tumor tissue specimen
- Measurable disease per Response Evaluation Criteria in Solid Tumors, Version 1.1 (RECIST v1.1)
- Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
- Adequate hematologic and organ function within 14 days prior to initiation of study treatment
Exclusion Criteria:
- Pregnant or breastfeeding, or intention of becoming pregnant during the study or within the time frame in which contraception is required
- Metaplastic breast cancer
- Any prior systemic therapy for locally advanced unresectable or metastatic breast cancer
- Type 2 diabetes requiring ongoing systemic treatment at the time of study entry; or any history of Type 1 diabetes
- Any history of leptomeningeal disease or carcinomatous meningitis
- Known and untreated, or active CNS metastases. Participants with a history of treated CNS metastases are eligible
- Active inflammatory or infectious conditions in either eye or history of idiopathic or autoimmune-associated uveitis in either eye
- Symptomatic active lung disease
- History of or active inflammatory bowel disease
- Any active bowel inflammation
- Prior hematopoietic stem cell or bone marrow transplantation
- Treatment with strong cytochrome P450 (CYP) 3A4 inhibitors or strong CYP3A4 inducers within 4 weeks or 5 drug-elimination half-lives, prior to initiation of study treatment