Study on LY4064809 with Other Cancer Treatments for Advanced Breast Cancer with a PIK3CA Genetic Change

Inclusion Criteria

• Willing to use contraception as required by local regulations during the study.
• Women of any menopausal status can participate, but pre- or peri-menopausal women must agree to use ovarian suppression therapy.
• Men with estrogen receptor-positive (ER+) breast cancer must agree to use hormone suppression therapy.
• Have confirmed advanced breast cancer that cannot be cured by surgery or has spread, and is HR+/HER2- or HR+/HER low.
• Have a PIK3CA mutation detected in tumor or blood samples.
• Have measurable or evaluable bone disease.
• Part 1: Received 0-2 prior treatments for advanced breast cancer, with up to 1 being chemotherapy.
• Part 2: Received no prior treatment for advanced breast cancer.
  • Population 1: Endocrine sensitive, newly diagnosed or relapsed after more than 12 months from previous treatment.
  • Population 2: Endocrine resistant, relapsed within 12 months of previous treatment.

Exclusion Criteria

• Have diabetes with poor blood sugar control or requiring insulin.
• Have inflammatory or metaplastic breast cancer.
• Have a history of cancer spread to the brain or spinal cord.
• Have untreated or active cancer spread to the central nervous system, unless treated and stable for at least 28 days.
• Have received any cancer treatment within 14 days or 4 half-lives before starting the study.
• Have an immune deficiency or are on long-term steroid therapy or other immune-suppressing treatments.
• Are pregnant, breastfeeding, or planning to become pregnant during the study or within 6 months after the last dose of the study drug.