This is a phase 2, open-label, singled-arm clinical trial determining efficacy of combination therapy with anastrozole, fulvestrant and abemaciclib in subjects with breast cancer. These are subjects who are newly diagnosed advanced or metastatic hormone receptor positive breast cancer or subjects who have progressed following treatment free interval of more than 12 months following adjuvant or neoadjuvant treatment.
Patients must have a diagnosis of HR+ breast cancer. To fulfill the requirement of HR+ disease, a breast cancer must express, by immunohistochemistry (IHC), at least one of the hormone receptors (ER, progesterone receptor [PgR]) as defined in the relevant American Society of Clinical Oncology/College of American Pathologists Guidelines: For ER and PgR assays to be considered positive, ≥1% of tumor cell nuclei must be immunoreactive by immunohistochemistry (IHC)
Patients must have newly diagnosed metastatic regional breast cancer (Stage IV per AJCC 8th edition criteria for staging of breast cancer) or local-regional advanced or recurrent cancer not amenable to curative treatment
Age ≥ 18 years
ECOG performance status 0-2
Localized breast cancer which is curable with surgery or radiation, with or without chemotherapy. This study will utilize the American Joint Committee on Cancer (AJCC) staging system, eight edition that provides a strategy for grouping patients with respect to prognosis. The AJCC has designated staging by TNM classification.
Current diagnosis of inflammatory breast cancer
Patients who have had chemotherapy or radiotherapy within 12 months prior to entering the study.
Prior treatment with Fulvestrant (Note: For the current diagnosis, fulvestrant initiated within 8 weeks prior to starting study intervention is allowed)