The primary hypothesis is that a Programmed death-ligand 1 (PD-L1) immune checkpoint inhibitor combined with a Cyclin-dependent kinase 4/6 (CDK4/6) inhibitor will be well tolerated in early stage, hormone receptor positive (HR+) breast cancer patients treated with neoadjuvant endocrine therapy (NET). The secondary hypothesis and biomarker based endpoint is that patients with HR positive locally advanced breast cancer with low to intermediate stromal tumor-infiltrating lymphocytes (TILs) will demonstrate an increase in stromal TILs following NET when combined with abemaciclib and durvalumab for 4 cycles (16 weeks).
The purpose of this study is to test the efficacy, safety and tolerability of a combination of immunotherapy and anticancer drugs presurgery in patients with hormone-receptor positive breast cancer.