Atezolizumab and Chemotherapy Treatment as T-cell Activators in Metastatic Triple Negative Breast Cancer Patients

Inclusion Criteria: * Signed Informed Consent Form * Patients with locally advanced or metastatic, histologically documented TNBC (absence of human epidermal growth factor 2 \[HER2\], estrogen receptor \[ER\], and progesterone receptor \[PR\] expression) PD-L1+ (Immune Cell \>1% using Ventana SP142 assay), not amenable to surgical therapy * Locally advanced or metastatic TNBC, who have received an anti-PD-1/PD-L1 containing regimen in the neoadjuvant/adjuvant setting * No prior chemotherapy or targeted systemic therapy (including endocrine therapy) or immunotherapy for inoperable locally advanced or metastatic TNBC * Tissue accessible for biopsies * Expected survival of \> 3 months * Female or male subject ≥18 years * Have measurable/evaluable metastatic disease (RECIST 1.1 criteria) * Performance status 0-1 on Eastern Cooperative Oncology Group Performance Status (ECOG PS) * Demonstrate adequate organ (kidney, liver) function Exclusion Criteria: * Patients with de novo metastatic TNBC OR those who have received 1 or more chemotherapy or targeted systemic therapy (including endocrine therapy) or immunotherapy regimens for advanced disease * Immunodeficiency or systemic steroid therapy/immunosuppressive therapy within 7 days prior to study entry * Known history of active Bacillus Tuberculosis (TBC) * Hypersensitivity to anti- PD-L1 antibodies or its excipients * Active autoimmune disease * Known history of non-infectious pneumonitis * Active infection requiring systemic therapy * Known history of Human Immunodeficiency Virus (HIV) * Known active Hepatitis B (e.g., HBsAg reactive) or Hepatitis C (e.g., HCV RNA \[qualitative\]) * Live vaccine within 30 days * Bone or brain metastases