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