A Study Comparing Atezolizumab (Anti PD-L1 Antibody) In Combination With Adjuvant Anthracycline/Taxane-Based Chemotherapy Versus Chemotherapy Alone In Patients With Operable Triple-Negative Breast Cancer

Inclusion Criteria:

- Non-metastatic operable Stage II-III breast cancer

- Histologically documented TNBC (Triple Negative Breast Cancer)

- Confirmed tumor PD-L1 evaluation as documented through central testing of a
representative tumor tissue specimen

- Adequately excised: Patients must have undergone either breast-conserving surgery or
mastectomy/nipple- or skin-sparing mastectomy

- Adequate hematologic and end-organ function

- For women of childbearing potential: agreement to remain abstinent (refrain from
heterosexual intercourse) or use contraceptive measures

- For men: agreement to remain abstinent (refrain from heterosexual intercourse) or use
contraceptive measures and agreement to refrain from donating sperm.

- No more than 8 weeks (56 days) may elapse between definitive breast surgery and
randomization.

- Representative formalin-fixed, paraffin embedded (FFPE) tumor specimen from surgical
resection in paraffin blocks (preferred) or at least 25 unstained slides.

Exclusion Criteria

- Prior history of invasive breast cancer

- For the currently diagnosed breast cancer, any previous systemic anti-cancer treatment
(e.g., neoadjuvant or adjuvant), including, but not limited to, chemotherapy,
anti-HER2 therapy.

- Previous therapy with anthracyclines or taxanes for any malignancy

- Cardiopulmonary dysfunction

- Prior malignancies within 5 years prior to randomization, with the exception of those
with a negligible risk of metastasis or death and treated with expected curative
outcome

- Active or history of autoimmune disease or immune deficiency

- History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced
pneumonitis, idiopathic pneumonitis, or evidence of active pneumonitis on screening
chest computed tomography (CT) scan

- Urinary outflow obstruction

- Active tuberculosis

- Major surgical procedure other than for diagnosis within 4 weeks prior to initiation
of study treatment or anticipation of need for a major surgical procedure during study
treatment or within 5 months following the last dose of Atezolizumab (for patients
randomized to Atezolizumab)

- Prior allogeneic stem cell or solid organ transplant

- Treatment with systemic immunosuppressive medications within 2 weeks prior to
initiation of study treatment or anticipation of need for systemic immunosuppressive
medication during the study