A Study to Investigate Atezolizumab and Chemotherapy Compared With Placebo and Chemotherapy in the Neoadjuvant Setting in Participants With Early Stage Triple Negative Breast Cancer

Inclusion criteria:

- Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

- Histologically documented TNBC (negative human epidermal growth factor receptor 2
[HER2], estrogen receptor [ER], and progesterone receptor [PgR] status)

- Confirmed tumor programmed death−ligand 1 (PD-L1) evaluation as documented through
central testing of a representative tumor tissue specimen

- Primary breast tumor size of greater than (>) 2 centimeters (cm) by at least one
radiographic or clinical measurement

- Stage at presentation: cT2-cT4, cN0-cN3, cM0

- Participant agreement to undergo appropriate surgical management including axillary
lymph node surgery and partial or total mastectomy after completion of neoadjuvant
treatment

- Baseline left ventricular ejection fraction (LVEF) greater than or equal to (>=) 53
percent (%) measured by echocardiogram (ECHO) or multiple-gated acquisition (MUGA)
scans

- Adequate hematologic and end-organ function

- Representative formalin-fixed, paraffin-embedded (FFPE) tumor specimen in paraffin
blocks (preferred) or at least 20 unstained slides, with an associated pathology
report documenting ER, PgR, and HER2 negativity

Exclusion criteria:

- Prior history of invasive breast cancer

- Stage 4 (metastatic) breast cancer

- Prior systemic therapy for treatment and prevention of breast cancer

- Previous therapy with anthracyclines or taxanes for any malignancy

- History of ductal carcinoma in situ (DCIS), except for participants treated
exclusively with mastectomy >5 years prior to diagnosis of current breast cancer

- History of pleomorphic lobular carcinoma in situ (LCIS), except for participants
surgically managed >5 years prior to diagnosis of current breast cancer

- Bilateral breast cancer

- Undergone incisional and/or excisional biopsy of primary tumor and/or axillary lymph
nodes

- Axillary lymph node dissection prior to initiation of neoadjuvant therapy

- History of other malignancy within 5 years prior to screening, with the exception of
those with a negligible risk of metastasis or death

- Cardiopulmonary dysfunction

- History of severe allergic, anaphylactic, or other hypersensitivity reactions to
chimeric or humanized antibodies or fusion proteins

- Known hypersensitivity to biopharmaceuticals produced in Chinese hamster ovary cells

- Known allergy or hypersensitivity to the components of the formulations of
atezolizumab, nab-paclitaxel, cyclophosphamide, or doxorubicin, filgrastim or
pegfilgrastim

- Active or history of autoimmune disease or immune deficiency diseases except history
of autoimmune-related hypothyroidism, controlled Type 1 diabetes mellitus, and
dermatologic manifestations of eczema, psoriasis, lichen simplex chronicus, or
vitiligo (e.g., participants with psoriatic arthritis are excluded)

- History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced
pneumonitis, idiopathic pneumonitis, or evidence of active pneumonitis on screening
chest computed tomography (CT) scan. History of radiation pneumonitis in the radiation
field (fibrosis) is permitted

- Positive human immunodeficiency virus (HIV) test at screening

- Active hepatitis B and hepatitis C virus infection

- Active tuberculosis

- Severe infections within 4 weeks prior to initiation of study treatment, including but
not limited to hospitalization for complications of infection, bacteremia, or severe
pneumonia

- Treatment with therapeutic oral or IV antibiotics within 2 weeks prior to initiation
of study treatment, except prophylactic antibiotics

- Major surgical procedure within 4 weeks prior to initiation of study treatment or
anticipation of need for a major surgical procedure during the course of the study

- Prior allogeneic stem cell or solid organ transplantation

- Administration of a live attenuated vaccine within 4 weeks prior to initiation of
study treatment or anticipation of need for such a vaccine during the study

- Any other disease, metabolic dysfunction, physical examination finding, or clinical
laboratory finding giving reasonable suspicion of a disease or condition that
contraindicates the use of an investigational drug or that may affect the
interpretation of the results or render the participant at high risk from treatment
complications

- Prior treatment with cluster of differentiation 137 (CD137) agonists or immune
checkpoint-blockade therapies, including anti-cluster of differentiation 40
(anti-CD40), anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4),
anti-programmed death-1 (anti-PD-1), and anti-PD-L1 therapeutic antibodies

- Treatment with systemic immunostimulatory agents within 4 weeks or 5 half-lives of the
drug, whichever is longer, prior to initiation of study treatment

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