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

This is a global Phase III, double-blind, randomized, placebo-controlled study designed to evaluate the efficacy and safety of neoadjuvant treatment with atezolizumab (anti-programmed death-ligand 1 \[anti-PD-L1\] antibody) and nab-paclitaxel followed by doxorubicin and cyclophosphamide (nab-pac-AC), or placebo and nab-pac-AC in participants eligible for surgery with initial clinically assessed triple-negative breast cancer (TNBC).


Eligibility Criteria:
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
* For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive methods, and agreement to refrain from donating eggs
* For men: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive measures and agreement to refrain from donating sperm
* Women who are not postmenopausal or have undergone a sterilization procedure must have a negative serum pregnancy test result within 14 days prior to initiation of study drug

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
* History of cerebrovascular accident within 12 months prior to randomization
* Pregnant or lactating, or intending to become pregnant during the study