Neoplasms

Skin and Connective Tissue Diseases

All Conditions

Breast Neoplasms

Breast Diseases

Skin Diseases

Antineoplastic Agents

All Drugs and Chemicals

Antirheumatic Agents

Anti-Arrhythmia Agents

Vasodilator Agents

Analgesics

Anti-Infective Agents

Docetaxel

Ado-Trastuzumab Emtansine

Trastuzumab

Pertuzumab

Atezolizumab

Carboplatin

Antibodies

Cyclophosphamide

Doxorubicin

Liposomal doxorubicin

Immunoglobulins

Taxane

Maytansine

Adenosine

Immunosuppressive Agents

Immunologic Factors

Antineoplastic Agents, Alkylating

Alkylating Agents

Tubulin Modulators

Antimitotic Agents

Anti-Bacterial Agents

Antibiotics, Antitubercular

Enzyme Inhibitors

Antineoplastic Agents, Immunological

Immune Checkpoint Inhibitors

Immunotoxins

Immunoconjugates

Participants will receive atezolizumab in combination with trastuzumab and pertuzumab every 3 weeks.

Participants will receive atezolizumab in combination with trastuzumab emtansine (3.6 mg/kg) every 3 weeks.

Participants will receive atezolimumab in combination with trastzumab emtansine (3.0 mg/kg) every 3 weeks.

Participants will receive atezolimumab in combination with trastzumab emtansine (2.4 mg/kg) every 3 weeks.

Participants with HER2-negative breast cancer will receive atezolizumab (every 2 weeks) in combination with doxorubicin (every 2 weeks) and cyclophosphamide for four cycles. After the completion of four cycles of combination atezolizumab /doxorubicin / cyclophosphamide, atezolizumab will be continued as a single-agent at a dose of 1200 mg every 3 weeks.

Participants will receive atezolizumab in combination with trastuzumab, pertuzumab, and docetaxel every 3 weeks.

Participants will receive atezolizumab in combination with trastuzumab and pertuzumab every 3 weeks for 2 cycles, followed by docetaxel, carboplatin, trastuzumab and pertuzumab every 3 weeks for 6 cycles. Breast surgery will be performed no later than 6 weeks after neoadjuvant therapy. Upon the completion of surgery, participants will receive 12 cycles of single-agent trastuzumab every 3 weeks.

Participants will receive atezolizumab in combination with trastuzumab emtansine every 3 weeks for 2 cycles, followed by docetaxel, carboplatin, trastuzumab and pertuzumab every 3 weeks for 6 cycles. Breast surgery will be performed no later than 6 weeks after neoadjuvant therapy. Upon the completion of surgery, participants will receive 12 cycles of single-agent trastuzumab every 3 weeks.

Participants with HER2-positive metastatic breast cancer/unresectable locally advanced breast cancer who received prior treatment with trastuzumab and a taxane chemotherapy will receive atezolizumab in combination with trastuzumab emtansine at the dose determined from stage 1, every 3 weeks until disease progression, lack of clinical benefit, or unacceptable toxicity.

Participants with HER2-positive metastatic breast cancer recently progressed on an HP containing regimen will receive atezolimumab in combination with trastuzumab and pertuzumab every 3 weeks until disease progression, lack of clinical benefit, or unacceptable toxicity.

Atezolizumab 1200 milligrams (mg) or 840 mg (Cohort 1E only) flat dose administered via intravenous (IV) infusion on Day 1 of every 21-day cycle.

Carboplatin will be administered at an initial target of area under the curve (AUC) of 6 milligrams per milliliter\*min (mg/mL\*min) via an IV infusion on Day 1 of every 21-days for 6 cycles.

Docetaxel 75 mg/m\^2 administered via IV infusion on Day 1 every 21-days for 6 cycles.

Pertuzumab 840 mg loading dose then 420 mg administered via IV infusion on Day 1 of every 21-day cycle.

Trastuzumab 8 milligram per kilogram (mg/kg) loading dose, then 6 mg/kg administered via IV infusion on Day 1 of every 21-day cycle.

Trastuzumab emtansine 3.6 mg/kg administered via IV infusion on Day 1 of every 21-day cycle. Dose de-escalation may occur for trastuzumab emtansine, from the full trastuzumab emtansine dose at 3.6 mg/kg on Day 1 of every 21-day cycle, potentially to 3.0 mg/kg (Cohort 1C) or 2.4 mg/kg q3w (Cohort 1D).

Trastuzumab emtansine

Doxorubicin will be administered at 60 mg/m\^2 every 2 weeks as an IV bolus over 3 to 5 minutes or as an infusion over 15 to 30 minutes.

Cyclophosphamide will be administered at 600 mg/m\^2 on Day 1 of each 21 day cycle as an IV bolus over 3 to 5 minutes or as an infusion, in accordance with local policy.

Clinical Trials

This is a Phase Ib, open-label, two-stage study with two active regimens in each stage designed to evaluate the safety and tolerability of combination treatment with atezolizumab, trastuzumab, and pertuzumab (with and without docetaxel) or atezolizumab and trastuzumab emtansine in participants with human epidermal growth factor receptor 2 (HER2) positive metastatic breast cancer (MBC) and locally advanced early breast cancer (EBC), and atezolizumab with doxorubicin and cyclophosphamide in HER2-negative breast cancer.

Safety and Pharmacokinetics of Atezolizumab Combination Treatments in Participants With HER2-Positive and HER2-Negative Breast Cancer

A Phase Ib, Open-Label Study Evaluating the Safety and Pharmacokinetics of Atezolizumab (Anti-PD-L1 Antibody) in Combination With Trastuzumab Emtansine or With Trastuzumab and Pertuzumab (With and Without Docetaxel) in Patients With HER2-Positive Breast Cancer and Atezolizumab With Doxorubicin and Cyclophosphamide in HER2-Negative Breast Cancer

Cohorts 1A, 1B, 1C, 1D, E1, 1F, 2A, 2B, 2C, 2D: 30 minutes after end of infusion on Day 1 Cycle 1 (cycle length=21 days); pre-infusion (Hour 0) on Day 1 of Cycle 1, 2, 3 (except cohort 1E), 4, 8, on Day 1 of every 8 cycles until study treatment/early discontinuation, 120 days after treatment completion/discontinuation (up to approximately 3 years)

Spots Global Cancer Trial Database for locally advanced or early breast cancer