A Study to Evaluate Patient Preference for Home Administration of Fixed-Dose Combination of Pertuzumab and Trastuzumab for Subcutaneous Administration in Participants With Early or Locally Advanced/Inflammatory HER2-Positive Breast Cancer

Inclusion Criteria:

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

• Intact skin at planned site of subcutaneous (SC) injections

• Left ventricular ejection fraction (LVEF) greater than or equal to (≥)55% byechocardiogram (ECHO) or multiple-gated acquisition scan (MUGA)

• Negative human immunodeficiency virus (HIV) test at screening

• Negative hepatitis B surface antigen (HBsAg) test at screening

• Positive hepatitis B surface antibody (HBsAb) test at screening, or negative HBsAbat screening accompanied by either of the following: Negative total hepatitis B coreantibody (HBcAb); Positive total HBcAb test followed by a negative (per locallaboratory definition) hepatitis B virus (HBV) DNA test

• Negative hepatitis C virus (HCV) antibody test at screening, or positive HCVantibody test followed by a negative HCV RNA test at screening

• For female participants of childbearing potential: agreement to remain abstinent oruse contraception and agree to refrain from donating eggs during the treatmentperiod and for 7 months after the final dose of the study treatment

• For male participants: agreement to remain abstinent or use a condom, and agree torefrain from donating sperm during the treatment period and for 7 months after thefinal dose of study treatment

Disease-specific Inclusion Criteria:

• Female and male participants with stage II-IIIC early or locallyadvanced/inflammatory human epidermal growth factor receptor 2-positive (HER2+)breast cancer

• Primary tumor >2 centimetres (cm) in diameter, or node-positive disease

• HER2+ breast cancer confirmed by a local laboratory prior to study enrollment. HER2+status will be determined based on pretreatment breast biopsy material and definedas 3+ by Immunohistochemistry (IHC) and/or positive by HER2 amplification by in situhybridization (ISH) following American Society of Clinical Oncology (ASCO)/Collegeof American Pathologists (CAP) guidelines 2018 and updates (Wolff et al. Arch PatholLab Med 2018)

• Hormone receptor status of the primary tumor determined by local assessmentfollowing American Society of Clinical Oncology (ASCO)/College of AmericanPathologists (CAP) guidelines and updates (Allison et al. J Clin Oncol 2020)

• Agreement to undergo mastectomy or breast conserving surgery after neoadjuvanttherapy, including the axillary nodes

• Availability of formalin-fixed, paraffin-embedded (FFPE) tumor tissue block forlocal confirmation of HER2 and hormone receptor status following current ASCO/CAPguidelines

Inclusion Criteria for Treatment with Adjuvant PH FDC SC:

• Completed the neoadjuvant phase of this study and underwent surgery, and achievedpathologic complete response (pCR), defined as eradication of invasive disease inthe breast and axilla according to the current American Joint Committee on Cancer (AJCC) staging system classification, and using the resected specimen by the localpathologist on the basis of guidelines to be provided in a pathology manual

• Adequate wound healing after breast cancer surgery per investigator's assessment toallow initiation of study treatment within less than or equal to (≤)9 weeks of lastsystemic neoadjuvant therapy

Exclusion Criteria:

• Stage IV (metastatic) breast cancer

• History of concurrent or previously treated non-breast malignancies, except forappropriately treated 1) non-melanoma skin cancer and/or 2) in situ carcinomas,including cervix, colon, and skin. A participant with previous invasive non-breastcancer is eligible provided he/she has been disease free for more than 5 years

• Participants who are pregnant or breastfeeding or intending to become pregnantduring the study or within 7 months after the final dose of study treatments

• Treatment with investigational therapy within 28 days prior to initiation of studytreatment

• Active, unresolved infections at screening requiring treatment

• Participants who may have had a recent episode of thromboembolism and are stilltrying to optimize the anticoagulation dose and/or have not normalized theirInternational Normalized Ratio (INR)

• Serious cardiac illness or medical conditions

• History of ventricular dysrhythmias or risk factors for ventricular dysrhythmias

• Inadequate bone marrow function

• Impaired liver function

• Renal function with creatinine clearance <50 mL/min using the Cockroft-Gault formulaand serum creatinine >1.5x upper limit of normal (ULN)

• Major surgical procedure unrelated to breast cancer within 28 days prior to studyentry or anticipation of the need for major surgery during the course of studytreatment

• Current severe, uncontrolled systemic disease that may interfere with plannedtreatment

• Any serious medical condition or abnormality in clinical laboratory tests thatprecludes an individual's safe participation in and completion of the study

• Treatment with a live vaccine (e.g., FluMist) in the 30 days prior to initiation ofstudy treatment, or anticipation of need for such a vaccine during treatment orwithin 90 days after the final dose of study treatment

• Known active liver disease, for example, active viral hepatitis infection,autoimmune hepatic disorders, or sclerosing cholangitis

• Known hypersensitivity to any of the study drugs, excipients, and/or murine proteinsor a history of severe allergic or immunological reactions, e.g., difficult tocontrol asthma

• Current chronic daily treatment with corticosteroids

• Assessment by the investigator as being unable or unwilling to comply with therequirements of the protocol

Cancer-specific Exclusion Criteria for Neoadjuvant Phase:

• Participants who have received any previous systemic therapy for treatment orprevention of breast cancer, or previous chest irradiation for the treatment ofcancer

• Participants who have a past history of ductal carcinoma in situ (DCIS) or lobularcarcinoma in situ (LCIS) if they have received any systemic therapy for itstreatment or radiation therapy to the ipsi- or contralateral breast cancer

• Participants with high-risk for breast cancer who have received chemopreventivedrugs in the past

• Participants with multicentric breast cancer, unless all tumors are HER2+

• Participants with bilateral breast cancer

• Participants who have undergone an excisional biopsy of primary tumor and/oraxillary lymph nodes

• Axillary lymph node dissection (ALND) prior to initiation of neoadjuvant therapy

• Sentinel lymph node biopsy (SLNB) prior to neoadjuvant therapy

Exclusion Criterion for Treatment with Adjuvant Trastuzumab Emtansine (Arm E):

• Current Grade ≥3 peripheral neuropathy (according to the NCI CTCAE v5.0)