This two-part study will evaluate the bioequivalence, safety, and tolerability of a single SC dose of trastuzumab administered via handheld syringe/syringe pump (HHS/SP) with infusion set (IS) and an on-body delivery system (OBDS).

Inclusion Criteria:

• Within body mass index (BMI) range 18 to 38 kilogram per meter square (kg/m2), inclusive. Body weight <=100 kg
• Left ventricular ejection fraction (LVEF) >= 55 percent (%) measured by echocardiogram (ECHO)
• Negative test result for drugs of abuse
• Negative test result for hepatitis B surface antigen, hepatitis C virus (HCV), or human immunodeficiency virus (HIV) antibody screen
• Negative test for latent Tuberculosis (TB) infection by QuantiFERON® TB Gold
• Agree to use contraception and will refrain from sperm donation

Exclusion Criteria:

• Significant history or clinical manifestation of any metabolic, allergic, dermatological, hepatic, renal, hematological, pulmonary, cardiovascular, respiratory, gastrointestinal, immunological, neurological, or psychiatric disorder; acute infection; or other unstable medical disease
• History of moderate or severe allergic, anaphylactic, or other hypersensitivity reactions to chimeric, human, or humanized antibodies or fusion proteins
• Known sensitivity to recombinant hyaluronidase or other form of hyaluronidase
• History or presence of atrial fibrillation
• History of any clinically significant or clinically relevant cardiac condition
• History or presence of clinically significant electrocardiogram (ECG) abnormalities
• History of uncontrolled hypertension, hyperlipidemia, thyroid disorder, or diabetes
• Family history of clinically significant and clinically relevant hypersensitivity, allergy, or severe cardiac diseases
• History of previous anti-cancer treatments including pertuzumab, trastuzumab, anthracyclines, or any cardiotoxic drugs
• History of active or latent TB, regardless of treatment history
• Poor peripheral venous access
• History or presence of any malignancy, with the exception of completely excised basal cell or squamous cell carcinoma of the skin