A Safety Extension Study of Trastuzumab Emtansine in Participants Previously Treated With Trastuzumab Emtansine Alone or in Combination With Other Anti-Cancer Therapy in One of the Parent Studies

Inclusion Criteria:

• Completed single-agent trastuzumab emtansine or combination trastuzumab emtansinetreatment in the parent study or who continue to receive single-agent trastuzumabemtansine or combination trastuzumab emtansine treatment at the time of the parentstudy closure and received the last study drug dose within the 6 weeks (42 days)prior to the first dose of study therapy on the extension study or Continue toreceive treatment in the control arm of study BO21976/TDM4450g (NCT00679341) at thetime of the parent study closure if the participant received the last dose ofcontrol arm study drug within the 6 weeks (42 days) prior to the first dose ofcontrol arm study therapy in the extension study

• Participants in the control arm from Study BO21976/TDM4450g whose diseaseprogression has occurred during the transition interval between the parent study andthis extension study may initiate trastuzumab emtansine treatment at the time ofenrollment into study TDM4529g (NCT00781612)

• Expectation by the investigator that the participant may continue to benefit fromadditional single-agent trastuzumab emtansine or combination trastuzumab emtansinetreatment or Expectation of the investigator that the participant may continue tobenefit from control arm treatment as given in study BO21976/TDM4450g and at thetime of disease progression may benefit from single-agent trastuzumab emtansinetreatment

• Women of childbearing potential and men with partners of childbearing potential,must be willing to use a highly effective form of non-hormonal contraception or twoeffective forms of non-hormonal contraception by the participants and/or partner,and to continue the use of contraception for the duration of study treatment and forat least 5 months after the final dose of atezolizumab (if applicable) or 7 monthsafter the final dose of trastuzumab, trastuzumab emtansine or pertuzumab, whicheveris later. Women must refrain from donating eggs during this same period

• Male participants whose partners are pregnant should use condoms for the duration ofthe pregnancy. Men must refrain from donating sperm during this same period

Exclusion Criteria:

• AEs leading to single-agent trastuzumab emtansine or combination trastuzumabemtansine treatment discontinuation in the parent study

• Ongoing SAEs from the parent study

• Progressive disease on single-agent trastuzumab emtansine or a trastuzumabemtansine-containing regimen during the parent study or before starting theextension study, with the exception of participants from study TDM4688g (NCT00943670) with early disease progression who went on to receive pertuzumab +trastuzumab emtansine treatment and have not experienced further disease progressionon the combination regimen

• Peripheral neuropathy of Grade greater than or equal to (>/=) 3 per the NationalCancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), Version 3.0, 4.0 or 5.0, as utilized in the parent study

• History of symptomatic congestive heart failure ([CHF]; New York Heart Association [NYHA] Classes II-IV), ventricular arrhythmia requiring treatment, current unstableangina, or history of myocardial infarction within 6 months prior to study entry

• Severe dyspnea at rest due to complications of advanced malignancy or currentrequirement for continuous oxygen therapy

• Current severe, uncontrolled systemic disease (for example [e.g.] clinicallysignificant cardiovascular, pulmonary, or metabolic disease)

• Major surgical procedure or significant traumatic injury within 28 days prior tostudy entry or anticipation of the need for major surgery during the course of studytreatment

• Current pregnancy or lactation

• History of receiving any investigational treatment or other systemic therapydirected at controlling cancer (e.g., chemotherapy, trastuzumab, etc.) since theparticipant's last study drug dose in the parent study

• History of hypersensitivity with previous trastuzumab emtansine or any agent usedwith trastuzumab emtansine in the parent study, precluding further dosing

• Assessed by the investigator to be unable or unwilling to comply with therequirements of the protocol