A Study of Trastuzumab Emtansine in Participants With Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Breast Cancer Who Have Received Prior Anti-HER2 And Chemotherapy-based Treatment

The AEPIs in this study were defined as the following: adverse events (AEs) Grade \>/= 3, specifically, hepatic events, allergic reactions, thrombocytopenia and hemorrhage events, all Grade \>/= 3 AEs related to trastuzumab emtansine and pneumonitis events of all grades.

Time frame: Baseline up to approximately 7 years

Population: The safety population included all participants who had received at least 1 dose of study medication.

DOR is defined as the period from the date of initial confirmed PR or CR (whichever occurs first) until the date of PD or death from any cause. CR: disappearance of all target lesions. PR: At least a 30% decrease in the sum of diameters of all target lesions, taking as reference the baseline sum of diameters, in the absence of CR. PD: at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum of diameters on study (including baseline). In addition to the relative increase of 20%, the sum of diameters must also demonstrate an absolute increase of \>/= 5 millimeters (mm).

Time frame: Baseline up to disease progression or death due to any cause, whichever occurs first (assessed every 12 weeks during treatment period thereafter 28-42 days after the last dose or every 3-6 months up to approximately 7 years)

Population: ITT Population included all participants enrolled in the study. Only participants with measurable disease were included in the analysis.

The number of hospital visits were recorded to evaluate the resoruce expenditures while participants were on study treatment.

Time frame: Baseline up to approximately 7 years

Population: The safety population included all participants who had received at least 1 dose of study medication.

Overall survival is defined as time to death, which is the time from the date of dosing until the date of death, regardless of the cause of death.

Time frame: Baseline until death (up to approximately 7 years)

Population: ITT Population included all participants enrolled in the study.

AESIs included: 1) Potential drug-induced liver injury, which included any potential case of drug-induced liver injury as, assessed by laboratory criteria for Hy's law (AST and/or ALT elevations that were \>3 × ULN, Concurrent elevation of total bilirubin \>2 × ULN (or clinical jaundice if total bilirubin measures were not available), except in participants with documented Gilbert's syndrome. Those with Gilbert's syndrome, elevation of direct bilirubin \>2 × ULN was used instead. 2) Suspected transmission of an infectious agent by study drug was defined as any organism, virus, or infectious particle (e.g., prion protein transmitting transmissible spongiform encephalopathy), pathogenic or non-pathogenic. A transmission of an infectious agent suspected from clinical symptoms or laboratory findings indicating an infection in a participant exposed to a medicinal product.

Time frame: Baseline up to approximately 7 years

Population: The safety population included all participants who had received at least 1 dose of study medication.

Best Overall Response reported here is the Best confirmed Overall Response. To be assigned a status of PR or CR, i.e., to be a responder, changes in tumor measurements had to be confirmed by repeat assessments that had to be performed no less than 4 weeks after the criteria for response were first met, i.e., participants needed to have two consecutive assessments of PR or CR. CR: disappearance of all target lesions. PR: At least a 30% decrease in the sum of diameters of all target lesions, taking as reference the baseline sum of diameters, in the absence of CR.

Time frame: Baseline up to disease progression or death due to any cause, whichever occurs first (assessed every 12 weeks during treatment period thereafter 28-42 days after the last dose or every 3-6 months up to approximately 7 years)

Population: ITT Population included all participants enrolled in the study. Only participants with measurable disease were included in the analysis.

Clinical Benefit was defined as CR plus PR plus SD. CR: disappearance of all target lesions. PR: At least a 30% decrease in the sum of diameters of all target lesions, taking as reference the baseline sum of diameters, in the absence of CR. SD: neither sufficient shrinkage to qualify for CR or PR nor sufficient increase to qualify for PD.

Time frame: Baseline up to disease progression or death due to any cause, whichever occurs first (assessed every 12 weeks during treatment period thereafter 28-42 days after the last dose or every 3-6 months up to approximately 7 years)

Population: ITT Population included all participants enrolled in the study. Only participants with measurable disease were included in the analysis.

The AEPIs in this study were defined as the following: adverse events (AEs) Grade \>/= 3, specifically, hepatic events, allergic reactions, thrombocytopenia and hemorrhage events, all Grade \>/= 3 AEs related to trastuzumab emtansine and pneumonitis events of all grades.

Time frame: Baseline up to approximately 7 years

Population: The safety population included all participants who had received at least 1 dose of study medication.

Progression free survival is defined as the time (in months) between the date of first dose and the date of disease progression or death from any cause. Progressive disease (PD) is defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum of diameters on study (including baseline). In addition to the relative increase of 20%, the sum of diameters must also demonstrate an absolute increase of \>/= 5 millimeters (mm).

Time frame: Baseline up to disease progression or death due to any cause, whichever occurs first (assessed every 12 weeks during treatment period thereafter 28-42 days after the last dose or every 3-6 months up to approximately 7 years)

Population: Intent to Treat (ITT) Population included all participants enrolled in the study.

Time to Response is defined as the time from first dose to first documentation of confirmed PR or CR (whichever occurs first). CR: disappearance of all target lesions. PR: At least a 30% decrease in the sum of diameters of all target lesions, taking as reference the baseline sum of diameters, in the absence of CR.

Time frame: Baseline up to disease progression or death due to any cause, whichever occurs first (assessed every 12 weeks during treatment period thereafter 28-42 days after the last dose or every 3-6 months up to approximately 7 years)

Population: ITT Population included all participants enrolled in the study. Only responders were included in the analysis.

The type of hospital visits (intensive care unit (ICU) versus other) were recorded to evaluate the resoruce expenditures while participants were on study treatment. The number of participants with at least one ICU visit are based on the number of participants with at least one hospital visit, in each group.

Time frame: Baseline up to approximately 7 years

Population: The safety population included all participants who had received at least 1 dose of study medication.