A Study of Trastuzumab Emtansine (T-DM1) Plus Pertuzumab/Pertuzumab Placebo Versus Trastuzumab [Herceptin] Plus a Taxane in Participants With Metastatic Breast Cancer (MARIANNE)

Study Overview
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Brief Summary
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This randomized, 3-arm, multicenter, phase III study will evaluate the efficacy and safety of trastuzumab emtansine (T-DM1) with pertuzumab or trastuzumab emtansine (T-DM1) with pertuzumab-placebo (blinded for pertuzumab), versus the combination of trastuzumab (Herceptin) plus taxane (docetaxel or paclitaxel) in participants with HER2-positive progressive or recurrent locally advanced or previously untreated metastatic breast cancer. Participants will be randomized to 1 of 3 treatment arms (Arms A, B or C). Arm A will be open-label, whereas Arms B and C will be blinded.

Official Title
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A Randomized, 3 Arm, Multicenter, Phase III Study to Evaluate the Efficacy and the Safety of T-DM1 Combined With Pertuzumab or T-DM1 Combined With Pertuzumab-Placebo (Blinded for Pertuzumab), Versus the Combination of Trastuzumab Plus Taxane, as First Line Treatment in HER2 Positive Progressive or Recurrent Locally Advanced or Metastatic Breast Cancer

Conditions
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Breast Cancer

Intervention / Treatment
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* Drug: docetaxel
* Drug: paclitaxel
* Drug: pertuzumab
* Drug: pertuzumab-placebo
* Drug: trastuzumab [Herceptin]
* Drug: trastuzumab emtansine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult participants >/=18 years of age HER2-positive breast cancer Histologically or cytologically confirmed adenocarcinoma of the breast with locally recurrent or metastatic disease, and be a candidate for chemotherapy. Participants with locally advanced disease must have recurrent or progressive disease, which must not be amenable to resection with curative intent. Participants must have measurable and/or non-measurable disease which must be evaluable per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1 Adequate organ function as determined by laboratory results Exclusion Criteria: History of prior (or any) chemotherapy for metastatic breast cancer or recurrent locally advanced disease An interval of <6 months from the last dose of vinca-alkaloid or taxane cytotoxic chemotherapy until the time of metastatic diagnosis Hormone therapy <7 days prior to randomization Trastuzumab therapy and/or lapatinib (neo- or adjuvant setting) <21 days prior to randomization Prior trastuzumab emtansine or pertuzumab therapy

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Trastuzumab + Taxane (docetaxel or paclitaxel)<br> | Drug: docetaxel<br>* 75 mg/m2 or 100 mg/m2 intravenously every 3 weeks for a minimum of 6 cycles.<br>Drug: paclitaxel<br>* 80 mg/m2 intravenously weekly for a minimum of 18 weeks<br>Drug: trastuzumab [Herceptin]<br>* trastuzumab [Herceptin] doses when administered with docetaxel: 8 mg/kg intravenously on cycle 1 followed by 6 mg/kg every 3 weeks in subsequent cycles or trastuzumab (Herceptin) doses when administered with paclitaxel: 4 mg/kg intravenously on day 1 of cycle 1 followed by 2 mg/kg weekly starting on day 8 of cycle 1.<br>|
| Experimental: Trastuzumab emtansine + pertuzumab<br> | Drug: pertuzumab<br>* 840 mg intravenously on day 1 of cycle 1 followed by 420 mg intravenously every 3 weeks in subsequent cycles<br>Drug: trastuzumab emtansine<br>* 3.6 mg/kg intravenously every 3 weeks<br>|
| Experimental: Trastuzumab emtansine + pertuzumab placebo<br> | Drug: pertuzumab-placebo<br>* 840 mg intravenously on day 1 of cycle 1 followed by 420 mg intravenously every 3 weeks in subsequent cycles<br>Drug: trastuzumab emtansine<br>* 3.6 mg/kg intravenously every 3 weeks<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Participants With Death or Disease Progression According to Independent Review Facility (IRF) Assessment | Tumor assessments were performed according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. Disease progression was defined as a greater than or equal to (≥) 20 percent (%) and 5-millimeter (mm) increase in sum of diameters of target lesions, taking as reference the smallest sum obtained during the study, or appearance of new lesion(s). The percentage of participants with death or disease progression was calculated as [number of participants with event divided by the number analyzed] multiplied by 100. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| Progression-Free Survival (PFS) According to IRF Assessment | Tumor assessments were performed according to RECIST version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. PFS was defined as the time from randomization to first documented disease progression or death from any cause. Disease progression was defined as a ≥20% and 5-mm increase in sum of diameters of target lesions, taking as reference the smallest sum obtained during the study, or appearance of new lesion(s). Median duration of PFS was estimated using Kaplan-Meier analysis, and corresponding confidence intervals (CIs) were computed using the Brookmeyer-Crowley method. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Participants Who Died Prior to Clinical Cutoff | The percentage of participants who died prior to clinical cutoff was calculated as [number of participants with event divided by the number analyzed] multiplied by 100. | Up to 70 months from randomization until clinical cutoff of 15-May-2016 (every 3 months until death, loss to follow-up, withdrawal, or study termination) | 
| Overall Survival (OS) at Clinical Cutoff | OS was defined as the time from randomization to death from any cause. Median duration of OS was estimated using Kaplan-Meier analysis, and corresponding CIs were computed using the Brookmeyer-Crowley method. | Up to 70 months from randomization until clinical cutoff of 15-May-2016 (every 3 months until death, loss to follow-up, withdrawal, or study termination) | 
| Percentage of Participants With Death or Disease Progression According to Investigator Assessment | Tumor assessments were performed by the investigator according to RECIST version 1.1. Disease progression was defined as a ≥20% and 5-mm increase in sum of diameters of target lesions, taking as reference the smallest sum obtained during the study, or appearance of new lesion(s). The percentage of participants with death or disease progression was calculated as [number of participants with event divided by the number analyzed] multiplied by 100. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| PFS According to Investigator Assessment | Tumor assessments were performed by the investigator according to RECIST version 1.1. PFS was defined as the time from randomization to first documented disease progression or death from any cause. Disease progression was defined as a ≥20% and 5-mm increase in sum of diameters of target lesions, taking as reference the smallest sum obtained during the study, or appearance of new lesion(s). Median duration of PFS was estimated using Kaplan-Meier analysis, and corresponding CIs were computed using the Brookmeyer-Crowley method. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| Percentage of Participants Experiencing Treatment Failure | Treatment failure was defined as the discontinuation of all study medications in the treatment arm for any reason including disease progression, treatment toxicity, death, physician decision, or participant withdrawal. The percentage of participants with treatment failure was calculated as [number of participants with event divided by the number analyzed] multiplied by 100. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 | 
| Time to Treatment Failure (TTF) | Treatment failure was defined as the discontinuation of all study medications in the treatment arm for any reason including disease progression, treatment toxicity, death, physician decision, or participant withdrawal. TTF was defined as the time from randomization to treatment failure. Median TTF was estimated using Kaplan-Meier analysis, and corresponding CIs were computed using the Brookmeyer-Crowley method. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 | 
| One-Year Survival Rate | The percentage of participants alive at 1 year after randomization was estimated as the one-year survival rate using Kaplan-Meier analysis, and corresponding CIs were computed using Greenwood's estimate of the standard error. | From randomization until 1 year | 
| Percentage of Participants With Grade ≥3 Adverse Events | Adverse events were graded according to National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Grade 3: Severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; limiting self care activity of daily living with inability to perform bathing, dressing and undressing, feeding self, using the toilet, taking medications but not bedridden. Grade 4: An immediate threat to life. Urgent medical intervention is required in order to maintain survival. Grade 5: Death. | Up to 50 months from randomization until clinical cutoff of 16-Sept-2014 (continuously until 28 days after last dose | 
| Percentage of Participants Who Died at 2 Years |  | From randomization until 2 years | 
| Overall Survival Truncated at 2 Years | Overall Survival truncated at 2 years was defined as the percentage of participants alive at 2 years. | From randomization until 2 years | 
| Percentage of Participants With Grade 5 Adverse Events | Adverse events were graded according to NCI CTCAE version 4.0. Grade 5 adverse events are those events which led to death. | Up to 50 months from randomization until clinical cutoff of 16-Sept-2014 (continuously until 28 days after last dose) | 
| Percentage of Participants With Grade 3-4 Laboratory Parameters | Laboratory results were graded according to NCI CTCAE version 4.0. Grade 3: Severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; limiting self care activity of daily living with inability to perform bathing, dressing and undressing, feeding self, using the toilet, taking medications but not bedridden. Grade 4: An immediate threat to life. Urgent medical intervention is required in order to maintain survival. | Day 1, 8, and 15 of Cycle 1-3 and on Day 1 of each subsequent cycle up to 50 months from randomization until clinical cutoff of 16-Sept-2014 | 
| Percentage of Participants With Decline of ≥2 Points From Baseline in Eastern Cooperative Oncology Group (ECOG) Performance Status | The ECOG performance status is a scale used to quantify cancer participants' general well-being and activities of daily life. The scale ranges from 0 to 5, with 0 denoting perfect health and 5 indicating death. The 6 categories are 0=Asymptomatic (Fully active, able to carry on all predisease activities without restriction), 1=Symptomatic but completely ambulatory (Restricted in physically strenuous activity but ambulatory and able to carry out work of a light or sedentary nature), 2=Symptomatic, < 50% in bed during the day (Ambulatory and capable of all self-care but unable to carry out any work activities. Up and about more than 50% of waking hours), 3=Symptomatic, > 50% in bed, but not bedbound (Capable of only limited self-care, confined to bed or chair 50% or more of waking hours), 4=Bedbound (Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair), 5=Death. | Baseline, Day 1 of every Cycle up to Clinical Data Cut (up to 48 months) | 
| Hospitalization Days | Hospitalization was defined as a non-administration-related hospitalization due to serious adverse event, while on study treatment. Reported values represent number of days admitted per participants. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 | 
| Percentage of Participants With Hospitalization | Hospitalization was defined as a non-administration-related hospitalization due to serious adverse event, while on study treatment. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 | 
| Percentage of Participants With Objective Response According to IRF Assessment | Objective response was defined as having complete response (CR) or partial response (PR), assessed according to RECIST version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. CR was defined as the disappearance of all target and non-target lesions and short-axis reduction in pathological lymph nodes to <10 mm. PR was defined as a ≥30% decrease in sum of diameters of target lesions, taking as reference the Baseline sum. Response was determined using 2 consecutive tumor assessments at least 4 weeks apart. The percentage of participants with a best overall response of CR or PR (ie, the objective response rate [ORR]) was calculated as [number of participants meeting the respective criteria divided by the number analyzed] multiplied by 100. Corresponding CIs were computed using the Blyth-Still-Casella exact method. | Up to 46 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| Percentage of Participants With Objective Response According to Investigator Assessment | Objective response was defined as having CR or PR, assessed according to RECIST version 1.1, by investigator. CR was defined as the disappearance of all target and non-target lesions and short-axis reduction in pathological lymph nodes to <10 mm. PR was defined as a ≥30% decrease in sum of diameters of target lesions, taking as reference the Baseline sum. Response was determined using 2 consecutive tumor assessments at least 4 weeks apart. The percentage of participants with a best overall response of CR or PR (ie, the ORR) was calculated as [number of participants meeting the respective criteria divided by the number analyzed] multiplied by 100. Corresponding CIs were computed using the Blyth-Still-Casella exact method. | Up to 46 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| Duration of Response According to IRF Assessment | Tumor assessments were performed according to RECIST version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. Duration of response was defined as the time from confirmed PR or CR to first documented disease progression or death from any cause. CR was defined as the disappearance of all target lesions and non-target lesions and short-axis reduction in pathological lymph nodes to <10 mm. PR was defined as a ≥30% decrease in sum of diameters of target lesions, taking as reference the Baseline sum. Response was determined using 2 consecutive tumor assessments at least 4 weeks apart. Median duration of response was estimated using Kaplan-Meier analysis, and corresponding CIs were computed using the Brookmeyer-Crowley method. | Up to 46 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| Percentage of Participants With a Best Overall Response of CR, PR, or Stable Disease (SD) According to IRF Assessment | Tumor assessments were performed according to RECIST version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. CR was defined as the disappearance of all target and non-target lesions and short-axis reduction in pathological lymph nodes to <10 mm. PR was defined as a ≥30% decrease in sum of diameters of target lesions, taking as reference the Baseline sum. SD was defined as neither sufficient shrinkage to quality for PR nor sufficient (20%) increase to qualify for disease progression. Response was determined using 2 consecutive tumor assessments at least 4 weeks apart. The percentage of participants with a best overall response of CR, PR, or SD was calculated as [number of participants meeting the respective criteria divided by the number analyzed] multiplied by 100. | Up to 46 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| Percentage of Participants Experiencing a Clinically Significant Increase in Taxane-Related Treatment Symptoms as Measured by Taxane Subscale of the Functional Assessment of Cancer Therapy (FACT) Taxane (FACT-TaxS) Score | The FACT-Taxane is a self-reported instrument which measures the health-related quality of life (HRQOL) of participants receiving taxane-containing chemotherapy. The FACT-TaxS consists of 16 items including 11 neurotoxicity-related questions and 5 additional questions assessing arthralgia, myalgia, and skin discoloration. Items are rated from 0 (not at all) to 4 (very much) and a total score is inversely derived. Scores may range from 0 to 64, with higher scores indicating fewer/no symptoms. A minimally clinically important difference in treatment-related symptoms was defined as a ≥5% decrease (ie, 3.2 points) in FACT-TaxS score from Baseline. The percentage of participants with treatment-related symptoms was calculated using following formula: [number of participants meeting the above threshold divided by the number analyzed] multiplied by 100. Corresponding CIs were computed using the Blyth-Still-Casella exact method. | Up to 39 months from randomization until clinical cutoff of 16-Sept-2014 (at Baseline, on Day 1 of Cycles 2 to 8 and every even-numbered cycle thereafter and/or up to 42 days after last dose) | 
| Percentage of Participants Reporting Nausea According to the Relevant Single Items of The FACT Colorectal Cancel (FACT-C) Module | The FACT-C is a self-reported instrument which measures HRQOL pertaining to colorectal cancer. Response options on each question may range from 0 (not at all) to 4 (very much). The percentage of participants with nausea was calculated using following formula: [number of participants with any level of either symptom divided by the number analyzed] multiplied by 100. | At Baseline, Day 8 of Cycle 1, and Days 1 and 8 of Cycle 2 | 
| Percentage of Participants Reporting Diarrhea According to the Relevant Single Items of The FACT-C Module | The FACT-C is a self-reported instrument which measures HRQOL pertaining to colorectal cancer. Response options on each question may range from 0 (not at all) to 4 (very much). The percentage of participants with diarrhea was calculated using following formula: [number of participants with any level of either symptom divided by the number analyzed] multiplied by 100. | At Baseline, Day 8 of Cycle 1, and Days 1 and 8 of Cycle 2 | 
| Percentage of Participants With a Clinically Significant Deterioration in Health Related Quality of Life (HRQoL) as Measured by FACT Breast (FACT-B) Trial Outcome Index-Physical Function Breast (TOI-PFB) Score | The FACT-B is a self-reported instrument which measures HRQOL of participants with breast cancer. It consists of 5 subscales including physical well-being (PWB), social well-being (SWB), emotional well-being (EWB), functional well-being (FWB), and a breast cancer subscale (BCS). The TOI-PFB score is taken by adding the scores from the PWB (7 items), FWB (7 items), and BCS (9 items) subscales. Items are rated from 0 (not at all) to 4 (very much) and a total score is derived. Scores may range from 0 to 92, with higher scores indicating better HRQOL. A 5 point change has been identified as the clinically minimal important difference (CMID) on the FACT-TOI-PFB scale. The percentage of participants with deterioration was calculated as [number of participants meeting the above threshold divided by the number analyzed] multiplied by 100. | Up to 39 months from randomization until clinical cutoff of 16-Sept-2014 (at Baseline, on Day 1 of Cycles 2 to 8 and every even-numbered cycle thereafter and/or up to 42 days after last dose) | 
| Time to Deterioration in HRQoL as Assessed by FACT-B TOI-PFB Score | The FACT-B is a self-reported instrument which measures HRQOL of participants with breast cancer. It consists of 5 subscales including PWB, SWB, EWB, FWB, and BCS. The TOI-PFB score is taken by adding the scores from the PWB (7 items), FWB (7 items), and BCS (9 items) subscales. Items are rated from 0 (not at all) to 4 (very much) and a total score is derived. Scores may range from 0 to 92, with higher scores indicating better HRQOL. A 5 point change has been identified as the clinically minimal important difference (CMID) on the FACT-TOI-PFB scale. Time to deterioration was defined as the time from Baseline until the first decrease in FACT-B TOI-PFB score. Median time to deterioration was estimated using Kaplan-Meier analysis, and corresponding CIs were computed using the Brookmeyer-Crowley method. | Baseline up to 39 months from randomization until clinical cutoff of 16-Sept-2014 | 
| Change From Baseline in Rotterdam Symptom Checklist (RSCL) Activity Level Scale Score | The RSCL is a self-reported instrument which consists of 4 domains including physical symptom distress, psychological distress, activity level, and overall global life quality. Only the activity level scale was collected and assessed. Scores may range from 0 to 100, with higher scores indicating increased burden of disease. Mean RSCL activity scale score changes were calculated as [mean score at the assessment visit minus mean score at Baseline]. The higher the score, the higher the level of impairment or burden. | Baseline, Cycle 7 (Week 18) | 
| Change From Baseline in Work Productivity According to Work Productivity and Activity Impairment (WPAI) Questionnaire Score | The WPAI is a patient-reported measure which assesses the effect of general health and symptom severity on work productivity and regular activities. The General Health questionnaire asks participants to estimate the number of hours missed from work due to reasons related and unrelated to their health problems, as well as the total number of hours actually worked in the preceding 7-day period. The percentage of participants reporting that they were employed (working for pay) was assessed at baseline was assessed along with Absenteeism (work time missed), Presenteeism (impairment at work / reduced on-the-job effectiveness), Work productivity loss (overall work impairment / absenteeism plus presenteeism), and Activity Impairment. The reported changes represent change from baseline at Cycle 7. The score range for the scales of the WPAI is between 0 (no effect) to 100% (max effect) | Baseline, Cycle 7 (Week 18) | 
| Change From Baseline in Activity Impairment According to Work Productivity and Activity Impairment (WPAI) Questionnaire Score | The WPAI is a patient-reported measure which assesses the effect of general health and symptom severity on work productivity and regular activities. The General Health questionnaire asks participants to estimate the number of hours missed from work due to reasons related and unrelated to their health problems, as well as the total number of hours actually worked in the preceding 7-day period. The percentage of participants reporting that they were employed (working for pay) was assessed at baseline was assessed along with Absenteeism (work time missed), Presenteeism (impairment at work / reduced on-the-job effectiveness), Work productivity loss (overall work impairment / absenteeism plus presenteeism), and Activity Impairment. The reported changes represent change from baseline at Cycle 7. The score range for the scales of the WPAI is between 0 (no effect) to 100% (max effect). | Baseline, Cycle 7 (Week 18) | 
| Percentage of Participants With a Best Overall Response of CR or PR According to IRF Assessment Among Those With High Human Epidermal Growth Factor Receptor 2 (HER2) Messenger Ribonucleic Acid (mRNA) Levels | Tumor assessments were performed according to RECIST version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. CR was defined as the disappearance of all target and non-target lesions and short-axis reduction in pathological lymph nodes to <10 mm. PR was defined as a ≥30% decrease in sum of diameters of target lesions, taking as reference the Baseline sum. Response was determined using 2 consecutive tumor assessments at least 4 weeks apart. The percentage of participants with a best overall response of CR or PR (ie, the ORR) was calculated as [number of participants meeting the respective criteria divided by the number analyzed] multiplied by 100. | Up to 46 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| Percentage of Participants With a Best Overall Response of CR or PR According to IRF Assessment Among Those With Low HER2 mRNA Levels | Tumor assessments were performed according to RECIST version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. CR was defined as the disappearance of all target and non-target lesions and short-axis reduction in pathological lymph nodes to <10 mm. PR was defined as a ≥30% decrease in sum of diameters of target lesions, taking as reference the Baseline sum. Response was determined using 2 consecutive tumor assessments at least 4 weeks apart. The percentage of participants with a best overall response of CR or PR (ie, the ORR) was calculated as [number of participants meeting the respective criteria divided by the number analyzed] multiplied by 100. | Up to 46 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| Percentage of Participants With Death or Disease Progression According to IRF Assessment Among Those With High HER2 mRNA Levels | Tumor assessments were performed according to RECIST version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. Disease progression was defined as a ≥20% and 5-mm increase in sum of diameters of target lesions, taking as reference the smallest sum obtained during the study, or appearance of new lesion(s). The percentage of participants with death or disease progression was calculated as [number of participants with event divided by the number analyzed] multiplied by 100. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| PFS According to IRF Assessment Among Those With High HER2 mRNA Levels | Tumor assessments were performed according to RECIST version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. PFS was defined as the time from randomization to first documented disease progression or death from any cause. Disease progression was defined as a ≥20% and 5-mm increase in sum of diameters of target lesions, taking as reference the smallest sum obtained during the study, or appearance of new lesion(s). Median duration of PFS was estimated using Kaplan-Meier analysis. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| Percentage of Participants With Death or Disease Progression According to IRF Assessment Among Those With Low HER2 mRNA Levels | Tumor assessments were performed according to RECIST version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. Disease progression was defined as a ≥20% and 5-mm increase in sum of diameters of target lesions, taking as reference the smallest sum obtained during the study, or appearance of new lesion(s). The percentage of participants with death or disease progression was calculated as [number of participants with event divided by the number analyzed] multiplied by 100. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| PFS According to IRF Assessment Among Those With Low HER2 mRNA Levels | Tumor assessments were performed according to RECIST version 1.1, using radiographic images submitted to the IRF up to and including the confirmatory tumor assessment 4 to 6 weeks after study drug discontinuation. PFS was defined as the time from randomization to first documented disease progression or death from any cause. Disease progression was defined as a ≥20% and 5-mm increase in sum of diameters of target lesions, taking as reference the smallest sum obtained during the study, or appearance of new lesion(s). Median duration of PFS was estimated using Kaplan-Meier analysis. | Up to 48 months from randomization until clinical cutoff of 16-Sept-2014 (at Screening, every 9 weeks for 81 weeks, then every 12 weeks thereafter and/or up to 42 days after last dose) | 
| Percentage of Participants Who Died Prior to Clinical Cutoff Among Those With High HER2 mRNA Levels | The percentage of participants who died prior to clinical cutoff was calculated as [number of participants with event divided by the number analyzed] multiplied by 100. | Up to 70 months from randomization until clinical cutoff of 15-May-2016 (every 3 months until death, loss to follow-up, withdrawal, or study termination) | 
| OS at Clinical Cutoff Among Those With High HER2 mRNA Levels | OS was defined as the time from randomization to death from any cause. Median duration of OS was estimated using Kaplan-Meier analysis. | Up to 70 months from randomization until clinical cutoff of 15-May-2016 (every 3 months until death, loss to follow-up, withdrawal, or study termination) | 
| Percentage of Participants Who Died Prior to Clinical Cutoff Among Those With Low HER2 mRNA Levels | The percentage of participants who died prior to clinical cutoff was calculated as [number of participants with event divided by the number analyzed] multiplied by 100. | Up to 70 months from randomization until clinical cutoff of 15-May-2016 (every 3 months until death, loss to follow-up, withdrawal, or study termination) | 
| OS at Clinical Cutoff Among Those With Low HER2 mRNA Levels | OS was defined as the time from randomization to death from any cause. Median duration of OS was estimated using Kaplan-Meier analysis. Reported upper bound of confidence interval for Trastuzumab Emtansine + Placebo and confidence interval values for Trastuzumab + Taxane and Trastuzumab Emtansine + Pertuzumab are censored values. | Up to 70 months from randomization until clinical cutoff of 15-May-2016 (every 3 months until death, loss to follow-up, withdrawal, or study termination) |