A Study Evaluating Trastuzumab Emtansine Plus Pertuzumab Compared With Chemotherapy Plus Trastuzumab and Pertuzumab for Participants With Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Breast Cancer

tpCR was assessed by local pathology review on samples taken at surgery following completion of neoadjuvant therapy. tpCR was defined as the absence of any residual invasive cancer on hematoxylin and eosin evaluation of the resected breast specimen and all sampled ipsilateral lymph nodes ( that is [i.e.], ypT0/is, ypN0 in the American Joint Committee on Cancer [AJCC] staging system, 7th edition). Percentage of participants with tpCR was reported.

Overall survival in the overall study population was defined as the time from the date of randomization to the date of death from any cause. 3 years OS event-free rate per randomized treatment arms in the ITT population were estimated using the Kaplan-Meier method and estimated the probability of a patient being event-free after 3 years after treatment.

BCS rate was defined as the percentage of participants who achieve BCS out of the ITT population of participants without inflammatory breast cancer.

Event-free survival (EFS) is defined as the time from randomization to disease progression or disease recurrence (local, regional, distant, or contralateral, invasive or non-invasive), or death from any cause. 3 years EFS rate per randomized treatment arms in the ITT population were estimated using the Kaplan-Meier method and estimated the probability of a patient being event-free after 3 years after treatment.

IDFS is defined only for participants who undergo surgery. IDFS is defined as the time from surgery to the first documented occurrence of an IDFS event, defined as: Ipsilateral invasive breast tumor recurrence; Ipsilateral local-regional invasive breast cancer recurrence; Distant recurrence; Contralateral invasive breast cancer; and death from any cause. 3 years of IDFS event-free rate per randomized treatment arms in the ITT population were estimated using the Kaplan-Meier method and estimated the probability of a patient being event-free after 3 years after treatment.

Participants answered the question "Did you have tingling hands/feet?", from the Modified Quality of Life Questionnaire Breast Cancer 23 (mQLQ-BR23), on a 5-point scale (1 'Not at all', 2 'A little', 3 'Somewhat', 4 'Quite a bit', 5 'Very much'). Percentage of participants by each response was reported.

Participants answered the Question 1 "Did itching skin bother you?" and Question 2 "Have you had skin problems?", from the mQLQ-BR23, on a 5-point scale (1 'Not at all', 2 'A little', 3 'Somewhat', 4 'Quite a bit', 5 'Very much'). Percentage of participants by each response was reported.

Participants rated their quality of life (global health status) on European Organization for the Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire-Core 30 (QLQ- C30), with total scores ranging from 0 (worst) to 100 (best); where higher score indicates better quality of life. Clinically meaningful deterioration in GHS/QoL was defined as a decrease in score of 10 points in GHS/QoL.

Participants rated their quality of life (global health status) on EORTC QLQ C-30, with total scores ranging from 0 (worst) to 100 (best); where higher score indicates better quality of life. Time to deterioration was defined as the time from baseline to first 10-point (or greater) decrease as measured by GHS/QoL. All valid GHS/QoL questionnaires of the neoadjuvant phase including surgery were used. Participants without deterioration were censored at the time of completing the last GHS/QoL plus 1 day. Median time to deterioration was estimated with Kaplan-Meier method. The 95% confidence interval (CI) for the median was computed using the method of Brookmeyer and Crowley.

Participants rated their function on EORTC QLQ C-30, with total scores ranging from 0 (worst) to 100 (best); where higher score indicates better functioning. Time to deterioration was defined as the time from baseline to first 10-point (or greater) decrease as measured by physical function; to first 14-point (or greater) decrease as measured by role function, to first 7-point (or greater) decrease as measured by cognitive function. Median time to deterioration was estimated with Kaplan-Meier method. The 95% CI for the median was computed using the method of Brookmeyer and Crowley.

Only participants who received trastuzumab were to be analyzed for this outcome.

Only participants who received trastuzumab emtansine were to be analyzed for this outcome.

Only participants who received trastuzumab were to be analyzed for this outcome.

Only participants who received trastuzumab emtansine were to be analyzed for this outcome.

DM1 is the metabolite of trastuzumab emtansine. Only participants who received trastuzumab emtansine were to be analyzed for this outcome.

Participants answered the Question "Have you lost any hair?", from the mQLQ-BR23, on a 5-point scale (1 'Not at all', 2 'A little', 3 'Somewhat', 4 'Quite a bit', 5 'Very much'). Percentage of participants by each response was reported.

Selected AEs included hepatotoxicity, pulmonary toxicity, cardiac dysfunction, neutropenia, thrombocytopenia, peripheral neuropathy, hemorrhage, infusion related reaction (IRR)/hypersensitivity, IRR/Hypersensitivity symptoms, rash, diarrhea and mucositis. An AE was defined as any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product, regardless of causal attribution.

Participants rated their function on EORTC QLQ C-30, with total score and single-item (physical, cognitive and role functioning) scores ranging from 0 (worst) to 100 (best); where higher score indicates better functioning. Clinically meaningful deterioration was defined as a decrease in score of 10 points in physical function; decrease of 7 points in cognitive function and decrease of 14 points in role function.

Participants were considered post-baseline ATA positive if they had ATAs post-baseline that were either treatment-induced or treatment-enhanced. Participants had treatment-induced ATAs if they had a negative or missing ATA result at baseline, and at least one positive ATA result post-baseline. Participants had treatment-enhanced ATAs if they had a positive ATA result at baseline, and at least one positive ATA result post-baseline that was greater than or equal to (>/=) 0.60 titer units higher than the result at baseline.

Participants rated their symptoms on EORTC QLQ C-30 and mQLQ-BR23, with total scores ranging from 0 (worst) to 100 (best); where higher score indicates greater degree of symptoms. Clinically meaningful increase in symptoms was defined as an increase in score (deterioration) of 11 points in nausea and vomiting, pain, dyspnea; increase of 9 points in insomnia; increase of 14 points in appetite loss; increase of 15 points in diarrhea, constipation; increase of 10 points in fatigue, systemic therapy side effects, hair loss.