A Study of Pertuzumab in Combination With Trastuzumab and Chemotherapy in Participants With Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Metastatic Gastroesophageal Junction or Gastric Cancer

Overall survival (OS) was defined as the time from randomization to death from any cause. For participants who were still alive on the date of clinical data cut-off for the OS analysis, the last date when the participant was known to be alive on, or prior to the clinical cut-off date, was used to determine the censoring date. Participants who did not have any post-baseline data (e.g., dosing records, imaging dates, visit dates) were censored at the date of randomization plus 1 day.

Progression-free survival (PFS) is defined as the time from randomization to the first occurrence of progressive disease (PD), as determined by the investigator using RECIST v1.1, or death from any cause, whichever occurred first. Tumor assessments with CT or MRI scans of the chest, abdomen, and pelvis were performed every 9 weeks. Participants without documented PD or death were censored at the tumor assessment date for which the participant was last known to be progression-free. Participants who did not have any post-baseline tumor assessment data were censored at the date of randomization plus 1 day. PD was defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study, including baseline; an absolute increase of at least 5 millimeters (mm) in the sum of diameters of target lesions; the appearance of one or more new lesions.

The overall objective response rate was defined as the percentage of participants with partial response (PR) or complete response (CR) occurring on two consecutive occasions ≥4 weeks apart, as determined by the investigator using RECIST v1.1. Tumor assessments with computed tomography (CT) or magnetic resonance imaging (MRI) scans of the chest, abdomen, and pelvis were performed every 9 weeks. PR: at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of diameters. CR: disappearance of all target lesions. Measurable disease is defined as tumor lesions measured in at least one dimension (longest diameter in plane of measurement) with a minimum size of: 10 mm by CT or MRI scan; 10 mm caliper measurement by clinical examination; 20 mm by chest X-ray. For a malignant lymph node to be considered pathologically enlarged and measurable, it must be greater than or equal to (≥) 15 mm in short axis when assessed by CT scan.

The overall objective response rate was defined as the percentage of participants with partial response (PR) or complete response (CR) occurring on two consecutive occasions ≥4 weeks apart, as determined by the investigator using RECIST v1.1. Tumor assessments with computed tomography (CT) or magnetic resonance imaging (MRI) scans of the chest, abdomen, and pelvis were performed every 9 weeks. PR: at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of diameters. CR: disappearance of all target lesions. Measurable disease is defined as tumor lesions measured in at least one dimension (longest diameter in plane of measurement) with a minimum size of: 10 mm by CT or MRI scan; 10 mm caliper measurement by clinical examination; 20 mm by chest X-ray. For a malignant lymph node to be considered pathologically enlarged and measurable, it must be greater than or equal to (≥) 15 mm in short axis when assessed by CT scan.

Duration of objective response is defined as the time from first occurrence of documented objective response to documented disease progression, as determined by the investigator using RECIST v1.1, or death from any cause. Objective response: PR or CR occurring on 2 consecutive occasions ≥4 weeks apart. PR: at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of diameters. CR: disappearance of all target lesions. PD: at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study, including baseline; an absolute increase of at least 5 mm in the sum of diameters of target lesions; the appearance of one or more new lesions. Measurable disease defined as tumor lesions with a minimum size of: 10 mm by CT or MRI scan; 10 mm caliper measurement by clinical examination; 20 mm by chest X-ray. For a malignant lymph node, it must be ≥15 mm in short axis when assessed by CT scan.

The clinical benefit rate was defined as best response of complete response (CR) or partial response (PR) or stable disease (SD) for 6 weeks or longer, as determined by the investigator using RECIST v1.1. CR: disappearance of all target lesions. PR: at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of diameters. SD: neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for disease progression, taking as reference the smallest sum diameters while on study. Measurable disease is defined as tumor lesions measured in at least one dimension (longest diameter in plane of measurement) with a minimum size of: 10 mm by CT or MRI scan; 10 mm caliper measurement by clinical examination; 20 mm by chest X-ray. For a malignant lymph node to be considered pathologically enlarged and measurable, it must be >/=15 mm in short axis when assessed by CT scan. The clinical benefit rate was not updated at the final analysis.

An adverse event (AE) is any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product, regardless of causal attribution. The investigator graded all AEs for severity per the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE), Version 4.03; if not listed, the AE was assessed as follows: Grade 1 = mild; Grade 2 = moderate; Grade 3 = severe; Grade 4 = life-threatening/disabling; Grade 5 = death. The investigator determined whether an AE was related to study drug and independently assessed severity and seriousness of each AE.

The number and percentage of participants with symptomatic left ventricular systolic dysfunction (LVSD) and asymptomatic LVSD events (defined as a left ventricular ejection fraction [LVEF] ≥10% decrease from baseline to an absolute value <50%) at any time during the study was summarized by treatment arm.

The EORTC QLQ-C30 included global health status, functional scales (physical, role, emotional, cognitive, and social), symptom scales (fatigue, nausea/vomiting, and pain) and single items (dyspnoea, insomnia, appetite loss, constipation, diarrhea, and financial difficulties). Most questions used a 4-point scale (1 'Not at all' to 4 'Very much'; 2 questions used 7-point scale [1 'very poor' to 7 'Excellent']). Scores were averaged and transformed to 0 - 100 scale, whereby higher scores indicate greater functioning, greater quality of life, or a greater degree of symptoms, with changes of 5 - 10 points considered to be a minimally important difference to participants. A positive value means an increase, while a negative value means a decrease, in score at the indicated time-point relative to the score at baseline (Cycle 1, Day 1).

The EORTC QLQ-STO22 is a gastric cancer quality of life questionnaire. There are 22 questions concerning disease, treatment related symptoms, side effects, dysphagia, nutritional aspects, and questions about the emotional problems of gastric cancer (dysphagia, pain, reflux, eating restrictions, anxiety, dry mouth, body image, and hair loss). The questions are grouped into five scales and 4 single items which are related to the symptoms of the disease. Most questions used 4-point scale (1 'Not at all' to 4 'Very much'; 1 question was a yes or no answer). A linear transformation was used to standardize all scores and single-items to a scale of 0 to 100; higher score=better level of functioning or greater degree of symptoms. A positive value means an increase, while a negative values means a decrease, in score at the indicated time-point relative to the score at baseline (Cycle 1, Day 1).