{"groups":[{"description":"Non-randomized cohort. Participants received Tucatinib 300 milligrams (mg) orally (PO) twice daily (BID) on Days 1 to 21 of each 21-day cycle. Trastuzumab 8 milligram/kilogram (mg/kg) by intravenous (IV) infusion on Day 1 of Cycle 1 and 6 mg/kg on Day 1 of each subsequent cycle until progressive disease (PD), death, withdrawal of consent, study closure, or alternative therapy.","id":"FG000","title":"Tucatinib+Trastuzumab (Cohort A)"},{"description":"Randomized cohort. Participants received Tucatinib 300 mg PO BID on Days 1 to 21 of each 21-day cycle. Trastuzumab 8 mg/kg by IV infusion on Day 1 of Cycle 1 and 6 mg/kg on Day 1 of each subsequent cycle until PD, death, withdrawal of consent, study closure, or alternative therapy.","id":"FG001","title":"Tucatinib+Trastuzumab (Cohort B)"},{"description":"Participants received Tucatinib 300 mg PO BID on Days 1 to 21 of each 21-day cycle. Participants who did not respond to monotherapy were given the option to receive tucatinib and trastuzumab until PD, death, withdrawal of consent, study closure, or alternative therapy based on radiographic progression (as determined by investigator assessment using response evaluation criteria in solid tumors \\[RECIST\\] version \\[v\\] 1.1), or if they had not achieved a partial response (PR) or complete response (CR) by the week 12 assessment.","id":"FG002","title":"Tucatinib Monotherapy (Cohort C)"}],"periods":[{"dropWithdraws":[{"reasons":[{"groupId":"FG000","numSubjects":"5"},{"groupId":"FG001","numSubjects":"1"},{"groupId":"FG002","numSubjects":"1"}],"type":"Withdrawal by Subject"},{"reasons":[{"groupId":"FG000","numSubjects":"1"},{"groupId":"FG001","numSubjects":"1"},{"groupId":"FG002","numSubjects":"0"}],"type":"Lost to Follow-up"},{"reasons":[{"groupId":"FG000","numSubjects":"28"},{"groupId":"FG001","numSubjects":"26"},{"groupId":"FG002","numSubjects":"17"}],"type":"Death"},{"reasons":[{"groupId":"FG000","numSubjects":"11"},{"groupId":"FG001","numSubjects":"13"},{"groupId":"FG002","numSubjects":"13"}],"type":"Participation terminated by sponsor"}],"milestones":[{"achievements":[{"groupId":"FG000","numSubjects":"45"},{"groupId":"FG001","numSubjects":"41"},{"groupId":"FG002","numSubjects":"31"}],"type":"STARTED"},{"achievements":[{"groupId":"FG000","numSubjects":"0"},{"groupId":"FG001","numSubjects":"0"},{"groupId":"FG002","numSubjects":"0"}],"type":"COMPLETED"},{"achievements":[{"groupId":"FG000","numSubjects":"45"},{"groupId":"FG001","numSubjects":"41"},{"groupId":"FG002","numSubjects":"31"}],"type":"NOT COMPLETED"}],"title":"Overall Study"}],"recruitmentDetails":"A total of 117 participants were enrolled at a total of 56 sites in the United States, Italy, France, Belgium, and Spain. The date of first participant enrollment was 23-Jun-2017. The date of last participant randomization was 02-Nov-2023."}