{"groups":[{"description":"Participants received pembrolizumab 200 mg intravenously (IV) on Day 1 of each 3-week cycle for up to 35 cycles (up to \\~2 years). Qualified participants who received the first course of pembrolizumab but continued to experience disease progression may have, at the investigator's discretion, initiated a second course of pembrolizumab at the same dose and schedule of 200 mg IV on Day 1 of each 3-week cycle for up to 17 cycles (up to \\~1 year).","id":"FG000","title":"Pembrolizumab Monotherapy (Pembro Mono)"},{"description":"Participants received pembrolizumab 200 mg IV on Day 1 of each 3-week cycle for up to 35 cycles (up to \\~2 years); plus cisplatin 100 mg/m\\^2 IV or carboplatin at a target area under the curve of 5 (AUC 5) IV, per Investigator's choice, on Day 1 of each 3-week cycle (6 cycle maximum \\[up to \\~4 months\\]); plus 5-Fluorouracil (5-FU) 1000 mg/m\\^2/day IV continuous from Day 1-4 of each 3-week cycle (6 cycle maximum \\[up to \\~4 months\\]). Qualified participants who received the first course of pembrolizumab but continued to experience disease progression may have, at the investigator's discretion, initiated a second course of pembrolizumab at the same dose and schedule of 200 mg IV on Day 1 of each 3-week cycle for up to 17 cycles (up to \\~1 year).","id":"FG001","title":"Pembrolizumab + Chemotherapy (Pembro Combo)"},{"description":"Participants received cetuximab on Day 1 at a dose of 400 mg/m\\^2 IV, and then 250 mg/m\\^2 IV on Day 1 of each subsequent week until disease progression or unacceptable toxicity; plus cisplatin 100 mg/m\\^2 IV or carboplatin AUC 5 IV (Investigator's choice) on Day 1 of each 3-week cycle (6 cycle maximum \\[up to \\~4 months\\] for platinum-based therapy); plus 5-FU 1000 mg/m\\^2/day IV continuous from Day 1-4 of each 3-week cycle (6 cycle maximum \\[up to \\~4 months\\]).","id":"FG002","title":"Cetuximab + Chemotherapy (Control)"}],"periods":[{"dropWithdraws":[{"reasons":[{"groupId":"FG000","numSubjects":"253"},{"groupId":"FG001","numSubjects":"237"},{"groupId":"FG002","numSubjects":"266"}],"type":"Death"},{"reasons":[{"groupId":"FG000","numSubjects":"1"},{"groupId":"FG001","numSubjects":"1"},{"groupId":"FG002","numSubjects":"0"}],"type":"Lost to Follow-up"},{"reasons":[{"groupId":"FG000","numSubjects":"19"},{"groupId":"FG001","numSubjects":"14"},{"groupId":"FG002","numSubjects":"18"}],"type":"Withdrawal by Subject"},{"reasons":[{"groupId":"FG000","numSubjects":"26"},{"groupId":"FG001","numSubjects":"28"},{"groupId":"FG002","numSubjects":"16"}],"type":"Sponsor Decision"}],"milestones":[{"achievements":[{"groupId":"FG000","numSubjects":"301"},{"groupId":"FG001","numSubjects":"281"},{"groupId":"FG002","numSubjects":"300"}],"type":"STARTED"},{"achievements":[{"groupId":"FG000","numSubjects":"300"},{"groupId":"FG001","numSubjects":"276"},{"groupId":"FG002","numSubjects":"287"}],"type":"Treated"},{"achievements":[{"groupId":"FG000","numSubjects":"301"},{"groupId":"FG001","numSubjects":"0"},{"groupId":"FG002","numSubjects":"300"}],"type":"Pembro Mono v Control Efficacy Analyses"},{"achievements":[{"groupId":"FG000","numSubjects":"0"},{"groupId":"FG001","numSubjects":"281"},{"groupId":"FG002","numSubjects":"278"}],"type":"Pembro Combo v Control Efficacy Analyses"},{"achievements":[{"groupId":"FG000","numSubjects":"8"},{"groupId":"FG001","numSubjects":"6"},{"groupId":"FG002","numSubjects":"0"}],"type":"Received Second Course of Pembrolizumab"},{"achievements":[{"groupId":"FG000","numSubjects":"2"},{"groupId":"FG001","numSubjects":"1"},{"groupId":"FG002","numSubjects":"0"}],"type":"COMPLETED"},{"achievements":[{"groupId":"FG000","numSubjects":"299"},{"groupId":"FG001","numSubjects":"280"},{"groupId":"FG002","numSubjects":"300"}],"type":"NOT COMPLETED"}],"title":"Overall Study"}],"preAssignmentDetails":"Of 1228 participants screened, 882 were randomized to the pembro mono arm, pembro combo arm, or control arm. 22 participants in the control arm that enrolled during an enrollment pause of the pembro combo arm were excluded from efficacy comparisons between the pembro combo arm and control arm.\n\nPer protocol, response/progression or adverse events (AEs) that occurred during the second pembrolizumab course were not counted towards efficacy outcome measures or safety outcome measures, respectively.","recruitmentDetails":"Participants with first line recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) were recruited to examine the efficacy and safety of pembrolizumab monotherapy (pembro mono) versus pembrolizumab plus chemotherapy (pembro combo) versus cetuximab plus chemotherapy (control)."}