Trial Outcomes & Findings for Study of Pembrolizumab Given Prior to Surgery and in Combination With Radiotherapy Given Post-surgery for Advanced Head and Neck Squamous Cell Carcinoma (MK-3475-689) (NCT NCT03765918)

Per protocol, patient-reported outcome (PRO) measures (European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 \[EORTC QLQ-C30\] Global Health Status \[GHS\]/Quality of Life \[QoL\]\[Items 29 and 30\], EORTC QLQ-C30 \[Items 1-5\], EORTC QLQ-Head and Neck Module 35 \[H\&N35\] \[Items 35-38\], EORTC QLQ-H\&N35 \[Items 46, 53-54\], and EORTC QLQ-H\&N35 \[Items 31-34\] were reported separately for neoadjuvant and adjuvant treatment periods.

Two participants in the SOC arm received neoadjuvant treatment in error (protocol deviations). One of the participants (who received one cycle of neoadjuvant treatment) was included in the SOC arm for the efficacy and safety analyses per protocol. The other participant (who received 2 cycles of neoadjuvant treatment) was included in the SOC arm for efficacy analysis and in the Pembrolizumab + SOC arm for the safety analysis per protocol.

Study of Pembrolizumab Given Prior to Surgery and in Combination With Radiotherapy Given Post-surgery for Advanced Head and Neck Squamous Cell Carcinoma (MK-3475-689)

EFS was based on Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as assessed by blinded independent central review (BICR) and was defined as the time from randomization to any of the following events: radiographic disease progression (RDP; participants who undergo a definitive biopsy of the progressed lesion and are found to have no histologic evidence of invasive cancer will not meet criteria for an event), RDP during the neoadjuvant phase that precluded surgery, local or distant disease progression or recurrence (as assessed with imaging or biopsy as indicated), or death due to any cause. A secondary malignancy was not considered an EFS event. Per protocol, RECIST 1.1 was modified to allow up to 10 target lesions total (up to 5 per organ). Per protocol, EFS per RECIST 1.1 as assessed by BICR in all randomized participants was presented.

EFS was based on RECIST 1.1 as assessed by BICR and was defined as the time from randomization to any of the following events: RDP (participants who undergo a definitive biopsy of the progressed lesion and are found to have no histologic evidence of invasive cancer will not meet criteria for an event), RDP during the neoadjuvant phase that precluded surgery, local or distant disease progression or recurrence (as assessed with imaging or biopsy as indicated), or death due to any cause. A secondary malignancy was not considered an EFS event. Per protocol, RECIST 1.1 was modified to allow up to 10 target lesions total (up to 5 per organ). Per protocol, EFS per RECIST 1.1 as assessed by BICR in participants with PD-L1 CPS ≥10 was presented.

EFS was based on RECIST 1.1 as assessed by BICR and was defined as the time from randomization to any of the following events: RDP (participants who undergo a definitive biopsy of the progressed lesion and are found to have no histologic evidence of invasive cancer will not meet criteria for an event), RDP during the neoadjuvant phase that precluded surgery, local or distant disease progression or recurrence (as assessed with imaging or biopsy as indicated), or death due to any cause. A secondary malignancy was not considered an EFS event. Per protocol, RECIST 1.1 was modified to allow up to 10 target lesions total (up to 5 per organ). Per protocol, EFS per RECIST 1.1 as assessed by BICR in participants with PD-L1 CPS ≥1 was presented.

mPR rate was defined as the percentage of participants having ≤10% invasive squamous cell carcinoma within the resected primary tumor specimen and all sampled regional lymph nodes. Per protocol, mPR rate as assessed by blinded independent pathologist review (BIPR) at the time of definitive surgery in all randomized participants was presented.

mPR rate was defined as the percentage of participants having ≤10% invasive squamous cell carcinoma within the resected primary tumor specimen and all sampled regional lymph nodes. Per protocol, mPR rate as assessed by BIPR at the time of definitive surgery in participants with PD-L1 CPS ≥10 was presented.

mPR rate was defined as the percentage of participants having ≤10% invasive squamous cell carcinoma within the resected primary tumor specimen and all sampled regional lymph nodes. Per protocol, mPR rate as assessed by BIPR at the time of definitive surgery in participants with PD-L1 CPS ≥1 was presented.

pCR rate was defined as the percentage of participants having no residual invasive squamous cell carcinoma within the resected primary tumor specimen and all sampled regional lymph nodes. The pCR rate as assessed by BIPR at the time of definitive surgery in all randomized participants was presented.

pCR rate was defined as the percentage of participants having no residual invasive squamous cell carcinoma within the resected primary tumor specimen and all sampled regional lymph nodes. The pCR rate as assessed by BIPR at the time of definitive surgery in all randomized participants with PD-L1 CPS ≥10 was presented.

pCR rate was defined as the percentage of participants having no residual invasive squamous cell carcinoma within the resected primary tumor specimen and all sampled regional lymph nodes. The pCR rate as assessed by BIPR at the time of definitive surgery in all randomized participants with PD-L1 CPS ≥1 was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants with PD-L1 CPS ≥10 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants with PD-L1 CPS ≥1 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants with PD-L1 CPS ≥10 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants with PD-L1 CPS ≥1 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants with PD-L1 CPS ≥10 was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants with PD-L1 CPS ≥1 was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants with PD-L1 CPS ≥10 was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to questions regarding GHS ("How would you rate your overall health during the past week?") and QoL ("How would you rate your overall quality of life during the past week?") were scored on a 7-point scale (1= Very poor to 7=Excellent). The combined score of GHS (Item 29) and QoL (Item 30) were computed by averaging the raw scores of the 2 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in GHS and QoL combined score for all randomized participants with PD-L1 CPS ≥1 was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants with PD-L1 CPS ≥10 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants with PD-L1 CPS ≥1 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants with PD-L1 CPS ≥10 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants with PD-L1 CPS ≥1 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants with PD-L1 CPS ≥10 was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants with PD-L1 CPS ≥1 was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants with PD-L1 CPS ≥10 was presented.

EORTC QLQ-C30 is a questionnaire to assess the overall QoL of cancer patients. Participant responses to 5 questions about their physical functioning (Items 1 to 5) are scored on a 4-point scale (1=Not at All to 4=Very Much). The combined score of items 1 to 5 was computed by averaging the raw scores of the 5 items and then applying a linear transformation to standardize the average score, so that the combined scores ranged from 0-100. A higher score indicated a better outcome. Per protocol, the change from baseline in EORTC QLQ-C30 physical functioning (Items 1-5) combined score for all randomized participants with PD-L1 CPS ≥1 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants with PD-L1 CPS ≥10 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants with PD-L1 CPS ≥1 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants with PD-L1 CPS ≥10 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants with PD-L1 CPS ≥1 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants with PD-L1 CPS ≥10 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants with PD-L1 CPS ≥1 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants with PD-L1 CPS ≥10 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the swallowing scale (Items 35-38) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 swallowing symptoms (Items 35-38) combined score for all randomized participants with PD-L1 CPS ≥1 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants with PD-L1 CPS ≥10 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants with PD-L1 CPS ≥1 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants with PD-L1 CPS ≥10 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants with PD-L1 CPS ≥1 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants with PD-L1 CPS ≥10 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants with PD-L1 CPS ≥1 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants with PD-L1 CPS ≥10 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the speech scale (Items 46, 53-54) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 speech symptoms (Items 46, 53-54) combined score for all randomized participants with PD-L1 CPS ≥1 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants with PD-L1 CPS ≥10 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants with PD-L1 CPS ≥1 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants with PD-L1 CPS ≥10 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants with PD-L1 CPS ≥1 in the pembrolizumab + SOC arm was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants with PD-L1 CPS ≥10 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants with PD-L1 CPS ≥1 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants with PD-L1 CPS ≥10 was presented.

EORTC QLQ-H\&N35 is a 35-item questionnaire to assess QoL of head and neck cancer participants and consists of 7 multi-item scales (pain in the mouth, problems with swallowing, senses, speech, social eating, social contact, and sexuality). Participant responses to the pain scale (Items 31-34) were scored on a 4-point scale (1=Not at all to 4=Very much). Raw scores were standardized by linear transformation so that scores ranged from 0 to 100; a higher score indicated more problems. Per protocol, the change from baseline in EORTC QLQ-H\&N35 pain symptoms (Items 31-34) combined score for all randomized participants with PD-L1 CPS ≥1 was presented.

OS was defined as the time from randomization to death due to any cause. OS for all randomized participants was presented.

OS was defined as the time from randomization to death due to any cause. OS for all randomized participants with PD-L1 CPS ≥10 was presented.

OS was defined as the time from randomization to death due to any cause. OS for all randomized participants with PD-L1 CPS ≥1 was presented.

An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. An AE could have been any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated). The number of participants who experienced one or more AEs was reported.

An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. An AE could have been any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated). The number of participants who discontinued study treatment due to an AE was reported.