Study of Zanzalintinib (XL092) + Pembrolizumab vs Pembrolizumab in Subjects With PD-L1 Positive Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma

Primary Outcome Measures

1. Progression-Free Survival (PFS) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) by Blinded Independent Central Review (BICR)
   Defined as the time from randomization to the earlier of either radiographic progressive disease (PD) per RECIST 1.1 as determined by the BICR or death from any cause
2. Overall Survival (OS)
   Defined as the time from randomization to death due to any cause

Secondary Outcome Measures

1. PFS per RECIST 1.1 by Investigator
   Defined as the time from randomization to the earlier of either radiographic PD per RECIST 1.1 as determined by the Investigator or death from any cause
2. Objective Response Rate (ORR) per RECIST 1.1 by the BICR and Investigator
   Defined as the proportion of subjects with the best overall response of complete response (CR) or partial response (PR) per RECIST 1.1 as determined by the BICR and Investigator
3. Duration of Response (DOR) Per RECIST 1.1 by BICR and Investigator
   Defined as the time from the first documentation of objective response (subsequently confirmed at a visit ≥ 28 days later) to disease progression or death due to any cause