Tislelizumab in Combination With Investigational Agents in Participants With Head and Neck Squamous Cell Carcinoma

Inclusion Criteria: Participants with histologically or cytologically confirmed R/M HNSCC that is considered incurable by local therapies The eligible primary tumor locations are oropharynx, oral cavity, hypopharynx, and larynx Participants should not have had prior systemic therapy administered in the R/M setting; systemic therapy which was completed prior to randomization/enrollment if given as part of multimodal treatment for locally or locoregionally advanced disease is allowed Participants must have positive PD-L1 expression (Combined Positive Score [CPS] ≥ 1) Have at least 1 measurable lesion as defined per RECIST v1.1 Eastern Cooperative Oncology Group Performance Status of 0 or 1 Adequate hematologic and organ function as indicated by specific laboratory values within 7 days of first dose of study drug Willing to use a highly effective method of birth control for the duration of the study and for ≥ 120 days after the last dose of study drug(s) Exclusion Criteria: Recurrent or metastatic carcinoma of the nasopharynx (any histology), squamous cell carcinoma of unknown primary, squamous cell carcinoma that originated from the skin and salivary gland primary tumor or non-squamous histologies (eg, mucosal melanoma) Prior therapy with an anti-PD-1, anti-PD-L1, PD-L2, T-cell immunoglobulin and mucin domain containing-3 (TIM-3), LAG-3, or any other antibody or drug specifically targeting T-cell costimulation or immune checkpoint pathways Any active malignancy ≤ 2 years before randomization/enrollment except for the specific cancer under investigation in this study, those with a negligible risk of metastasis or death, and any locally recurring cancer that has been treated curatively (eg, resected basal or squamous cell skin cancer, superficial bladder cancer, localized prostate cancer, and carcinoma in situ of the cervix or breast) History of interstitial lung disease, noninfectious pneumonitis, or uncontrolled lung diseases including pulmonary fibrosis, and acute lung diseases A history of severe hypersensitivity reactions to other monoclonal antibodies or has experienced a severe immune-mediated adverse event (imAE), an imAE that led to treatment discontinuation, or a cardiac or ocular imAE of any grade with prior immunotherapy Note: Other inclusion and exclusion criteria may apply