Precision immunotherapy for head and neck cancer: therapeutic combinations, biomarker strategies, and translational challenges.

Immune checkpoint inhibitors (ICIs) have fundamentally altered the therapeutic paradigm for head and neck squamous cell carcinoma (HNSCC); however, durable clinical benefit remains limited to biologically defined patient populations. These clinical limitations necessitate a shift away from empirical monotherapy toward precision-guided combination strategies that actively reprogram immune resistance. In this review, we integrate contemporary clinical and translational evidence regarding ICI-based combinations with radiotherapy (RT), chemotherapy, and emerging non-cytotoxic sensitization approaches, with particular emphasis on neoadjuvant and perioperative treatment settings. Central to these strategies is the dynamic remodeling of the tumor immune microenvironment (TIME), rather than simple amplification of immune activation. Recent studies demonstrate that immune-sensitizing interventions - including RT-induced immunogenic cell death, innate immune pathway activation, metabolic and microbiome modulation, and bioengineered drug delivery systems-can convert immunologically inert tumors into immune-interrogable tissues by restoring antigen presentation, spatial immune organization, and effector T-cell competence. Concurrently, integrative biomarker frameworks-encompassing PD-L1 expression, tumor mutational burden, tertiary lymphoid structures, tissue-resident memory T cells, and immune spatial organization-are redefining approaches to patient stratification and therapeutic sequencing. Despite compelling mechanistic rationale, clinical translation remains hindered by inadequate biomarker integration, heterogeneous clinical trial design, and discordance between biological endpoints and survival outcomes. Collectively, these advances delineate a transition from empiric combination therapy toward immune-centric precision immuno-oncology in HNSCC, underscoring the necessity for biomarker-driven trial design, longitudinal immune monitoring, and multidisciplinary collaboration to translate mechanistic synergy into durable clinical benefit.