Longitudinal liquid biopsy identifies an early predictive biomarker of immune checkpoint blockade response in head and neck squamous cell carcinoma [bulk RNA-seq]

Immune checkpoint blockade (ICB) has improved outcomes in head and neck squamous cell carcinoma (HNSCC), yet there is an unmet need for predictive, blood-based biomarkers to guide treatment. We longitudinally profiled peripheral immune responses in a mouse HNSCC model treated with anti–PD-1, using single-cell and bulk RNA sequencing with paired TCR sequencing. Early expansion of effector memory T cells (Tem) and B cells was associated with ICB response. Here, we show that the LiBIO score, a composite of Tem and B cell signatures, robustly predicts ICB response in HNSCC blood and tumor cohorts, outperforming existing biomarkers. Furthermore, the LiBIO score generalizes to melanoma, non-small cell lung cancer, and breast cancer, demonstrating potential as a clinically applicable blood-based biomarker for ICB response across multiple cancer types.