Focusing on B2M, cases at the top tertile of tumor B2M expression were associated with improved PFS and OS [HR, 0.43; 95% confidence interval (CI), 0.21-0.9; p = 0.034 and HR, 0.41; 95% CI, 0.18-0.90; p = 0.047, respectively], by an orthogonal QIF method...Our study indicates that intact, highly functional antigen presentation, sustained by high B2M expression in tumor, confers survival benefit in ITx treated R/M HNSCC patients, an effect driven by increased intra-tumoral immunogenicity.