Ultra-high combined positive score and high serum albumin are favorable prognostic biomarkers for immune checkpoint inhibitors in head and neck squamous cell carcinoma

Background: Biomarkers that predict response to immune checkpoint inhibitor (ICI) in recurrent metastatic squamous cell carcinoma of the head and neck (RMHNSCC) are not well known.Methods: We prospectively measured the combined positive score (CPS) and administered ICI to patients with RMHNSCC.Results: Of 51 patients, 23 patients had a CPS <20 and 12 patients (23.5%) had a CPS >= 90. CPS showed a negative correlation with serum albumin. Survival analysis showed a 2-year survival rate of 24.1%. In multivariate analysis, CPS >= 90 (HR 0.3026, p = 0.02614) and albumin >3.5 (HR 0.3463, p = 0.01354) were the significant factors and plus chemotherapy (HR 0.4648, p = 0.07632) was not significant. Seven patients (14%) with CPS >= 90 and albumin >3.5 showed a 2-year survival rate of 66. 7%.Conclusions: CPS >= 90 and albumin >3.5 cases are a subgroup of RMHNSCC that respond extremely well to ICI.