Abstract 5210: Tumor immune characterization identifies age-stratified biomarkers for nivolumab in patients with head and neck squamous cell carcinoma: A nationwide collaborative study in Japan

Background: Biomarkers predicting therapeutic response to immunotherapy have been widely explored via monitoring the liquid and tissue-derived components. Increasing treatment options for recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC) mandates prediction of the therapeutic response of anti-PD-1 antibody alone as well as optimization of the treatment sequence. In view of improving biomarkers predicting the efficacy of immunotherapy for R/M HNSCC, we hypothesized that biomarkers can be personalized depending on clinicopathological backgrounds and treatment sequence. Methods: In this study, we retrospectively included formalin-fixed paraffin-embedded (FFPE) samples, peripheral blood cell counts at treatment, clinicopathological information, and outcome data for patients with R/M HNSCC receiving nivolumab across 22 institutions in Japan (N = 100). FFPE samples were subjected to 14-marker multiplex immunohistochemistry (IHC) and image cytometry analysis (Tsujikawa T et al. Cell Reports, 2017) to quantitatively evaluate CD8+ T cells, helper T cells, regulatory T cells, B cells, natural killer (NK) cells, macrophages, dendritic cells, CD66b+ granulocytes, mast cells, programmed death ligand 1 (PD-L1) and PD-1 expression in a single slide. Intratumoral and circulating immune cell frequencies were comparatively analyzed between responders (CR, n = 14; PR, n = 39) and non-responders (SD, n = 2; PD, n = 45). Results: Of 100 patients included, responders had significantly lower smoking and alcohol index, higher incidence of immune related adverse events, and higher PD-L1 expression in immune cells as well as PD-L1 combined positive score (CPS) than non-responders. Next, focusing on the history of prior therapy, stratified analysis revealed that the frequency of NK cells was associated with nivolumab response in patients with prior cetuximab use, but not in cetuximab-naïve status. Furthermore, stratified analysis by patient age revealed that nivolumab response was significantly associated with high CPS and lymphoid-inflamed profiles based on cell densities of nine immune cell lineages in the group aged 65 years or older, but not in the group under 65 years of age. On the contrary, the neutrophil/lymphocyte ratios (NLR) in peripheral blood counts at nivolumab treatment were significantly lower in responders (mean 4.96) than those in non-responders (mean 10.46) in the group under 65 years of age, but not in those over 65 years of age (7.41 versus