Rationale: Uncovering landscapes and mechanisms within the tumor microenvironment is critical for identifying new therapeutic modalities to improve outcomes in head and neck squamous cell carcinoma (HNSCC). We sought to determine whether discrete cell interactions within the head and neck squamous cell carcinoma tumor microenvironment drive tumor growth and result in worsened patient outcomes.

Materials and methods: To identify motifs that define patient subsets and their clinical outcomes, the multiplexed tissue imaging platform Co-Detection by IndEXing (CODEX) was used to analyze 56 markers in single cells on formalin-fixed paraffin embedded (FFPE) HNSCC tissue samples. Random survival forest (RSF) was utilized for survival analysis. Peripheral blood mononuclear cells (PBMC) were isolated from HNSCC patients and co-cultured with normal fibroblasts or HNSCC-associated fibroblasts. A panel of 48-71 soluble factors was assayed in cell-free supernatant.

Results: Using CODEX and RSF, we delineated the spatial proteome of 86 HNSCC patients and stratified patients into low-risk and high-risk populations. Among factors most predictive of survival, immune cell-fibroblast interactions were found to be enriched in tumors of HNSCC patients that succumbed to disease (C-index = 0.689, p = 1.183e-6). We discovered that HNSCC-associated fibroblast induced immune cell IL-22 secretion (fold change = 43.9, P = 0.004) and supernatant obtained from fibroblast/PBMC co-culture activated STAT3, a key driver of head and neck carcinogenesis. Furthermore, HNSCC-associated fibroblast/PBMC supernatant enhanced HNSCC growth, a finding that was reversed with IL-22 blockade.

Conclusions: Our findings indicate that immune cell-fibroblast interactions within HNSCC TME induce IL-22 secretion and drive tumor growth. These findings suggest that targeting the IL-22 pathway may be beneficial in HNSCC.