The immune microenvironment of HPV-negative oral squamous cell carcinoma from never-smokers and never-drinkers patients suggests higher clinical benefit of IDO1 and PD1/PD-L1 blockade.

BACKGROUND: Never-smokers and never-drinkers patients (NSND) suffering from oral squamous cell carcinoma (OSCC) are epidemiologically different from smokers drinkers (SD). We therefore hypothesized that they harbored distinct targetable molecular alterations. PATIENTS AND METHODS: Data from The Cancer Genome Atlas (TCGA) (discovery set), Gene Expression Omnibus and Centre Léon Bérard (CLB) (three validation sets) with available gene expression profiles of HPV-negative OSCC from NSND and SD were mined. Protein expression profiles and genomic alterations were also analyzed from TCGA, and a functional pathway enrichment analysis was carried out. Formalin-fixed paraffin-embedded samples from 44 OSCC including 20 NSND and 24 SD treated at CLB were retrospectively collected to perform targeted-sequencing of 2559 transcripts (HTG EdgeSeq system), and CD3, CD4, CD8, IDO1, and PD-L1 expression analyses by immunohistochemistry (IHC). Enrichment of a six-gene interferon-γ signature of clinical response to pembrozulimab (PD-1 inhibitor) was evaluated in each sample from all cohorts, using the single sample gene set enrichment analysis method. RESULTS: A total of 854 genes and 29 proteins were found to be differentially expressed between NSND and SD in TCGA. Functional pathway analysis highlighted an overall enrichment for immune-related pathways in OSCC from NSND, especially involving T-cell activation. Interferon-γ response and PD1 signaling were strongly enriched in NSND. IDO1 and PD-L1 were overexpressed and the score of response to pembrolizumab was higher in NSND than in SD, although the mutational load was lower in NSND. IHC analyses in the CLB cohort evidenced IDO1 and PD-L1 overexpression in tumor cells that was associated with a higher rate of tumor-infiltrating T-cells in NSND compared with SD. CONCLUSION: The main biological and actionable difference between OSCC from NSND and SD lies in the immune microenvironment, suggesting a higher clinical benefit of PD-L1 and IDO1 inhibition in OSCC from NSND.

Pattern recognition receptors: immune targets to enhance cancer immunotherapy.

Durable tumor responses and significant levels of disease control rates have been described in more than 20 advanced/metastatic cancer types with B7-family immune checkpoint-targeted anti-CTLA-4, anti-PD-1, and anti-PD-L1 monoclonal antibodies. These results and the recent approvals of ipilimumab, pembrolizumab, nivolumab and atezolizumab are currently revolutionizing the way we envision the future of cancer care. However these clinical benefits are not observed in all cancer types and in every patient. Therefore, our clinical challenge is to identify therapeutic strategies which could overcome the primary and secondary resistances to these novel cancer immunotherapies. Pattern recognition receptors (PRRs) are other critical costimulatory molecules of immune cells, notably myeloid cells (macrophages and dendritic cells). They were initially described as sensors for 'danger signals' released by pathogens (e.g. viral DNA and bacterial proteins). We know now that PRRs can also be recruited and activated upon recognition of endogenous stress signals such as molecules released upon self-cell death (e.g. ATP and HMGB1). Natural endo/exogenous or synthetic PRRs agonists have notably the ability to activate phagocytosis and antigen presentation by myeloid cells residing in the tumor micro-environment. In pre-clinical models, these PRRs agonists have also been shown to overcome the resistance to T-cell targeted immune checkpoints anti-CTLA-4 and anti-PD-1/PD-L1. This manuscript reviews the current knowledge on this major family of immune receptors and the molecules targeting them which are currently in clinical development.