Circulating T cell status and molecular imaging may predict clinical benefit of neoadjuvant PD-1 blockade in oral cancer.

BACKGROUND: Addition of neoadjuvant immune checkpoint inhibition to standard-of-care interventions for locally advanced oral cancer could improve clinical outcome. METHODS: In this study, 16 evaluable patients with stage III/IV oral cancer were treated with one dose of 480 mg nivolumab 3 weeks prior to surgery. Primary objectives were safety, feasibility, and suitability of programmed death receptor ligand-1 positron emission tomography (PD-L1 PET) as a biomarker for response. Imaging included 18F-BMS-986192 (PD-L1) PET and 18F-fluorodeoxyglucose (FDG) PET before and after nivolumab treatment. Secondary objectives included clinical and pathological response, and immune profiling of peripheral blood mononuclear cells (PBMCs) for response prediction. Baseline tumor biopsies and postnivolumab resection specimens were evaluated by histopathology. RESULTS: Grade III or higher adverse events were not observed and treatment was not delayed in relation to nivolumab administration and other study procedures. Six patients (38%) had a pathological response, of whom three (19%) had a major (≥90%) pathological response (MPR). Tumor PD-L1 PET uptake (quantified using standard uptake value) was not statistically different in patients with or without MPR (median 5.3 vs 3.4). All major responders showed a significantly postnivolumab decreased signal on FDG PET. PBMC immune phenotyping showed higher levels of CD8+ T cell activation in MPR patients, evidenced by higher baseline expression levels of PD-1, TIGIT, IFNγ and lower levels of PD-L1. CONCLUSION: Together these data support that neoadjuvant treatment of advanced-stage oral cancers with nivolumab was safe and induced an MPR in a promising 19% of patients. Response was associated with decreased FDG PET uptake as well as activation status of peripheral T cell populations.

Immune cell topography of head and neck cancer.

BACKGROUND: Approximately 50% of head and neck squamous cell carcinomas (HNSCC) recur after treatment with curative intent. Immune checkpoint inhibitors are treatment options for recurrent/metastatic HNSCC; however, less than 20% of patients respond. To increase this response rate, it is fundamental to increase our understanding of the spatial tumor immune microenvironment (TIME). METHODS: In total, 53 HNSCC specimens were included. Using a seven-color multiplex immunohistochemistry panel we identified tumor cells, CD163+macrophages, B cells, CD8+T cells, CD4+T helper cells and regulatory T cells (Tregs) in treatment-naive surgical resection specimens (n=29) and biopsies (n=18). To further characterize tumor-infiltrating CD8+T cells, we stained surgical resection specimens (n=12) with a five-color tumor-resident panel including CD103, Ki67, CD8 and pan-cytokeratin. Secretome analysis was performed on matched tumor suspensions (n=11) to measure protein levels. RESULTS: Based on CD8+T cell infiltrates, we identified four different immunotypes: fully infiltrated, stroma-restricted, immune-excluded, and immune-desert. We found higher cytokine levels in fully infiltrated tumors compared with other immunotypes. While the highest immune infiltrates were observed in the invasive margin for all immune cells, CD163+macrophages and Tregs had the highest tendency to infiltrate the tumor center. Within the tumor center, especially B cells stayed at the tumor stroma, whereas CD163+macrophages, followed by T cells, were more often localized within tumor fields. Also, B cells were found further away from other cells and often formed aggregates while T cells and CD163+macrophages tended to be more closely located to each other. Across resection specimens from various anatomical sites within the head and neck, oral cavity tumors exhibited the highest densities of Tregs. Moreover, the distance from B cells and T cells to tumor cells was shortest in oral cavity squamous cell carcinoma (OCSCC), suggesting more interaction between lymphocytes and tumor cells. Also, the fraction of T cells within 10 µm of CD163+macrophages was lowest in OCSCC, indicating fewer myeloid/T-cell suppressive interactions in OCSCC. CONCLUSIONS: We comprehensively described the TIME of HNSCC using a unique data set of resection specimens. We discovered that the composition, as well as the relative localization of immune cells in the TIME, differed in distinct anatomical sites of the head and neck.

Exploring the predictive potential of programmed death ligand 1 expression in healthy organs and lymph nodes as measured by 18F-BMS986-192 PET: pooled analysis of data from four solid tumor types.

INTRODUCTION: Immune checkpoint inhibitors (ICIs) can elicit anticancer immune responses, but predictive biomarkers are needed. We measured programmed death ligand 1 (PD-L1) expression in organs and lymph nodes using 18F-BMS-986192 positron emission tomography (PET)-imaging and looked for correlations with response and immune-related adverse events. METHODS: Four 18F-BMS-986192 PET studies in patients with melanoma, lung, pancreatic and oral cancer, receiving ICI treatment, were combined. Imaging data (organ standardized uptake value (SUV)mean, lymph node SUVmax) and clinical data (response to treatment and incidence of immune-related adverse events) were extracted. RESULTS: Baseline PD-L1 uptake in the spleen was on average higher in non-responding patients than in responders (spleen SUVmean 16.1±4.4 vs 12.5±3.4, p=0.02). This effect was strongest in lung cancer, and not observed in oral cancer. In the oral cancer cohort, benign tumor-draining lymph nodes (TDLNs) had higher PD-L1 uptake (SUVmax 3.3 IQR 2.5-3.9) compared with non-TDLNs (SUVmax 1.8, IQR 1.4-2.8 p=0.04). Furthermore, in the same cohort non-responders showed an increase in PD-L1 uptake in benign TDLNs on-treatment with ICIs (+15%), while for responders the PD-L1 uptake decreased (-11%). PD-L1 uptake did not predict immune-related adverse events, though elevated thyroid uptake on-treatment correlated with pre-existing thyroid disease or toxicity. CONCLUSION: PD-L1 PET uptake in the spleen is a potential negative predictor of response to ICIs. On-treatment with ICIs, PD-L1 uptake in benign TDLNs increases in non-responders, while it decreases in responders, potentially indicating a mechanism for resistance to ICIs in patients with oral cancer.

Comparative analysis of immune infiltrates in head and neck cancers across anatomical sites.

BACKGROUND: The response rate to immune checkpoint inhibitors targeting programmed cell death 1 (PD-1) receptor is 13%-18% for patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). Detailed understanding of the tumor immune microenvironment (TIME) is crucial in order to explain and improve this response rate. HNSCCs arise at various anatomical locations including the oral cavity, hypopharynx, larynx and oropharynx. Studies directly comparing immune infiltration between anatomical sites are scarce. Since the distinct locations could drive deviating microenvironments, we questioned whether the immune composition varies across these HNSCC sites. METHODS: Here, we characterized the TIME of 76 fresh tumor specimens using flow cytometry and performed single-cell RNA-sequencing on nine head and neck tumor samples. RESULTS: We found major differences in the composition of the TIME between patients. When comparing anatomical sites: tumors originating from the oral cavity had higher T cell infiltrates than tumors from other anatomical sites. The percentage of tumor-infiltrating T-lymphocytes positive for the immune checkpoint PD-1 varied considerably between patients, with the highest fraction of PD-1+ T cells found in larynx squamous cell carcinomas (SCCs). While we had hypothesized that the anatomical sites of tumor origin would drive sample clustering, our data showed that the type of TIME was more dominant and was particularly driven by the fraction of T cells positive for PD-1. Moreover, a high proportion of PD-1+ CD8+ T cells associated with an improved overall survival. Using single-cell RNA-sequencing, we observed that PD-1 expression was highest in the CD8-ENTPD1 tissue resident memory T cell/exhausted T cell and CD4-CXCL13 type 1 T helper cell clusters. CONCLUSIONS: We found that oral cavity SCCs had the highest frequencies of T cells. We also observed considerable interpatient heterogeneity for PD-1 on T cells, with noticeably higher frequencies of PD-1+ CD4+ T helper cells in larynx SCCs. Within the entire cohort, a higher fraction of CD8+ T cells positive for PD-1 was linked to improved overall survival. Whether the fraction of PD-1+ T cells within the TIME enables immune checkpoint inhibitor response prediction for patients with head and neck cancer remains to be determined.