Comprehensive T-cell immunophenotyping and next-generation sequencing of human papillomavirus (HPV)-positive and HPV-negative head and neck squamous cell carcinomas

Host-specific differences in top-expanded TCR clonotypes correlate with divergent outcomes of anti-PD-L1 treatment in responders versus non-responders

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment; however, the responses to ICI treatment are highly variable in different individuals and the underlying mechanisms remain poorly understood. Here, we employed a mouse squamous cell carcinoma (SCC) model where tumor-bearing recipients diverged into responders (R) versus non-responders (NR) upon anti-PD-L1 treatment. We performed in-depth TCRβ sequencing with immunoSEQ platform to delineate the differences in CD8 tumor-infiltrating lymphocytes (TILs). We found that R and NR CD8 TILs both exhibited evidence of clonal expansion, suggesting activation regardless of response status. We detected no differences in clonal expansion or clonal diversity indexes between R vs. NR. However, the top expanded (>1%) TCRβ clonotypes appeared to be mutually exclusive between R and NR CD8 TILs, showing a preferential expansion of distinct TCRβ clonotypes in response to the same SCC tumor in R vs. NR. Notably, the mutual exclusivity of TCR clonotypes in R vs. NR was only observed when top TCRβ clonotypes were counted, because such top-expanded clonotypes are present in the opposite outcome group at a much lower frequency. Many TCRβ sequences were detected in only one recipient at a high frequency, implicating highly individualized anti-tumor immune responses. We conclude that differences in the clonal frequency of top TCR clonotypes between R and NR CD8 TILs may be one of the factors underlying differential anti-PD-L1 responses. This notion may offer a novel explanation for variable ICI responses in different individuals, which may substantially impact the development of new strategies for personalized cancer immunotherapy.

Cetuximab Responses in Patients with HNSCC Correlate to Clonal Expansion Feature of Peripheral and Tumor-Infiltrating T Cells with Top T-Cell Receptor Clonotypes

PURPOSE

Cetuximab is a standard-of-care treatment for head and neck squamous cell carcinoma (HNSCC). Well-defined correlative markers of therapeutic responses are still lacking. Characterizing dynamic changes of T-cell receptor (TCR) repertoire in peripheral blood and tumor tissue may facilitate developing markers for cetuximab response in HNSCCs.

EXPERIMENTAL DESIGN

We analyzed high-throughput TCRβ sequencing data generated with ImmunoSEQ platform using peripheral blood mononuclear cells (PBMC) and tumor-infiltrating lymphocytes (TIL) from patients with HNSCC before and after cetuximab treatment (pre-/post-PBMC vs. pre-/post-TIL). Multiple analytic approaches were employed to normalize sequencing data.

RESULTS

Normalized TCR richness was significantly lower in post-TIL than pre-TIL, suggesting that cetuximab reduced TCR diversity and promoted TCR expansion in TIL samples, regardless of response status. The magnitude of clonal expansion (defined as expansion rate) in top 20 TCR clonotypes was significantly higher in responder PBMC with or without normalization, and in responder TIL upon normalization, than nonresponder ones. Notably, the expanded top 20 or top 50 TCR clonotypes overlapped between PBMC and TIL samples, which occurred significantly more frequently in responders than nonresponders.

CONCLUSIONS

Patients with cetuximab-treated HNSCC harbor dynamic changes of TCR repertoires correlative to therapeutic responses. The expansion rate of top TCR clonotypes in peripheral blood may serve as a minimally invasive, readily accessible, and feasible marker for predicting cetuximab responses in HNSCCs and beyond, and the expansion rate of top TCR clonotypes in TILs and their overlapping probability between PBMC and TIL may serve as additional predictive markers. Our study also highlights the importance of data normalization for TCR repertoire analysis.

Proliferative exhausted CD8+ T cells exacerbate long-lasting anti-tumor effects in human papillomavirus-positive head and neck squamous cell carcinoma

The survival prognosis of human papillomavirus (HPV)-positive and HPV-negative head and neck squamous cell carcinoma (HNSCC) is largely different, and little is known about the anti-tumor mechanism of tumor-infiltrated exhausted CD8⁺ T cells (Tex) in HNSCC. We performed cell-level multi-omics sequencing on human HNSCC samples to decipher the multi-dimensional characteristics of Tex cells. A proliferative exhausted CD8⁺ T cell cluster (P-Tex) which was beneficial to survival outcomes of patients with HPV-positive HNSCC was identified. Interestingly, P-Tex cells expressed CDK4 genes as high as cancer cells, which could be simultaneously inhibited by CDK4 inhibitors and might be a potential reason for the ineffectiveness of CDK4 inhibitors in treating HPV-positive HNSCC. P-Tex cells could aggregate in the antigen-presenting cell niches and activate certain signaling pathways. Together, our findings suggest a promising role for P-Tex cells in the prognosis of patients with HPV-positive HNSCC by providing modest but persistent anti-tumor effects.

Fluid Biomarkers in HPV and Non-HPV Related Oropharyngeal Carcinomas: From Diagnosis and Monitoring to Prognostication-A Systematic Review

Biomarkers are crucial in oncology, from detection and monitoring to guiding management and predicting treatment outcomes. Histological assessment of tissue biopsies is currently the gold standard for oropharyngeal cancers, but is technically demanding, invasive, and expensive. This systematic review aims to review current markers that are detectable in biofluids, which offer promising non-invasive alternatives in oropharyngeal carcinomas (OPCs). A total of 174 clinical trials from the PubMed search engine in the last 5 years were identified and screened by 4 independent reviewers. From these, 38 eligible clinical trials were found and subsequently reviewed. The biomarkers involved, categorized by human papillomavirus (HPV)-status, were further divided according to molecular and cellular levels. Recent trials investigating biomarkers for both HPV-positive and HPV-negative OPCs have approaches from various levels and different biofluids including plasma, oropharyngeal swabs, and oral rinse. Promising candidates have been found to aid in detection, staging, and predicting prognosis, in addition to well-established factors including HPV-status, drinking and smoking status. These studies also emphasize the possibility of enhancing prediction results and increasing statistical significance by multivariate analyses. Liquid biopsies offer promising assistance in enhancing personalized medicine for cancer treatment, from lowering barriers towards early screening, to facilitating de-escalation of treatment. However, further research is needed, and the combination of liquid biopsies with pre-existing methods, including in vivo imaging and invasive techniques such as neck dissections, could also be explored in future trials.

PD1+CD8+ Cells Are an Independent Prognostic Marker in Patients with Head and Neck Cancer

Head and neck squamous cell carcinomas (HNSCCs) belong to a group of diverse tumors, which can be induced by infection with human papillomavirus (HPV) or tobacco and alcohol consumption. The viral etiology of HNSCC relates to better clinical outcomes reflecting a different immune system response. Here, we retrospectively analyzed 97 tissue samples from oral and oropharyngeal carcinomas associated and non-associated with HPV infection using multispectral fluorescent immunohistochemistry. To evaluate the immune cell infiltration in tumor and stroma compartments, we designed four panels of four to five antibodies. We detected more T lymphocytes in the stroma, compared to the tumor parenchyma. In HPV positive (HPV+) in comparison to HPV negative (HPV−) tumors, higher counts of CD3+CD4+, CD3+CD8+, PD1+CD4+, PD1+CD8+ T cells, and ICOS− Treg cells were detected while more ICOS+ Treg cells and CTLA4+CD4+ T cells were observed in HPV− than in HPV+ tumors. The results of the univariate and multivariate analyses confirmed the predominant impact of HPV status on prognosis. More importantly, the number of CD8+PD-1+ T cells was identified as an independent factor, influencing the overall and/or disease-specific survival of patients with oral cavity or oropharyngeal carcinomas.

The Evolving Landscape of PD-1/PD-L1 Pathway in Head and Neck Cancer

Over the past 10 years, cancer immunotherapy has made significant progress in multiple cancer types and has been gradually been applied to clinical cancer care, in which the programmed cell death protein-1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway is one of the most attractive targets. Compared with traditional therapies, the emerging PD-1/PD-L1 blockade immunotherapy exhibited more satisfactory curative effects and lower toxicity for patients with advanced head and neck squamous cell carcinoma (HNSCC). This review analyzes the expression characteristics and clinical significance of PD-1/PD-L1 in HNSCC, the immunosuppressive roles of tumor cell and stromal cell expressing PD-1/PD-L1 in this disease, and presents the development landscape of PD-1/PD-L1 inhibitors, which may provide new curative alternatives for recurrent or metastatic HNSCC.

Immune Checkpoint Inhibitors in Oral Cavity Squamous Cell Carcinoma and Oral Potentially Malignant Disorders: A Systematic Review

Cancers of the oral cavity cause significant cancer-related death worldwide. While survival rates have improved in recent years, new methods of treatment are being investigated to limit disease progression and to improve outcomes, particularly in oral cavity squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMD). The emerging treatment modality of immunotherapy targets immune checkpoint molecules including PD-1 and its ligand PD-L1, CTLA-4, LAG-3, and TIM-3 to enhance the host immune response against tumours, and to limit the growth and progression of cancer cells. In this systematic review, we searched five databases for keywords pertaining to oral cancers and OPMDs, along with immune checkpoint inhibitors, in order to summarize the current status of their use and efficacy in these diseases. A total of 644 different articles were identified between 2004 and 2019, with 76 deemed suitable for inclusion in the study, providing a total of 8826 samples. Combined results show expression of PD-1 and PD-L1 in the majority of OPMD and OSCC samples, with expression correlating with increased progression and decreased survival rates. Immunotherapy agents pembrolizumab and nivolumab target PD-1 and have been shown to prolong survival rates and improve disease outcomes, especially in combination with chemotherapy or radiotherapy. Despite the equivocal nature of current evidence, there is support for the prognostic and predictive value of immune checkpoint molecules, especially PD-L1, and many studies provide support for the effective use of immune checkpoint inhibitors in the management of OSCC. Limited data is available for OPMD, therefore this should be the focus of future research.

OX40+ plasmacytoid dendritic cells in the tumor microenvironment promote antitumor immunity

Plasmacytoid DCs (pDCs), the major producers of type I interferon, are principally recognized as key mediators of antiviral immunity. However, their role in tumor immunity is less clear. Depending on the context, pDCs can promote or suppress antitumor immune responses. In this study, we identified a naturally occurring pDC subset expressing high levels of OX40 (OX40+ pDC) enriched in the tumor microenvironment (TME) of head and neck squamous cell carcinoma. OX40+ pDCs were distinguished by a distinct immunostimulatory phenotype, cytolytic function, and ability to synergize with conventional DCs (cDCs) in generating potent tumor antigen-specific CD8+ T cell responses. Transcriptomically, we found that they selectively utilized EIF2 signaling and oxidative phosphorylation pathways. Moreover, depletion of pDCs in the murine OX40+ pDC-rich tumor model accelerated tumor growth. Collectively, we present evidence of a pDC subset in the TME that favors antitumor immunity.

Coupling Fluorescence-Activated Cell Sorting and Targeted Analysis of Histone Modification Profiles in Primary Human Leukocytes

Histone posttranslational modifications (PTMs) are essential for regulating chromatin and maintaining gene expression throughout cell differentiation. Despite the deep level of understanding of immunophenotypic differentiation pathways in hematopoietic cells, few studies have investigated global levels of histone PTMs required for differentiation and maintenance of these distinct cell types. Here, we describe an approach to couple fluorescence-activated cell sorting (FACS) with targeted mass spectrometry to define global "epi-proteomic" signatures for primary leukocytes. FACS was used to sort closely and distantly related leukocytes from normal human peripheral blood for quantitation of histone PTMs with a multiple reaction monitoring LC-MS/MS method measuring histone PTMs on histones H3 and H4. We validate cell sorting directly into H₂SO₄ for immediate histone extraction to decrease time and number of steps after FACS to analyze histone PTMs. Relative histone PTM levels vary in T cells across healthy donors, and the majority of PTMs remain stable up to 2 days following initial blood draw. Large differences in the levels of histone PTMs are observed across the mature lymphoid and myeloid lineages, as well as between different types within the same lineage, though no differences are observed in closely related T cell subtypes. The results show a streamlined approach for quantifying global changes in histone PTMs in cell types separated by FACS that is poised for clinical deployment.

Elemental Zn and its Binding Protein Zinc-α2-Glycoprotein are Elevated in HPV-Positive Oropharyngeal Squamous Cell Carcinoma

Human papillomavirus (HPV)-positive head and neck squamous cell carcinoma (HNSCC) is biologically distinct from HPV-negative HNSCC. Outside of HPV-status, few tumor-intrinsic variables have been identified that correlate to improved survival. As part of exploratory analysis into the trace elemental composition of oropharyngeal squamous cell carcinoma (OPSCC), we performed elemental quanitification by X-ray fluorescence microscopy (XFM) on a small cohort (n = 32) of patients with HPV-positive and -negative OPSCC and identified in HPV-positive cases increased zinc (Zn) concentrations in tumor tissue relative to normal tissue. Subsequent immunohistochemistry of six Zn-binding proteins—zinc-α2-glycoprotein (AZGP1), Lipocalin-1, Albumin, S100A7, S100A8 and S100A9—revealed that only AZGP1 expression significantly correlated to HPV-status (p < 0.001) and was also increased in tumor relative to normal tissue from HPV-positive OPSCC tumor samples. AZGP1 protein expression in our cohort significantly correlated to a prolonged recurrence-free survival (p = 0.029), similar to HNSCC cases from the TCGA (n = 499), where highest AZGP1 mRNA levels correlated to improved overall survival (p = 0.023). By showing for the first time that HPV-positive OPSCC patients have increased intratumoral Zn levels and AZGP1 expression, we identify possible positive prognostic biomarkers in HNSCC as well as possible mechanisms of increased sensitivity to chemoradiation in HPV-positive OPSCC.

High PD-L1 expression in the tumour cells did not correlate with poor prognosis of patients suffering for oral squamous cells carcinoma: A meta-analysis of the literature

OBJECTIVES

Oral cancer represents one of the most common malignancies in humans. Its prognosis is still poor, despite the most recent improvements in therapies. An increasing attention is placed on the role of programmed death ligand 1 (PD-L1) in the tumour immunity and its potential function as a marker for tumour prognosis. Whether PD-L1 expression is a prognostic factor for the poor outcomes in oral squamous cell carcinoma is still controversial. This study aimed to investigate, through a meta-analysis, a potential correlation between PD-L1 expression and the prognostic outcomes in patients with oral squamous cell carcinoma.

MATERIALS AND METHODS

The studies were identified by searching PubMed, SCOPUS, Web of Science and were assessed by two of the authors. After the selection process, 11 articles met eligibility criteria and were included in the meta-analysis. Quality assessment of studies was performed according to the REMARK guidelines, and the risk of biases across studies was investigated through Q and I² tests. Meta-analysis was performed to investigate the association between the PD-L1 expression either overall survival (OS), disease-free survival (DFS), disease-specific survival (DSS), gender and lymph node metastasis.

RESULTS

A total of 1060 patients were analysed in the 11 studies included in the meta-analysis. Pooled analysis revealed that the expression of PD-L1 did not correlate with poor OS (HR, 0.60; 95% CI: [0.33, 1.10]; P = 0.10), DFS (HR, 0.62; 95% CI: [0.21, 1.88]; P = 0.40), DSS (HR, 2.05; 95% CI: [0.53, 7.86]; P = 0.29 and lymph node metastasis (HR, 1.15; 95% CI: [0.74, 1.81]; P = 0.53). Furthermore, results of the meta-analysis showed that high expression of PD-L1 is two times more frequent in female patients (OR, 0.5; 95% CI: [0.36, 0.69]; P < 0.0001) compared to males. For all the three outcomes analysed, a high rate of heterogeneity was detected (I²  > 50%).

DISCUSSION

High PD-L1 expression did not correlate with poor prognosis of patients suffering for oral squamous cell carcinoma. Studies published on the topic showed a significant variation in results, limiting the use of PD-L1 expression by immunohistochemistry as prognostic biomarker in clinical practice.

Utility of CD8 score by automated quantitative image analysis in head and neck squamous cell carcinoma

INTRODUCTION

In head and neck squamous cell carcinoma (HNSCC) high numbers of tumor infiltrating CD8 T cells in the tumor microenvironment are associated with better outcome. However, no investigators have employed automated image analysis on whole slide images to permit CD8 scores for use in clinical practice. The aim of this study was to develop and validate an image analysis algorithm to automatically quantify CD8 T cells in patients with oropharyngeal HNSCC.

MATERIALS AND METHODS

Using brightfield image analysis results were cross-validated with fluorescence based quantification (AQUA™). A nuclear image algorithm designed to run on whole slide images was optimized to manual count. The algorithm was locked down and used on a cohort of whole tissue sections from HNSCC patients. Multivariate clinicopathologic parameters and outcomes were statistically correlated with image analysis results.

RESULTS

Linear correlation between manual counts and the customized CD8 algorithm was 0.943. A total of 74 oropharyngeal HNSCC cases were analyzed for CD8 immune cell infiltrate using this image analysis algorithm. A CD8 immune cell density above 136 cells/mm² was associated with median survival of 18 years compared to 5 years. When multivariate modeling was performed, HPV infection was the only predictor of survival; however, when HPV was excluded only CD8 cell density predicts survival.

CONCLUSIONS

We report the successful technical development and clinical validation of an image algorithm to automate CD8 immune cell density for oropharyngeal HNSCC. Employing brightfield image analysis on entire tumor sections instead of tumor subcompartments permits this strategy to be widely implemented.

T cell receptor richness in peripheral blood increases after cetuximab therapy and correlates with therapeutic response

The role of T cell receptor (TCR) signaling for adaptive immune responses is essential. The ability to respond to a broad spectrum of tumor antigens requires an adaptive selection of various TCR. So far, little is known about the role of TCR richness and clonality in the cellular immune response to head and neck cancer (HNC), though the Endothelial Growth Factor Receptor (EGFR)-specific CD8⁺ T cell response can be enhanced by cetuximab therapy. Therefore, we investigated differences in TCR sequences between human papillomavirus (HPV)⁺ and HPV^- HNC patients, as well as differences in TCR sequence characteristics between T cells of peripheral blood mononuclear cells (PBMC) and tumor infiltrating lymphocytes (TIL). Additionally, we were able to investigate the TCR richness and clonality in samples pre- and post- treatment in a prospective clinical trial of neoadjuvant cetuximab. Interestingly, HPV⁺ and HPV^- HNSCC did not significantly differ in the extent of TCR clonality and richness in PBMC or TIL. However, neoadjuvant cetuximab treatment increased the number of unique TCR sequences in PBMC (p = 0.0003), which was more prominent in the clinical responder patients compared to non-responders (p = 0.04). A trend toward TCR gene focusing was observed in TIL (p = 0.1) post-treatment. Thus, an increase in richness of TCR sequences in the periphery with a focusing at the tumor site is associated with an improved treatment response, suggesting an influence of peripheral quantity and intratumoral quality on adaptive immunity in cetuximab treated patients.