Transcriptomic and Immunophenotypic Characterization of Tumor Immune Microenvironment in Squamous Cell Carcinoma of the Oral Tongue

Investigating Tumor-Infiltrating Lymphocytes in the Microenvironment of Oral Squamous Cell Carcinoma (OSCC) and Oral Potentially Malignant Disorders (OPMDs): Can They Shift Our Perspective? A Scoping Review

Background/Objectives: Tumor-infiltrating lymphocytes (TILs) play a crucial role in the tumor microenvironment (TME), influencing the progression, prognosis, and response to treatment in oral squamous cell carcinoma (OSCC) and its precursors, oral potentially malignant disorders (OPMDs). This scoping review assesses the current literature on TILs in the TME of OSCC and OPMDs, aiming to identify trends and gaps in the research. Methods: A comprehensive search was performed in PubMed, using the following query terms: "Tumor Microenvironment AND (mouth neoplasms OR oral lichen OR leukoplakia OR oral lichenoid OR dysplasia OR GVHD OR lupus)". Based on the inclusion criteria, we selected in vivo human original research and clinical observational studies that focused on TILs within the TME of OSCC and OPMDs. Results: Out of 1152 results in PubMed, 58 studies were selected and analyzed. These studies investigated various TILs, including T cells, B cells, and natural killer (NK) cells. Of these, 47 studies focused on the OSCC TME, 4 examined the OPMDs ME, and 7 compared OSCC TME and OPMDs ME. Discussion: While TILs in OSCC have been extensively studied, research on infiltrating lymphocytes in OPMDs is still limited. In OSCC, CD8+ T cells, T helper 1 cells, and NK cells are associated with strong antitumor activity, whereas CD4+ T cells, including T helper 2 and regulatory T cells, are linked to protumoral effects. B cells remain less explored due to their low frequency in the TME. In OPMDs, trends suggest an increase in activated CD8+ T cells in OLP and lower NK cell numbers compared to OSCC, which may contribute to malignant transformation. Understanding the spatial distribution and activation status of TILs within the TME is essential for deciphering their role. The variability in TIL composition highlights the complexity of the TME. Conclusions: Current knowledge remains preliminary, though it highlights the crucial role of TILs in carcinogenesis and OSCC. A more in-depth understanding could improve diagnostic and therapeutic strategies, including the assessment of the risk of malignant transformation in OPMDs.

Tumor microenvironment in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a highly aggressive and malignant tumor of oral cavity with a poor prognosis and high mortality due to the limitations of existing therapies. The significant role of tumor microenvironment (TME) in the initiation, development, and progression of OSCC has been widely recognized. Various cells in TME, including tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), T lymphocytes, tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs) and dendritic cells (DCs), form a complicated and important cellular network to modulate OSCC proliferation, invasion, migration, and angiogenesis by secreting RNAs, proteins, cytokines, and metabolites. Understanding the interactions among cells in TME provides the foundation for advanced clinical diagnosis and therapies. This review summarizes the current literature that describes the role of various cellular components and other TME factors in the progression of OSCC, hoping to provide new ideas for the novel OSCC treatment strategies targeting the complicated cellular network and factors that mediate the interactive loops among cells in TME.

Oral cancer in young adults: incidence, risk factors, prognosis, and molecular biomarkers

Oral cavity squamous cell carcinoma (OCSCC) predominantly affects the tongue and the floor of the mouth, primarily in patients over 50 years of age. Incidence and mortality rates vary significantly worldwide, influenced by geographic areas and demographic characteristics. Epidemiological studies revealed an increase in incidence of OCSCC among young adults (YA) <44 years old. This narrative review, provides updated information on the incidence, risk factors, and prognosis of YA-OCSCC using data published from 2018 to 2023 from different geographic locations. The studies indicate that the incidence of YA-OCSCC in Asia is approximately twice that in the US and that the incidence is strongly linked to risk factors such as betel quid chewing, tobacco use, and high alcohol consumption. The prognosis for YA-OCSCC, compared to that in older patients, shows similar or better overall survival, even in cases with relapses, but worse 5-year disease-free survival, despite receiving similar treatments. Consequently, a concerted effort is crucial to raise awareness about the cessation of tobacco and areca nut use, alcohol control, and the promotion of healthy lifestyle behaviors. Recent molecular data on YA-OCSCC suggests a potential profile characterized by epidermal growth factor receptor overexpression, low tumor mutation burden and an attenuated immune response. Upon confirmation in larger cohorts of YA-OCSCC patients from different geographical areas, the validated markers could aid in selecting tailored treatments.

Immunoexpression of Tumor Infiltrating Lymphocytes(TILS) CD4 + and CD8 + in Oral Squamous Cell Carcinoma (OSCC) in Correlations with Clinicopathological Characteristics and Prognosis

OBJECTIVE

This study aimed to analyze CD4 +and CD8 + TILs in oral squamous cell carcinoma (OSCC) and to correlate it with histologic grade of malignancy and clinicopathologic data.

METHODS

The sample was composed of 43 archived specimens. Clinical features and histological grade of malignancy were obtained. The infiltrating intensity of CD4 +, CD8 positive cells were assessed by immunohistochemistry. One-way ANOVA was used to study the association between CD4 +, CD8 + and the grade of OSCC. The cut-off values of the proposed diagnostic indices were received from calculating the coordinates of the receiver operating characteristic (ROC) curve. For clinicopathologic data Independent-Samples T test, Pearson Correlation Coefficient, Correlation Coefficient were used clinicopathologic characteristics.

RESULTS

CD4 +and CD8 + were observed in all specimens. CD4 + were more frequent in poorly differentiated specimens (74.14) (P= 0.021<0.05). CD8 + were more frequent in well- differentiated  specimens (51.18). None of these correlations were significant (P=0.454>0.05). CD4 +/ CD8 ratio was higher in low-grade specimens (180.28) (P=0.017<0.05). No differences between CD4 +, CD8 +and CD4 +/ CD8 ratio between poorly- differentiated   and moderately- differentiated   groups ROC P value (0.370, 0.248, 0.126) respectively. there is a difference between CD4 +, CD4 +/ CD8ratio between poorly- differentiated   and well- differentiated   groups ROC P value (0.022, 0.341, 0.012) Sensitivity (0.857, 0.882), specificity (0.706, 0.857) respectively. and no differences between CD8 + poorly- differentiated and well- differentiated groups ROC P value (0.341). there is a difference between CD4 + between moderately - differentiated   and well- differentiated groups ROC P value (0.038) Sensitivity (0.368), specificity (0,765). No significant correlation was obtained with clinicopathologic findings of OSCC.

CONCLUSION

CD4 + and CD4 +/ CD8 + ratio are independent prognostic factor in OSCC.

Immunology of Oral Squamous Cell Carcinoma-A Comprehensive Insight with Recent Concepts

This review aims to understand the concept of oral cancer immunology through the notion of immune profiling, immunoediting and immunotherapy, and to gain knowledge regarding its application for the management of oral cancer patients. Oral cancer is an immunogenic tumor where the cells of the tumor microenvironment play an important role in tumorigenesis. Understanding the mechanism of these modulations can help design immunotherapeutic strategies in oral cancer patients. This article gives an overview of immunomodulation in the oral cancer tumor microenvironment, with concepts of immune profiling, immunoediting and immunotherapy. English literature searches via Google Scholar, Web of Science, EBSCO, Scopus, and PubMed database were performed with the key words immunology, tumor microenvironment, cells, cross talk, immune profiling, biomarkers, inflammation, gene expression, techniques, immunoediting, immunosurveillance, tumor escape, immunotherapy, immune checkpoint inhibitors, vaccines in cancer, oral cancer, and head and neck cancer. Original research articles, reviews, and case reports published from 2016-2021 (n = 81) were included to appraise different topics, and were discussed under the following subsections. Literature published on oral cancer immunology reveals that oral cancer immune profiling with appropriate markers and techniques and knowledge on immunoediting concepts can help design and play an effective role in immunotherapeutic management of oral cancer patients. An evaluation of oral cancer immunology helps to determine its role in tumorigenesis, and immunotherapy could be the emerging drift in the effective management of oral cancer.

Evaluation of CD4+ tumor-infiltrating lymphocyte association with some clinicopathological indices of oral squamous cell carcinoma

BACKGROUND

The delayed diagnosis of oral squamous cell carcinoma (OSCC) affects therapeutic and prognostic strategies, and provides regional recurrence or distant metastasis. The tumor-infiltrating lymphocytes (TILs) are known as a critical diagnostic biomarker in antitumor immune response. We evaluated the association between CD4⁺ T-lymphocyte marker, some clinicopathological indices, and the impact of TILs on the stage and grade of OSCC.

MATERIALS AND METHODS

In this cross-sectional study, 37 OSCC specimens including 16 early and 21 advanced stages (categorized base-on recent clinical oncology references) and their related healthy surgical margin (as internal control group) were collected. Obtained histochemical data were analyzed by SPSS V.23 software. The expression of CD4⁺ marker in tumor microenvironment (TME) was compared by nonparametric Mann-Whitney and Kruskal-Wallis as well as Fisher's exact tests. P < 0.05 was remarked statistically significant.

RESULTS

The low-grade patients represented more CD4⁺ TIL that was statistically significant (P = 0.011). However, there was no statistically significant difference in CD4⁺ TIL between various stages (P = 0.404), tumor size, and lymph node involvement (P > 0.05). Moreover, there was no significant relation between TIL infiltration, age, and tumor localization (P > 0.05), however CD4⁺ expression in women was more than men (P = 0.008). The CD4⁺ T-lymphocyte infiltration in TME was more significant than healthy surgical margin (P < 0.001). There was a statistically significant difference between healthy surgical margin and different grades and stages of OSCCs that lower grades demonstrated more CD4⁺ TIL infiltration (P < 0.001).

CONCLUSION

The CD4⁺ T-lymphocytes may play important role in differentiation and maturity of epithelial cell, tumorigenesis, and progression of OSCC.

Prognostic Role of Combined EGFR and Tumor-Infiltrating Lymphocytes in Oral Squamous Cell Carcinoma

Background

Epidermal growth factor receptor (EGFR) is well known as a general prognostic biomarker for head and neck tumors, however the specific prognostic value of EGFR in oral squamous cell carcinoma (OSCC) is controversial. Recently, the presence of tumor-infiltrating T cells has been associated with significant survival advantages in a variety of disease sites. The present study will determine if the inclusion of T cell specific markers (CD3, CD4 and CD8) would enhance the prognostic value of EGFR in OSCCs.

Methods

Tissue microarrays containing 146 OSCC cases were analyzed for EGFR, CD3, CD4 and CD8 expression using immunohistochemical staining. EGFR and T cell expression scores were correlated with clinicopathological parameters and survival outcomes.

Results

Results showed that EGFR expression had no impact on overall survival (OS), but EGFR-positive (EGFR+) OSCC patients demonstrated significantly worse progression free survival (PFS) compared to EGFR-negative (EGFR-) patients. Patients with CD3, CD4 and CD8-positive tumors had significantly better OS compared to CD3, CD4 and CD8-negative patients respectively, but no impact on PFS. Combined EGFR+/CD3+ expression was associated with cases with no nodal involvement and significantly more favorable OS compared to EGFR+/CD3- expression. CD3 expression had no impact on OS or PFS in EGFR- patients. Combinations of EGFR/CD8 and EGFR/CD4 expression showed no significant differences in OS or PFS among the expression groups.

Conclusion

Altogether these results suggest that the expression of CD3+ tumor-infiltrating T cells can enhance the prognostic value of EGFR expression and warrants further investigation as prognostic biomarkers for OSCC.

Tissue and circulating PD-L2: moving from health and immune-mediated diseases to head and neck oncology

Amongst the chief targets of immune-checkpoint inhibitors (ICIs), namely the Programmed cell death protein 1 (PD-1)/PD-Ligands (Ls) axis, most research has focused on PD-L1, while to date PD-L2 is still under-investigated. However, emerging data support PD-L2 relevant expression in malignancies of the head and neck area, mostly in head and neck squamous cell carcinoma (HNSCC) and salivary gland cancers (SGCs). In this context, ICIs have achieved highly heterogeneous outcomes, emphasizing an urgent need for the identification of predictive biomarkers. With the present review, we aimed at describing PD-L2 biological significance by focusing on its tissue expression, its binding to PD-1 and RGMb receptors, and its impact on physiological and anti-cancer immune response. Specifically, we reported PD-L2 expression rates and significant clinical correlates among different head and neck cancer histotypes. Finally, we described the biology of soluble PD-L2 form and its potential application as a prognostic and/or predictive circulating biomarker.

Effector T cell responses unleashed by regulatory T cell ablation exacerbate oral squamous cell carcinoma

Immune suppression by CD4+FOXP3+ regulatory T (Treg) cells and tumor infiltration by CD8+ effector T cells represent two major factors impacting response to cancer immunotherapy. Using deconvolution-based transcriptional profiling of human papilloma virus (HPV)-negative oral squamous cell carcinomas (OSCCs) and other solid cancers, we demonstrate that the density of Treg cells does not correlate with that of CD8+ T cells in many tumors, revealing polarized clusters enriched for either CD8+ T cells or CD4+ Treg and conventional T cells. In a mouse model of carcinogen-induced OSCC characterized by CD4+ T cell enrichment, late-stage Treg cell ablation triggers increased densities of both CD4+ and CD8+ effector T cells within oral lesions. Notably, this intervention does not induce tumor regression but instead induces rapid emergence of invasive OSCCs via an effector T cell-dependent process. Thus, induction of a T cell-inflamed phenotype via therapeutic manipulation of Treg cells may trigger unexpected tumor-promoting effects in OSCC.