EGFR signaling suppresses type 1 cytokine-induced T-cell attracting chemokine secretion in head and neck cancer

Future investigative directions for novel therapeutic targets in head and neck cancer

AREAS COVERED

Here we describe novel agents, their mechanism(s) of action, preclinical results, and ongoing clinical trials in HNSCC.

EXPERT OPINION

Established therapeutic targets in HNSCC include EGFR (cetuximab) and PD-1 (pembrolizumab and nivolumab). Despite the detection of many other possible targets in HNSCC cell lines and patient tumors, no other therapies have successfully advanced to date. Identification of predictive biomarkers may guide the use of targeted agents and combination therapies. Clinical trials supported by strong preclinical data in relevant models are more likely to advance treatment options.

An investigation of the clinical impact and therapeutic relevance of a DNA damage immune response (DDIR) signature in patients with advanced gastroesophageal adenocarcinoma

BACKGROUND

An improved understanding of which gastroesophageal adenocarcinoma (GOA) patients respond to both chemotherapy and immune checkpoint inhibitors (ICI) is needed. We investigated the predictive role and underlying biology of a 44-gene DNA damage immune response (DDIR) signature in patients with advanced GOA.

MATERIALS AND METHODS

Transcriptional profiling was carried out on pretreatment tissue from 252 GOA patients treated with platinum-based chemotherapy (three dose levels) within the randomized phase III GO2 trial. Cross-validation was carried out in two independent GOA cohorts with transcriptional profiling, immune cell immunohistochemistry and epidermal growth factor receptor (EGFR) fluorescent in situ hybridization (FISH) (n = 430).

RESULTS

In the GO2 trial, DDIR-positive tumours had a greater radiological response (51.7% versus 28.5%, P = 0.022) and improved overall survival in a dose-dependent manner (P = 0.028). DDIR positivity was associated with a pretreatment inflamed tumour microenvironment (TME) and increased expression of biomarkers associated with ICI response such as CD274 (programmed death-ligand 1, PD-L1) and a microsatellite instability RNA signature. Consensus pathway analysis identified EGFR as a potential key determinant of the DDIR signature. EGFR amplification was associated with DDIR negativity and an immune cold TME.

CONCLUSIONS

Our results indicate the importance of the GOA TME in chemotherapy response, its relationship to DNA damage repair and EGFR as a targetable driver of an immune cold TME. Chemotherapy-sensitive inflamed GOAs could benefit from ICI delivered in combination with standard chemotherapy. Combining EGFR inhibitors and ICIs warrants further investigation in patients with EGFR-amplified tumours.

N-allyl quinoxaline derivative exhibited potent and selective cytotoxicity through EGFR/VEGFR-mediated apoptosis: In vitro and in vivo studies

The cytotoxic activity, EGFR/VEGFR2 target inhibition, apoptotic activity, RT-PCR gene expression, in vivo employing a solid-Ehrlich carcinoma model, and in silico investigations for highlighting the binding affinity of eight quinoxaline derivatives were tested for anticancer activities. The results showed that compound 8 (N-allyl quinoxaline) had potent cytotoxicity against A594 and MCF-7 cancer cells with IC50 values of 0.86 and 1.06 µM, respectively, with noncytotoxic activity against WISH and MCF-10A cells having IC50 values more than 100 µM. Furthermore, it strongly induced apoptotic cell death in A549 and MCF-7 cells by 43.13% and 34.07%, respectively, stopping the cell cycle at S and G1-phases. For the molecular target, the results showed that compound 8 had a promising EGFR inhibition activity with an IC50 value of 0.088 µM compared to Sorafenib (IC50  = 0.056 µM), and it had a promising VEGFR2 inhibition activity with an IC50 value of 0.108 µM compared to Sorafenib (IC50  = 0.049 µM). Treatment with compound 8 ameliorated biochemical and histochemical parameters near normal in the in vivo investigation, with a tumor inhibition ratio of 68.19% compared to 64.8% for 5-FU treatment. Finally, the molecular docking study demonstrated the binding affinity through binding energy and interactive binding mode inside the EGFR/VEGFR2 proteins. Potent EGFR and VEGFR2 inhibition of compound 8 suggests its potential for development as a selective anticancer drug.

An integrated genomic approach identifies follistatin as a target of the p63-epidermal growth factor receptor oncogenic network in head and neck squamous cell carcinoma

Although numerous putative oncogenes have been associated with the etiology of head and neck squamous cell carcinoma (HNSCC), the mechanisms by which these oncogenes and their downstream targets mediate tumor progression have not been fully elucidated. We performed an integrative analysis to identify a crucial set of targets of the oncogenic transcription factor p63 that are common across multiple transcriptomic datasets obtained from HNSCC patients, and representative cell line models. Notably, our analysis revealed FST which encodes follistatin, a secreted glycoprotein that inhibits the transforming growth factor TGFβ/activin signaling pathways, to be a direct transcriptional target of p63. In addition, we found that FST expression is also driven by epidermal growth factor receptor EGFR signaling, thus mediating a functional link between the TGF-β and EGFR pathways. We show through loss- and gain-of-function studies that FST predominantly imparts a tumor-growth and migratory phenotype in HNSCC cells. Furthermore, analysis of single-cell RNA sequencing data from HNSCC patients unveiled cancer cells as the dominant source of FST within the tumor microenvironment and exposed a correlation between the expression of FST and its regulators with immune infiltrates. We propose FST as a prognostic biomarker for patient survival and a compelling candidate mediating the broad effects of p63 on the tumor and its associated microenvironment.

PI3K/AKT/mTOR Signaling Pathway in HPV-Driven Head and Neck Carcinogenesis: Therapeutic Implications

High-risk human papillomaviruses (HR-HPVs) are the causal agents of cervical, anogenital and a subset of head and neck carcinomas (HNCs). Indeed, oropharyngeal cancers are a type of HNC highly associated with HR-HPV infections and constitute a specific clinical entity. The oncogenic mechanism of HR-HPV involves E6/E7 oncoprotein overexpression for promoting cell immortalization and transformation, through the downregulation of p53 and pRB tumor suppressor proteins, among other cellular targets. Additionally, E6/E7 proteins are involved in promoting PI3K/AKT/mTOR signaling pathway alterations. In this review, we address the relationship between HR-HPV and PI3K/AKT/mTOR signaling pathway activation in HNC with an emphasis on its therapeutic importance.

EGFR pathway targeting drugs in head and neck cancer in the era of immunotherapy

Receptor tyrosine kinases (RTKs) are cell surface receptors that bind growth factor ligands and initiate cellular signaling. Of the 20 classes of RTKs, 7 classes, I-V, VIII, and X, are linked to head and neck cancers (HNCs). We focus on the first class of RTK, epidermal growth factor receptor (EGFR), as it is the most thoroughly studied class. EGFR overexpression is observed in 20% of tumors, and expression of EGFR variant III is seen in 15% of aggressive chemoradiotherapy resistant HNCs. Currently, the EGFR monoclonal antibody (mAb) cetuximab is the only FDA approved RTK-targeting drug for the treatment of HNCs. Clinical trials have also included EGFR mAbs, with tyrosine kinase inhibitors, and small molecule inhibitors targeting the EGFR, MAPK, and mTOR pathways. Additionally, Immunotherapy has been found to be effective in 15 to 20% of patients with recurrent or metastatic HNC as a monotherapy. Thus, attempts are underway for the combinatorial treatment of immunotherapy and EGFR mAbs to determine if the recruitment of immune cells in the tumor microenvironment can overcome EGFR resistance.

Identification and Experimental Validation of Immune-Associate lncRNAs for Predicting Prognosis in Cervical Cancer

Purpose

Cervical cancer (CC) is a major risk for health of modern women. Immune-related long non-coding RNAs (lncRNAs) can also serve as prognostic markers of overall survival (OS) in patients with CC. This study aimed to identify an immune-related lncRNA signature for the prospective assessment of prognosis in CC patients.

Methods

We first calculated immune scores of CC patients in the Cancer Genome Atlas (TCGA) database. Univariate Cox, Lasso Cox and multivariate Cox regression analyses were perfumed to establish an immune-relative lncRNA signature. In addition, we processed pathway enrichment analysis and immune infiltration analysis between patients with higher or lower risk. Finally, T-cell Chemotaxis assays were processed to verify the function of 2 key lncRNAs.

Results

Our results suggested that patients with higher immune scores had longer survival time and some lncRNAs expressed differentially between two groups. Eight lncRNAs (LINC02802, LINC01877, RBAKDN, LINC02480, WWC2-AS2, LINC01281, ZBTB20-AS1, IFNG-AS1) were identified as prognostic signatures for CC. The immune-related lncRNA signature was correlated with disease progression and worse prognosis. Immune infiltration analysis indicated that the expression of 8-lncRNA signatures were corrected with infiltration level of immune cell subtypes. In addition, T-cell Chemotaxis assay validated that 2 key lncRNAs (ZBTB20-AS1 and LINC01281) could significantly promote the migration ability of T cells to CC cells.

Conclusion

Our finding demonstrated the value of lncRNAs in evaluating the immune infiltrate of the tumor. The 8-lncRNA signature could predict the prognosis of CC and contribute to decisions regarding the immunotherapeutic strategy.

Current landscape of immunotherapy trials in locally advanced and high-risk head and neck cancer

The current standard of therapy for locally advanced (LA) head and neck squamous cell carcinoma (HNSCC) is limited by toxicity and suboptimal control. The role of immunotherapy (IO) is being evaluated in the LA setting. This review aims to summarize the recent advances and the direction of clinical trials in IO in LA or high-risk HNSCC. Despite negative results in some studies, several early phase trials suggest the feasibility and efficacy of IO-based strategies in LA or high-risk HNSCC. Further refining of patient selection and biomarker development is warranted for successful incorporation of IO in this patient population.

A cytokine in turmoil: Transforming growth factor beta in cancer

Cancer remains one of the debilitating health threats to mankind in view of its incurable nature. Many factors are complicit in the initiation, progression and establishment of cancers. Early detection of cancer is the only window of hope that allows for appreciable management and possible limited survival. However, understanding of cancer biology and knowledge of the key factors that interplay at multi-level in the initiation and progression of cancer may hold possible avenues for cancer treatment and management. In particular, dysregulation of growth factor signaling such as that of transforming growth factor beta (TGF-β) and its downstream mediators play key roles in various cancer subtypes. Expanded understanding of the context/cell type-dependent roles of TGF-β and its downstream signaling mediators in cancer may provide leads for cancer pharmacotherapy. Reliable information contained in original articles, reviews, mini-reviews and expert opinions on TGF-β, cancer and the specific roles of TGF-β signaling in various cancer subtypes were retrieved from major scientific data bases including PubMed, Scopus, Medline, Web of Science core collections just to mention but a sample by using the following search terms: TGF-β in cancer, TGF-β and colorectal cancer, TGF-β and brain cancer, TGF-β in cancer initiation, TGF-β and cell proliferation, TGF-β and cell invasion, and TGF-β-based cancer therapy. Retrieved information and reports were carefully examined, contextualized and synchronized into a coherent scientific content to highlight the multiple roles of TGF-β signaling in normal and cancerous cells. From a conceptual standpoint, development of pharmacologically active agents that exert non-specific inhibitory effects on TGF-β signaling on various cell types will undoubtedly lead to a plethora of serious side effects in view of the multi-functionality and pleiotropic nature of TGF-β. Such non-specific targeting of TGF-β could derail any beneficial therapeutic intention associated with TGF-β-based therapy. However, development of pharmacologically active agents designed specifically to target TGF-β signaling in cancer cells may improve cancer pharmacotherapy. Similarly, specific targeting of downstream mediators of TGF-β such as TGF-β type 1 and II receptors (TβRI and TβRII), receptor-mediated Smads, mitogen activated protein kinase (MAPK) and importing proteins in cancer cells may be crucial for cancer pharmacotherapy.

Antitumour immunity regulated by aberrant ERBB family signalling

Aberrant signalling of ERBB family members plays an important role in tumorigenesis and in the escape from antitumour immunity in multiple malignancies. Molecular-targeted agents against these signalling pathways exhibit robust clinical efficacy, but patients inevitably experience acquired resistance to these molecular-targeted therapies. Although cancer immunotherapies, including immune checkpoint inhibitors (ICIs), have shown durable antitumour response in a subset of the treated patients in multiple cancer types, clinical efficacy is limited in cancers harbouring activating gene alterations of ERBB family members. In particular, ICI treatment of patients with non-small cell lung cancers with epidermal growth factor receptor (EGFR) alterations and breast cancers with HER2 alterations failed to show clinical benefits, suggesting that EGFR and HER2 signalling may have an essential role in inhibiting antitumour immune responses. Here, we discuss the mechanisms by which the signalling of ERBB family members affects not only autonomous cancer hallmarks, such as uncontrolled cell proliferation, but also antitumour immune responses in the tumour microenvironment and the potential application of immune-genome precision medicine into immunotherapy and molecular-targeted therapy focusing on the signalling of ERBB family members.

Role of epidermal growth factor receptor inhibitor-induced interferon pathway signaling in the head and neck squamous cell carcinoma therapeutic response

BACKGROUND

Epidermal growth factor receptor (EGFR) is frequently amplified or overexpressed in head and neck squamous cell carcinoma (HNSCC) and is a clinically validated target for the therapeutic antibody, cetuximab, in the management of this cancer. The degree of response to EGFR inhibitors measured by tumor shrinkage varies widely among HNSCC patients, and the biological mechanisms that underlie therapeutic heterogeneity amongst HNSCC patients remain ill-defined.

METHODS

EGFR-dependent human and murine HNSCC cell lines were treated with the EGFR/ERBB inhibitors, gefitinib and AZD8931, and submitted to RNAseq, GSEA, and qRT-PCR. Conditioned media was analyzed by ELISA and Luminex assays. Murine HNSCC tumors were stained for T cell markers by immunofluorescence. Primary HSNCC patient specimens treated with single agent cetuximab were stained with Vectra multispectral immunofluorescence.

RESULTS

The transcriptional reprogramming response to EGFR/ERBB-specific TKIs was measured in a panel of EGFR-dependent human HNSCC cell lines and interferon (IFN) α and γ responses identified as top-ranked TKI-induced pathways. Despite similar drug sensitivity, responses among 7 cell lines varied quantitatively and qualitatively, especially regarding the induced chemokine and cytokine profiles. Of note, the anti-tumorigenic chemokine, CXCL10, and the pro-tumorigenic factor, IL6, exhibited wide-ranging and non-overlapping induction. Similarly, AZD8931 exerted potent growth inhibition, IFNα/IFNγ pathway activation, and CXCL10 induction in murine B4B8 HNSCC cells. AZD8931 treatment of immune-competent mice bearing orthotopic B4B8 tumors increased CD8 + T cell content and the therapeutic response was abrogated in nu/nu mice relative to BALB/c mice. Finally, Vectra 3.0 analysis of HNSCC patient tumors prior to and after 3-4 weeks of single agent cetuximab treatment revealed increased CD8 + T cell content in specimens from patients exhibiting a therapeutic response relative to non-responders.

CONCLUSIONS

The findings reveal heterogeneous, tumor cell-intrinsic, EGFR/ERBB inhibitor-induced IFN pathway activation in HNSCC and suggest that individual tumor responses to oncogene-targeted agents are a sum of direct growth inhibitory effects and variably-induced participation of host immune cells.

Identification of Immune-Related Prognostic Biomarkers Associated with HPV-Positive Head and Neck Squamous Cell Carcinoma

Background

As a type of malignant tumor, head and neck squamous cell carcinoma (HNSCC) seriously threatens human health. This study is aimed at constructing a new, reliable prognostic model.

Method

The gene expression profile data of HNSCC patients were downloaded from the Gene Expression Omnibus and The Cancer Genome Atlas databases. The immune-related differentially expressed genes (IRDEGs) related to HNSCC were identified. We then used Cox regression analysis and least absolute shrinkage and selection operator (LASSO) analysis to explore IRDEGs related to the HNSCC prognosis and to construct and validate a risk scoring model and used ESTIMATE to evaluate tumor immune infiltration in HNSCC patients. Finally, we validated IGSF5 expression and function in HNSCC cells.

Results

A total of 1,195 IRDEGs were found from the GSE65858 dataset. Thirty-one of the 1,195 IRDEGs were associated with the prognosis of HNSCC. Nine key IRDEGs were further selected using the LASSO method, and a risk scoring model was established for predicting the survival of HNSCC patients. According to the risk scoring model, the prognosis of patients in the high-risk group was worse than that of the low-risk group; the high-risk group had significantly higher immune scores than the low-risk group; and between the high- and low-risk samples, there were significant differences in the proportion of 10 types of cells, including naive cells, plasma cells, and resting CD4⁺ memory T cells. IGSF5 has low expression in HNSCC, and overexpression of IGSF5 significantly impaired HNSCC cell proliferation.

Conclusion

This prognostic risk assessment model can help systematically evaluate the survival prognosis of HNSCC patients and provides a new research direction for the improvement of the survival prognosis of HNSCC patients in clinical practice.

The Tumor Microenvironment and Immunotherapy of Oropharyngeal Squamous Cell Carcinoma

Oropharyngeal squamous cell carcinoma (OPSCC) develops as a consequence of several mutations in the tumor suppressor pathways or after a progressive infection with high risk human papillomavirus (HPV). The dismal side effects of the current standard of care and the clear involvement of the immune system has led to a surge in clinical trials that aim to reinforce the tumor-specific immune response as a new treatment option. In this review, we have focused on the most recent literature to discuss the new findings and insights on the role of different immune cells in the context of OPSCC and its etiology. We then applied this knowledge to describe potential biomarkers and analyzed the rationale and outcomes of earlier and ongoing immunotherapy trials. Finally, we describe new developments that are still at the preclinical phase and provide an outlook on what the near future may bring, now that several new and exciting techniques to study the immune system at the single cell level are being exploited.

Tumor-targeting anti-EGFR x anti-PD1 bispecific antibody inhibits EGFR-overexpressing tumor growth by combining EGFR blockade and immune activation with direct tumor cell killing

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The anti-PD1 x anti-EGFR bispecific antibody (BsAb) exhibited all in-vitro bioactivities comparable to that of the parental mAbs and showed anti-tumor efficacies of each of the two arms on par with the mAbs in-vivo.

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The anti-PD1 x anti-EGFR bispecific antibody (BsAb) retained full ADCC towards cancer cells but not to T cells. Thus the BsAb is capable of killing tumor cells via ADCC while sparing T cells for T cell-induced anti-tumor immunity.

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The anti-PD1 x anti-EGFR bispecific antibody (BsAb) exhibited significantly stronger tumor cell killing effects in the presence of PBMC relative to that of combination of cetuximab with an anti-PD1 mAb, 609A.

We developed a strategy to combine conventional targeted therapy with immune checkpoint blockade using a tumor-targeting bispecific antibody (BsAb) to treat solid tumors. The BsAb was designed to simultaneously engage a tumor-associated antigen, epidermal growth factor receptor (EGFR), and programed cell death protein 1 (PD1). In addition to its direct anti-tumor activity via EGFR inhibition, the BsAb mediated efficient antibody-dependent cellular cytotoxicity (ADCC) and activated T cell antitumor im munity through blockade of PD1 from interacting with its counterpart, programed cell death ligand 1 (PDL1). Further, the BsAb exhibited a potent direct tumor cell killing activity in the presence of PBMC, most likely, via activating and, at the same time, physically engaging T cells with tumor cells. Taken together, we here illustrate a new strategy in the design and production of novel BsAbs with enhanced therapeutic efficacy through both direct tumor growth inhibition and T cell activation via tumor-targeted immune checkpoint blockade.

Overexpression of β-Adrenergic Receptors and the Suppressive Effect of β2-Adrenergic Receptor Blockade in Oral Squamous Cell Carcinoma

PURPOSE

The purpose of this project was to investigate the expression of β-adrenergic receptors in oral squamous cell carcinoma (OSCC) and the tumor suppressive activity of β₂-adrenergic receptor (β₂-AR) blockade.

MATERIALS AND METHODS

Samples of 15 normal oral mucosal epithelial tissues, 60 surgically resected OSCC tissues, and 60 adjacent para-carcinoma tissues were collected. The expression of β₁-adrenergic receptor and β₂-AR was detected by real-time quantitative polymerase chain reaction and the Western blot test. SCC9 and Cal27 cell lines and primary OSCC cells also were included and treated with ICI-118,551 (MedChemExpress, Monmouth Junction, NJ), a selective β₂-AR blocker. In addition, the Cal27 cell line was treated with propranolol (a nonselective β-adrenergic receptor blocker) to verify the suppressive effect of β₂-AR blockade. For in vivo assays, Cal27 cells were subcutaneously injected in the tongue flank of nude mice. ICI-118,551 was orally administered to the mice in the treatment group daily. High-throughput sequencing was used to screen for changes in gene expression.

RESULTS

Real-time quantitative polymerase chain reaction and the Western blot test both showed that β₁-adrenergic receptor and β₂-AR were overexpressed in OSCC tissues and cells. A relationship was found between β₂-AR and a more advanced clinical stage, as well as preoperative lymphatic metastasis. After treatment with ICI-118,551 or propranolol, the capacities for proliferation, invasion, and metastasis of OSCC cells were significantly inhibited. Tumor size was significantly different between the ICI-118,551 and control groups. The survival time in the ICI-118,551 group also was prolonged significantly. Moreover, high-throughput sequencing identified 19 affected signaling pathways, including mitogen-activated protein kinase and PI3K-Akt. We confirmed a significant change to the expression of several genes closely related to the progression of cancer.

CONCLUSION

This study showed that β₂-AR is related to a more advanced clinical stage and preoperative lymphatic metastasis. Additionally, a β₂-AR blocker has a significant suppressive effect in OSCC.

[Comparison of T cell response in the tumor milieu of patients with HPV+ and HPV- head and neck cancer]

BACKGROUND

The incidence of HPV-associated squamous cell carcinoma of the head and neck region (HNSCC) has increased dramatically in recent years. Despite a similar localization (oropharyngeal squamous cell epithelia) to smoking- and alcohol-associated cancers, HPV-associated carcinomas are considered to represent a distinct entity. Reasons for the different therapeutic responses of the two tumor entities are not yet fully understood.

METHODS AND OBJECTIVE

This review investigates the importance of tumor-infiltrating lymphocytes in HPV⁺ and HPV^- HNSCC by means of articles and publications concerning the tumor micromilieu, effects on prognosis, and patients' therapeutic responses.

RESULTS

HNSCC patients with a positive HPV status and increased frequencies of CD8⁺ T cells (CD, cluster of differentiation) demonstrated an improved therapeutic response and improved outcomes. Decreased expression of the EGF (epidermal growth factor) receptor correlates with increased T_H1 cytokine secretion by CD4⁺ T cells, which, in their role as T helper cells, can activate macrophages, dendritic cells, and cytotoxic T cells, amongst others. Regulatory T cells (T_reg) execute an immune-suppressive effect in the tumor micromilieu through different metabolic and signaling pathways (IL[interleukin]‑4, IL-10, TGF‑β ["transforming growth factor‑β"]).

CONCLUSION

The importance of the adaptive immune response for treatment response and patients' prognosis has been supported by different investigations. Understanding the immunological processes in the tumor environment plays an important role for the development of new treatment approaches.

Mitochondrial Dysfunction Pathway Networks and Mitochondrial Dynamics in the Pathogenesis of Pituitary Adenomas

Mitochondrion is a multi-functional organelle, which is associated with various signaling pathway networks, including energy metabolism, oxidative stress, cell apoptosis, cell cycles, autophagy, and immunity process. Mitochondrial proteins have been discovered to modulate these signaling pathway networks, and multiple biological behaviors to adapt to various internal environments or signaling events of human pathogenesis. Accordingly, mitochondrial dysfunction that alters the bioenergetic and biosynthetic state might contribute to multiple diseases, including cell transformation and tumor. Multiomics studies have revealed that mitochondrial dysfunction, oxidative stress, and cell cycle dysregulation signaling pathways operate in human pituitary adenomas, which suggest mitochondria play critical roles in pituitary adenomas. Some drugs targeting mitochondria are found as a therapeutic strategy for pituitary adenomas, including melatonin, melatonin inhibitors, temozolomide, pyrimethamine, 18 beta-glycyrrhetinic acid, gossypol acetate, Yougui pill, T-2 toxin, grifolic acid, cyclosporine A, dopamine agonists, and paeoniflorin. This article reviews the latest experimental evidence and potential biological roles of mitochondrial dysfunction and mitochondrial dynamics in pituitary adenoma progression, potential molecular mechanisms between mitochondria and pituitary adenoma progression, and current status and perspectives of mitochondria-based biomarkers and targeted drugs for effective management of pituitary adenomas.

Adaptive Responses to Monotherapy in Head and Neck Cancer: Interventions for Rationale-Based Therapeutic Combinations

Most Phase II and III clinical trials in head and neck cancer (HNC) combine two or more treatment modalities, which are based, in part, on knowledge of the molecular mechanisms of innate and acquired resistance to monotherapy. In this review, we describe the range of tumor-cell autonomously derived (intrinsic) and tumor-microenvironment-derived (extrinsic) acquired-resistance mechanisms to various FDA-approved monotherapies for HNC. Specifically, we describe how tumor cells and the tumor microenvironment (TME) respond to radiation, chemotherapy, targeted therapy (cetuximab), and immunotherapies [programmed cell death 1 (PD-1) inhibitors] and adapt to the selective pressure of these monotherapies. Due to the diversity of adaptive responses to monotherapy, monitoring the response to treatment in patients is critical to understand the path that leads to resistance and to guide the optimal therapeutic drug combinations in the clinical setting. We envisage that applying such a rationale-based therapeutic strategy will improve treatment efficacy in HNC patients.

Molecular Markers of Anticancer Drug Resistance in Head and Neck Squamous Cell Carcinoma: A Literature Review

This manuscript provides an update to the literature on molecules with roles in tumor resistance therapy in head and neck squamous cell carcinoma (HNSCC). Although significant improvements have been made in the treatment for head and neck squamous cell carcinoma, physicians face yet another challenge-that of preserving oral functions, which involves the use of multidisciplinary therapies, such as multiple chemotherapies (CT) and radiotherapy (RT). Designing personalized therapeutic options requires the study of genes involved in drug resistance. This review provides an overview of the molecules that have been linked to resistance to chemotherapy in HNSCC, including the family of ATP-binding cassette transporters (ABCs), nucleotide excision repair/base excision repair (NER/BER) enzymatic complexes (which act on nonspecific DNA lesions generated by gamma and ultraviolet radiation by cross-linking and forming intra/interchain chemical adducts), cisplatin (a chemotherapeutic agent that causes DNA damage and induces apoptosis, which is a paradox because its effectiveness is based on the integrity of the genes involved in apoptotic signaling pathways), and cetuximab, including a discussion of the genes involved in the cell cycle and the proliferation of possible markers that confer resistance to cetuximab.