13-cis-retinoic acid in the treatment of oral leukoplakia

Analysis of nuclear receptor expression in head and neck cancer

OBJECTIVE

Studies of squamous cell carcinoma of the head and neck (HNSCC) have demonstrated the importance of nuclear receptors and their associated coregulators in the development and treatment of HNSCC. We sought to characterize members of the nuclear receptor super family through interrogation of RNA-Seq and microarray data.

MATERIALS AND METHODS

TCGA RNA-Seq data within the cBioportal platform comparing HNSCC samples (n = 515 patients with RNA-Seq data) to normal tissue (n = 82 patients) was interrogated for significant differences in nuclear receptor expression. Affymetrix microarray analysis of HNSCC tumors relative to normal oral mucosa (41 tumor, 13 normal) was analyzed.

RESULTS

Of the 48 NR genes and 19 NR cofactors examined, 99 % of tumor samples in the TCGA had some form of NR gene 'alteration' compared to normal tissue. These alterations predominantly encompass expression changes. NR genes (PPARG) and (RORC), and the NR cofactor, (NCOA1), were differentially expressed and downregulated in tumors compared to normal tissue.

CONCLUSION

We have discovered significant decreases in PPARG expression with co-occurring changes in genes involved with lipid metabolism and cell cycle progression in HNSCC. We are targeting PPARγ with thiazolidinediones in a series of clinical trials to restore normal signaling via differentiation to hopefully reverse carcinogenesis. We also observed several receptors with differential expression associated with clinical factors that may become the focus of interest in future targeting efforts. These data provide evidence for nuclear receptors playing a role in the dysregulation of gene expression in HNSCC and illustrate the utility of current bioinformatic tools for interrogating complex, high throughput data sets.

Chemoprevention of Head and Neck Cancer: A Review of Current Approaches and Future Perspectives

Head and neck squamous cell carcinoma (HNSCC) is a spectrum of heterogeneous malignancies. A variety of genetic, environmental, and lifestyle factors contribute to the development of HNSCC. Carcinogenesis is a multistep process in which cell proliferation-associated oncogenes and cell-cycle regulation-associated tumor suppressor genes are dysregulated, resulting in premalignant lesions. Immune evasion is a critical step in the progression of benign lesions to advanced cancer. This review discusses the advances that have been made in chemoprevention strategies for HNSCC. The rationale for the use of chemopreventive agents to inhibit head and neck cancer development is highlighted by the positive outcomes of several clinical trials. We discuss the potential of some of the commonly studied agents including vitamin A analogs, EGFR inhibitors, COX-2 inhibitors, metabolic modulators, and natural compounds such as green tea, as well as immunotherapy and photodynamic therapy to prevent HNSCC. Our review provides insight into the potential benefits of these agents and the gaps that remain to be addressed. The published results reaffirm the promise of chemoprevention in head and neck cancer and suggest that continued exploration is needed to overcome the limitations. Because the current focus on chemopreventive agents is limited, major efforts in precision oncology approaches and substantial increase in funding will promote research into chemoprevention, which will eventually decrease the incidence of HNSCC.

Oral Pre-malignancy: An Update on Novel Therapeutic Approaches

PURPOSE OF REVIEW

This review aims to provide a comprehensive overview of the current advances in managing and preventing progression of oral potentially malignant disorders (OPMDs), focusing on their histological and clinicopathological features, and management.

RECENT FINDINGS

Recent studies, including a multicenter cross-sectional study, have identified oral leukoplakia as the most prevalent form of OPMD, comprising over half of the cases examined. Advances in histological grading, specifically the World Health Organization's three-tier system (mild, moderate, and severe dysplasia), have significantly enhanced the accuracy of risk assessment for malignant transformation. Additionally, treatments such as surgical interventions, photodynamic therapy, and chemopreventive and molecularly targeted agents are being evaluated for their safety and efficacy as well as, immune checkpoint inhibitors being evaluated as potential preventive strategies to halt the progression of OPMDs. The management of OPMDs remains challenging due to the lack of standardized screening protocols and varied clinical management approaches. Despite this, recent advancements in diagnostic grading and therapeutic interventions provide a framework for improved treatment outcomes. Continued research into the molecular and cellular mechanisms driving development and progression of OPMDs and innovative treatment trials are essential to optimize strategies that prevent malignant progression and thereby reduce the global health burden of oral cancer.

Chemopreventive and Biological Strategies in the Management of Oral Potentially Malignant and Malignant Disorders

Oral potentially malignant disorders (OPMD) and oral squamous cell carcinoma (OSCC) represent a significant global health burden due to their potential for malignant transformation and the challenges associated with their diagnosis and treatment. Chemoprevention, an innovative approach aimed at halting or reversing the neoplastic process before full malignancy, has emerged as a promising avenue for mitigating the impact of OPMD and OSCC. The pivotal role of chemopreventive strategies is underscored by the need for effective interventions that go beyond traditional therapies. In this regard, chemopreventive agents offer a unique opportunity to intercept disease progression by targeting the molecular pathways implicated in carcinogenesis. Natural compounds, such as curcumin, green tea polyphenols, and resveratrol, exhibit anti-inflammatory, antioxidant, and anti-cancer properties that could make them potential candidates for curtailing the transformation of OPMD to OSCC. Moreover, targeted therapies directed at specific molecular alterations hold promise in disrupting the signaling cascades driving OSCC growth. Immunomodulatory agents, like immune checkpoint inhibitors, are gaining attention for their potential to harness the body's immune response against early malignancies, thus impeding OSCC advancement. Additionally, nutritional interventions and topical formulations of chemopreventive agents offer localized strategies for preventing carcinogenesis in the oral cavity. The challenge lies in optimizing these strategies for efficacy, safety, and patient compliance. This review presents an up to date on the dynamic interplay between molecular insights, clinical interventions, and the broader goal of reducing the burden of oral malignancies. As research progresses, the synergy between early diagnosis, non-invasive biomarker identification, and chemopreventive therapy is poised to reshape the landscape of OPMD and OSCC management, offering a glimpse of a future where these diseases are no longer insurmountable challenges but rather preventable and manageable conditions.

Bioactive phytocompounds for oral cancer prevention and treatment: A comprehensive and critical evaluation

The high incidence of oral cancer combined with excessive treatment cost underscores the need for novel oral cancer preventive and therapeutic options. The value of natural agents, including plant secondary metabolites (phytochemicals), in preventing carcinogenesis and representing expansive source of anticancer drugs have been established. While fragmentary research data are available on antioral cancer effects of phytochemicals, a comprehensive and critical evaluation of the potential of these agents for the prevention and intervention of human oral malignancies has not been conducted according to our knowledge. This study presents a complete and critical analysis of current preclinical and clinical results on the prevention and treatment of oral cancer using phytochemicals. Our in-depth analysis highlights anticancer effects of various phytochemicals, such as phenolics, terpenoids, alkaloids, and sulfur-containing compounds, against numerous oral cancer cells and/or in vivo oral cancer models by antiproliferative, proapoptotic, cell cycle-regulatory, antiinvasive, antiangiogenic, and antimetastatic effects. Bioactive phytochemicals exert their antineoplastic effects by modulating various signaling pathways, specifically involving the epidermal growth factor receptor, cytokine receptors, toll-like receptors, and tumor necrosis factor receptor and consequently alter the expression of downstream genes and proteins. Interestingly, phytochemicals demonstrate encouraging effects in clinical trials, such as reduction of oral lesion size, cell growth, pain score, and development of new lesions. While most phytochemicals displayed minimal toxicity, concerns with bioavailability may limit their clinical application. Future directions for research include more in-depth mechanistic in vivo studies, administration of phytochemicals using novel formulations, investigation of phytocompounds as adjuvants to conventional treatment, and randomized clinical trials.

A comparative study to evaluate the therapeutic effects of nutraceuticals in oral leukoplakia:- A randomized clinical trail

Background

Oral leukoplakia, usually white changes in the oral mucosa, is one of the most common conditions affecting the oral cavity. Oral leukoplakia can occur anywhere in the mouth and is usually asymptomatic. Clinical diagnosis is reliant on visual inspection and manual palpation. It has a global prevalence of 2.6% and a malignant transformation rate of 0.13-34%. In India, OL has a higher prevalence (0.2-5.2%) but a lower a malignant transformation rate (0.13-10%).

Methodology

It was a randomized control trial in which study was conducted on clinically diagnosed 300 oral leukoplakia patients. All patients were randomly categorized in three groups of 100 each. Group-A: Patients were given commercially available curcumin 500 mg. daily orally. Group-B: Patients were given 4 mg of oral lycopene daily. Group-C: Patients were treated with 4 mg of lycopene + 500 mg curcumin daily by oral route. After recording the pre-treatment clinical findings, all the participants were evaluated regularly after 30 days, 60 days and 90 days of active treatment and once in a month for another 3 months of post-treatment follow-up and to evaluate concomitant medication, lesion(s), compliance, and adverse events. The clinical response was evaluated by bi-dimensional measurement of the lesions and color photography. Safety assessment measures: Physical examination and laboratory tests were performed at baseline, and every 30 days for 3 months after randomization.

Result

Number of participants cured after treatment with oral curcumin was 51%. Participants took lycopene tablets showed 63% cure rate and 72% participants cured after treatment with combination curcumin and lycopene.

Conclusion

Results showed that curcumin, lycopene, and a combination of the two are effective in the treatment of oral leukoplakia. When compared, we found that lycopene is a better nutraceutical as compared to curcumin. When both nutraceuticals were given to the participants, they showed better results than single nutraceuticals when the data were analyzed after 90 days of treatment. There is a significant difference in the response of curcumin and combinations of both nutraceuticals, although the difference between lycopene and combinations of curcumin and lycopene is insignificant.

Oral Isotretinoin and Its Uses in Dermatology: A Review

In 1982, the Food and Drug Administration (FDA) of the United States of America approved isotretinoin (13-cis-retinoic acid), a retinoid derivative of vitamin A, to treat severe recalcitrant acne vulgaris. Apart from its prescribed use for severe acne, evidence suggests that isotretinoin is commonly used off-label to treat mild-to-moderate acne, inflammatory skin conditions, genodermatoses, skin cancer, and other skin disorders. This is due to its anti-inflammatory, immunomodulatory, and antineoplastic properties. Some "off-label" use is successful, while others are ineffective. Therefore, this information is essential to clinicians for deciding on the appropriate use of isotretinoin. In this article, we aim to review the most updated evidence-based data about the use of oral isotretinoin in dermatology.

Developmental synergism in the management of oral potentially malignant disorders

Oral potentially malignant disorders (OPMDs) are associated with an increased risk of occurrence of cancers of the oral cavity or lips. The unifying theme of OPMDs is their potential risk for cancer development. Therefore, the primary objective of the management should be to prevent carcinogenesis. Beyond diagnosis, current strategies for the management of OPMDs predominantly include non-surgical and surgical interventions and a "watch-and-see" approach, such as disease monitoring or surveillance, and preventive strategies. Though no optimal clinical treatment has gained universal approval for reducing or preventing malignant development of OPMDs. Therefore, an urgent need exits for improved treatment properties and effective predictive markers for OPMDs treatment. This review aims to outline recent synergism regarding to the management of OPMDs. Developing new technologies and improved application parameters to promote the treatment efficacy and a novel management prescription approach to OPMDs are proposed.

Chemoprevention of oral cancer: A review and future perspectives

BACKGROUND

Oral cancer causes significant morbidity and mortality. Chemoprevention utilizes medication or natural compounds to reverse oral premalignant lesions and to prevent second primary tumors.

METHODS

A comprehensive PubMed database and Cochrane Library search from 1980 to 2021 was performed using the keywords "leukoplakia," "oral premalignant lesion," and "chemoprevention."

RESULTS

Chemopreventive agents included retinoids, carotenoids, cyclooxygenase inhibitor, herbal extracts, bleomycin, tyrosine kinase inhibitors, metformin, and immune checkpoint inhibitors. Although some agents demonstrated effect in reducing premalignant lesions and preventing second primary tumors, the results among different studies were highly variable.

CONCLUSIONS

The results of different trials, albeit inconsistent, provided substantial information for future studies. In the era of personalized medicine, future studies will focus on identifying specific biomarkers and molecular profile to monitor and to prevent malignant transformation. Larger trials are warranted to validate the effect of chemopreventive agents.

Curcumin a Natural Phenol and Its Therapeutic Role in Cancer and Photodynamic Therapy: A Review

Cancer continues to cause an alarming number of deaths globally, and its burden on the health system is significant. Though different conventional therapeutic procedures are exploited for cancer treatment, the prevalence and death rates remain elevated. These, therefore, insinuate that novel and more efficient treatment procedures are needed for cancer. Curcumin, a bioactive, natural, phenolic compound isolated from the rhizome of the herbaceous plant turmeric, is receiving great interest for its exciting and broad pharmacological properties. Curcumin presents anticancer therapeutic capacities and can be utilized as a photosensitizing drug in cancer photodynamic therapy (PDT). Nonetheless, curcumin's poor bioavailability and related pharmacokinetics limit its clinical utility in cancer treatment. This review looks at the physical and chemical properties, bioavailability, and safety of curcumin, while focusing on curcumin as an agent in cancer therapy and as a photosensitizer in cancer PDT. The possible mechanisms and cellular targets of curcumin in cancer therapy and PDT are highlighted. Furthermore, recent improvements in curcumin's bioavailability in cancer therapy using nanoformulations and delivery systems are presented.

Treating Head and Neck Cancer in the Age of Immunotherapy: A 2023 Update

Most patients diagnosed with head and neck squamous cell carcinoma (HNSCC) will present with locally advanced disease, requiring multimodality therapy. While this approach has a curative intent, a significant subset of these patients will develop locoregional failure and/or distant metastases. The prognosis of these patients is poor, and therapeutic options other than palliative chemotherapy are urgently needed. Epidermal growth factor receptor (EGFR) overexpression is an important factor in the pathogenesis of HNSCC, and a decade ago, the EGFR targeting monoclonal antibody cetuximab was approved for the treatment of late-stage HNSCC in different settings. In 2016, the anti-programmed death-1 (PD-1) immune checkpoint inhibitors nivolumab and pembrolizumab were both approved for the treatment of patients with recurrent or metastatic HNSCC with disease progression on or after platinum-containing chemotherapy, and in 2019, pembrolizumab was approved for first-line treatment (either as monotherapy in PD-L1 expressing tumors, or in combination with chemotherapy). Currently, trials are ongoing to include immune checkpoint inhibition in the (neo)adjuvant treatment of HNSCC as well as in novel combinations with other drugs in the recurrent/metastatic setting to improve response rates and survival and help overcome resistance mechanisms to immune checkpoint blockade. This article provides a comprehensive review of the management of head and neck cancers in the current era of immunotherapy.

Chemotherapy for primary cancer can reduce the risk of head and neck second primary malignancy: a propensity-matched analysis

OBJECTIVES

To investigate the effect of chemotherapy versus no chemotherapy on the risk of second primary head and neck malignancies (SPHNMs) in patients with locally advanced oral squamous cell carcinoma (OSCC) and to assess the survival outcomes of patients with SPHNM.

MATERIALS AND METHODS

A total of 937 OSCC patients were divided into chemotherapy and nonchemotherapy groups by propensity score matching (PSM). In the presence of the competing event of non-SPHNM death, the fine and gray modified Cox proportional hazard model was fitted to detect the impact of various factors, including the history of chemotherapy, on SPHNM risk. The Kaplan-Meier method was used to assess the survival outcomes of patients.

RESULTS

After PSM, the 10-year cumulative probability of SPHNM was 10.7% for patients who received chemotherapy and 22.1% for patients who did not. The fine and gray regression model showed that prior chemotherapy was associated with a 51% reduced risk of SPHNM (adjusted subdistribution hazard ratio (sHR): 0.49, 95% confidence interval (CI): 0.29-0.84, P = 0.1). The disease-free survival (DFS) rates did not differ significantly between the SPHNM and non-SPHNM groups. And there were no significant differences in DFS rates between the patients with and those without prior chemotherapy in the SPHNM group.

CONCLUSIONS

Chemotherapy for locally advanced primary OSCC is associated with a decreased incidence of subsequent SPHNM. However, chemotherapy for the primary cancer does not improve DFS in patients with SPHNM.

CLINICAL RELEVANCE

Chemotherapy plays a positive role in preventing SPHNMs for patients with oral squamous cell carcinoma.

CLINICAL TRIAL REGISTRATION

Before January 2015, the data were retrieved retrospectively, while after January 2015, the data were collected prospectively in a POROMS database (ClinicalTrials.gov ID: NCT02395367).

Toxicity, Genotoxicity, and Carcinogenicity of Isotretinoin

BACKGROUND

Acne is a chronic inflammatory disease mainly observed in adolescence, but it can also be seen during the neonatal, infantile, pre-pubertal, and adult periods. Isotretinoin (13-cis-retinoic acid) is a first-generation retinoid and is the most effective treatment for acne vulgaris.

OBJECTIVE

The present study has been systematically designed to figure out the toxic, genotoxic, and carcinogenic activities of isotretinoin.

METHODS

In this study, a systematic approach was followed by focusing on the possible links between these topics. The search of the databases was carried out author in accordance with the guidelines of the Centre for Reviews and Dissemination (2009) developed by York University National Institute of Health Research. The search was concentrated on the Web of Science, PubMed, Science Direct, Scopus, EBSCO Host, and Google Scholar databases.

RESULTS

Isotretinoin was found as a toxic agent in all studies. All researchers proposed that apoptosis is the only pathway of adverse effects of isotretinoin. However, genotoxicity, teratogenicity, and carcinogenicity information of isotretinoin is very limited and controversial.

CONCLUSION

More detailed studies need to clarify the genotoxic and carcinogenic potential of isotretinoin. Patients should be informed correctly, the risks of treatment should be explained, and awareness should be raised.

Vocal Folds Leukoplakia: The Efficacy of Vitamin A in the Initial Treatment

Introduction  Laryngeal leukoplakia corresponds to a white lesion in the mucosa developed by the deposit of keratin in the epithelium, potentiated by chronic smoking. It is considered a preneoplastic lesion. Surgery is the most adopted treatment; however, non-surgical treatment is advocated by some authors. Objective  To evaluate the effectiveness of vitamin A in the management of vocal fold leukoplakia. Methods  Patients with videolaryngoscopy diagnosis of vocal fold leukoplakia were selected. The endoscopic images were photographed and with the aid of the ImageJ software (National Institutes of Health, Bethesda, MD, USA), the proportion of the size of the leukoplakia was calculated. Eligible patients were prescribed 50,000U of vitamin A, twice daily for 2 months, at which point videolaryngostroboscopy was repeated for comparative analysis between pre and posttreatment. The efficacy of the treatment was classified as: outcome I - complete improvement of the lesion, outcome II - partial improvement, and outcome III - no difference or increased lesion size. Results  Fifteen patients (eight women, seven men) were included, six of whom had bilateral lesions. Smoking was reported in 86.8% of patients. Complete improvement of the lesion was found in 7 cases (33.4%, outcome I), partial improvement in 6 (28.6%, outcome II), and worsening of the injury in 8 (38.1%, outcome III). Of the latter, 6 underwent microsurgery; histopathology indicated absence of dysplasia in 3, and mild dysplasia in 3. Conclusions  In this study, the treatment with vitamin A at a dose of 100,000 IU daily for 2 months was effective in reducing the laryngeal leukoplakia size in 62% of cases.

Randomized Crossover Trial Evaluating Detoxification of Tobacco Carcinogens by Broccoli Seed and Sprout Extract in Current Smokers

Consumption of cruciferous vegetables, rich in the isothiocyanate glucoraphanin, is associated with reduced risk of tobacco-related cancers. Sulforaphane, released by hydrolysis of glucoraphanin, potently induces cytoprotective phase II enzymes. Sulforaphane decreased the incidence of oral cancer in the 4NQO carcinogenesis model. In residents of Qidong, China, broccoli seed and sprout extracts (BSSE) increased detoxification of air pollutants benzene and acrolein, also found in tobacco smoke. This randomized, crossover trial evaluated detoxification of tobacco carcinogens by the BSSE Avmacol® in otherwise healthy smokers. Participants were treated for 2 weeks with both low and higher-dose BSSE (148 µmol vs. 296 µmol of glucoraphanin daily), separated by a 2-week washout, with randomization to low-high vs. high-low sequence. The primary endpoint was detoxification of benzene, measured by urinary excretion of its mercapturic acid, SPMA. Secondary endpoints included bioavailability, detoxification of acrolein and crotonaldehyde, modulation by GST genotype, and toxicity. Forty-nine participants enrolled, including 26 (53%) females with median use of 20 cigarettes/day. Low and higher-dose BSSE showed a mean bioavailability of 11% and 10%, respectively. Higher-dose BSSE significantly upregulated urinary excretion of the mercapturic acids of benzene (p = 0.04), acrolein (p < 0.01), and crotonaldehyde (p = 0.02), independent of GST genotype. Retention and compliance were high resulting in early study completion. In conclusion, BSSE significantly upregulated detoxification of the tobacco carcinogens benzene, acrolein, and crotonaldehyde in current tobacco smokers.

Isotretinoin and neuropsychiatric side effects: Continued vigilance is needed

Background

Isotretinoin (13-cis-retinoic acid, marketed under the names Accutane, Roaccutane, and others) is an effective treatment for acne that has been on the market for over 30 years, although reports of neuropsychiatric side effects continue to be reported. Isotretinoin is an isomer of the active form of Vitamin A, 13-trans-retinoic acid, which has known psychiatric side effects when given in excessive doses, and is part of the family of compounds called retinoids, which have multiple functions in the central nervous system.

Methods

The literature was reviewed in pubmed and psychinfo for research related to isotretinoin and neuropsychiatric side effects including depression, suicidal thoughts, suicide, mania, anxiety, impulsivity, emotional lability, violence, aggression, and psychosis.

Results

Multiple case series have shown that successful treatment of acne with isotretinoin results in improvements in measures of quality of life and self esteem However, studies show individual cases of clinically significant depression and other neuropsychiatric events that, although not common, are persistent in the literature. Since the original cases of depression were reported to the United States Food and Drug Administration, numerous cases have been reported to regulatory agencies in the United Kingdom, France, Ireland, Denmark, Australia, Canada, and other countries, making isotretinoin one of the top five medications in the world associated with depression and other neuropsychiatric side effects. Clinicians are advised to warn patients of the risks of neuropsychiatric side effects with isotretinoin which may arise from the medication itself, and not just as a side effect of acne or youth.

New Scenarios in Pharmacological Treatments of Head and Neck Squamous Cell Carcinomas

Head and neck squamous cell carcinoma (HNSCC) is one of the most frequent types of cancer with a lethal outcome in half of the diagnosed cases. Mostly, HNSCC develops in the oral cavity, and its development is associated with tobacco and areca nut/betel quid usage, alcohol consumption, and HPV infection. Oral squamous cell carcinoma, as other head and neck cancers, presents a high degree of intratumor heterogeneity, which makes their treatment difficult, and directly correlates with drug resistance. Since the classical treatments for HNSCC oftentimes do not resolve the clinical picture, there is great need for novel therapeutic approaches, models for drug testing, and new drug delivery systems.

An overview of effect of lycopene and curcumin in oral leukoplakia and oral submucous fibrosis

The purpose of the current article was to evaluate the recently published researches on the use of lycopene and curcumin in oral leukoplakia (OL) and oral submucous fibrosis (OSF). A comprehensive review of the current researches enveloping PubMed, Ovid, and Cochrane was made using the keywords [(Lycopene) OR (Curcumin) AND (Leukoplakia OR OL OR OSF OR OSMF OR OSF OR Submucous Fibrosis)]. We included only randomized control trials and in the English language. The search covers the data from 1994 to August 2020. Six studies (2 of OL and 4 of OSF) finally qualified are included in the study for the qualitative analysis of the result. Out of these six studies, four were found having high risk, one with unclear risk and one with low risk. Only one study came out as finally suitable for the quantitative analysis of the result. A total of 90 participants were included in this review, with a mean age of 32 with a range of 17–60 years. Out of 90 participants, 70 were male and 20 were female. It is evident from the result of this study that the use of oral curcumin and lycopene has significant improvement in the mouth opening, burning sensation, and cheek flexibility in comparison to the placebo. The use of oral curcumin and lycopene appears to be effective and safe in the treatment of OL and OSF but to read the result of use of oral curcumin and lycopene in OL caution should be taken because of bias.

RARβ Expression in Keratinocytes from Potentially Malignant Oral Lesions: The Functional Consequences of Re-Expression by De-Methylating Agents

Simple Summary

Patients may develop white or red patches of the lining of the mouth with an increased risk of developing oral cancer. Treatment with Vitamin A derivatives (retinoids) results in some improvement in these lesions, but this is not maintained, and there are side effects. We know that the cells of the mouth lose cellular receptors for retinoids as these lesions develop, initially by a reversible alteration to the DNA (DNA methylation). Drugs, such as 5-AZA-CdR, which reduce DNA methylation, may restore sensitivity to the effects of retinoids. Treatment of a panel of cells from mouth precancer white patches with retinoids, 5-AZA-CdR and a combination results in varied responses: some cells re-sensitise to retinoids, whereas in others, the main effects on cell division rate and cell lifespan seem related to the effects of 5-AZA-CdR alone. These findings help us to understand the varied responses to retinoids in the clinical setting.

Abstract

Loss of RARβ2 expression by promoter methylation is an early event in oral carcinogenesis. Understanding the mechanisms and consequences of RARβ loss may aid in understanding the disappointing results of retinoid chemoprevention trials. This study aimed to describe the effects of all-trans retinoic acid (ATRA) and the de-methylating agent 5-Aza-2′ deoxycytidine (5-AZA-CdR) on a panel of immortal potentially malignant oral lesion (PMOL) cell cultures. RARβ expression was assessed in PMOL tissues by immunohistochemistry. Cells were treated with ATRA ± 5-AZA-CdR, and the effects on the cell cycle and senescence were assessed. In PMOL tissues, RARβ expression was variable, but lower in biopsies which gave rise to immortal cell cultures. Treatment of iPMOL cells with ATRA resulted in little change in RARβ expression, but the addition of 5-AZA-CdR resulted in significant increases. The effects on the cell cycle and senescence were variable and may be related to 5-AZA-CdR, as this has wider effects on the cell cycle. Overall, the response of iPMOL cells to ATRA and 5-AZA-CdR treatment was variable and is dependent on several factors, including RARβ-promoter methylation. These findings may help to explain the lack of consistent effect of retinoids in PMOLs seen in chemoprevention trials.

Early-Phase Interventional Trials in Oral Cancer Prevention

Simple Summary

Oral cancer is a devastating disease with increasing incidence worldwide. Oral epithelial dysplasia (OED) is a potentially malignant disorder and patients with OED are at increased risk of developing oral cancer. Current strategies for management of OED include surgery or close observation and both fail to address the underlying pathogenesis of the disease. There is an urgent need for evidence-based medical treatments for OED to prevent oral cancer development in this cohort. Chemoprevention trials to date have not delivered therapeutic agents for routine clinical practice. Historically, there has been significant heterogeneity in the design of oral cancer chemoprevention trials, with most failing to selectively recruit patients with biopsy-proven OED, which limits the usefulness of the findings in the OED population. The present paper aims to review the current evidence and the methodology of early-phase trials in oral cancer chemoprevention. Novel strategies in oral cancer chemoprevention will also be discussed.

Abstract

The increasing breadth of molecular targets, promise of immune-targeted therapies and repurposed agents have heightened interest in cancer prevention. While, to date, testing of oral cancer chemoprevention strategies has failed to deliver therapeutic agents for routine clinical practice, there remains an urgent need for further clinical research to overcome this hurdle. Patients at the greatest risk of disease stand to benefit the most from inclusion in clinical trials; therefore, there is a need to carefully define this population using validated clinical and molecular markers. Safety, tolerability and the efficacy of interventions is assessed through carefully selected endpoints. These endpoints may include pharmacodynamic, clinical, histological and on-target molecular modifications as an individual or as a composite endpoint. Early-phase trials provide an area of opportunity to explore novel and repurposed agents in the setting of oral cancer chemoprevention, eventually leading to phase III trials with clinical endpoints such as transformation and clinical outcome; these studies are large, lengthy and expensive and should be reserved for the most promising of agents. This paper will explore current evidence in oral cancer chemoprevention, drug repurposing, selection of appropriate endpoints for early-phase trials and novel therapeutic angles in oral cancer chemoprevention.

Management of Oral Potentially Malignant Disorders

Patients with oral potentially malignant disorders (OPMDs), including oral leukoplakia and erythroplakia, proliferative verrucous leukoplakia, oral submucous fibrosis, and oral lichen planus/lichenoid lesions can be challenging to manage. A small proportion will undergo cancer development and determining a patient's cancer risk is key to making management decisions. Yet, our understanding of the natural history of OPMDs has not been fully elucidated, and a precision approach based on the integration of numerous predictive markers has not been validated by prospective studies. Evidence-based health promotion by clinicians and healthcare systems is not embraced universally. Medical and surgical interventions evaluated by rigorous research measuring important endpoints, such as cancer development, mortality, or survival are difficult and expensive to run. Most of these studies employ non-ideal surrogate endpoints and have deep methodologic flaws. Diagnostic criteria for enrolling research subjects are not uniform, and patients with the highest risk for cancer development comprise small proportions of those enrolled. Few studies explore quality of life and patient preferences. It is time to rethink how we approach the management of these patients, across each OPMD, and considering the healthcare infrastructure and cost effectiveness. Global networks with well-characterized patient populations with OPMDs and well-designed interventional trials using validated outcome measures are needed.

Phytochemicals as Potential Chemopreventive and Chemotherapeutic Agents for Emerging Human Papillomavirus-Driven Head and Neck Cancer: Current Evidence and Future Prospects

Head and neck cancer (HNC) usually arises from squamous cells of the upper aerodigestive tract that line the mucosal surface in the head and neck region. In India, HNC is common in males, and it is the sixth most common cancer globally. Conventionally, HNC attributes to the use of alcohol or chewing tobacco. Over the past four decades, portions of human papillomavirus (HPV)-positive HNC are increasing at an alarming rate. Identification based on the etiological factors and molecular signatures demonstrates that these neoplastic lesions belong to a distinct category that differs in pathological characteristics and therapeutic response. Slow development in HNC therapeutics has resulted in a low 5-year survival rate in the last two decades. Interestingly, HPV-positive HNC has shown better outcomes following conservative treatments and immunotherapies. This raises demand to have a pre-therapy assessment of HPV status to decide the treatment strategy. Moreover, there is no HPV-specific treatment for HPV-positive HNC patients. Accumulating evidence suggests that phytochemicals are promising leads against HNC and show potential as adjuvants to chemoradiotherapy in HNC. However, only a few of these phytochemicals target HPV. The aim of the present article was to collate data on various leading phytochemicals that have shown promising results in the prevention and treatment of HNC in general and HPV-driven HNC. The review explores the possibility of using these leads against HPV-positive tumors as some of the signaling pathways are common. The review also addresses various challenges in the field that prevent their use in clinical settings.

Inhibition of mTOR signaling and clinical activity of metformin in oral premalignant lesions

BACKGROUND

The aberrant activation of the PI3K/mTOR signaling circuitry is one of the most frequently dysregulated signaling events in head and neck squamous cell carcinoma (HNSCC). Here, we conducted a single-arm, open-label phase IIa clinical trial in individuals with oral premalignant lesions (OPLs) to explore the potential of metformin to target PI3K/mTOR signaling for HNSCC prevention.

METHODS

Individuals with OPLs, but who were otherwise healthy and without diabetes, underwent pretreatment and posttreatment clinical exam and biopsy. Participants received metformin for 12 weeks (week 1, 500 mg; week 2, 1000 mg; weeks 3–12, 2000 mg daily). Pretreatment and posttreatment biopsies, saliva, and blood were obtained for biomarker analysis, including IHC assessment of mTOR signaling and exome sequencing.

RESULTS

Twenty-three participants were evaluable for response. The clinical response rate (defined as a ≥50% reduction in lesion size) was 17%. Although lower than the proposed threshold for favorable clinical response, the histological response rate (improvement in histological grade) was 60%, including 17% complete responses and 43% partial responses. Logistic regression analysis revealed that when compared with never smokers, current and former smokers had statistically significantly increased histological responses (P = 0.016). Remarkably, a significant correlation existed between decreased mTOR activity (pS6 IHC staining) in the basal epithelial layers of OPLs and the histological (P = 0.04) and clinical (P = 0.01) responses.

CONCLUSION

To our knowledge this is the first phase II trial of metformin in individuals with OPLs, providing evidence that metformin administration results in encouraging histological responses and mTOR pathway modulation, thus supporting its further investigation as a chemopreventive agent.

TRIAL REGISTRATION

NCT02581137

FUNDING

NIH contract HHSN261201200031I, grants R01DE026644 and R01DE026870

Precision and Immunoprevention Strategies for Tobacco-Related Head and Neck Cancer Chemoprevention

OPINION STATEMENT

To date, there is no FDA-approved chemoprevention approach for tobacco-related HNSCC. Effective chemoprevention approaches validated in sufficiently powered randomized trials are needed to reduce the incidence and improve survival. In this review, we recap the challenges encountered in past chemoprevention trials and discuss emerging approaches, with major focus on green chemoprevention, precision prevention, and immunoprevention. As our current depth of knowledge expands in the arena of cancer immunotherapy, the field of immunoprevention is primed for new discoveries and successes in cancer prevention.

New Insights into Oral Cancer-Risk Factors and Prevention: A Review of Literature

The oral cancer constitutes 48% of head and neck cancer cases. Ninety percent of oral cancer cases are histologically diagnosed as oral squamous cell carcinomas (OSCCs). Despite new management strategies, the 5-year survival rate of oral cancer is still below 50% in most countries. Head and neck cancers are heterogeneous tumors, and this characteristic of them provides a challenge to treatment plan. Due to the poor outcomes in oral cancer, prevention is a necessity. In this review, a relevant English Literature search in PubMed, ScienceDirect, and Google Scholar from 2000 to mid-2018 was performed. All published articles related to oral cancer and its prevention were included. The risk factors of oral cancer and strategies of oral cancer prevention will be discussed.

Comprehensive analysis of circular RNA in oral leukoplakia: upregulated circHLA-C as a potential biomarker for diagnosis and prognosis

Background

Emerging evidence indicates that circular RNAs (circRNAs) play an indispensable role in a variety of tumors, yet the function of circRNAs in premalignant lesions is still obscure. Oral leukoplakia (OLK) is one of the most common premalignant lesions of the oral mucosa. Our study aimed to comprehensively investigate whether circRNAs contribute to the occurrence and development of OLK.

Methods

We obtained six pairs of OLK and normal oral mucosal (NOM) tissue samples and subjected them to high-throughput sequencing to detect the expression of circRNA. In total, 26 pairs of NOM and OLK tissues were used for validation. Key circRNAs were selected and further validated by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), ribonuclease (RNase) R digestion, and Sanger sequencing. Visualization analysis of circular human leukocyte antigen-C (circHLA-C) was performed in the UCSC Genome Browser (genome.ucsc.edu). Functional analysis of differentially expressed (DE) circRNAs were processed by Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Furthermore, TargetScan (www.targetscan.org) was applied to predict targeted micro RNAs (miRNAs) and messenger RNAs (mRNAs) of circRNAs and a competing endogenous RNA (ceRNA) network related with identified circRNAs was constructed in Cytoscape (v2.8.0).

Results

Profile data showed that 366 circRNAs were significantly altered in OLK tissues, including 65 upregulated and 301 downregulated circRNA transcripts. Compared with sequencing results, seven selected circRNAs expressed the same changing tendency. The amplest upregulated circRNA in our sequencing data, circHLA-C, was confirmed through back-splice junction sequences by Sanger sequencing after RNase R digestion. Correlation analysis demonstrated that circHLA-C correlated positively with the degree of dysplasia. Furthermore, receiver operating characteristic (ROC) curve analysis indicated that circHLA-C had potential diagnostic value with excellent accuracy and specificity.

Conclusions

According to the literature, we were the first to uncover the expression profiles of circRNAs in OLK. Our research performed a comprehensive bioinformatics analysis of DE circRNAs in OLK and identified circHLA-C as a promising diagnostic biomarker with potential as a therapeutic genetic target for OLK.

Head and neck squamous cell carcinoma

Most head and neck cancers are derived from the mucosal epithelium in the oral cavity, pharynx and larynx and are known collectively as head and neck squamous cell carcinoma (HNSCC). Oral cavity and larynx cancers are generally associated with tobacco consumption, alcohol abuse or both, whereas pharynx cancers are increasingly attributed to infection with human papillomavirus (HPV), primarily HPV-16. Thus, HNSCC can be separated into HPV-negative and HPV-positive HNSCC. Despite evidence of histological progression from cellular atypia through various degrees of dysplasia, ultimately leading to invasive HNSCC, most patients are diagnosed with late-stage HNSCC without a clinically evident antecedent pre-malignant lesion. Traditional staging of HNSCC using the tumour-node-metastasis system has been supplemented by the 2017 AJCC/UICC staging system, which incorporates additional information relevant to HPV-positive disease. Treatment is generally multimodal, consisting of surgery followed by chemoradiotherapy (CRT) for oral cavity cancers and primary CRT for pharynx and larynx cancers. The EGFR monoclonal antibody cetuximab is generally used in combination with radiation in HPV-negative HNSCC where comorbidities prevent the use of cytotoxic chemotherapy. The FDA approved the immune checkpoint inhibitors pembrolizumab and nivolumab for treatment of recurrent or metastatic HNSCC and pembrolizumab as primary treatment for unresectable disease. Elucidation of the molecular genetic landscape of HNSCC over the past decade has revealed new opportunities for therapeutic intervention. Ongoing efforts aim to integrate our understanding of HNSCC biology and immunobiology to identify predictive biomarkers that will enable delivery of the most effective, least-toxic therapies.

Tumor-specific lytic path “hyperploid progression mediated death”: Resolving side effects through targeting retinoblastoma or p53 mutant

A major advance was made to reduce the side effects of cancer therapy via the elucidation of the tumor-specific lytic path “hyperploid progression-mediated death” targeting retinoblastoma (Rb) or p53-mutants defective in G1 DNA damage checkpoint. The genetic basis of human cancers was uncovered through the cloning of the tumor suppressor Rb gene. It encodes a nuclear DNA-binding protein whose self-interaction is regulated by cyclin-dependent kinases. A 3D-structure of Rb dimer is shown, confirming its multimeric status. Rb assumes a central role in cell cycle regulation and the “Rb pathway” is universally inactivated in human cancers. Hyperploidy refers to a state in which cells contain one or more extra chromosomes. Hyperploid progression occurs due to continued cell-cycling without cytokinesis in G1 checkpoint-defective cancer cells. The evidence for the triggering of hyperploid progression-mediated death in RB-mutant human retinoblastoma cells is shown. Hence, the very genetic mutation that predisposes to cancer can be exploited to induce lethality. The discovery helped to establish the principle of targeted cytotoxic cancer therapy at the mechanistic level. By triggering the lytic path, targeted therapy with tumor specificity at the genetic level can be developed. It sets the stage for systematically eliminating side effects for cytotoxic cancer therapy.

Oral isotretinoin for the treatment of dermatologic conditions other than acne: a systematic review and discussion of future directions

While isotretinoin has been the gold-standard of therapy for severe acne since its approval in 1982, its anti-inflammatory properties makes it a potentially applicable and versatile therapy for a wide variety of dermatologic conditions yet to be explored. This systematic review comprehensively recounts the success of oral isotretinoin in non-acne cutaneous diseases and provide insight into future directions of isotretinoin utility. A systematic literature review was performed using PubMed. Search terms included "isotretinoin" OR "accutane" AND "skin" OR "dermatology" OR "hair" OR "nails" OR "rosacea" OR "psoriasis" OR "pityriasis rubra pilaris" OR "condyloma acuminata" OR "granuloma annulare" OR "darier's disease" OR "non-melanoma skin cancer" OR "frontal fibrosing alopecia" OR "cutaneous lupus erythematosus" OR "hidradenitis suppurativa" OR "photodamaged skin" OR "skin aging" OR "wart" OR "flat warts" OR "plane warts" OR "lichen planus" OR "dissecting cellulitis" OR "folliculitis decalvans" OR "sebaceous hyperplasia" OR "cutaneous t-cell lymphoma" OR "mycosis fungoides." A total of 169 studies discuss the use of oral isotretinoin for 16 non-acne dermatologic conditions, the most common being non-melanoma skin cancers (0.2-8.2 mg/kg/day), cutaneous T-cell lymphomas (0.5-2 mg/kg/day), and rosacea (0.22-1 mg/kg/day). Inflammatory conditions such as rosacea, granuloma annulare, and hidradenitis suppurativa benefit from lower oral isotretinoin dosage of 0.3-1 mg/kg/day, whereas, hyperkeratotic diseases such as psoriasis and pityriasis rubra pilaris, consistently respond better to higher dosages of up to 2-4 mg/kg/day for lesion clearance. Recurrence of disease following discontinuation of isotretinoin have been reported for rosacea, psoriasis, granuloma annulare, Darier's disease, dissecting cellulitis, and non-melanoma skin cancers. Disease exacerbation was reported in some patients with hidradenitis suppurativa. Off-label isotretinoin is an effective treatment choice for dermatological conditions beyond acne. Further prospective, randomized human trials are needed to clarify when and how to prescribe off-label isotretinoin for maximum efficacy and safety.

Leukoplakia and Immunology: New Chemoprevention Landscapes?

Oral potentially malignant disorders (OPMDs) comprise a range of clinical-pathological alterations frequently characterized by an architectural and cytological derangements upon histological analysis. Among them, oral leukoplakia is the most common type of these disorders. This work aims to analyze the possible use of drugs such as immunochemopreventive agents for OPMDs. Chemoprevention is the use of synthetic or natural compounds for the reversal, suppression, or prevention of a premalignant lesion conversion to malignant form. Experimental and in vivo data offer us the promise of molecular prevention through immunomodulation; however, currently, there is no evidence for the efficacy of these drugs in the chemoprevention action. Alternative ways to deliver drugs, combined use of molecules with complementary antitumor activities, diet influence, and better definition of individual risk factors must also be considered to reduce toxicity, improve compliance to the protocol treatment and offer a better individualized prevention. In addition, we must carefully reconsider the mode of action of many traditional cancer chemoprevention agents on the immune system, such as enhancing immunosurveillance and reversing the immune evasion. Several studies emphasize the concept of green chemoprevention as an alternative approach to accent healthy lifestyle changes in order to decrease the incidence of HNSCC.

Phase Ib Study of Chemoprevention with Green Tea Polyphenon E and Erlotinib in Patients with Advanced Premalignant Lesions (APL) of the Head and Neck

PURPOSE

On the basis of synergistic effects between green tea polyphenon E (PPE) and EGFR-tyrosine kinase inhibitor in preclinical studies, we conducted a phase Ib study of the PPE and erlotinib combination in patients with advanced premalignant lesions (APL) of the oral cavity and larynx.

PATIENTS AND METHODS

Patients were treated with a fixed dose of PPE (200 mg three times a day) and dose escalation of erlotinib (50, 75, 100 mg daily) for 6 months with tissue biopsy at baseline and 6 months. Primary endpoints were safety and toxicity; secondary endpoints were evaluation of pathologic response, cancer-free survival (CFS), overall survival (OS), and biomarker modulation.

RESULTS

Among 21 enrolled patients, 19 began treatment and 17 completed 6 months of treatment with PPE and erlotinib. Main characteristics of treated patients: 15 severe dysplasia or carcinoma in situ and 17 oral cavity. Only skin rash was associated with dose-limiting toxicity and MTD. Recommended doses for phase II studies are PPE 600 mg daily plus erlotinib 100 mg daily for 6 months. Pathologic responses in 17 evaluable patients: pathologic complete response (47%) and pathologic partial response (18%). The 5-year CFS and OS were 66.3% and 93%, respectively. Among tested biomarkers, only phosphorylated ERK was correlated with response to treatment.

CONCLUSIONS

Treatment with PPE and erlotinib combination was well tolerated in patients with APLs of the head and neck, and showed a high rate of pathologic response with excellent CFS. This combination deserves further investigation for the chemoprevention and/or prevention of second primary tumors in early-stage head and neck cancer.

An Integrated Approach for Preventing Oral Cavity and Oropharyngeal Cancers: Two Etiologies with Distinct and Shared Mechanisms of Carcinogenesis

Head and neck squamous cell carcinoma (HNSCC) was the 7th most common malignancy worldwide in 2018 and despite therapeutic advances, the overall survival rate for oral squamous cell carcinoma (OSCC; ∼50%) has remained unchanged for decades. The most common types are OSCC and oropharyngeal squamous cell carcinoma (OPSCC, survival rate ∼85%). Tobacco smoking is a major risk factor of HNSCC. In the developed world, the incidence of OSCC is declining as a result of tobacco cessation programs. However, OPSCC, which is also linked to human papillomavirus (HPV) infection, is on the rise and now ranks as the most common HPV-related cancer. The current state of knowledge indicates that HPV-associated disease differs substantially from other types of HNSCC and distinct biological differences between HPV-positive and HPV-negative HNSCC have been identified. Although risk factors have been extensively discussed in the literature, there are multiple clinically relevant questions that remain unanswered and even unexplored. Moreover, existing approaches (e.g., tobacco cessation, vaccination, and chemoprevention) to manage and control this disease remain a challenge. Thus, in this review, we discuss potential future basic research that can assist in a better understanding of disease pathogenesis which may lead to novel and more effective preventive strategies for OSCC and OPSCC.

Long-term follow-up of oral epithelial dysplasia: A hospital based cross-sectional study

Background/purpose

Oral epithelial dysplasia (OED) is characterized histopathologically by cellular and morphological changes that remain the single most important factor predicting risk for subsequent development of invasive neoplasia. Hence the aims of the present study were to determine the rate of malignant change of OED in a group of patients followed-up for a number of years, and hence determine factors likely to influence this malignant change, and to describe the clinical characteristics of patients who developed recurrence of OED and second dysplastic lesions.

Materials and methods

This is hospital based cross-sectional study of all biopsy reports with histologically confirmed OED between 2012 and 2018 were retrospectivelly reviewed.

Results

A total of 359 patients with histologically confirmed OED were reviewed, twenty (5.5%) of the 359 patients developed an invasive squamous cell carcinoma (SCC) of the oral mucosa over a period of 2 to 274 months with mean transformation time of 3.3 years.

Conclusion

The high risk of malignant transformation of OED seems to be related to patients older than 50 years when lesions were on the floor of mouth with severe dysplastic changes.

Cancer prevention and treatment using combination therapy with natural compounds

Introduction: Naturally occurring compounds play an essential role in the prevention and treatment of various cancers. There are more than 100 plant and animal based natural compounds currently in clinical use.Areas covered: 1) The importance of natural products combinations in the prevention and treatment of cancer, 2) the need to maximize efficacy while minimizing side effects when using natural product combinations, and 3) specifics related to plant and animal derived natural products, as well as agents derived from natural products. Therapies using natural compounds that have been investigated, their rationale, mechanism of action and findings are reviewed. When the data warrant it, combined interventions that appear to increase efficacy (compared with monotherapy) while minimizing toxicity have been highlighted. Pubmed was used to search for relevant publications.Expert opinion: Combination therapy with natural compounds has the potential to be more effective than single agent therapy. Similar to pharmacologic agents, the goal is to maximize efficacy while mimimizing potential side effects. There is an increasing research focus on the development of agents derived from natural products, with notable successes already achieved from the effort.

Inhibitory Effects of Glucosylceramide on Tumorigenesis Induced by a Carcinogen in Mice

Objective

Glucosylceramide (Glu‐Cer), a glycosylated form of ceramide, has been reported to have cytotoxic effects in the cells of various cancers. We previously reported that dietary Glu‐Cer from rice bran had inhibitory effects on human head and neck squamous cell carcinoma (HNSCC) in nonobese diabetes (NOD)/severe combined immunodeficiency (SCID) mice. In HNSCC, preventing recurrence and second primary cancer is required to improve prognosis. The purpose of the present study was to determine whether dietary Glu‐Cer had anticarcinogenic and antitumorigenic effects in a mouse model of HNSCC.

Methods

A total of 40 CB6F1‐Tg rasH2@Jcl mice were divided into two groups: control and Glu‐Cer. All mice were given 4‐nitroquinoline 1‐oxide for 24 weeks. Control group mice were fed the normal diet without Glu‐Cer. The Glu‐Cer group mice were given a mixture of the normal diet plus 0.25% Glu‐Cer for 24 weeks. Microscopic examination was performed to identify grossly visible preneoplasms and neoplasms in the mouth, pharynx, and esophagus. Epithelial regions were classified as normal tissue, carcinoma in situ (CIS), or SCC; and the number of each type of region was counted.

Results

Compared with the Glu‐Cer group mice, control group mice more frequently developed individual and multiple tumors of each type, including CIS and SCC, in the mouth, pharynx, or esophagus.

Conclusion

Tumor development was effectively inhibited by dietary Glu‐Cer derived from rice bran, indicating that this and related compounds show promise as prophylactic agents for human HNSCC.

Level of Evidence

NA Laryngoscope, 130:E593–E597, 2020

Oral epithelial dysplasia: Causes, quantification, prognosis, and management challenges

Oral epithelial dysplasia is a spectrum of architectural and cytological epithelial changes caused by accumulation of genetic changes, and is associated with an increased risk of progression to squamous cell carcinoma. It is a microscopic diagnosis of immense clinical importance. The initial reports of oral potentially malignant disorders with oral epithelial dysplasia transforming to oral cancer helped in understanding the nature of oral malignancies. Since then, clinical studies on oral potentially malignant disorders have combined microscopic findings of oral epithelial dysplasia to assess the malignant transformation potential of different grades of epithelial dysplasia. A significant amount of scientific literature has amassed on oral epithelial dysplasia relating to aspects of its diagnosis and management. However, the evidence base is weak as a result of the significant variability of published research. Poorly described study methods, variability in different oral epithelial dysplasia grading systems, inter- and intra-examiner variability causing issues of reliability, inadequate sample size, and inconsistent durations of follow-up are some of the methodological issues contributing to the failure to provide dependable information. Randomized clinical trials on the malignant transformation potential of oral epithelial dysplasia and its treatment outcomes are limited. This comprehensive literature review on oral epithelial dysplasia summarizes the scientific knowledge published in the scientific literature in English since its first description. The historical development, etiological factors, grading systems, diagnostic criteria, assessment of risk factors and prevention of malignant transformation, management principles of different grades of oral epithelial dysplasia (surgical and nonsurgical), recommendations on follow-up, and prognostic indicators are discussed in detail.

Gene targets of sulforaphane in head and neck squamous cell carcinoma

Patients who have undergone curative‑intent therapy for head and neck squamous cell carcinoma (HNSCC) exhibit a high rate of development of second primary tumors (SPTs), which are frequently lethal. A chemoprevention strategy that prevents SPTs would have a major impact on patient outcomes. Sulforaphane, a naturally‑occurring compound derived from cruciferous vegetables exhibits chemopreventive activity against HNSCC in a preclinical model. The effects of sulforaphane are considered to be mediated, in large part, through increased protein expression of the transcription factor nuclear factor erythroid 2‑related factor 2 (NRF2). Development of sulforaphane chemoprevention for HNSCC would benefit from the identification of robust biomarkers of sulforaphane activity in HNSCC cells and normal mucosal epithelial cells. The present study revealed that sulforaphane potently induces multiple oxidative stress‑associated genes at the RNA and protein levels, in HNSCC cells and Het‑1A cells, a non‑tumorigenic mucosal epithelial cell line. In the present analysis, HMOX1 and HSPA1A were identified as the most highly upregulated genes following sulforaphane treatment, suggesting their potential value as biomarkers to guide clinical trials. Sulforaphane induction of HMOX1 and HSPA1A was validated in vivo in murine tissues. Furthermore, the impact of sulforaphane treatment of HNSCC cells on the expression levels of natural killer group 2D (NKG2D) and DNAX accessory molecule‑1 (DNAM‑1) ligands, which are activators of natural killer (NK) cells, was examined. NRF2‑dependent upregulation of the NKG2D ligand MICA/B was observed. However, only one of the six HNSCC cell lines studied exhibited enhanced sensitivity to NK cell‑mediated killing following sulforaphane treatment, suggesting that this may not be a general mechanism of sulforaphane chemopreventive activity in HNSCC. In summary, the present study identified robust biomarkers of sulforaphane activity in HNSCC and normal tissues, supporting their application in the development of sulforaphane chemoprevention approaches for HNSCC.

Catalytic synthesis of 9-cis-retinoids: mechanistic insights

The regioselective Z-isomerization of thermodynamically stable all-trans retinoids remains challenging, and ultimately limits the availability of much needed therapeutics for the treatment of human diseases. We present here a novel, straightforward approach for the catalytic Z-isomerization of retinoids using conventional heat treatment or microwave irradiation. A screen of 20 transition metal-based catalysts identified an optimal approach for the regioselective production of Z-retinoids. The most effective catalytic system was comprised of a palladium complex with labile ligands. Several mechanistic studies, including isotopic H/D exchange and state-of-the-art quantum chemical calculations using coupled cluster methods indicate that the isomerization is initiated by catalyst dimerization followed by the formation of a cyclic, six-membered chloropalladate catalyst-substrate adduct, which eventually opens to produce the desired Z-isomer. The synthetic development described here, combined with thorough mechanistic analysis of the underlying chemistry, highlights the use of readily available transition metal-based catalysts in straightforward formats for gram-scale drug synthesis.

Chemoprevention of Head and Neck Cancers: Does It Have Only One Face?

Head and neck squamous cell cancer (HNSCC) represents a significant burden worldwide. Chemoprevention of HNSCC is a means of cancer control with a use of drugs or natural agents in order to hinder or delay the cancer development. The purpose of this article is to review mechanism of action of different chemopreventive agents' groups and results of most important researches concerning them. The safety issues of HNSCC chemoprevention are also discussed. In case of HNSCC there is currently no agent, which would give positive result in the third phase of clinical trials. Promising results of preclinical trials are not always confirmed by further tests. Main problems are low effectiveness, high toxicity, and lack of highly specificity biomarkers for monitoring the research. New trials concerning many agents, as well as novel technologies for provision of pharmaceutical forms of them, including drug nanocarriers, are currently underway, which gives hope for finding the perfect chemopreventive agent formula.

Immunological and classical subtypes of oral premalignant lesions

Oral squamous cell carcinoma (OSCC) is a major cause of cancer-associated morbidity and mortality and may develop from oral premalignant lesions (OPL). An improved molecular classification of OPL may help refining prevention strategies. We identified two main OPL gene-expression subtypes, named immunological and classical, in 86 OPL (discovery dataset). A gene expression-based score was then developed to classify OPL samples from three independent datasets, including 17 (GSE30784),13 (GSE10174) and 15 (GSE85195) OPLs, into either one of the two gene-expression subtypes. Using the single sample gene set enrichment analysis, enrichment scores for immune-related pathways were different between the two OPL subtypes. In OPL from the discovery set, loss of heterozygosities (LOH) at 3p14, 17p13, TP53, 9p21 and 8p22 and miRNA gene expression profiles were analyzed. Deconvolution of the immune infiltrate was performed using the Microenvironment Cell Populations-counter tool. A multivariate analysis revealed that decreased miRNA-142-5p expression (P = 0.0484) and lower T-cell, monocytic and myeloid dendritic cells (MDC) immune infiltration (T-cells, P = 0.0196; CD8 T cells, P = 0.0129; MDC, P = 0.0481; and monocytes, P = 0.0212) were associated with oral cancer development in the immunological subtype only. In contrast, LOH at 3p14 (P = 0.0241), 17p13 (P = 0.0348) and TP53 (P = 0.004) were associated with oral cancer development in the classical subtype only. In conclusion, we identified 2 subtypes of OPLs, namely immune and classical, which may benefit from different and specific personalized prevention interventions.

A Review of Promising Natural Chemopreventive Agents for Head and Neck Cancer

Head and neck squamous cell carcinoma (HNSCC) accounts for 300,000 deaths per year worldwide, and overall survival rates have shown little improvement over the past three decades. Current treatment methods including surgery, chemotherapy, and radiotherapy leave patients with secondary morbidities. Thus, treatment of HNSCC may benefit from exploration of natural compounds as chemopreventive agents. With excellent safety profiles, reduced toxicities, antioxidant properties, and general acceptance for use as dietary supplements, natural compounds are viewed as a desirable area of investigation for chemoprevention. Though most of the field is early in development, numerous studies display the potential utility of natural compounds against HNSCC. These compounds face additional challenges such as low bioavailability for systemic delivery, potential toxicities when consumed in pharmacologic doses, and acquired resistance. However, novel delivery vehicles and synthetic analogues have shown to overcome some of these challenges. This review covers 11 promising natural compounds in the chemoprevention of HNSCC including vitamin A, curcumin, isothiocyanate, green tea, luteolin, resveratrol, genistein, lycopene, bitter melon, withaferin A, and guggulsterone. The review discusses the therapeutic potential and associated challenges of these agents in the chemopreventive efforts against HNSCC. Cancer Prev Res; 11(8); 441-50. ©2018 AACR.

Cancer Prevention: Lessons Learned and Future Directions

In this review, we address selected areas that are central to the state-of-the-art of cancer prevention science. The emphasis on prevention as a viable and critical approach to decreasing cancer mortality has gained traction in recent years, evidenced by its inclusion in the US Vice President's Cancer Initiative (also termed 'Moonshot'). Cancer prevention occurs by arresting, slowing down, or reversing the carcinogenic process before invasion into surrounding tissue or by avoiding or blocking causative exposure. An important challenge is to identify individuals who will benefit most from preventive interventions with the least possible harm. Preventive interventions range from avoiding known carcinogens (e.g., tobacco or asbestos) to intervening with anticarcinogenic strategies (behavioral modifications , such as diet and exercise; medications; nutritional agents; and vaccination against causative agents). Here, we focus on active intervention with measures involving pharmaceutical and immunological agents.

Evaluation and Management of Oral Potentially Malignant Disorders

Oral potentially malignant disorders (OPMDs) refer to epithelial lesions and conditions with an increased risk for malignant transformation; oral leukoplakia is the most commonly encountered. Overall, OPMDs have a low risk for malignant transformation, yet the challenge is the difficulty to reliably identify and predict which patients with OPMDs are at the highest risk for malignant transformation. Future research is needed to elucidate the molecular aspects of OPMDs, to improve current diagnostic strategies, leading to personalized management.

Novel Molecular Targets for Chemoprevention in Malignancies of the Head and Neck

Cancers of the head and neck region are among the leading causes of cancer-related mortalities worldwide. Oral leukoplakia and erythroplakia are identified as precursor lesions to malignancy. Patients cured of an initial primary head and neck cancer are also susceptible to developing second primary tumors due to cancerization of their mucosal field. Multi-step acquisition of genetic mutations leading to tumorigenesis and development of invasive cancer has been previously described. Recently, whole exome sequencing of tumor specimens has helped to identify driver mutations in this disease. For these reasons, chemoprevention or the use of systemic or biologic agents to prevent carcinogenesis is an attractive concept in head and neck cancers. Nonetheless, despite extensive clinical research in this field over the past couple decades, no standard of care option has emerged. This review article reports on targeted interventions that have been attempted in clinical trials to date, and focuses on novel molecular pathways and drugs in development that are worthy of being tested for this indication as part of future endeavors.

Double-blind, randomized phase 3 trial of low-dose 13-cis retinoic acid in the prevention of second primaries in head and neck cancer: Long-term follow-up of a trial of the Eastern Cooperative Oncology Group-ACRIN Cancer Research Group (C0590)

BACKGROUND

13-Cis retinoic acid (13-CRA) is a synthetic vitamin A derivative. High-dose 13-CRA in patients with squamous cell cancers of the head and neck (SCCHNs) reduces the incidence of second primary tumors (SPTs). The authors report long-term results from a phase 3 randomized trial that compared treatment with low-dose 13-CRA versus placebo for patients who had early stage SCCHN, with a focus on the development of SPTs and overall survival (OS).

METHODS

In total, 176 patients who received treatment for stage I/II SCCHN were randomized to receive either low-dose 13-CRA (weight-based dose of 7.5 mg or 10 mg) or placebo for 2 years. A competing-risk approach and the log-rank test were used to compare the time to SPT and OS, respectively, between groups.

RESULTS

13-CRA neither significantly reduced the cumulative incidence of SPT (P = .61) nor improved the time to SPT (hazard ratio [HR] for 13-CRA/placebo; 0.86; P = .61). Despite limited power, there was a trend toward improved OS for the 13-CRA arm (HR, 0.75; P = .14), particularly among patients whose index tumor was surgically excised (N = 26; HR, 0.50; P = .057) and among women (N = 39; HR, 0.44; P = .065) and never/former smokers (N = 129; HR, 0.61; P = .055), with a median follow-up of 16 years. The main 13-CRA related toxicities were dry skin and cheilitis.

CONCLUSIONS

Treatment with low-dose 13-CRA for 2 years did not decrease the incidence of SPT; subset analysis indicates a potential survival advantage among patients who are women and never/former smokers. More targeted interventions based on clinical risk factors and molecular characterization of tumors may yield greater success in future prevention trials. Cancer 2017;123:4653-4662. © 2017 American Cancer Society.