Confounding factors associated with oral mucositis assessment in patients receiving chemoradiotherapy for head and neck cancer.

PURPOSE: The aim of this study was to identify patient-centered, mucositis-associated adverse impact factors and events that might confound physician-assessed oral mucositis (OM) in head and neck cancer (HNC) patients receiving chemoradiotherapy. METHODS: This was a post hoc analysis of a previously conducted randomized trial to determine the efficacy of 5% phenylbutyrate mouthwash in preventing chemoradiotherapy-induced OM. This analysis identified patient-centered symptomatic, observable, and measurable factors that may confound physician scoring of the severity of OM during chemoradiotherapy. Confounding factors were then combined with physician-rated OM scores according to World Health Organization (WHO) and OM Assessment Scale (OMAS) criteria to investigate the therapeutic implications of OM treatment. RESULTS: The original analysis found no significant differences between experimental and placebo groups with respect to the cumulative incidence of physician-recorded severe OM (WHO ≥3 or OMAS ≥2), patient-reported adverse events, and opioid use. However, patients in the experimental arm had relatively lower rates of OM-associated adverse clinical issues including unplanned short radiation breaks, skipping of chemotherapy, nausea/vomiting, late loss of body weight, and early opioid use, all of which could potentially interfere with physician-assessed OM scoring. When WHO OM grade (functional impact and pain), OMAS ulceration size (organic impact), and prolonged radiation treatment time (cancer treatment impact) were combined, there were significantly fewer interruptions of chemoradiotherapy treatment in symptomatic OM patients in the experimental compared to the placebo group. The benefits conferred by reducing the amount of chemoradiotherapy-related, OM-associated adverse impacts in the experimental group were reflected by better 5-year locoregional recurrence-free survival. CONCLUSIONS: This exploratory study raises questions as to whether the severity reflected by physician-rated OM scores is in concordance with OM-induced adverse impacts on HNC patients. Further investigations are warranted to identify patient-related and cancer-associated symptom burdens that may affect tolerance, compliance, and outcome of chemoradiotherapy and confound the evaluation of therapeutic effects on chemoradiotherapy-induced OM.

Dynamics of wound healing signaling as a potential therapeutic target for radiation-induced tissue damage.

We hypothesized the histone deacetylase inhibitor phenylbutyrate (PB) has beneficial effects on radiation-induced injury by modulating the expression of DNA repair and wound healing genes. Hamsters received a radiosurgical dose of radiation (40 Gy) to the cheek and were treated with varying PB dosing regimens. Gross alteration of the irradiated cheeks, eating function, histological changes, and gene expression during the course of wound healing were compared between treatment groups. Pathological analysis showed decreased radiation-induced mucositis, facilitated epithelial cell growth, and preventing ulcerative wound formation, after short-term PB treatment, but not after vehicle or sustained PB. The radiation-induced wound healing gene expression profile exhibited a sequential transition from the inflammatory and DNA repair phases to the tissue remodeling phase in the vehicle group. Sustained PB treatment resulted in a prolonged wound healing gene expression profile and delayed the wound healing process. Short-term PB shortened the duration of inflammatory cytokine expression, triggered repeated pulsed expression of cell cycle and DNA repair-regulating genes, and promoted earlier oscillatory expression of tissue remodeling genes. Distinct gene expression patterns between sustained and short-term treatment suggest dynamic profiling of wound healing gene expression can be an important part of a biological therapeutic strategy to mitigate radiation-related tissue injury.

Phenylbutyrate suppresses distinct skin reactions that are enhanced by blockade of epidermal growth factor receptor signaling.

BACKGROUND: Epidermal growth factor receptor inhibitors (EGFRIs) cause skin inflammation, and understanding the factors that mediate this reaction is fundamental for designing therapies for EGFRI-related cutaneous side effects. OBJECTIVE: We characterized EGFRI-enhanced skin reactions and evaluated the therapeutic efficacy of phenylbutyrate, a histone deacetylase inhibitor. METHODS: PD168393, an EGFRI, was applied topically to the ear skin of mice with or without mast cell deficiency. The skin was then irritated once or pre-sensitized and repeatedly challenged with 2,4-dinitrofluorobenzene (DNFB). The reaction pattern, the type and number of infiltrating cells, changes in protein, cytokine (TNF-α) and chemokine (CCL2) expression, and the immune response were analyzed. Phenylbutyrate, formulated as a gel for topical treatment or dissolved in water for intraperitoneal administration, was tested as a treatment. RESULTS: EGFRI rapidly upregulated the mast cell chemotactic factor, stem cell factor (SCF) and augmented DNFB-induced immediate contact dermatitis within hours of treatment in the presence of mast cells. Topical phenylbutyrate treatment suppressed EGFRI-induced SCF expression in the epithelium, inhibited DNFB-induced mast cell recruitment in the dermis, and ameliorated the EGFRI-enhanced acute skin reaction. EGFRI also enhanced the delayed-type DNFB-induced hypersensitive reaction that was mast-cell independent but was associated with T lymphocytes. Systemic phenylbutyrate administration suppressed EGFRI-enhanced delayed-type skin hypersensitivity by increasing the number and function of Foxp3(+) T regulatory suppressor cells, which inhibited T helper cell proliferation. CONCLUSIONS: Our data suggest that phenylbutyrate has dual beneficial therapeutic effects on EGFRI-enhanced acute (local inflammatory) and late (systemic immune) skin reactions.

Epigenetic therapy using the histone deacetylase inhibitor for increasing therapeutic gain in oral cancer: prevention of radiation-induced oral mucositis and inhibition of chemical-induced oral carcinogenesis.

In addition to genetic changes, epigenetic aberrations also play important roles in radiation- and chemical-induced disorders and carcinogenesis. The present study investigated whether epigenetic therapy with a histone deacetylase (HDAC) inhibitor has dual benefits for radiation-induced oral mucositis and chemical-induced oral carcinogenesis, which should be treated at the same time. The HDAC inhibitor phenylbutyrate was first tested to determine if it influences DNA damage repair and survival in irradiated normal cells in vitro by investigating the patterns and dynamics of phospho-gammaH2AX foci, Rad51 foci and phospho-gammaH2AX/Rad51 colocalization and using the comet and clonogenic assays. Oral mucositis or carcinogenesis was induced in hamsters using radiation or 7,12-dimethylbenz[a]anthracene (DMBA) irritation to the cheek pouch. The ability of phenylbutyrate formed in proper carriers to prevent radiation-induced oral mucositis and inhibit chemical-induced oral carcinogenesis was assessed. The treated or untreated irradiated or DMBA-irritated oral tissues or mucosal epithelia were subjected to the studies of histology, immunohistochemistry, gene expression, comet assay, HDAC activity or oxidative stress. We found that phenylbutyrate promoted DNA repair and survival in normal cells after radiation. Compared with blank or vehicle-treated hamsters, the irradiated mucosa treated with phenylbutyrate had significantly lower oxidative stress and tumor necrosis factor-alpha expression and less severe oral mucositis of a shorter duration. A reduction of the oral tumor incidence, burden and progression by phenylbutyrate correlated with the suppression of oncomiRs and Rad51 overexpression, the upregulation of differentiation markers and the decrease of intracellular HDAC activity and oxidative stress during DMBA-induced oral carcinogenesis. Thus, epigenetic therapy using the HDAC inhibitor as an adjuvant to radiotherapy for chemical-induced oral cancer may provide a promising strategy combining the prevention of radiation-induced oral mucositis and the inhibition of oral carcinogenesis.