Efficacy and safety of rebamipide liquid for chemoradiotherapy-induced oral mucositis in patients with head and neck cancer: a multicenter, randomized, double-blind, placebo-controlled, parallel-group phase II study

BACKGROUND

Recent preclinical and phase I studies have reported that rebamipide decreased the severity of chemoradiotherapy-induced oral mucositis in patients with oral cancer. This placebo-controlled randomized phase II study assessed the clinical benefit of rebamipide in reducing the incidence of severe chemoradiotherapy-induced oral mucositis in patients with head and neck cancer (HNC).

METHODS

Patients aged 20-75 years with HNC who were scheduled to receive chemoradiotherapy were enrolled. Patients were randomized to receive rebamipide 2% liquid, rebamipide 4% liquid, or placebo. The primary endpoint was the incidence of grade ≥ 3 oral mucositis determined by clinical examination and assessed by central review according to the Common Terminology Criteria of Adverse Events version 3.0. Secondary endpoints were the time to onset of grade ≥ 3 oral mucositis and the incidence of functional impairment (grade ≥ 3) based on the evaluation by the Oral Mucositis Evaluation Committee.

RESULTS

From April 2014 to August 2015, 97 patients with HNC were enrolled, of whom 94 received treatment. The incidence of grade ≥ 3 oral mucositis was 29% and 25% in the rebamipide 2% and 4% groups, respectively, compared with 39% in the placebo group. The proportion of patients who did not develop grade ≥ 3 oral mucositis by day 50 of treatment was 57.9% in the placebo group, whereas the proportion was 68.0% in the rebamipide 2% group and 71.3% in the rebamipide 4% group. The incidences of adverse events potentially related to the study drug were 16%, 26%, and 13% in the placebo, rebamipide 2%, and rebamipide 4% groups, respectively. There was no significant difference in treatment compliance among the groups.

CONCLUSIONS

The present phase II study suggests that mouth washing with rebamipide may be effective and safe for patients with HNC receiving chemoradiotherapy, and 4% liquid is the optimal dose of rebamipide.

TRIAL REGISTRATION

ClinicalTrials.gov under the identifier NCT02085460 (the date of trial registration: March 11, 2014).

Comparative Studies on Lipid Peroxidation in the Kidney of Rats, Mice, and Hamsters and on the Effect of Cysteine, Glutathione, and Diethyl Maleate Treatment on Mortality and Nephrotoxicity After Administration of Potassium Bromate

As an index of lipid peroxidation (LPO), levels of thiobarbituric acid (TBA)-reactive substances were examined in the kidneys of male F344 rats, BDF1, CDF1, and B6C3F1 mice, and Syrian golden hamsters after a single intravenous (IV) administration of potassium bromate (KBrO3) at various doses. In the rats, LPO levels were significantly increased in both a dose-dependent and time-dependent manner. However, when the rats were given intraperitoneal (IP) injection of cysteine, the levels of LPO were not significantly different between KBrO3-treated animals and controls. In CDF1 mice, the slight increases in LPO levels observed were much weaker and not statistically significant. On the other hand, treatment of BDF1 and B6C3F1 mice or hamsters with KBrO3 resulted in decreased values as compared to controls. The effect of treatment with cysteine, glutathione (GSH), or diethyl maleate (DEM) on mortality was tested in male F344 rats given IV injection of KBrO3 at various doses. Significant reduction and elevation in the mortality were observed in rats treated with cysteine or GSH and DEM, respectively. Significant dose-dependent and time-dependent increases were observed in the levels of serum non-protein nitrogen (NPN), blood urea nitrogen (BUN), and creatinine, and absolute and relative weight of the kidneys in male F344 rats administered KBrO3 IV. Microscopically, the appearance of numerous eosinophilic droplets in the cytoplasm of proximal tubular epithelium of KBrO3-treated rats was noteworthy. All these changes were reduced and exacerbated by treatment with cysteine or GSH and DEM, respectively. The possibility of LPO formation in the kidney by active oxygen radicals generated by KBrO3 is suggested. A possible relationship between LPO levels in the kidney and species differences in the renal toxicity and carcinogenicity of KBrO3 is implicated.

Abstract 4619: DNA adductome analyses at multiple sites of human gastric mucosa, resected for gastric cancer

DNA adducts are recognized as an initiative step of mutagenesis, but the measurement of them is still a technical challenge. So-called adductome approach, based on LC-MS/MS, is a popular procedure to identify multiple DNA adducts in various tissues at a single experiments. Recently we reported 7 lipid peroxidation-induced DNA adducts in human gastric mucosa resected for gastric cancer in two countries for the first time, and showed the profile of these DNA adducts could indicate geo-pathological background of gastric mucosa (Matsuda 2013). Though DNA adductome approach posesses the high throghput potential in terms of finding numerous specis of DNA adducts having different molecular weights, there are still challenges to overcome. First of all, the numbers of the standards of DNA adducts molecules available are less than the species with identified molecular weight. This implies there are much more DNA modifications in human tissues than previously characterized. The other challaenge is that the absolute quantifications of these adducts requires isotopic standard chemicals. In this study, we strengthened DNA adductome method by including as many as known adducts in the assay system. Mass/Charge value and liquid chromatography retention time of known 254 DNA addcuts were collected and incoporated into LC-MS/MS machine (4000-QTRAP; Thermo). By this procedure we could measure the 254 DNA adducts at one time in MRM mode. Using this system, we measured 254 DNA adducts in the following human gastric mucosa. Written informed consents were obtained from the patients who took gastrectomy for gastric cancer. Under the hypothesis of field cancerization of gastric mucosa, in order to analyze the spatial influence of the exposure of the potential carcinogens toward cancer site, muocsal tissue at multiple sites with different distance to cancer, (10cm and more distant from the tumor site in the stomach to the site adjacent to the tumor) were taken. Three to 10 sites/case were investigated for DNA adducts measurements. Totally 11 cases and 77 sites are analyzed.

Considerable numbers of known DNA adducts were present in human gastric mucosa in different quantities. Among them, tobacco-related and lipid-peroxidation-induced DNA adducts were noted. We also did the same measurements in proximal, middle, and distal gastric mucosa from autospy cases without gastric cancer and compared them to those of the cancer cases. Among them, etheno-dA was able to be quantitatively measured using isotopic standard. The mean level of etheno dA in the gastric mucosa of autopsy cases without gastric cancer was 8.02/107 nucleotides, while that of gastric cancer patients mucosae was 4.80/107 nucleotides. These comprehensive identifications in adducts in human gastric mucosa will provide the basic information for dosimetry and risk assessment of environmental chemicals toward gastric cancer.

Citation Format: Nobuya Kurabe, Ippei Ohnishi, Masako Suzuki, Yusuke Inoue, Tomoaki Kahyo, Moriya Iwaizumi, Yoshitaka Matsushima, Yukari Totsuka, Hitoshi Nakagama, Masako Kasami, Hideto Ochiai, Keigo Matsumoto, Shioto Suzuki, Fumihiko Tanioka, Haruhiko Sugimura. DNA adductome analyses at multiple sites of human gastric mucosa, resected for gastric cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4619. doi:10.1158/1538-7445.AM2015-4619

Genetic analyses of GII.17 norovirus strains in diarrheal disease outbreaks from December 2014 to March 2015 in Japan reveal a novel polymerase sequence and amino acid substitutions in the capsid region

A novel GII.P17-GII.17 variant norovirus emerged as a major cause of norovirus outbreaks from December 2014 to March 2015 in Japan. Named Hu/GII/JP/2014/GII.P17-GII.17, this variant has a newly identified GII.P17 type RNA-dependent RNA polymerase, while the capsid sequence displays amino acid substitutions around histo-blood group antigen (HBGA) binding sites. Several variants caused by mutations in the capsid region have previously been observed in the GII.4 genotype. Monitoring the GII.17 variant's geographical spread and evolution is important.

Robust quantitative assessments of cytosine modifications and changes in the expressions of related enzymes in gastric cancer

BACKGROUND

The rediscovery of 5-hydroxymethylcytosine, the ten-eleven translocation (TET) family, thymine-DNA glycosylase (TDG) and isocitrate dehydrogenase (IDH) have opened new avenues in the study of DNA demethylation pathways in gastric cancer (GC). We performed a comprehensive and robust analysis of these genes and modified cytosines in gastric cancer.

METHODS

Liquid chromatography mass spectrometry/mass spectrometry (LC-MS/MS) was used to assess 5-methyldeoxycytidine (5-mC), 5-hydroxymethyldeoxycytidine (5-hmC), 5-formyldeoxycytidine (5-fC) and 5-carboxyldeoxycytidine (5-caC) quantitatively in tumorous and non-tumorous regions of GCs; [D2]-5-hmC was used as an internal standard. Expression levels of the genes TET1, TET2, TET3, TDG, IDH1 and IDH2 were measured using a real-time reverse transcription polymerase chain reaction (RT-PCR) and were compared to the clinical attributes of each case. Using HEK293T cells the effects of introducing plasmids containing full-length TET1, TET2, and TET3 and 7 variants of the TET2 catalytic domain were evaluated in terms of their effect on cytosine demethylation.

RESULTS

LC-MS/MS showed that 5-hmC was significantly decreased in tumorous portions. 5-mC was also moderately decreased in tumors, while 5-fC and 5-caC were barely detectable. The expressions of TET1, TET2, TET3, TDG and IDH2, but not IDH1, were notably decreased in GCs, compared with the adjacent non-tumor portion. TET1 expression and the 5-hmC levels determined using LC-MS/MS had a significantly positive correlation and TET1 protein had a greater effect on the increase in 5-hmC than TET2 and TET3 in HEK293T cells.

CONCLUSIONS

The loss of 5-hmC and the down-regulation of TET1-3, TDG and IDH2 were found in GCs. The loss of 5-hmC in GCs was mainly correlated with the down-regulation of TET1.

Human DNA glycosylase enzyme TDG repairs thymine mispaired with exocyclic etheno-DNA adducts

Lipid peroxidation directly reacts with DNA and produces various exocyclic etheno-base DNA adducts, some of which are considered to contribute to carcinogenesis. However, the system for repairing them in humans is largely unknown. We hypothesized that etheno-DNA adducts are repaired by base excision repair initiated by DNA glycosylase. To test this hypothesis, we examined the activities of the DNA glycosylase proteins OGG1, SMUG1, TDG, NEIL1, MUTYH, NTH1, MPG, and UNG2 against double-stranded oligonucleotides containing 1,N(6)-ethenoadenine (εA), 3,N(4)-ethenocytosine (εC), butanone-ethenocytosine (BεC), butanone-ethenoguanine (BεG), heptanone-ethenocytosine (HεC), or heptanone-ethenoguanine (HεG) using a DNA cleavage assay. We found that TDG is capable of removing thymine that has mispaired with εC, BεC, BεG, HεC, or HεG in vitro. We next examined the effect of TDG against etheno-DNA adducts in human cells. TDG-knockdown cells exhibited the following characteristics: (a) higher resistance to cell death caused by the induction of etheno-DNA adducts; (b) lower repair activity for εC; and (c) a modest acceleration of mutations caused by εC, compared with the rate in control cells. All these characteristics suggest that TDG exerts a repair activity against etheno-DNA adducts in human cells. These results suggest that TDG has novel repair activities toward etheno-DNA adducts.

Roles of taurine-mediated tonic GABAA receptor activation in the radial migration of neurons in the fetal mouse cerebral cortex

γ-Aminobutyric acid (GABA) depolarizes embryonic cerebrocortical neurons and continuous activation of the GABA_A receptor (GABA_AR) contributes to their tonic depolarization. Although multiple reports have demonstrated a role of GABA_AR activation in neocortical development, including in migration, most of these studies have used pharmacological blockers. Herein, we performed in utero electroporation in GABA synthesis-lacking homozygous GAD67-GFP knock-in mice (GAD67^GFP/GFP) to label neurons born in the ventricular zone. Three days after electroporation, there were no differences in the distribution of labeled cells between the genotypes. The dose–response properties of labeled cells to GABA were equivalent among genotypes. However, continuous blockade of GABA_AR with the GABA_AR antagonist SR95531 accelerated radial migration. This effect of GABA_AR blockade in GAD67^GFP/GFP mice suggested a role for alternative endogenous GABA_AR agonists. Thus, we tested the role of taurine, which is derived from maternal blood but is abundant in the fetal brain. The taurine-evoked currents in labeled cells were mediated by GABA_AR. Taurine uptake was blocked by a taurine transporter inhibitor, 2-(guanidino)ethanesulfonic acid (GES), and taurine release was blocked by a volume-sensitive anion channel blocker, 4-(2-butyl-6,7-dichlor-2-cyclopentylindan-1-on-5-yl) oxobutyric acid, as examined through high-performance liquid chromatography. GES increased the extracellular taurine concentration and induced an inward shift of the holding current, which was reversed by SR95531. In a taurine-deficient mouse model, the GABA_AR-mediated tonic currents were greatly reduced, and radial migration was accelerated. As the tonic currents were equivalent among the genotypes of GAD67-GFP knock-in mice, taurine, rather than GABA, might play a major role as an endogenous agonist of embryonic tonic GABA_AR conductance, regulating the radial migration of neurons in the developing neocortex.

Abstract 47: DNA adductome: An ultimate exposome of human tissues

The formation of DNA adducts and the subsequent generation of mutations in the genome is believed to be a pivotal event in the pathogenesis of cancer, but several obstacles have hampered a concrete demonstration of the molecular species, quantity, and significance of DNA adducts in human tissues. For the last few years, we have attempted to demonstrate the existence of multiple DNA adducts in human tissues using a single experiment involving liquid chromatography tandem mass spectrometry. This procedure discloses a hundred to a few hundred peaks with distinct mass/charge and retention times in each sample. In previous experiments, we validated the presence of some tobacco-related and other DNA adducts in the lungs of a smoker and a non-smoker. Recently, we demonstrated the presence of lipid peroxidation-induced DNA adducts in several autopsy tissues including the lung, liver, pancreas, and spleen. In this presentation, we would like to show an adductome map for two regions of the human stomach in which the prevalence of gastric cancer differs. The DNA samples were obtained under anti-oxidation conditions from the gastric mucosa from regions adjacent to, but distant from, the cancer lesion in 22 patients with gastric cancer (12 cases in China and 10 cases in Japan) who underwent a gastrectomy. We identified 141 peaks in the Japanese sample and 159 peaks in the Chinese sample. Ninety-two of these peaks were present in both the Japanese and Chinese samples. Seven lipid peroxidation-related DNA adducts (1,N6-etheno-2′-deoxyadenosine [ϵdA], butanone-etheno-2′-deoxycytidine [BϵdC], butanone-etheno-2′-deoxy-5-methylcytidine [BϵmedC], butanone-etheno-2′-deoxyadenosine [BϵdA], heptanone-etheno-2′-deoxycytidine [HϵdC], heptanone-etheno-2′-deoxyadenosine [HϵdA], and heptanone-etheno-2′-deoxyguanosine [HϵdG]) were identified in a total of 22 gastric mucosa samples. The levels of these adducts ranged from 0 to 30,000 per 109 bases, and the levels of BedC, BedA, and HedA were higher in the Japanese gastric mucosa samples. Next, the mutation spectrum for p53 in gastric cancer tissues from the same hospital in China was investigated and compared with that of gastric cancer tissues obtained in Japan. The prevalence of a G-to-A transition in a non-GC area was higher in those derived from China; that is, G-to-A transitions in a GC rich area, which has been assumed to be related to endogenous inflammation, were more prevalent in the Japanese gastric cancer specimens. We interpreted these results as indicating that inflammation can mediate carcinogenesis via lipid peroxidation-induced adducts, and the mutation process that may consequently arise may play a greater role in Japanese gastric cancers than in Chinese gastric cancers. To delve into the mechanism of the cellular reactions to these adducts, oligonucleotides containing ϵdA, ϵdC, BϵdC, BϵdG, HϵdC, and HϵdG were synthesized and used as substrates for a gel retardation assay using the recombinant proteins of 8 different base excision repair genes. In contrast to their considerable capacity to repair smaller modified bases, such as ϵdA and ϵdC, the base excision repair gene products seemed to be less capable of repairing the larger modified bases BϵdC, BϵdG, HϵdC, and HϵdG, except for a few combinations.

While a comprehensive understanding of the modifications of DNA bases, both endogenous and exogenous, and the corresponding host machineries might seem like a distant goal and an adductome approach is admittedly at a burgeoning stage, combing every un-annotated spot in an adductome map could help to realize a comprehensive understanding of the effects of exposures of various kinds.

Citation Format: Haruhiko Sugimura, Hong Tao, Nobuya Kurabe, Masanori Goto, Yoshitaka Matsushima, Hidetaka Yamada, Kazuya Shinmura, Yohei Miyagi, Akira Tsuburaya, Takaki Yoshikawa, Yukari Totsuka, Hitoshi Nakagama, Yaping Wang, Tomonari Matsuda. DNA adductome: An ultimate exposome of human tissues. [abstract]. In: Proceedings of the AACR Special Conference on Post-GWAS Horizons in Molecular Epidemiology: Digging Deeper into the Environment; 2012 Nov 11-14; Hollywood, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(11 Suppl):Abstract nr 47.

Lipid peroxidation-induced DNA adducts in human gastric mucosa

DNA adducts are a major cause of DNA mutation and DNA mutation-related diseases, but the simultaneous identification of multiple DNA adducts has been a challenge for a decade. An adductome approach using consecutive liquid chromatography and double mass spectrometry after micrococcal nuclease treatment has paved the way to demonstrations of numerous DNA adducts in a single experiment and is expected to contribute to the comprehensive understanding of overall environmental and endogenous exposures to possible mutagens in individuals. In this report, we applied an adductome approach to gastric mucosa samples taken at the time of a gastrectomy for gastric cancer in Lujiang, China, and in Hamamatsu, Japan. Seven lipid peroxidation-related DNA adducts [1,N6-etheno-2'-deoxyadenosine, butanone-etheno-2'-deoxycytidine (BεdC), butanone-etheno-2'-deoxy-5-methylcytidine, butanone-etheno-2'-deoxyadenosine (BεdA), heptanone-etheno-2'-deoxycytidine, heptanone-etheno-2'-deoxyadenosine (HεdA) and heptanone-etheno- 2'-deoxyguanosine] were identified in a total of 22 gastric mucosa samples. The levels of these adducts ranged from 0 to 30,000 per 10(9) bases. Although the presence of Helicobacter pylori DNA in the mucosa was not related to these adducts level, the levels of BεdC, BεdA and HεdA were higher in the Japanese gastric mucosa samples. The profiles of these 7 adduct levels among the 21 cases were capable of discriminating between the possible origins (China or Japan) of the gastric mucosa samples. Our report is the first demonstration of lipid peroxidation-related DNA adducts in the human stomach, and these observations warrant further investigation in the context of the significance of DNA adducts in human gastric carcinogenesis.

Temperature-Responsive Chromatography Using Poly(N-isopropylacrylamide)-Modified Silica

A new concept in chromatography is proposed that utilizes a temperature-responsive surface with a constant aqueous mobile phase. The surface of the silica stationary phase in high-performance liquid chromatography (HPLC) has been modified with temperature-responsive polymers to exhibit temperature-controlled hydrophilic/hydrophobic changes. Poly(N-isopropylacrylamide) (PIPAAm) was grafted onto (aminopropyl)silica using an activated ester-amine coupling method. These grafted silica surfaces show hydrophilic properties at lower temperatures which, as temperature increases, transform to hydrophobic surface properties. The elution profile of five mixed steroids on an HPLC column packed with this material depends largely on the temperature of the aqueous mobile phase. Retention times increase with increasing temperature without any change in the eluent. Changes in the retention times of hydrophobic steroids were larger than those for hydrophilic steroids. The temperature-responsive interaction between PIPAAm-modified silica and these steroids is proposed to result from changes in the surface properties of the HPLC stationary phase by the transition of hydrophilic/hydrophobic surface-grafted IPAAm polymers. We demonstrate a novel and useful new chromatography system in which surface properties and the resulting function of the HPLC stationary phase are controlled by external temperature changes. This method should be effective in biological and biomedical separations of peptides and proteins using only aqueous mobile phases.

Genetic susceptibility to lung cancer

Lung cancer is a highly environmental disease, but cancer researchers have long been interested in investigating genetic susceptibility to lung cancer. This paper is a historical review and provides updated perspectives on lung cancer susceptibility research. The recent introduction of easier genotyping methods and the availability of an almost complete human genome database facilitated the association study to thousands of cases and controls for millions of genetic markers. Discoveries in the field of behavior genetics, that is, the genetic aspects of smoking behavior and nicotine addiction, unexpectedly indicated that polymorphisms in the human central nervous system play an important role in eventually leading to lung cancer. These findings were achieved by using comprehensive approaches, such as a genome, transcriptome, or proteome approach, and the studies were often conducted without a hypothesis. Another-omics approach, the "adductome" or "exposome" approach to how life style information can be integrated into the framework of genetic association studies, has recently emerged. These new paradigms will influence the area of lung cancer risk evaluation in genome cohort studies.

Partial cation-order and early-stage, phase separation in phase W, Li x Co 1− x O: 0.075≤ x ≤0.24−0.31

We report the characterization using X-ray and neutron powder diffraction, transmission electron microscopy and extended X-ray absorption fine structure of a new, partially ordered rock-salt-like solid solution phase Li x Co 1− x O: 0.075≤ x ≤0.24−0.31. The cation stacking sequence along [111] consists of alternating planes of Co and Co/Li. Nano-sized domains of this cation-ordered phase appear alongside disordered regions; domain size increases from 2 to 8 nm with increasing Li content. Compositions of ordered and disordered regions are Li- and Co-rich, respectively, and, therefore, the phase exhibits frozen-in, incipient phase separation. This microstructure could be considered as a precursor to precipitation of fully ordered, rhombohedral LiCoO 2 .