Combination therapy with WEE1 inhibition and trifluridine/tipiracil against esophageal squamous cell carcinoma.

Despite advanced therapeutics, esophageal squamous cell carcinoma (ESCC) remains one of the deadliest cancers. Here, we propose a novel therapeutic strategy based on synthetic lethality combining trifluridine/tipiracil and MK1775 (WEE1 inhibitor) as a treatment for ESCC. This study demonstrates that trifluridine induces single-strand DNA damage in ESCC cells, as evidenced by phosphorylated replication protein 32. The DNA damage response includes cyclin-dependent kinase 1 (CDK1) (Tyr15) phosphorylation as CDK1 inhibition and a decrease of the proportion of phospho-histone H3 (p-hH3)-positive cells, indicating cell cycle arrest at the G2 phase before mitosis entry. The WEE1 inhibitor remarkedly suppressed CDK1 phosphorylation (Try15) and reactivated CDK1, and also increased the proportion of p-hH3-positive cells, which indicates an increase of the number of cells into mitosis. Trifluridine combined with a WEE1 inhibitor increased trifluridine-mediated DNA damage, namely DNA double-strand breaks, as shown by increased γ-H2AX expression. Moreover, the combination treatment with trifluridine/tipiracil and a WEE1 inhibitor significantly suppressed tumor growth of ESCC-derived xenograft models. Hence, our novel combination treatment with trifluridine/tipiracil and a WEE1 inhibitor is considered a candidate treatment strategy for ESCC.

HER2 G776S mutation promotes oncogenic potential in colorectal cancer cells when accompanied by loss of APC function.

Clinical cancer genome sequencing detects oncogenic variants that are potential targets for cancer treatment, but it also detects variants of unknown significance. These variants may interact with each other to influence tumor pathophysiology, however, such interactions have not been fully elucidated. Additionally, the effect of target therapy for those variants also unclarified. In this study, we investigated the biological functions of a HER2 mutation (G776S mutation) of unknown pathological significance, which was detected together with APC mutation by cancer genome sequencing of samples from a colorectal cancer (CRC) patient. Transfection of the HER2 G776S mutation alone slightly increased the kinase activity and phosphorylation of HER2 protein, but did not activate HER2 downstream signaling or alter the cell phenotype. On the other hand, the HER2 G776S mutation was shown to have strong oncogenic potential when loss of APC function was accompanied. We revealed that loss of APC function increased Wnt pathway activity but also increased RAS-GTP, which increased ERK phosphorylation triggered by HER2 G776S transfection. In addition, afatinib, a pan-HER tyrosine kinase inhibitor, suppressed tumor growth in xenografts derived from HER2 G776S-transfected CRC cells. These findings suggest that this HER2 mutation in CRC may be a potential therapeutic target.

Repeated talaporfin sodium photodynamic therapy for esophageal cancer: safety and efficacy.

BACKGROUND: Talaporfin sodium photodynamic therapy (tPDT) is an effective salvage treatment for local failure after chemoradiotherapy for esophageal cancer. Repeated tPDT could also be indicated for local recurrence or residue after the first salvage tPDT. However, the safety and efficacy of repeated tPDT have not been elucidated. METHODS: We reviewed 52 patients with esophageal cancer who were treated with the first tPDT at Kyoto University Hospital between October 2015 and April 2020. RESULTS: Among 52 patients, repeated tPDT after the first tPDT was indicated for 13 patients (25%), of which six had residual tumor, four had local recurrence after complete response (CR) after the first tPDT at the primary site, and six had metachronous lesion. The total session of repeated tPDT was 25; 16 were for primary sites and nine were for metachronous sites. Among them, six patients (46.2%) achieved local (L)-CR and nine lesions (56.3%) achieved lesion L-CR. By session, 10 sessions (40%) achieved L-CR. There were no severe adverse events except for one patient; this patient showed grade 3 esophageal stenosis and perforation after the third tPDT on the same lesion that was previously treated with porfimer sodium photodynamic therapy four times. CONCLUSION: Repeated tPDT could be an effective and safe treatment for local failure even after salvage tPDT for esophageal cancer.

Cancer of unknown primary with EGFR mutation successfully treated with targeted therapy directed by clinical next-generation sequencing: a case report.

BACKGROUND: Cancer of unknown primary (CUP) is usually treated with nonselective and empirical chemotherapy; however, its prognosis is generally poor, with a median survival of less than a year. Thus, clinicians eagerly await the development of more effective treatment strategies. In recent years, advances in next-generation sequencing (NGS) have made it possible to analyze comprehensively the genome of individual cancers. NGS has identified many genomic alterations, some of which are potential molecular targets of specific agents. We report a case of CUP that was successfully treated with targeted therapy directed by the genomic data obtained from an NGS-based multiplex assay. CASE PRESENTATION: A 52-year-old Asian woman with right hip joint pain underwent fluorodeoxyglucose-positron emission tomography/computed tomography, which showed multiple metastatic tumors in her right hip joint, thyroid gland, lung, and vertebrae. Brain magnetic resonance imaging showed multiple cerebral metastases. Additional tests, including pathology examination and conventional epidermal growth factor receptor (EGFR) gene mutation analysis (single-strand conformation polymorphism assay), could not identify the primary origin of the tumors, so the patient was diagnosed with CUP. After empirical chemotherapy for CUP, an NGS-based multiplex assay performed using a resected specimen of thyroid tumor detected the EGFR mutation c.2573 T > G p.Leu858Arg (L858R). Her treatment was changed to erlotinib, an EGFR tyrosine-kinase inhibiter, which dramatically shrank the tumors and decreased her serum carcinoembryonic antigen level. She achieved long-term disease control and survived for 2 years and 9 months from the first diagnosis. CONCLUSION: This case might support the strategy that NGS-based multiplex assays could identify actionable molecular targets for individual patients with CUP.

Synthetic Lethality with Trifluridine/Tipiracil and Checkpoint Kinase 1 Inhibitor for Esophageal Squamous Cell Carcinoma.

Esophageal squamous cell carcinoma (ESCC) is a disease characterized by a high mutation rate of the TP53 gene, which plays pivotal roles in the DNA damage response (DDR) and is regulated by checkpoint kinase (CHK) 2. CHK1 is another key DDR-related protein, and its selective inhibition is suggested to be particularly sensitive to TP53-mutated cancers, because a loss of both pathways (CHK1 and/or CHK2-p53) is lethal due to the serious impairment of DDR. Such a therapeutic strategy is termed synthetic lethality. Here, we propose a novel therapeutic strategy based on synthetic lethality combining trifluridine/tipiracil and prexasertib (CHK1 inhibitor) as a treatment for ESCC. Trifluridine is a key component of the antitumor drug combination with trifluridine/tipiracil (an inhibitor of trifluridine degradation), also known as TAS-102. In this study, we demonstrate that trifluridine increases CHK1 phosphorylation in ESCC cells combined with a reduction of the S-phase ratio as well as the induction of ssDNA damage. Because CHK1 phosphorylation is considered to be induced as DDR for trifluridine-mediated DNA damage, we examined the effects of CHK1 inhibition on trifluridine treatment. Consequently, CHK1 inhibition by short hairpin RNA or treatment with the CHK1 inhibitor, prexasertib, markedly enhanced trifluridine-mediated DNA damage, represented by an increase of γH2AX expression. Moreover, the combination of trifluridine/tipiracil and CHK1 inhibition significantly suppressed tumor growth of ESCC-derived xenograft tumors. Furthermore, the combination of trifluridine and prexasertib enhanced radiosensitivity both in vitro and in vivo Thus, the combination of trifluridine/tipiracil and a CHK1 inhibitor exhibits effective antitumor effects, suggesting a novel therapeutic strategy for ESCC.

Experimental model for the irradiation-mediated abscopal effect and factors influencing this effect.

Radiotherapy (RT) is the primary treatment for cancer. Ionizing radiation from RT induces tumor damage at the irradiated site, and, although clinically infrequent, may cause regression of tumors distant from the irradiated site-a phenomenon known as the abscopal effect. Recently, the abscopal effect has been related to prolongation of overall survival time in cancer patients, though the factors that influence the abscopal effect are not well understood. The aim of this study is to clarify the factors influencing on abscopal effect. Here, we established a mouse model in which we induced the abscopal effect. We injected MC38 (mouse colon adenocarcinoma) cells subcutaneously into C57BL/6 mice at two sites. Only one tumor was irradiated and the sizes of both tumors were measured over time. The non-irradiated-site tumor showed regression, demonstrating the abscopal effect. This effect was enhanced by an increase in the irradiated-tumor volume and by administration of anti-PD1 antibody. When the abscopal effect was induced by a combination of RT and anti-PD1 antibody, it was also influenced by radiation dose and irradiated-tumor volume. These phenomena were also verified in other cell line, B16F10 cells (mouse melanoma cells). These findings provide further evidence of the mechanism for, and factors that influence, the abscopal effect in RT.

Protective effects of Alda-1, an ALDH2 activator, on alcohol-derived DNA damage in the esophagus of human ALDH2*2 (Glu504Lys) knock-in mice.

Alcohol consumption is the key risk factor for the development of esophageal squamous cell carcinoma (ESCC), and acetaldehyde, a metabolite of alcohol, is an alcohol-derived major carcinogen that causes DNA damage. Aldehyde dehydrogenase2 (ALDH2) is an enzyme that detoxifies acetaldehyde, and its activity is reduced by ALDH2 gene polymorphism. Reduction in ALDH2 activity increases blood, salivary and breath acetaldehyde levels after alcohol intake, and it is deeply associated with the development of ESCC. Heavy alcohol consumption in individuals with ALDH2 gene polymorphism significantly elevates the risk of ESCC; however, effective prevention has not been established yet. In this study, we investigated the protective effects of Alda-1, a small molecule ALDH2 activator, on alcohol-mediated esophageal DNA damage. Here, we generated novel genetically engineered knock-in mice that express the human ALDH2*1 (wild-type allele) or ALDH2*2 gene (mutant allele). Those mice were crossed, and human ALDH2*1/*1, ALDH2*1/*2 and ALDH2*2/*2 knock-in mice were established. They were given 10% ethanol for 7 days in the presence or absence of Alda-1, and we measured the levels of esophageal DNA damage, represented by DNA adduct (N2-ethylidene-2'-deoxyguanosine). Alda-1 significantly increased hepatic ALDH2 activity both in human ALDH2*1/*2 and/or ALDH2*2/*2 knock-in mice and reduced esophageal DNA damage levels after alcohol drinking. Conversely, cyanamide, an ALDH2-inhibitor, significantly exacerbated esophageal DNA adduct level in C57BL/6N mice induced by alcohol drinking. These results indicate the protective effects of ALDH2 activation by Alda-1 on esophageal DNA damage levels in individuals with ALDH2 gene polymorphism, providing a new insight into acetaldehyde-mediated esophageal carcinogenesis and prevention.

Combination treatment with highly bioavailable curcumin and NQO1 inhibitor exhibits potent antitumor effects on esophageal squamous cell carcinoma.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is one of the most intractable cancers, so the development of novel therapeutics has been required to improve patient outcomes. Curcumin, a polyphenol from Curcuma longa, exhibits various health benefits including antitumor effects, but its clinical utility is limited because of low bioavailability. Theracurmin® (THC) is a highly bioavailable curcumin dispersed with colloidal submicron particles. METHODS: We examined antitumor effects of THC on ESCC cells by cell viability assay, colony and spheroid formation assay, and xenograft models. To reveal its mechanisms, we investigated the levels of reactive oxygen species (ROS) and performed microarray gene expression analysis. According to those analyses, we focused on NQO1, which involved in the removal of ROS, and examined the effects of NQO1-knockdown or overexpression on THC treatment. Moreover, the therapeutic effect of THC and NQO1 inhibitor on ESCC patient-derived xenografts (PDX) was investigated. RESULTS: THC caused cytotoxicity in ESCC cells, and suppressed the growth of xenografted tumors more efficiently than curcumin. THC increased ROS levels and activated the NRF2-NMRAL2P-NQO1 expressions. Inhibition of NQO1 in ESCC cells by shRNA or NQO1 inhibitor resulted in an increased sensitivity of cells to THC, whereas overexpression of NQO1 antagonized it. Notably, NQO1 inhibitor significantly enhanced the antitumor effects of THC in ESCC PDX tumors. CONCLUSIONS: These findings suggest the potential usefulness of THC and its combination with NQO1 inhibitor as a therapeutic option for ESCC.

Potential cancer chemopreventive activity of simple isoquinolines, 1-benzylisoquinolines, and protoberberines.

Seventeen simple isoquinolines, 15 1-benzylisoquinolines, and 19 protoberberines were tested for their inhibitory activities against Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. Among the tested alkaloids, the inhibitory activity of all 1-benzylisoquinolines and 11 protoberberines was higher than that of beta-carotene. The 1-benzylisoquinolines 19, 21, 22, 29, and 34 and protoberberines 41, 47-49, 51, 52, and 55 showed potent inhibitory effects on EBV-EA induction (96-100% inhibition at 1 x 10(3) mol ratio/TPA). These alkaloids were more active than the naturally occurring alkaloids, 23, 25, 33, 53, and 54. In addition, fifteen simple isoquinolines, eighteen 1-benzylisoquinolines and eight protoberberines were evaluated with respect to their ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. Nine simple isoquinolines, ten 1-benzylisoquinolines, and four protoberberines were more potent than alpha-tocopherol, and four 1-benzylisoquinolines, 20 and 28-30, exhibited potent activities (SC50 4.5-5.8 microM). Their activities were higher than the naturally occurring alkaloids, 23, 25, and 33. Therefore, some of the isoquinoline alkaloids indicating the high activity on both assays may be potentially valuable cancer chemopreventive agents. Structure-activity relationships are discussed for both tests.