Current status of treatment with immune checkpoint inhibitors for gastrointestinal, hepatobiliary, and pancreatic cancers

The development of immune checkpoint inhibitors (ICIs) targeting cytotoxic T lymphocyte antigen 4 (CTLA-4), programmed cell death protein 1 (PD-1), or programmed cell death protein ligand 1 (PD-L1) has revolutionized the treatment strategy in various types of cancers. In addition, recent studies have revealed that tumor microsatellite instability (MSI) status and tumor mutation burden (TMB) contribute significantly to the therapeutic response to anti-PD-1 monoclonal antibody (mAb), which led to an accelerated approval to pembrolizumab for the treatment of MSI-high or mismatch-repair-deficient solid tumors after conventional chemotherapies in 2017 and for the treatment of TMB-high solid tumors in 2020 by the United States Food and Drug Administration (FDA). In the field of gastrointestinal cancers, many clinical trials evaluating the safety and efficacy of various regimens such as ICI monotherapy, the combination of anti-CTLA-4 mAb and anti-PD-1/PD-L1 mAb, and combination of ICI and conventional chemotherapy or tyrosine kinase inhibitor have been reported or are in progress. This review summarizes MSI status and TMB in gastrointestinal, hepatobiliary, and pancreatic cancers, and provides the results of most relevant clinical trials evaluating ICIs. We also discuss the development of biomarkers required for improving the selection of patients with a high probability of benefiting from treatment with ICIs, and potential therapeutic strategies that could help to enhance anticancer responses of ICIs

Pretreatment neutrophil-to-lymphocyte ratio as a predictive marker of response to atezolizumab plus bevacizumab for hepatocellular carcinoma

Background: Combination therapy with anti-programmed death-ligand 1 monoclonal antibody atezolizumab plus anti-vascular endothelial growth factor agent bevacizumab (Atezo/Bev) was approved in 2020 as a first-line treatment for unresectable hepatocellular carcinoma (HCC). Atezo/Bev therapy is relatively well tolerated; however, factors that can predict its response have not yet been reported. Thus, we aimed to investigate whether the pretreatment neutrophil-to-lymphocyte ratio (NLR) could predict the therapeutic response in patients with HCC treated with Atezo/Bev therapy. Methods: We analyzed the course of 40 patients with HCC who received Atezo/Bev therapy at our hospital and attempted to identify pretreatment factors that could predict response by comparing those who achieved disease control with those who did not. Results: The pretreatment NLR value in patients who achieved disease control was significantly lower than that in patients with disease progression (2.47 vs. 4.48, p = 0.013). Using the optimal NLR cut-off value for predicting response (3.21) determined by receiver operating characteristic curve analysis, patients with NLR ≤ 3.21 had significantly better progression-free survival than those with NLR > 3.21 (p < 0.0001), although there were no significant differences in liver function or tumor-related background factors between the two groups. Conclusions: The pretreatment NLR value may be a useful predictor of response to Atezo/Bev therapy for HCC

Hepatic inflammation facilitates transcription-associated mutagenesis via AID activity and enhances liver tumorigenesis.

First published online: May 12, 2015Chronic inflammation triggers the aberrant expression of a DNA mutator enzyme, activation-induced cytidine deaminase (AID), and contributes to tumorigenesis through the accumulation of genetic aberrations. To gain further insight into the inflammation-mediated genotoxic events required for carcinogenesis, we examined the role of chronic inflammation in the emergence of genetic aberrations in the liver with constitutive AID expression. Treatment with thioacetamide (TAA) at low-dose concentrations caused minimal hepatic inflammation in both wild-type (WT) and AID transgenic (Tg) mice. None of the WT mice with low-dose TAA administration or AID Tg mice without hepatic inflammation developed cancers in their liver tissues over the 6 month study period. In contrast, all the AID Tg mice with TAA treatment developed multiple macroscopic hepatocellular carcinomas during the same observation period. Whole exome sequencing and additional deep-sequencing analyses revealed the enhanced accumulation of somatic mutations in various genes, including dual specificity phosphatase 6 (Dusp6), early growth response 1 (Egr1) and inhibitor of DNA binding 2 (Id2), which are putative tumor suppressors, in AID-expressing liver with TAA-mediated hepatic inflammation. Microarray and quantitative reverse transcription-polymerase chain reaction analyses showed the transcriptional upregulation of various genes including Dusp6, Egr1 and Id2 under hepatic inflammatory conditions. Together, these findings suggest that inflammation-mediated transcriptional upregulation of target genes, including putative tumor suppressor genes, enhances the opportunity for inflamed cells to acquire somatic mutations and contributes to the acceleration of tumorigenesis in the inflamed liver tissues

A simplified method to quantitatively predict the effect of lenvatinib on hepatocellular carcinoma using contrast-enhanced ultrasound with perfluorobutane microbubbles

Contrast-enhanced computed tomography (CECT) is generally used to evaluate the response to treatment of hepatocellular carcinoma (HCC); however, CECT is unsuitable for the early prediction of therapeutic effects and frequent monitoring. We aimed to investigate the usefulness of our simplified method for the quantification of tumor vascularity using contrast-enhanced ultrasound (CEUS) with perfluorobutane microbubbles [Sonazoid® (GE Healthcare, Oslo, Norway)] to predict the therapeutic effect of lenvatinib. Among the 13 patients studied, nine who had more than a 20% reduction in tumor vascularity within 2 weeks of starting treatment experienced complete response or partial response at 8-12 weeks as assessed by CECT. In contrast, three patients without reductions and one patient with only a slight decrease in tumor vascularity had a poor response to lenvatinib. Quantitative assessment of tumor vascularity by our simplified CEUS-based method could be a useful predictor of therapeutic responses to lenvatinib in patients with HCC

DNA methyltransferase 3B plays a protective role against hepatocarcinogenesis caused by chronic inflammation via maintaining mitochondrial homeostasis

Most hepatocellular carcinomas (HCCs) develop on the basis of chronic hepatitis, but the mechanism of epigenetic regulation in inflammatory hepatocarcinogenesis has yet to be elucidated. Among de novo DNA methyltransferases (DNMTs), DNMT3B has lately been reported to act specifically on actively transcribed genes, suggesting the possibility that it plays a role in the pathogenesis of cancer. We confirmed that DNMT3B isoforms lacking its catalytic domain were highly expressed in HCCs compared with non-tumorous liver tissue. To elucidate the role of DNMT3B in hepatocarcinogenesis, we generated a genetically engineered mouse model with hepatocyte-specific Dnmt3b deletion. The liver of the Dnmt3b-deficient mice exhibited an exacerbation of thioacetamide-induced hepatitis, progression of liver fibrosis and a higher incidence of HCC compared with the liver of the control mice. Whole-genome bisulfite sequencing verified a lower CG methylation level in the Dnmt3b-deficient liver, demonstrating differentially methylated regions throughout the genome. Transcriptome analysis revealed decreased expression of genes related to oxidative phosphorylation in the Dnmt3b-deficient liver. Moreover, primary hepatocytes isolated from the Dnmt3b-deficient mice showed reduced mitochondrial respiratory capacity, leading to the enhancement of oxidative stress in the liver tissue. Our findings suggest the protective role of DNMT3B against chronic inflammation and HCC development via maintaining mitochondrial homeostasis

Evolutional transition of HBV genome during the persistent infection determined by single-molecule real-time sequencing

BACKGROUND: Although HBV infection is a serious health issue worldwide, the landscape of HBV genome dynamics in the host has not yet been clarified. This study aimed to determine the continuous genome sequence of each HBV clone using a single-molecule real-time sequencing platform, and clarify the dynamics of structural abnormalities during persistent HBV infection without antiviral therapy. PATIENTS AND METHODS: Twenty-five serum specimens were collected from 10 untreated HBV-infected patients. Continuous whole-genome sequencing of each clone was performed using a PacBio Sequel sequencer; the relationship between genomic variations and clinical information was analyzed. The diversity and phylogeny of the viral clones with structural variations were also analyzed. RESULTS: The whole-genome sequences of 797, 352 HBV clones were determined. The deletion was the most common structural abnormality and concentrated in the preS/S and C regions. Hepatitis B e antibody (anti-HBe)-negative samples or samples with high alanine aminotransferase levels have significantly diverse deletions than anti-HBe-positive samples or samples with low alanine aminotransferase levels. Phylogenetic analysis demonstrated that various defective and full-length clones evolve independently and form diverse viral populations. CONCLUSIONS: Single-molecule real-time long-read sequencing revealed the dynamics of genomic quasispecies during the natural course of chronic HBV infections. Defective viral clones are prone to emerge under the condition of active hepatitis, and several types of defective variants can evolve independently of the viral clones with the full-length genome

Mutational spectrum of hepatitis C virus in patients with chronic hepatitis C determined by single molecule real-time sequencing

The emergence of hepatitis C virus (HCV) with resistance-associated substitution (RAS), produced by mutations in the HCV genome, is a major problem in direct acting antivirals (DAA) treatment. This study aimed to clarify the mutational spectrum in HCV-RNA and the substitution pattern for the emergence of RASs in patients with chronic HCV infection. HCV-RNA from two HCV replicon cell lines and the serum HCV-RNA of four non-liver transplant and four post-liver transplant patients with unsuccessful DAA treatment were analyzed using high-accuracy single-molecule real-time long-read sequencing. Transition substitutions, especially A>G and U>C, occurred prominently under DAAs in both non-transplant and post-transplant patients, with a mutational bias identical to that occurring in HCV replicon cell lines during 10-year culturing. These mutational biases were reproduced in natural courses after DAA treatment. RASs emerged via both transition and transversion substitutions. NS3-D168 and NS5A-L31 RASs resulted from transversion mutations, while NS5A-Y93 RASs was caused by transition substitutions. The fidelity of the RNA-dependent RNA polymerase, HCV-NS5B, produces mutational bias in the HCV genome, characterized by dominant transition mutations, notably A>G and U>C substitutions. However, RASs are acquired by both transition and transversion substitutions, and the RASs-positive HCV clones are selected and proliferated under DAA treatment pressure

Anti-integrin αvβ6 autoantibodies in patients with primary sclerosing cholangitis

[Background] Patients with primary sclerosing cholangitis (PSC) possess autoantibodies against biliary epithelial cells. However, the target molecules remain unknown. [Methods] The sera of patients with PSC and controls were subjected to enzyme-linked immunosorbent assays to detect autoantibodies using recombinant integrin proteins. Integrin αvβ6 expression in the bile duct tissues was examined using immunofluorescence. The blocking activity of the autoantibodies was examined using solid-phase binding assays. [Results] Anti-integrin αvβ6 antibodies were detected in 49/55 (89.1%) patients with PSC and 5/150 (3.3%) controls (P < 0.001), with a sensitivity and specificity of 89.1% and 96.7%, respectively, for PSC diagnosis. When focusing on the presence or absence of IBD, the proportion of the positive antibodies in PSC with IBD was 97.2% (35/36) and that in PSC alone was 73.7% (14/19) (P = 0.008). Integrin αvβ6 was expressed in bile duct epithelial cells. Immunoglobulin (Ig)G from 15/33 patients with PSC blocked integrin αvβ6-fibronectin binding through an RGD (Arg–Gly–Asp) tripeptide motif. [Conclusions] Autoantibodies against integrin αvβ6 were detected in most patients with PSC; anti-integrin αvβ6 antibody may serve as a potential diagnostic biomarker for PSC

MSH2発現低下は炎症性サイトカイン刺激により惹起され、肝発癌に関与する

京都大学0048新制・課程博士博士(医学)甲第20073号医博第4166号新制||医||1018(附属図書館)33189京都大学大学院医学研究科医学専攻(主査)教授 高田 穣, 教授 武藤 学, 教授 武田 俊一学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA