Synthesis of the Carba-Analogs of the α-Pyranose and β-Pyranose Forms of Sedoheptulose 7-Phosphate and Probing the Stereospecificity of Sedoheptulose 7-Phosphate Cyclases

Sedoheptulose 7-phosphate (SH7P) cyclases are a subset of sugar phosphate cyclases that are known to catalyze the first committed step in many biosynthetic pathways in primary and secondary metabolism. Among them are 2-epi-5-epi-valiolone synthase (EEVS) and 2-epi-valiolone synthase (EVS), two closely related SH7P cyclases that catalyze the conversion of SH7P to 2-epi-5-epi-valiolone and 2-epi-valiolone, respectively. However, how these two homologous enzymes use a common substrate to produce stereochemically different products is unknown. Two competing hypotheses have been proposed for the stereospecificity of EEVS and EVS: (1) variation in aldol acceptor geometry during enzyme catalysis, and (2) preselection of the α-pyranose or β-pyranose forms of the substrate by the enzymes. Yet, there is no direct evidence to support or rule out either of these hypotheses. Here we report the synthesis of the carba-analogs of the α-pyranose and β-pyranose forms of SH7P and their use in probing the stereospecificity of ValA (EEVS from Streptomyces hygroscopicus subsp. jinggangensis) and Amir_2000 (EVS from Actinosynnema mirum DSM 43827). Kinetic studies of the enzymes in the presence of the synthetic compounds as well as docking studies of the enzymes with the α- and β-pyranose forms of SH7P suggest that the inverted configuration of the products of EEVS and EVS is not due to the preselection of the different forms of the substrate by the enzymes.

Identification of a new oligomycin derivative as a specific inhibitor of the alternative peptidoglycan biosynthetic pathway

Peptidoglycan is an important macromolecule in bacterial cell walls to maintain cell integrity, and its biosynthetic pathway has been well studied. Recently, we demonstrated that some bacteria such as Xanthomonas oryzae, a pathogen causing bacterial blight of rice, used an alternative pathway for peptidoglycan biosynthesis. In this pathway, MurD2, a MurD homolog, catalyzed the attachment of L-Glu to UDP-MurNAc-L-Ala and MurL, which did not show homology to any known protein, catalyzed epimerization of the terminal L-Glu of the MurD2 product to generate UDP-MurNAc-L-Ala-D-Glu. Because the alternative pathway also operates in some other plant pathogens and opportunistic pathogens, specific inhibitors of the alternative pathway could function as pesticides and antibiotics for these pathogens. In this study, we searched for specific inhibitors of the alternative pathway from metabolites produced by actinomycetes and identified a new oligomycin-class polyketide, which was revealed to inhibit the MurD2 reaction, in culture broth of Micromonospora sp. K18-0097.

Peptide Epimerase Responsible for d-Amino Acid Introduction in Poly-γ-glutamic Acid Biosynthesis

Poly-γ-glutamic acid (PGA) is a natural polymer of d- and/or l-glutamic acid (Glu) linked by isopeptide bonds. We recently showed that PGA synthetase, an enzyme complex composed of PgsB, PgsC, and PgsA, uses only l-Glu for polymerization, and d-Glu residues are introduced by peptide epimerization. However, it remains unclear which of the three enzymes is responsible for epimerization because in vitro functional characterization of the membrane-associated PgsBCA complex has never been successful. Here, we performed gene exchange experiments and showed that PgsA is responsible for the epimerization. Additionally, we identified a region in PgsA that modulates epimerization activity based on homology modeling from the recently solved structure of MslH, which showed 53% identity to PgsA. Our results suggested that d/l-ratios of the PGA product can be altered by introducing amino acid substitutions in this region, which will be useful for the production of PGA with controlled d/l-ratios.

Peptide epimerase-dehydratase complex responsible for biosynthesis of the linaridin class ribosomal peptides

Grisemycin, salinipeptin, and cypemycin belong to the linaridin class of ribosomally synthesized and posttranslationally modified peptides that contain multiple dehydrobutyrine and D-amino acid residues. The biosynthetic gene clusters of these linaridins lack obvious candidate genes for the dehydratase and epimerase required to introduce dehydrobutyrine and D-amino acid residues, respectively. However, we previously demonstrated that the grisemycin (grm) cluster contained cryptic dehydratase and epimerase genes by heterologous expression of this biosynthetic gene cluster in Streptomyces lividans and proposed that two genes (grmH and grmL) with unknown functions catalyze dehydration and epimerization reactions. In this study, we confirmed that both GrmH and GrmL, which were shown to constitute a protein complex by a co-purification experiment, were required to catalyze the dehydration, epimerization, and proteolytic cleavage of a precursor peptide GrmA by in vivo experiments. Furthermore, we demonstrated that GrmH/GrmL complex accepted salinipeptin and cypemycin precursor peptides, which possess three additional amino acids.

Catalytic Mechanism of Nonglycosidic C-N Bond Formation by the Pseudoglycosyltransferase Enzyme VldE

The pseudoglycosyltransferase (PsGT) enzyme VldE is a homologue of the retaining glycosyltransferase (GT) trehalose 6-phosphate synthase (OtsA) that catalyzes a coupling reaction between two pseudo-sugar units, GDP-valienol and validamine 7-phosphate, to give a product with α,α-N-pseudo-glycosidic linkage. Despite its biological importance and unique catalytic function, the molecular bases for its substrate specificity and reaction mechanism are still obscure. Here, we report a comparative mechanistic study of VldE and OtsA using various engineered chimeric proteins and point mutants of the enzymes, X-ray crystallography, docking studies, and kinetic isotope effects. We found that the distinct substrate specificities between VldE and OtsA are most likely due to topological differences within the hot spot amino acid regions of their N-terminal domains. We also found that the Asp158 and His182 residues, which are in the active site, play a significant role in the PsGT function of VldE. They do not seem to be directly involved in the catalysis but may be important for substrate recognition or contribute to the overall architecture of the active site pocket. Moreover, results of the kinetic isotope effect experiments suggest that VldE catalyzes a C-N bond formation between GDP-valienol and validamine 7-phosphate via an SNi-like mechanism. The study provides new insights into the substrate specificity and catalytic mechanism of a member of the growing family of PsGT enzymes, which may be used as a basis for developing new PsGTs from GTs.

Modifications of acyl carrier protein-bound glycosylated polyketides in pactamycin biosynthesis

The potent antitumor antibiotic pactamycin is an aminocyclopentitol-containing natural product produced by the soil bacterium Streptomyces pactum. Recent studies showed that the aminocyclopentitol unit is derived from N-acetyl-D-glucosamine, which is attached to an acyl carrier protein (ACP)-bound polyketide by a glycosyltransferase enzyme, PtmJ. Here, we report a series of post-glycosylation modifications of the sugar moiety of the glycosylated polyketide while it is still attached to the carrier protein. In vitro reconstitution of PtmS (an AMP-ligase), PtmI (an ACP), PtmJ, PtmN (an oxidoreductase), PtmA (an aminotransferase), and PtmB (a putative carbamoyltransferase) showed that the N-acetyl-D-glucosamine moiety of the glycosylated polyketide is first oxidized by PtmN and then transaminated by PtmA to give ACP-bound 3-amino-3-deoxy-N-acetyl-D-glucosaminyl polyketide. The amino group is then coupled with carbamoyl phosphate by PtmB to give a urea functionality. We also show that PtmG is a deacetylase that hydrolyses the C-2 N-acetyl group to give a free amine.

Acarbose May Function as a Competitive Exclusion Agent for the Producing Bacteria

Acarbose is a well-known microbial specialized metabolite used clinically to treat type 2 diabetes. This natural pseudo-oligosaccharide (PsOS) shows potent inhibitory activity toward various glycosyl hydrolases, including α-glucosidases and α-amylases. While acarbose and other PsOSs are produced by many different bacteria, their ecological or biological role in microbial communities is still an open question. Here, we show that several PsOS-producing actinobacteria, i.e., Actinoplanes sp. SE50/110 (acarbose producer), Streptomyces glaucescens GLA.O (acarbose producer), and Streptomyces dimorphogenes ATCC 31484 (trestatin producer), can grow in the presence of acarbose, while the growth of the non-PsOS-producing organism Streptomyces coelicolor M1152 was suppressed when starch is the main source of energy. Further investigations using recombinant α-amylases from S. coelicolor M1152 and the PsOS-producing actinobacteria revealed that the S. coelicolor α-amylase was inhibited by acarbose, whereas those from the PsOS-producing bacteria were not inhibited by acarbose. Bioinformatic and protein modeling studies suggested that a point mutation in the α-amylases of the PsOS-producing actinobacteria is responsible for the resistance of those enzymes toward acarbose. Converting the acarbose-resistant α-amylase AcbE to its A304H variant diminished its acarbose-resistance property. Taken together, the results suggest that acarbose is used by the producing bacteria as a competitive exclusion agent to suppress the growth of other microorganisms in their natural environment, while the producing organisms equip themselves with α-amylase variants that are resistant to acarbose.

Biochemical Characterization of GacI, a Bifunctional Glycosyltransferase-Phosphatase Enzyme Involved in Acarbose Biosynthesis in Streptomyces glaucescens GLA.O

Acarbose, a pseudotetrasaccharide produced by several strains of Actinoplanes and Streptomyces, is an α-glucosidase inhibitor clinically used to control type II diabetes. Bioinformatic analysis of the biosynthetic gene clusters of acarbose in Actinoplanes sp. SE50/110 (the acb cluster) and Streptomyces glaucescens GLA.O (the gac cluster) revealed their distinct genetic organizations and presumably biosynthetic pathways. However, to date, only the acarbose pathway in the SE50/110 strain has been extensively studied. Here, we report that GacI, one of the proteins that appear to be different between the two pathways, is a bifunctional glycosyltransferase family 5 (GT5)-phosphatase (PP) enzyme that functions at two different steps in acarbose biosynthesis in S. glaucescens GLA.O. In the acb pathway, the GT and the PP reactions are performed by two different enzymes. Truncated GacI proteins having only the GT or the PP domain showed comparable catalytic activity with the full-length GacI, indicating that domain separation does not significantly affect their respective catalytic activity. GacI, which is widely distributed in many Streptomyces, represents the first example of naturally occurring GT5-PP bifunctional enzymes biochemically characterized.

Complete biosynthetic pathway to the antidiabetic drug acarbose

Acarbose is a bacterial-derived α-glucosidase inhibitor clinically used to treat patients with type 2 diabetes. As type 2 diabetes is on the rise worldwide, the market demand for acarbose has also increased. Despite its significant therapeutic importance, how it is made in nature is not completely understood. Here, we report the complete biosynthetic pathway to acarbose and its structural components, GDP-valienol and O-4-amino-(4,6-dideoxy-α-D-glucopyranosyl)-(1→4)-O-α-D-glucopyranosyl-(1→4)-D-glucopyranose. GDP-valienol is derived from valienol 7-phosphate, catalyzed by three cyclitol modifying enzymes, whereas O-4-amino-(4,6-dideoxy-α-D-glucopyranosyl)-(1→4)-O-α-D-glucopyranosyl-(1→4)-D-glucopyranose is produced from dTDP-4-amino-4,6-dideoxy-D-glucose and maltose by the glycosyltransferase AcbI. The final assembly process is catalyzed by a pseudoglycosyltransferase enzyme, AcbS, which is a homologue of AcbI but catalyzes the formation of a non-glycosidic C-N bond. This study clarifies all previously unknown steps in acarbose biosynthesis and establishes a complete pathway to this high value pharmaceutical.

The market demand for acarbose, a drug used for treatment of patients affected by type-2 diabetes, has increased. In this article, the authors report the acarbose complete biosynthetic pathway, clarifying previously unknown steps and identifying a pseudoglycosyltransferase enzyme, AcbS, a homologue of AcbI that catalyzes the formation of a non-glycosidic C-N bond.

The chemistry and biology of natural ribomimetics and related compounds

Natural ribomimetics represent an important group of specialized metabolites with significant biological activities. Many of the activities, e.g., inhibition of seryl-tRNA synthetases, glycosidases, or ribosomes, are manifestations of their structural resemblance to ribose or related sugars, which play roles in the structural, physiological, and/or reproductive functions of living organisms. Recent studies on the biosynthesis and biological activities of some natural ribomimetics have expanded our understanding on how they are made in nature and why they have great potential as pharmaceutically relevant products. This review article highlights the discovery, biological activities, biosynthesis, and development of this intriguing class of natural products.

Verification of the Usefulness of an Assessment and Risk Control Sheet that Promotes Management of Cancer Drug Therapy

Background: Proper management of adverse events is crucial for the safe and effective implementation of anticancer drug treatment. Showa University Hospital uses our interview sheet (assessment and risk control [ARC] sheet) for the accurate evaluation of adverse events. On the day of anticancer drug treatment, a nurse conducts a face-to-face interview. As a feature of the ARC sheet, by separately describing the symptoms the day before treatment and the day of treatment and sharing the information on the medical record, it is possible to clearly determine the status of adverse events. In this study, we hypothesized that the usefulness and points for improvement of the ARC sheet would be clarified by using and evaluating a patient questionnaire.

Methods: This study included 174 patients (144 at Showa University Hospital (Hatanodai Hospital) and 30 at Showa University Koto Toyosu Hospital (Toyosu Hospital) who underwent pre-examination interviews by nurses and received cancer chemotherapy at the outpatient center of Hatanodai and Toyosu Hospital. In the questionnaire survey, the ARC sheet’s content and quality, respondents’ satisfaction, structural strengths, and points for improvement were evaluated on a five-point scale.

Results: The patient questionnaire received responses from 160 participants, including the ARC sheet use group (132 people) and the non-use group (28 people). Unlike the ARC sheet non-use group, the ARC sheet use group recognized that the sheet was useful to understand the adverse events of aphthous ulcers (p = 0.017) and dysgeusia (p = 0.006). In the satisfaction survey questionnaire, there was a high sense of security in the pre-examination interviews by nurses using the ARC sheet.

Conclusions: The ARC sheet is considered an effective tool for comprehensively evaluating adverse events. Pre-examination interviews by nurses using ARC sheets accurately determined the adverse events experienced by patients with anxiety and tension due to confrontation with physicians.

Stereochemistry in the Reaction of the myo-Inositol Phosphate Synthase Ortholog Ari2 during Aristeromycin Biosynthesis

The myo-inositol-1-phosphate synthase (MIPS) ortholog Ari2, which is encoded in the aristeromycin biosynthetic gene cluster, catalyzes the formation of five-membered cyclitol phosphate using d-fructose 6-phosphate (F6P) as a substrate. To understand the stereochemistry during the Ari2 reaction in vivo, we carried out feeding experiments with (6S)-d-[6-²H₁]- and (6R)-d-[6-²H₁]glucose in the aristeromycin-producing strain Streptomyces citricolor. We observed retention of the ²H atom of (6S)-d-[6-²H₁]glucose and no incorporation of the ²H atom from (6R)-d-[6-²H₁]glucose in aristeromycin. This indicates that Ari2 abstracts the pro-R proton at C6 of F6P after oxidation of C5-OH by nicotinamide adenine dinucleotide (NAD⁺) to generate the enolate intermediate, which then attacks the C2 ketone to form the C-C bond via aldol-type condensation. The reaction of Ari2 with (6S)-d-[6-²H₁]- and (6R)-d-[6-²H₁]F6P in vitro exhibited identical stereochemistry compared with that observed during the feeding experiments. Furthermore, analysis of the crystal structure of Ari2, including NAD⁺ as a ligand, revealed the active site of Ari2 to be similar to that of MIPS of Mycobacterium tuberculosis, supporting the similarity of the reaction mechanisms of Ari2 and MIPS.

Metabolic reprogramming of oncogene-addicted cancer cells to OXPHOS as a mechanism of drug resistance

The ability to selectively eradicate oncogene-addicted tumors while reducing systemic toxicity has endeared targeted therapies as a treatment strategy. Nevertheless, development of acquired resistance limits the benefits and durability of such a regime. Here we report evidence of enhanced reliance on mitochondrial oxidative phosphorylation (OXPHOS) in oncogene-addicted cancers manifesting acquired resistance to targeted therapies. To that effect, we describe a novel OXPHOS targeting activity of the small molecule compound, OPB-51602 (OPB). Of note, a priori treatment with OPB restored sensitivity to targeted therapies. Furthermore, cancer cells exhibiting stemness markers also showed selective reliance on OXPHOS and enhanced sensitivity to OPB. Importantly, in a subset of patients who developed secondary resistance to EGFR tyrosine kinase inhibitor (TKI), OPB treatment resulted in decrease in metabolic activity and reduction in tumor size. Collectively, we show here a switch to mitochondrial OXPHOS as a key driver of targeted drug resistance in oncogene-addicted cancers. This metabolic vulnerability is exploited by a novel OXPHOS inhibitor, which also shows promise in the clinical setting.

Five-Membered Cyclitol Phosphate Formation by a myo-Inositol Phosphate Synthase Orthologue in the Biosynthesis of the Carbocyclic Nucleoside Antibiotic Aristeromycin

Aristeromycin is a unique carbocyclic nucleoside antibiotic produced by Streptomyces citricolor. In order to elucidate its intriguing carbocyclic formation, we used a genome-mining approach to identify the responsible enzyme. In silico screening with known cyclitol synthases involved in primary metabolism, such as myo-inositol-1-phosphate synthase (MIPS) and dehydroqunate synthase (DHQS), identified a unique MIPS orthologue (Ari2) encoded in the genome of S. citricolor. Heterologous expression of the gene cluster containing ari2 with a cosmid vector in Streptomyces albus resulted in the production of aristeromycin, thus indicating that the cloned DNA region (37.5 kb) with 33 open reading frames contains its biosynthetic gene cluster. We verified that Ari2 catalyzes the formation of a novel five-membered cyclitol phosphate from d-fructose 6-phosphate (F6P) with NAD⁺ as a cofactor. This provides insight into cyclitol phosphate synthase as a member of the MIPS family of enzymes. A biosynthetic pathway to aristeromycin is proposed based on bioinformatics analysis of the gene cluster.

Genome-wide association study identifies pharmacogenomic loci linked with specific antihypertensive drug treatment and new-onset diabetes

We conducted a discovery genome-wide association study with expression quantitative trait loci (eQTL) annotation of new-onset diabetes (NOD) among European Americans, who were exposed to a calcium channel blocker-based strategy (CCB strategy) or a β-blocker-based strategy (β-blocker strategy) in the INternational VErapamil SR Trandolapril STudy. Replication of the top signal from the SNP*treatment interaction analysis was attempted in Hispanic and African Americans, and a joint meta-analysis was performed (total 334 NOD cases and 806 matched controls). PLEKHH2 rs11124945 at 2p21 interacted with antihypertensive exposure for NOD (meta-analysis p=5.3×10⁻⁸). rs11124945 G allele carriers had lower odds for NOD when exposed to the β-blocker strategy compared with the CCB strategy [OR=0.38 (0.24-0.60), p=4.0×10⁻⁵], while A/A homozygotes exposed to the β-blocker strategy had increased odds for NOD compared with the CCB strategy [OR=2.02 (1.39-2.92), p=2.0×10⁻⁴]. eQTL annotation of the 2p21 locus provides functional support for regulating gene expression.

Abstract 3080: OPB-51602: a novel STAT3 inhibitor that targets mitochondrial respiratory chain and triggers STAT3 dependent ROS production

Signal transducer and activator of Transcription (STAT) proteins are activated upon extracellular signals resulting in their phosphorylation and nuclear translocation. Once in the nucleus, STAT proteins, in specific STAT3 activates gene transcription of factors involved in a myriad of cellular processes, including proliferation and survival. By implication, increased expression and activity of STAT3 are associated with human cancers, which argue strongly for the development of STAT inhibitors as a promising chemotherapeutic strategy. We are working with a novel STAT3 inhibitor, OPB-51602, that not only block STAT3 phosphorylation but also inhibits growth and colony formation in a variety of human cancer cell lines. Of note, in addition to targeting STAT3, the compound inhibits mitochondrial respiratory chain and triggers a significant increase in mitochondrial superoxide (O2-) production (within 1 hour of exposure) in NSCLC cell line H1975. Using functional mutants of pY705 and pS727 STAT3, the growth inhibitory activity of the compound could be compromised, however, only S727 mutant rescued the mitochondrial effects. In addition, exposure of cells to OPB-51602 resulted in extracellular acidification (ECAR) together with a complete shutdown of mitochondrial ATP production. Interestingly, these effects could be rescued by 2-deoxyglucose. These data provide evidence that the pharmacological inhibition of STAT3 not only blocks cell proliferation but also induces mitochondrial redox catastrophe and bio-energetic crisis, which could have potential therapeutic implications against cancers that are rendered drug resistant due to the activation of surrogate STAT3 signaling axis.

Citation Format: Jayshree L. Hirpara, Kumi Higuchi, Takeshi Tsunoda, Boon Cher Goh, Shazib Pervaiz. OPB-51602: a novel STAT3 inhibitor that targets mitochondrial respiratory chain and triggers STAT3 dependent ROS production. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3080.

Targeted next-generation sequencing in the diagnosis of neurodevelopmental disorders

We developed a next-generation sequencing (NGS) based mutation screening strategy for neurodevelopmental diseases. Using this system, we screened 284 genes in 40 patients. Several novel mutations were discovered. Patient 1 had a novel mutation in ACTB. Her dysmorphic feature was mild for Baraitser-Winter syndrome. Patient 2 had a truncating mutation of DYRK1A. She lacked microcephaly, which was previously assumed to be a constant feature of DYRK1A loss of function. Patient 3 had a novel mutation in GABRD gene. She showed Rett syndrome like features. Patient 4 was diagnosed with Noonan syndrome with PTPN11 mutation. He showed complete agenesis of corpus callosum. We have discussed these novel findings.

Phase I study of OPB-51602, an oral inhibitor of signal transducer and activator of transcription 3, in patients with relapsed/refractory hematological malignancies

We carried out a multicenter dose-escalation phase I study of oral OPB-51602, a signal transducer and activator of transcription 3 phosphorylation inhibitor, in patients with relapsed or refractory hematological malignancies to evaluate the safety, maximum tolerated dose (MTD), pharmacokinetics, and preliminary antitumor activity. Twenty patients were treated with OPB-51602 at doses of 1, 2, 3, 4, and 6 mg in the “3 + 3” dose escalation design. The most common treatment-related adverse events included nausea (55%), peripheral sensory neuropathy (45%), and diarrhea (40%). The most frequently observed grade 3 or 4 drug-related adverse events were neutropenia (20%), leukopenia (15%), lymphopenia (10%), and thrombocytopenia (10%). The MTD was 6 mg, with dose-limiting toxicities of grade 3 lactic acidosis and increased blood lactic acid levels observed in one of three patients and grade 1–2 peripheral neuropathy in three of three patients. The recommended dose was determined to be 4 mg. OPB-51602 was rapidly absorbed, and exposure tended to increase in a dose-dependent manner. Accumulation of OPB-51602 was seen with 4 weeks of multiple treatments. No clear therapeutic response was observed. Durable stable disease was observed in two patients with acute myeloid leukemia and one with myeloma. In conclusion, the MTD of OPB-51602 was 6 mg. OPB-51602 was safe and well tolerated in a dose range of 1–4 mg. However, long-term administration at higher doses was difficult with the daily dosing schedule, and no response was seen. Therefore, further clinical development of OPB-51602 for hematological malignancies with a daily dosing schedule was terminated.

Phase I and biomarker study of OPB-51602, a novel signal transducer and activator of transcription (STAT) 3 inhibitor, in patients with refractory solid malignancies

BACKGROUND

The aim of this study was to determine the maximum-tolerated dose (MTD), safety, pharmacokinetics, and pharmacodynamics of OPB-51602, an oral, direct signal transduction activator of transcription 3 (STAT3) inhibitor, in patients with refractory solid tumors.

PATIENTS AND METHODS

Three cohorts were studied: cohort A, a sequential dose escalation of OPB-51602 administered intermittently (days 1-14 every 21 days); cohort B, an expansion cohort evaluating the dose lower than the MTD; cohort C, evaluating continuous daily dosing.

RESULTS

Fifty-one patients were studied at 2, 4, and 5 mg per day dosing. The MTD was 5 mg; first-cycle dose-limiting toxicities (DLTs) were grade 3 hyponatremia in one patient, and grade 3 dehydration in another. Intermittent dosing of both 2 and 4 mg doses were tolerable, and the recommended phase II dose was 4 mg. Cohort B investigated 4 mg intermittently, whereas cohort C investigated 4 mg continuously. Common toxicities included fatigue, nausea/vomiting, diarrhea, anorexia, and early-onset peripheral neuropathy. Drug-induced pneumonitis occurred in two patients in cohort C. Continuous dosing was associated with a higher incidence of peripheral neuropathy and a lower mean relative dose intensity, compared with intermittent dosing. Steady-state pharmacokinetics was characterized by high oral clearance, mean elimination half-life ranging from 44 to 61 h, and a large terminal-phase volume of distribution. An active metabolite, OPB-51822, accumulated to a greater extent than OPB-51602. Flow cytometry of peripheral blood mononuclear cells demonstrated pSTAT3 (Tyr(705)) inhibition following exposure. Two patients achieved partial responses at 5 mg intermittently and 4 mg continuously; both had epidermal growth factor receptor (EGFR) mutation-positive non-small-cell lung cancer (NSCLC) with prior EGFR tyrosine kinase inhibitor exposure.

CONCLUSION

OPB-51602 demonstrates promising antitumor activity, particularly in NSCLC. Its long half-life and poorer tolerability of continuous dosing, compared with intermittent dosing, suggest that less frequent dosing should be explored.

CLINICALTRIALSGOV IDENTIFIER

NCT01184807.

Laparoscopy-assisted spleen-preserving pancreatic resection for epidermoid cyst in an intrapancreatic accessory spleen

A rare case of an epidermoid cyst originating in an intrapancreatic accessory spleen in a 50-year-old Japanese female is reported. A hypoechoic cystic tumor was detected incidentally by abdominal ultrasonography. It appeared to be a single cyst in the pancreatic tail with a contrasted mass lesion beside it. Laparoscopy-assisted spleen-preserving pancreatic tail resection was performed. Microscopic examination revealed that the cyst was surrounded by fibrous tissue and a thin layer of splenic tissue, adjacent to normal pancreatic parenchyma. The inner surface of the cyst was lined with non-keratinizing squamous epithelium. The diagnosis of an epidermoid cyst occurring in an intrapancreatic accessory spleen was confirmed. Laparoscopy-assisted spleen-preserving pancreatic resection is a safe and effective procedure for benign or low-grade malignant cystic diseases in the pancreas.

Common variant in 6q26-q27 is associated with distal colon cancer in an Asian population

BACKGROUND AND AIM

Colorectal cancer (CRC) is a multifactorial disease with both environmental and genetic factors contributing to its development. The incidence of CRC is increasing year by year in Japan. Patients with CRC in advanced stages have a poor prognosis, but detection of CRC at earlier stages can improve clinical outcome. Therefore, identification of epidemiologial factors that influence development of CRC would facilitate the prevention or early detection of disease.

METHODS

To identify loci associated with CRC risk, we performed a genome-wide association study (GWAS) for CRC and sub-analyses by tumour location using 1583 Japanese CRC cases and 1898 controls. Subsequently, we conducted replication analyses using a total of 4809 CRC cases and 2973 controls including 225 Korean subjects with distal colon cancer and 377 controls.

RESULTS

We identified a novel locus on 6q26-q27 region (rs7758229 in SLC22A3, p = 7.92 × 10⁻⁹, OR of 1.28) that was significantly associated with distal colon cancer. We also replicated the association between CRC and SNPs on 8q24 (rs6983267 and rs7837328, p = 1.51 × 10⁻⁸ and 7.44 × 10⁻⁸, ORs of 1.18 and 1.17, respectively). Moreover, we found cumulative effects of three genetic factors (rs7758229, rs6983267, and rs4939827 in SMAD7) and one environmental factor (alcohol drinking) which appear to increase CRC risk approximately twofold.

CONCLUSIONS

We found a novel susceptible locus in SLC22A3 that contributes to the risk of distal colon cancer in an Asian population. These findings would further extend our understanding of the role of common genetic variants in the aetiology of CRC.

Risk factors for depression after kidney transplantation

OBJECTIVE

Kidney transplantation is recognized as the only potentially curative treatment for end-stage renal failure. But many psychiatric problems are associated with the procedure. The purpose of this study was to identify predictors of a risk for depression after kidney transplantation.

MATERIALS AND METHODS

This retrospective cohort study recruited 116 first kidney-only Japanese recipients whose mean age was 50.2 +/- 11.87 years include a male/female ratio of 63/53. They underwent transplantation between 1990 and 2008. At enrollment, we used the Zung Self-rating Depression Scale score as well as characterized demographic and clinical features of recipients and donors. Comparisons between depressed and non-depressed patients concerning sociodemographic and clinical characteristics were used chi(2) tests for categorical variables and Student's t-tests for continuous variables. Risk factors with significant correlation coefficients (P < .05) were entered into a stepwise logistic regression model to identify the best single risk factor for depression after kidney transplantation.

RESULT

The prevalence of depression in this study was 41.4%. Depressed patients were significantly more likely to not have regular incomes, nor to have desired kidney transplantation, to have experienced a rejection episode, and to live alone (P < .05). The single best predictor of future depression was living alone; subjects living alone were 2.51 times more likely to be depressed as those living with others (adjusted odds ratio [OR], 2.51; 95% confidence interval [CI], 1.31-5.22; P < .05).

CONCLUSION

Although depression after kidney transplantation is driven by multiple, complex, and often overlapping risk factors, we observed characteristic features of recipients including their social environment and follow-up treatment.

Phase I clinical trial with VEGFR2-epitope peptide and gemcitabine for patients with advanced pancreatic cancer

2567

Background: The prognosis of pancreatic cancer patients is one of the most dismal of all cancers. Gemcitabine is a potent anticancer drug for pancreatic cancer, however, one should consider that the clinical benefit of anticancer drugs is limited and other potent therapeutic tool is eagerly awaited. Vascular endothelial growth factor (VEGF) is a glycoprotein which is predominantly related to the neoplastic angiogenesis. VEGF-receptor 2 (VEGFR2; Flk-1 and KDR) is an essential target for tumor angiogenesis. We first identify the epitope peptides of vascular endothelial growth factor receptor 2 (VEGFR2) and confirmed that stimulation using these peptides induces CTLs with potent cytotoxicity in HLA class I-restricted fashion. Methods: We proceeded to Phase I clinical trial using gemcitabine and one of these peptides. Patients were sequentially allocated to cohorts of 6 patients per group receiving 0.5, 1.0, 2.0mg of peptides/body. No intra-patient dose escalation was permitted. The eligibility criteria are: being aged between 20- and 80- year old, expecting the survival more than 3 months after the initiation of this treatment, adequate organ function including bone marrow function, and having HLA-A*2402 (A24) genotype. The enrolled patients received 4 cycles of VEGFR2 peptide sc. and 3 cycles of 1,000 mg/m2 gemcitabine weekly. Results: No patients had grade 3 and 4 toxicity, and dose escalation was succeeded without any DLT. CTL response was observed in 50%, 67%, and 67% of 0.5mg, 1.0mg, and 2.0mg cohort, respectively. The delayed type hypersensitivity of the peptide-injection site was recognized in 83%, 67%, and 100% of 0.5mg, 1.0mg, and 2.0mg cohort, respectively. Therefore, we concluded that MTD should be 2.0mg of peptide. Disease control rate (>SD) was 67% (12/18 patients), and one patient had PR. The median survival time was 8.72 months. Conclusions: These results are promising to proceed the pivotal clinical trial, and the randomized phase II/III trial will start in 2009.

No significant financial relationships to disclose.

Kernohan's phenomenon associated with left ruptured occipital arteriovenous malformation

A 23-year-old woman presented with ipsilateral hemiparesia due to rupture of a left occipital arteriovenous malformation (AVM). Emergency decompression (the onset-operation interval was 46 minutes,) was carried out and the patient could leave the hospital upon recovery without neurological deficits. In general, Kernohan's phenomenon is caused by the gradual displacement of the cerebral peduncle against the tentorial edge caused by compression by the contralateral mass. This phenomenon is very rare among the cases with spontaneous intracranial hemorrhage and only three cases including the present one have been reported in the literature. In all cases the onset-operation intervals of were very short. Kernohan's phenomenon associated with a ruptured AVM is a rare condition and emergency decompression is required.

A study of the pharmacokinetics of 5-FU when S-1 was administered orally as an adjuvant agent in gastric cancer patients

15024

Background: S-1 is an effective oral anti-cancer drug which is formulation of 5-FU, and it is widely used for gastric cancers in Japan. However, the compliance of S-1 treatment is not satisfactory due to its side effects. We hypothesized that the plasma concentration of 5-FU could be verified individually, because the drug is administered orally. Therefore, we investigated the pharmacokinetics of 5-FU when it was administered orally in the form of S-1. Methods: The plasma concentration of 5-FU after S-1 oral administration for adjuvant chemotherapy was measured in 22 advanced gastric cancer patients (Stage II or III). Total gastrectomy was performed in 12 patients and distal gastrectomy was performed in 10 patients. All patients were given S-1 (80mg/m2) orally at 8:00 and 20:00, daily. Blood samples were collected at 10:00, 12:00, 14:00 and 16:00 on the 7th day after S-1 administration and we measured 5-FU concentration of plasma. Results: Pharmacokinetic parameters of plasma concentration of 5-FU were as follows: Cmax, 157.92 ± 42.9 ng/ml; Tmax, 2.36 ± 0.79 h; T1/2, 2.90 ± 2.36 h; and AUC 0–8 ,731.8 ± 236.4 ng ·h/ml in all patients given the usual dosage. The plasma concentration of 5-FU was quite different between patients. The difference of Cmax and AUC was 3∼ 4 times. The AUC0- 8 in the total gastrectomy patients (752.6± 273.3 ng·h/ml) was higher than that in distal gastrectomy patients (714.5±211.7 ng·h/ml), however this difference did not reach significance. Adverse events of more than grade 3 were observed in 7 patients. AUC0–8 of 4 of 7 patients were more than 800 ng·h/ml and those of 2 other patients were more than 750 ng·h/ml. The patients with high AUC0–8 levels had a tendency to show more severe adverse events. Conclusions: We conclude that physicians should pay close attention to individual differences in the plasma concentration of 5-FU in postoperative gastric cancer patients when this drug is given orally as S- 1.

No significant financial relationships to disclose.

A phase I/II study of docetaxel /S-1 with radiation for esophageal cancer patients

15061

Background: The combined therapy of CDDP/5-FU with radiation is the standard therapy for esophageal cancer patients. However, this therapy is associated with a comparatively high incidence of gastrointestinal disorders resulting in therapy interruptions and long hospital stays. Herein, we propose a new regimen of Docetaxel / S-1 combined with radiation to improve the success rate and outcome. The clinical phase Istudy was conducted from May, 2004 until June, 2006. and we report on the results in this paper. Methods: Patients were given S-1 (60mg/m2/day) orally from days 1 to 14, and Docetaxel (20mg/m2 in level 1, 25mg/m2 in level 2, and 30 mg/m2 in level 3) intravenously on days 1 and 8. Patients received radiation in 2.0 Gy daily fractions from days 1 to 21, for a total of 30 Gy. Patients were given a seven-day rest after the first course, and then treated with the same regimen from days 28 to 49.P The phase I study was completed for 10 cases. Results: All patients completed the treatment schedule, with no treatment-related deaths and no grade 4 adverse events were observed. As for hematotoxicity, one case revealed leucopenia of grade 3 and neutropenia of grade 2. A non-hematotoxic adverse event (grade 3 anorexia) was observed in one patient. The response rate evaluated by RECIST was 66 % (CR in 2 cases, PR in 4 cases). We assumed that the recommended dosage of TXT and S-1 was 30mg/m2 and 60mg/m2, respectively, combined with a radiotherapy dose of 60Gy. Conclusions: This combination therapy may be superior to other treatments because of its lower rate of adverse events and higher response rates. We continue this study to Phase II in order to generate data on the response rate and adverse effect rate in a greater number of patients with esophageal cancer.

No significant financial relationships to disclose.

Efficacy of carotid artery stenting

SUMMARY

Carotid Artery Stenting(CAS) was performed for 51 lesions in 46 patients for almost clinically symptomatic stenotic (> 70%)lesions of cervical carotid arteries. The lesions involved the contralateral occlusion cases in eight cases, the bilateral stenotic cases in six cases and the ipsilateral internal carotid artery stenotic cases in two cases. In all cases, endovascular technique was performed from a transfemoral approach under local anesthesia primarily. Under systemic heparinization, CAS was performed using a selfexpanding stent system. For the pre-stenting and post-stenting dilatation, percutaneous transluminal angioplasty (PTA) balloon catheters were used. The balloon was inflated up to the pressure of six to ten atoms for 20 to 30 seconds.After CAS, stenotic lesion dilated successfully in all cases (0-20% residual stenosis; mean, 5.5%) even if in the case of the contra-lateral occlusion cases, more than 90% severe stenotic cases, and the tortuous artery cases. The cerebral protection system was always used, mainly distal blocking balloon type. Only one symptomatic complication occurred after CAS. Follow-up ultrasonic carotid echogram was performed in 30 cases.No cases showed restenosis (more than 50% restenosis). Clinical follow up was performed in all cases for one to 41 months (mean, 15.2 months) and no clinical deterioration such as TIA or stroke occurred. CAS is technically feasible and can be performed with relatively low morbidity even if complicated stenotic cases. It may be useful, but the increase the number of patients and the long-term follow-up are necessary to evaluate the safety and usefulness of this method.

Risk factors for de novo acute cardiac events in patients initiating hemodialysis with no previous cardiac symptom

An initial major adverse cardiac event (MACE) is an important predictor of future cardiovascular events in patients with chronic kidney disease (CKD). We sought to identify factors influencing occurrence of initial MACE in new maintenance hemodialysis patients without previous cardiac symptoms during the predialysis phase of CKD. Among 112 participating patients with no predialysis cardiac history, 57 underwent coronary angiography, whereas the other 55 underwent stress thallium-201 single-photon emission computed tomography within 1 month of beginning hemodialysis to detect asymptomatic coronary artery disease (CAD). In subsequent follow-up for a median of 24 months, subjects experiencing an initial MACE were compared with those who did not have such an event based on several clinical parameters at the end of predialysis phase. Asymptomatic CAD was present in 47 patients (42%), who had a higher cumulative MACE rate, than subjects without CAD (49 vs 3%, P<0.001). Multivariate Cox's regression analysis showed that three variables independently predicted initial MACE: asymptomatic CAD (hazard ratio or HR, 611.31; 95% confidence interval or CI, 14.07-26549.23; P<0.001), diabetes (HR, 20.41; 95% CI, 2.07-200.00; P=0.010), and each 1 mg/l increment in C-reactive protein (CRP) (HR, 1.94; 95% CI, 1.27-2.94; P=0.002). In conclusion, detection of asymptomatic CAD, presence of diabetes, or elevated CRP at the end of the predialysis phase were significantly associated with occurrence of an initial MACE in CKD patients starting hemodialysis who had no CAD symptoms.

Single nucleotide polymorphisms in the gene encoding Krüppel-like factor 7 are associated with type 2 diabetes

AIMS/HYPOTHESIS

Although genetic susceptibility plays an important role in the pathogenesis of type 2 diabetes, most of the genes that influence susceptibility to type 2 diabetes have yet to be identified. Krüppel-like transcription factors are known to play important roles in development and cell differentiation, and have recently been implicated in the pathogenesis of type 2 diabetes. The present study aimed to examine the associations of single nucleotide polymorphisms (SNPs) in genes encoding members of the Krüppel-like-factor (KLF) family with type 2 diabetes in a large cohort of Japanese subjects.

METHODS

We genotyped 33 SNP loci found in 12 KLF genes in subjects with type 2 diabetes and in subjects from the general population using the PCR-Invader assay. We also examined the effects of the overexpression of KLF7 on adipogenesis in 3T3-L1 cells.

RESULTS

We identified a significant association between an SNP in KLF7 and type 2 diabetes (A vs C: p=0.004 after Bonferroni's correction, odds ratio=1.59, 95% CI 1.27-2.00). The expression of Klf7 decreased in response to the differentiation of 3T3-L1 adipocytes, and the overexpression of KLF7 resulted in significant inhibition of adipogenesis in 3T3-L1 cells.

CONCLUSIONS/INTERPRETATION

These results indicate that the gene encoding KLF7 is a novel candidate for conferring genetic susceptibility to type 2 diabetes.