Improving Visualization of In-stent Lumen Using Prototype Photon-counting Detector Computed Tomography with High-resolution Plaque Kernel.

The study aimed to compare the performance of photon-counting detector computed tomography (PCD CT) with high-resolution (HR)-plaque kernel with that of the energy-integrating detector CT (EID CT) in terms of the visualization of the lumen size and the in-stent stenotic portion at different coronary vessel angles. The lumen sizes in PCD CT and EID CT images were 2.13 and 1.80 mm at 0°, 2.20 and 1.77 mm at 45°, and 2.27 mm and 1.67 mm at 90°, respectively. The lumen sizes in PCD CT with HR-plaque kernel were wider than those in EID CT. The mean degree of the in-stent stenotic portion at 50% was 69.7% for PCD CT and 90.4% for EID CT. PCD CT images with HR-plaque kernel enable improved visualization of lumen size and accurate measurements of the in-stent stenotic portion compared to conventional EID CT images regardless of the stent direction.

Inhibitory effect of atomoxetine on Nav1.2 voltage-gated sodium channel currents.

BACKGROUND: Atomoxetine (ATX), a norepinephrine reuptake inhibitor (NRI), is used to attenuate the symptoms of Attention Deficit/Hyperactivity Disorder (AD/HD) by increasing neurotransmitter concentrations at the synaptic cleft. Although Nav1.2 voltage-gated sodium channels (VGSCs) are thought to play a role in monoamine transmitter release in the synaptic junction, it is unclear how atomoxetine affects Nav1.2 VGSCs. METHODS: In this study, we investigated the effect of ATX on Nav1.2 VGSC-transfected HEK293 cells with the whole-patch clamp technique. RESULTS: Nav1.2 VGSC current decreased by 51.15 ± 12.75% under treatment with 50 µM ATX in the resting state (holding membrane potential at - 80 mV). The IC50 of ATX against Nav1.2 VGSC current was 45.57 µM. The activation/inactivation curve of Nav1.2 VGSC currents was shifted toward hyperpolarization by 50 µM ATX. In addition, the inhibitory effect of ATX increased with membrane depolarization (holding membrane potential at - 50 mV) and its IC50 was 10.16 µM. Moreover, ATX showed the time-dependent interaction in the inactivation state. CONCLUSION: These findings suggest that ATX interacts with Nav1.2 VGSCs producing the inhibition of current and the modification of kinetic properties in the state-dependent manner.

Iterative reconstruction with multifrequency signal recognition technology to improve low-contrast detectability: A phantom study.

Background: Brain CT needs more attention to improve the extremely low image contrast and image texture. Purpose: To evaluate the performance of iterative progressive reconstruction with visual modeling (IPV) for the improvement of low-contrast detectability (IPV-LCD) compared with filtered backprojection (FBP) and conventional IPV. Materials and methods: Low-contrast and water phantoms were used. Helical scans were conducted with the use of a CT scanner with 64 detectors. The tube voltage was set at 120 kVp; the tube current was adjusted from 60 to 300 mA with a slice thickness of 0.625 mm and from 20 to 150 mA with a slice thickness of 5.0 mm. Images were reconstructed with the FBP, conventional IPV, and IPV-LCD algorithms. The channelized Hotelling observer (CHO) model was applied in conjunction with the use of low-contrast modules in the low-contrast phantom. The noise power spectrum (NPS) and normalized NPS were calculated. Results: At the same standard and strong levels, the IPV-LCD method improved low-contrast detectability compared with the conventional IPV, regardless of contrast-rod diameters. The mean CHO values at a slice thickness of 0.625 mm were 1.83, 3.28, 4.40, 4.53, and 5.27 for FBP, IPV STD, IPV-LCD STD, IPV STR, and IPV-LCD STR, respectively. The normalized NPS for the IPV-LCD STD and STR images were slightly shifted to the higher frequency compared with that for the FBP image. Conclusion: IPV-LCD images further improve the low-contrast detectability compared with FBP and conventional IPV images while maintaining similar FBP image appearances.

Convolutional neural network for classification of two-dimensional array images generated from clinical information may support diagnosis of rheumatoid arthritis.

This research aimed to study the application of deep learning to the diagnosis of rheumatoid arthritis (RA). Definite criteria or direct markers for diagnosing RA are lacking. Rheumatologists diagnose RA according to an integrated assessment based on scientific evidence and clinical experience. Our novel idea was to convert various clinical information from patients into simple two-dimensional images and then use them to fine-tune a convolutional neural network (CNN) to classify RA or nonRA. We semi-quantitatively converted each type of clinical information to four coloured square images and arranged them as one image for each patient. One rheumatologist modified each patient's clinical information to increase learning data. In total, 1037 images (252 RA, 785 nonRA) were used to fine-tune a pretrained CNN with transfer learning. For clinical data (10 RA, 40 nonRA), which were independent of the learning data and were used as testing data, we compared the classification ability of the fine-tuned CNN with that of three expert rheumatologists. Our simple system could potentially support RA diagnosis and therefore might be useful for screening RA in both specialised hospitals and general clinics. This study paves the way to enabling deep learning in the diagnosis of RA.

Improving Low-contrast Detectability and Noise Texture Pattern for Computed Tomography Using Iterative Reconstruction Accelerated with Machine Learning Method: A Phantom Study.

RATIONALE AND OBJECTIVES: To evaluate the performance of iterative reconstruction (IR) and filtered back projection (FBP) images in terms of low-contrast detectability at different radiation doses, IR levels, and slice thickness using the mathematical model observer with a focus on low-contrast detectability. MATERIALS AND METHODS: The CCT189 MITA CT IQ Low-Contrast Phantom was used and helical scans were performed using a 64-detector CT scanner. Tube voltage was set at 120 kVp and tube current was adjusted from 45 to 600 mA. Images were reconstructed at slice thicknesses of 0.625 and 5.0 mm with FBP and five types of iterative progressive reconstruction with visual modeling (IPV) algorithms. The noise power spectrum (NPS) and normalized NPS were calculated. To evaluate low-contrast detectability, the model observer with the channelized Hotelling observer model was applied using low-contrast modules in the phantom. RESULTS: The NPS and normalized NPS for IPV images had similar curves as that for FBP images. At a slice thickness of 0.625 mm and equivalent radiation dose level, the mean improvement of low-contrast detectability for IPV images was 1.19-2.15-fold greater than FBP images with corresponding noise reduction levels. At equivalent noise levels of 5.0-8.0 HU, low-contrast detectability of the IPVstd2 to IPVstr2 images as almost the same or better than that of the FBP images. However, the detectability of the IPVstr4 image was lower than that of the FBP image (p = 0.02). CONCLUSION: Low-contrast detectability of the IPV images was improved with a similar normalized NPS as with FBP images. Furthermore, a radiation reduction of >50% was achieved for the IPV images, while maintaining similar low-contrast detectability.

No Evidence for Particular Association Between HLA-Haploidentical Hematopoietic Stem Cell Transplantation and Psychological Distress.

BACKGROUND: The psychological distress experienced by patients scheduled for hematopoietic stem cell transplantation (HSCT) is of clinical concern. However, distress experienced by patients scheduled for HLA-haploidentical HSCT vs that of patients scheduled for other types of matched HSCT is unknown. We conducted a retrospective study to clarify whether the type of HSCT influences the appearance of psychological distress in patients anticipating HSCT. METHODS: One hundred fifty-seven patients who had undergone any of 4 types of HSCT at Tokyo Metropolitan Komagome Hospital between October 2013 and September 2016 and had completed the Profile of Mood States (POMS) questionnaire within 2 weeks before the procedure were included. We computed T-scores for the tension-anxiety (TA) and depression (D) subscales, took scores ≥ 60 to represent mood disturbance of clinical concern, and examined scores and other clinical variables in relation to each procedure. RESULTS: Twenty-two (14.0%) patients had a POMS-TA score ≥ 60, and 26 (16.6%) had a POMS-D score ≥ 60. The numbers of POMS-TA and POMS-D scores ≥ 60 did not differ significantly with respect to age, sex, leukemia type, number of previous transplants, disease status, comorbidity index, or transplant type. A multivariate logistic regression analysis confirmed the absence of an influence of the type of HSCT on the incidence of POMS-TA or POMS-D scores ≥60. CONCLUSION: Attention should be paid to the matter of psychological distress in patients with leukemia who will be treated by HSCT, even HLA-haploidentical HSCT. Such patients need psychological support, especially during the waiting period immediately prior to the transplantation procedure.

Active synovitis in the presence of osteitis predicts residual synovitis in patients with rheumatoid arthritis with a clinical response to treatment.

AIM: To clarify the relationship between active synovitis/osteitis and subsequent residual synovitis (R-synovitis) in patients with rheumatoid arthritis (RA). METHODS: Three hundred and twenty finger joints of 16 patients with active RA at baseline (Disease Activity Score with 28 joints - erythrocyte sedimentation rate > 3.2) who subsequently achieved clinical low disease activity or remission afterwards were analyzed. Synovial vascularity (SV) was assessed according to a semi-quantitative ultrasound score (grades 0-3). Active synovitis was defined by SV positivity at baseline. R-synovitis was defined by the presence of grade > 2 SV at the 24th week. Osteitis was detected by magnetic resonance imaging (MRI) at baseline as trabecular bone lesions with water content and indistinct margins. RESULTS: Ultrasonography detected active synovitis in 116 joints at baseline. Forty-seven joints had R-synovitis at the 24th week. MRI detected osteitis in 12 joints at baseline. The presence of active synovitis with osteitis at baseline was significantly correlated with R-synovitis at the 24th week. CONCLUSIONS: Active synovitis in the presence of osteitis predicted R-synovitis regardless of whether there was a clinical improvement in RA.

Computer-Based Radiographic Quantification of Joint Space Narrowing Progression Using Sequential Hand Radiographs: Validation Study in Rheumatoid Arthritis Patients from Multiple Institutions.

We have developed a refined computer-based method to detect joint space narrowing (JSN) progression with the joint space narrowing progression index (JSNPI) by superimposing sequential hand radiographs. The purpose of this study is to assess the validity of a computer-based method using images obtained from multiple institutions in rheumatoid arthritis (RA) patients. Sequential hand radiographs of 42 patients (37 females and 5 males) with RA from two institutions were analyzed by a computer-based method and visual scoring systems as a standard of reference. The JSNPI above the smallest detectable difference (SDD) defined JSN progression on the joint level. The sensitivity and specificity of the computer-based method for JSN progression was calculated using the SDD and a receiver operating characteristic (ROC) curve. Out of 314 metacarpophalangeal joints, 34 joints progressed based on the SDD, while 11 joints widened. Twenty-one joints progressed in the computer-based method, 11 joints in the scoring systems, and 13 joints in both methods. Based on the SDD, we found lower sensitivity and higher specificity with 54.2 and 92.8%, respectively. At the most discriminant cutoff point according to the ROC curve, the sensitivity and specificity was 70.8 and 81.7%, respectively. The proposed computer-based method provides quantitative measurement of JSN progression using sequential hand radiographs and may be a useful tool in follow-up assessment of joint damage in RA patients.

Japanese traditional herbal medicine reduces use of pregabalin and opioids for pain in patients with lumbar spinal canal stenosis: a retrospective cohort study.

BACKGROUND: There has been an increase in the number of Japanese patients with lumbar spinal canal stenosis (LSCS) who complain of chronic pain or motor disturbance in the lower back or extremities. These patients are often treated with anti-convulsive drugs, opioids, antidepressants, acetaminophen, or nonsteroidal anti-inflammatory drugs, all of which can cause side effects. For this reason, Japanese traditional herbal medicine (Kampo) is of interest, because it produces fewer adverse reactions. The aim of this retrospective cohort study was to analyze the effects of Kampo in patients with LSCS. FINDINGS: A total of 151 patients with LSCS were divided into two groups based on treatment with (n = 111, group K) and without (n = 40, group N) Kampo. Use of pregabalin and opioids decreased significantly in group K (p < 0.001). The hazard ratio for opioid discontinuation was 0.220 (p = 0.004) for group N vs. group K, while that for pregabalin and antidepressants discontinuation were 0.589 (p = 0.202) and 0.509 (p = 0.377), respectively. The mean duration of hospital visits and treatment did not differ between the groups, but the number of dropouts was significantly higher in group N (p < 0.0001). The hazard ratio for patient dropout was 4.118 (p = 0.001) for group N vs. group K. CONCLUSIONS: Kampo led to discontinuation of opioid use for pain in patients with LSCS, and patients who were treated with Kampo were more likely to continue treatment.

ERK Signal Suppression and Sensitivity to CH5183284/Debio 1347, a Selective FGFR Inhibitor.

Drugs that target specific gene alterations have proven beneficial in the treatment of cancer. Because cancer cells have multiple resistance mechanisms, it is important to understand the downstream pathways of the target genes and monitor the pharmacodynamic markers associated with therapeutic efficacy. We performed a transcriptome analysis to characterize the response of various cancer cell lines to a selective fibroblast growth factor receptor (FGFR) inhibitor (CH5183284/Debio 1347), a mitogen-activated protein kinase kinase (MEK) inhibitor, or a phosphoinositide 3-kinase (PI3K) inhibitor. FGFR and MEK inhibition produced similar expression patterns, and the extracellular signal-regulated kinase (ERK) gene signature was altered in several FGFR inhibitor-sensitive cell lines. Consistent with these findings, CH5183284/Debio 1347 suppressed phospho-ERK in every tested FGFR inhibitor-sensitive cell line. Because the mitogen-activated protein kinase (MAPK) pathway functions downstream of FGFR, we searched for a pharmacodynamic marker of FGFR inhibitor efficacy in a collection of cell lines with the ERK signature and identified dual-specificity phosphatase 6 (DUSP6) as a candidate marker. Although a MEK inhibitor suppressed the MAPK pathway, most FGFR inhibitor-sensitive cell lines are insensitive to MEK inhibitors and we found potent feedback activation of several pathways via FGFR. We therefore suggest that FGFR inhibitors exert their effect by suppressing ERK signaling without feedback activation. In addition, DUSP6 may be a pharmacodynamic marker of FGFR inhibitor efficacy in FGFR-addicted cancers.

Somatic copy number alterations associated with Japanese or endometriosis in ovarian clear cell adenocarcinoma.

When compared with other epithelial ovarian cancers, the clinical characteristics of ovarian clear cell adenocarcinoma (CCC) include 1) a higher incidence among Japanese, 2) an association with endometriosis, 3) poor prognosis in advanced stages, and 4) a higher incidence of thrombosis as a complication. We used high resolution comparative genomic hybridization (CGH) to identify somatic copy number alterations (SCNAs) associated with each of these clinical characteristics of CCC. The Human Genome CGH 244A Oligo Microarray was used to examine 144 samples obtained from 120 Japanese, 15 Korean, and nine German patients with CCC. The entire 8q chromosome (minimum corrected p-value: q = 0.0001) and chromosome 20q13.2 including the ZNF217 locus (q = 0.0078) were amplified significantly more in Japanese than in Korean or German samples. This copy number amplification of the ZNF217 gene was confirmed by quantitative real-time polymerase chain reaction (Q-PCR). ZNF217 RNA levels were also higher in Japanese tumor samples than in non-Japanese samples (P = 0.027). Moreover, endometriosis was associated with amplification of EGFR gene (q = 0.047), which was again confirmed by Q-PCR and correlated with EGFR RNA expression. However, no SCNAs were significantly associated with prognosis or thrombosis. These results indicated that there may be an association between CCC and ZNF217 amplification among Japanese patients as well as between endometriosis and EGFR gene amplifications.

CH5137291, an androgen receptor nuclear translocation-inhibiting compound, inhibits the growth of castration-resistant prostate cancer cells.

Resistance of prostate cancer to castration is currently an unavoidable problem. The major mechanisms underlying such resistance are androgen receptor (AR) overexpression, androgen-independent activation of AR, and AR mutation. To address this problem, we developed an AR pure antagonist, CH5137291, with AR nuclear translocation-inhibiting activity, and compared its activity and characteristics with that of bicalutamide. Cell lines corresponding to the mechanisms of castration resistance were used: LNCaP-BC2 having AR overexpression and LNCaP-CS10 having androgen-independent AR activation. VCaP and LNCaP were used as hormone-sensitive prostate cancer cells. In vitro functional assay clearly showed that CH5137291 inhibited the nuclear translocation of wild-type ARs as well as W741C- and T877A-mutant ARs. In addition, it acted as a pure antagonist on the transcriptional activity of these types of ARs. In contrast, bicalutamide did not inhibit the nuclear translocation of these ARs, and showed a partial/full agonistic effect on the transcriptional activity. CH5137291 inhibited cell growth more strongly than bicalutamide in VCaP and LNCaP cells as well as in LNCaP-BC2 and LNCaP-CS10 cells in vitro. In xenograft models, CH5137291 strongly inhibited the tumor growth of LNCaP, LNCaP-BC2, and LNCaP-CS10, whereas bicalutamide showed a weaker effect in LNCaP and almost no effect in LNCaP-BC2 and LNCaP-CS10 xenografts. Levels of prostate-specific antigen (PSA) in plasma correlated well with the antitumor effect of both agents. CH5137291 inhibited the growth of LNCaP tumors that had become resistant to bicalutamide treatment. A docking model suggested that CH5137291 intensively collided with the M895 residue of helix 12, and therefore strongly inhibited the folding of helix 12, a cause of AR agonist activity, in wild-type and W741C-mutant ARs. In cynomolgus monkeys, the serum concentration of CH5137291 increased dose-dependently and PSA level decreased 80% at 100 mg/kg. CH5137291 is expected to offer a novel therapeutic approach against major types of castration-resistant prostate cancers.

Inhibition of metastasis of rhabdomyosarcoma by a novel neutralizing antibody to CXC chemokine receptor-4.

Rhabdomyosarcoma is the most common soft tissue sarcoma affecting children, and the overall cure rate of children with metastatic disease remains below 30%. The CXC chemokine receptor-4 (CXCR4)/stromal cell-derived factor-1 (SDF1) axis has been implicated in the promotion of metastatic potential in several tumors. In this study, we developed a novel anti-CXCR4 mAb, CF172, and investigated its antimetastatic activity against rhabdomyosarcoma cells in vitro and in vivo, to evaluate its potential as a therapeutic antibody to treat rhabdomyosarcoma. The CF172 molecule showed a specific binding reactivity against human CXCR4, as well as a specific neutralizing activity against CXCR4/SDF1 signal transduction. Using CF172, we determined that SJCRH30 rhabdomyosarcoma cells expressed high levels of CXCR4. In addition, CF172 was found to inhibit the SDF1-induced migration activity of SJCRH30 cells in vitro. Using xenograft models of SJCRH30 cells, we carried out in vivo efficacy studies for peritoneal and lymph node metastasis, which were clinically observed in rhabdomyosarcoma. These studies indicated that CF172 significantly decreased both types of metastasis of SJCRH30. In conclusion, we found that a novel anti-CXCR4 mAb, CF172, with specific reactivity against human CXCR4, prevented peritoneal metastasis and lymph node metastasis of rhabdomyosarcoma in animal models. These results suggest that CF172 is a potential antimetastasis therapeutic antibody for rhabdomyosarcoma treatment.

The fibroblast growth factor receptor genetic status as a potential predictor of the sensitivity to CH5183284/Debio 1347, a novel selective FGFR inhibitor.

The FGF receptors (FGFR) are tyrosine kinases that are constitutively activated in a subset of tumors by genetic alterations such as gene amplifications, point mutations, or chromosomal translocations/rearrangements. Recently, small-molecule inhibitors that can inhibit the FGFR family as well as the VEGF receptor (VEGFR) or platelet-derived growth factor receptor (PDGFR) family displayed clinical benefits in cohorts of patients with FGFR genetic alterations. However, to achieve more potent and prolonged activity in such populations, a selective FGFR inhibitor is still needed. Here, we report the identification of CH5183284/Debio 1347, a selective and orally available FGFR1, FGFR2, and FGFR3 inhibitor that has a unique chemical scaffold. By interacting with unique residues in the ATP-binding site of FGFR1, FGFR2, or FGFR3, CH5183284/Debio 1347 selectively inhibits FGFR1, FGFR2, and FGFR3 but does not inhibit kinase insert domain receptor (KDR) or other kinases. Consistent with its high selectivity for FGFR enzymes, CH5183284/Debio 1347 displayed preferential antitumor activity against cancer cells with various FGFR genetic alterations in a panel of 327 cancer cell lines and in xenograft models. Because of its unique binding mode, CH5183284/Debio 1347 can inhibit FGFR2 harboring one type of the gatekeeper mutation that causes resistance to other FGFR inhibitors and block FGFR2 V564F-driven tumor growth. CH5183284/Debio 1347 is under clinical investigation for the treatment of patients harboring FGFR genetic alterations.

Optimizing the Physicochemical Properties of Raf/MEK Inhibitors by Nitrogen Scanning.

Substituting a carbon atom with a nitrogen atom (nitrogen substitution) on an aromatic ring in our leads 11a and 13g by applying nitrogen scanning afforded a set of compounds that improved not only the solubility but also the metabolic stability. The impact after nitrogen substitution on interactions between a derivative and its on- and off-target proteins (Raf/MEK, CYPs, and hERG channel) was also detected, most of them contributing to weaker interactions. After identifying the positions that kept inhibitory activity on HCT116 cell growth and Raf/MEK, compound 1 (CH5126766/RO5126766) was selected as a clinical compound. A phase I clinical trial is ongoing for solid cancers.

The sulfamide moiety affords higher inhibitory activity and oral bioavailability to a series of coumarin dual selective RAF/MEK inhibitors.

Introducing a sulfamide moiety to our coumarin derivatives afforded enhanced Raf/MEK inhibitory activity concomitantly with an acceptable PK profile. Novel sulfamide 17 showed potent HCT116 cell growth inhibition (IC50=8 nM) and good PK profile (bioavailability of 51% in mouse), resulting in high in vivo antitumor efficacy in the HCT116 xenograft (ED50=4.8 mg/kg). We confirmed the sulfamide moiety showed no negative impact on tests run on the compound to evaluate DMPK (PK profiles in three animal species, CYP inhibition and CYP induction) and the safety profile (hERG and AMES tests). Sulfamide 17 had favorable properties that warranted further preclinical assessment.

Enhanced antitumor activity of erlotinib in combination with the Hsp90 inhibitor CH5164840 against non-small-cell lung cancer.

Inhibition of heat shock protein 90 (Hsp90) can lead to degradation of multiple client proteins, which are involved in tumor progression. Epidermal growth factor receptor (EGFR) is one of the most potent oncogenic client proteins of Hsp90. Targeted inhibition of EGFR has shown clinical efficacy in the treatment of patients with non-small-cell lung cancer (NSCLC). However, primary and acquired resistance to the existing EGFR inhibitors is a major clinical problem. In the present study, we investigated the effect of the novel Hsp90 inhibitor CH5164840 on the antitumor activity of erlotinib. The NSCLC cell lines and xenograft models were treated with CH5164840 and erlotinib to examine their mechanisms of action and cell growth inhibition. We found that CH5164840 showed remarkable antitumor activity against NSCLC cell lines and xenograft models. The addition of CH5164840 enhanced the antitumor activity of erlotinib against NCI-H292 EGFR-overexpressing xenograft models. Phosphorylation of Stat3 increased with erlotinib treatment in NCI-H292 cells, which was abrogated by Hsp90 inhibition. Furthermore, in a NCI-H1975 T790M mutation erlotinib-resistant model, CH5164840 enhanced the antitumor activity of erlotinib despite the low efficacy of erlotinib treatment alone. In addition, ERK signaling was effectively suppressed by combination treatment with erlotinib and CH5164840 in a NCI-H1975 erlotinib-resistant model. Taken together, these data indicate that CH5164840 has potent antitumor activity and is highly effective in combination with erlotinib against NSCLC tumors with EGFR overexpression and mutations. Our results support the therapeutic potential of CH5164840 as a Hsp90 inhibitor for combination therapy with EGFR-targeting agents against EGFR-addicted NSCLC.

A serine palmitoyltransferase inhibitor blocks hepatitis C virus replication in human hepatocytes.

BACKGROUND & AIMS: Host cell lipid rafts form a scaffold required for replication of hepatitis C virus (HCV). Serine palmitoyltransferases (SPTs) produce sphingolipids, which are essential components of the lipid rafts that associate with HCV nonstructural proteins. Prevention of the de novo synthesis of sphingolipids by an SPT inhibitor disrupts the HCV replication complex and thereby inhibits HCV replication. We investigated the ability of the SPT inhibitor NA808 to prevent HCV replication in cells and mice. METHODS: We tested the ability of NA808 to inhibit SPT's enzymatic activity in FLR3-1 replicon cells. We used a replicon system to select for HCV variants that became resistant to NA808 at concentrations 4- to 6-fold the 50% inhibitory concentration, after 14 rounds of cell passage. We assessed the ability of NA808 or telaprevir to inhibit replication of HCV genotypes 1a, 1b, 2a, 3a, and 4a in mice with humanized livers (transplanted with human hepatocytes). NA808 was injected intravenously, with or without pegylated interferon alfa-2a and HCV polymerase and/or protease inhibitors. RESULTS: NA808 prevented HCV replication via noncompetitive inhibition of SPT; no resistance mutations developed. NA808 prevented replication of all HCV genotypes tested in mice with humanized livers. Intravenous NA808 significantly reduced viral load in the mice and had synergistic effects with pegylated interferon alfa-2a and HCV polymerase and protease inhibitors. CONCLUSIONS: The SPT inhibitor NA808 prevents replication of HCV genotypes 1a, 1b, 2a, 3a, and 4a in cultured hepatocytes and in mice with humanized livers. It might be developed for treatment of HCV infection or used in combination with pegylated interferon alfa-2a or HCV polymerase or protease inhibitors.

Enhanced inhibition of ERK signaling by a novel allosteric MEK inhibitor, CH5126766, that suppresses feedback reactivation of RAF activity.

Tumors with mutant RAS are often dependent on extracellular signal-regulated kinase (ERK) signaling for growth; however, MEK inhibitors have only marginal antitumor activity in these tumors. MEK inhibitors relieve ERK-dependent feedback inhibition of RAF and cause induction of MEK phosphorylation. We have now identified a MEK inhibitor, CH5126766 (RO5126766), that has the unique property of inhibiting RAF kinase as well. CH5126766 binding causes MEK to adopt a conformation in which it cannot be phosphorylated by and released from RAF. This results in formation of a stable MEK/RAF complex and inhibition of RAF kinase. Consistent with this mechanism, this drug does not induce MEK phosphorylation. CH5126766 inhibits ERK signaling output more effectively than a standard MEK inhibitor that induces MEK phosphorylation and has potent antitumor activity as well. These results suggest that relief of RAF feedback limits pathway inhibition by standard MEK inhibitors. CH5126766 represents a new type of MEK inhibitor that causes MEK to become a dominant-negative inhibitor of RAF and that, in doing so, may have enhanced therapeutic activity in ERK-dependent tumors with mutant RAS.

Enantioselective synthesis of derivatives and structure-activity relationship study in the development of NA255 as a novel host-targeting anti-HCV agent.

Hepatitis C virus (HCV) infection represents a serious health-care problem. Previously we reported the identification of NA255 from our natural products library using a HCV sub-genomic replicon cell culture system. Herein, we report how the absolute stereochemistry of NA255 was determined and an enantioselective synthetic method for NA255 derivatives was developed. The structure-activity relationship of the NA255 derivatives and rat pharmacokinetic profiles of the representative compounds are disclosed.