Idelalisib, a potent phosphatidylinositol-3-kinase delta (PI3Kδ) inhibitor, is metabolized primarily by aldehyde oxidase to form GS-563117 and to a lesser extent by cytochrome P450 (CYP) 3A and uridine 5′-diphospho-glucuronosyltransferase 1A4. In vitro, idelalisib inhibits P-glycoprotein (P-gp) and organic anion transporting polypeptides 1B1 and 1B3, and GS-563117 is a time-dependent CYP3A inhibitor. This study enrolled 24 healthy subjects and evaluated (1) the effect of idelalisib on the pharmacokinetics (PK) of digoxin, a P-gp probe substrate, rosuvastatin, a breast cancer resistance protein, and OATP1B1/OATP1B3 substrate, and midazolam, a CYP3A substrate; and (2) the effect of a strong inducer, rifampin, on idelalisib PK. On treatment, the most common clinical adverse events (AEs) were headache and pyrexia. Grade 3 transaminase increases were observed in 5 of 24 subjects and were reversible. Two subjects had serious AEs after treatment completion (grade 3 pyrexia and/or drug-induced liver injury). Idelalisib coadministration did not affect digoxin and rosuvastatin PK. Coadministration with idelalisib increased plasma exposures of midazolam (138% and 437% for maximum observed plasma concentration [Cmax ] and area under the plasma concentration-time curve from time 0 extrapolated to infinity [AUCinf ], respectively), consistent with the in vitro finding of CYP3A inhibition by GS-563117. Rifampin caused a substantial decrease in idelalisib (58% and 75%, Cmax and AUCinf , respectively) and GS-563117 exposures, indicating an enhanced contribution of CYP3A to idelalisib metabolism under a strongly induced state.
© 2015, The American College of Clinical Pharmacology.

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In the phase III AVAGAST trial, the addition of bevacizumab to chemotherapy improved progression-free survival (PFS) but not overall survival (OS) in patients with advanced gastric cancer. We studied the role of Angiopoietin-2 (Ang-2), a key driver of tumour angiogenesis, metastasis and resistance to antiangiogenic treatment, as a biomarker.
Previously untreated, advanced gastric cancer patients were randomly assigned to receive bevacizumab (n=387) or placebo (n=387) in combination with chemotherapy. Plasma collected at baseline and at progression was analysed by ELISA. The role of Ang-2 as a prognostic and a predictive biomarker of bevacizumab efficacy was studied using a Cox proportional hazards model. Logistic regression analysis was applied for correlations with metastasis.
Median baseline plasma Ang-2 levels were lower in Asian (2143 pg ml(-1)) vs non-Asian patients (3193 pg ml(-1)), P<0.0001. Baseline plasma Ang-2 was identified as an independent prognostic marker for OS but did not predict bevacizumab efficacy alone or in combination with baseline VEGF. Baseline plasma Ang-2 correlated with the frequency of liver metastasis (LM) at any time: Odds ratio per 1000 pg ml(-1) increase: 1.19; 95% CI 1.10-1.29; P<0.0001 (non-Asians) and 1.37; 95% CI 1.13-1.64; P=0.0010 (Asians).
Baseline plasma Ang-2 is a novel prognostic biomarker for OS in advanced gastric cancer strongly associated with LM. Differences in Ang-2 mediated vascular response may, in part, account for outcome differences between Asian and non-Asian patients; however, data have to be further validated. Ang-2 is a promising drug target in gastric cancer.British Journal of Cancer advance online publication, 31 March 2016; doi:10.1038/bjc.2016.30 www.bjcancer.com.

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Improved therapies for peginterferon/ribavirin null or partial responders are needed. This study evaluated daclatasvir (NS5A inhibitor) and asunaprevir (NS3 protease inhibitor) plus peginterferon alfa-2a and ribavirin in this patient population.
This open-label, phase 3 study (HALLMARK-QUAD; NCT01573351) treated patients with chronic hepatitis C virus (HCV) genotype 1 (n=354) or 4 (n=44) infection who had a prior null or partial response to peginterferon/ribavirin. Patients received daclatasvir 60 mg once-daily plus asunaprevir 100mg twice-daily, with weekly peginterferon alfa-2a and weight-based ribavirin for 24 weeks. The primary endpoint was sustained virological response at post-treatment week 12 (SVR12) among genotype 1-infected patients.
Daclatasvir plus asunaprevir and peginterferon/ribavirin demonstrated SVR12 rates of 93% (95% CI 90-96) in prior non-responders infected with HCV genotype 1. SVR12 rates among genotype 4-infected patients were 98% (95% CI 93-100); one patient had a missing post-treatment week-12 HCV-RNA measurement, but achieved an SVR at post-treatment week 24, yielding a 100% SVR rate in genotype 4 patients. Prior peginterferon/ribavirin response, sex, age, IL28B genotype, or cirrhosis status did not influence SVR12 rates. Serious adverse events occurred in 6% of patients; 5% discontinued treatment due to an adverse event. Grade 3/4 laboratory abnormalities included neutropenia (22%), lymphopenia (16%), anemia (6%), thrombocytopenia (4%), and ALT/AST elevations (3% each).
Daclatasvir plus asunaprevir and peginterferon/ribavirin demonstrated high rates of SVR12 in genotype 1- or 4-infected prior null or partial responders. The combination was well tolerated and no additional safety and tolerability concerns were observed compared with peginterferon/ribavirin regimens.
Copyright © 2015 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

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The spindle assembly checkpoint (SAC) is an essential safeguarding mechanism devised to ensure equal chromosome distribution in daughter cells upon mitosis. The proteins Bub3 and BubR1 are key components of the mitotic checkpoint complex (MCC), an essential part of the molecular machinery on which the SAC relies. In the present work we have performed a detailed functional and biochemical characterization of the interaction between human Bub3 and BubR1 in cells and in vitro. Our results demonstrate that genetic knock down of Bub3 abrogates the SAC, promotes apoptosis and inhibits the proliferation of human cancer cells. We also show that the integrity of the human MCC depends on the specific recognition between BubR1 and Bub3, for which the BubR1 GLEBS motif is essential. This 1:1 binding event is high affinity, enthalpy-driven and with slow dissociation kinetics. The affinity, kinetics and thermodynamic parameters of the interaction are differentially modulated by small regions in the N- and C-termini of the GLEBS domain sequence, suggesting the existence of "hotspots" for this protein-protein interaction. Furthermore, we show that specific disruption of endogenous BubR1-Bub3 complexes in human cancer cells phenocopies the effects observed in gene targeting experiments. Our work enhances the current understanding of key members of the SAC and paves the road for the pursuit of novel targeted cancer therapies based on SAC inhibition.
Copyright © 2016, The American Society for Biochemistry and Molecular Biology.

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The poor regioselectivity of the [4 + 2] cycloaddition of 3-azetidinones with internal alkynes bearing two alkyl substituents via nickel-catalyzed carbon-carbon activation is addressed using 1,3-enynes as substrates. The judicious choice of substitution on the enyne enables complementary access to each regioisomer of 3-hydroxy-4,5-alkyl-substituted pyridines, which are important building blocks in medicinal chemistry endeavors.

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