Patrice H. Gibbons

Safety of Anacetrapib in Patients with or at High Risk for Coronary Heart Disease

BACKGROUND Anacetrapib is a cholesteryl ester transfer protein inhibitor that raises high-density lipoprotein (HDL) cholesterol and reduces low-density lipoprotein (LDL) cholesterol. METHODS We conducted a randomized, double-blind, placebo-controlled trial to assess the efficacy and safety profile of anacetrapib in patients with coronary heart disease or at high risk for coronary heart disease. Eligible patients who were taking a statin and who had an LDL cholesterol level that was consistent with that recommended in guidelines were assigned to receive 100 mg of anacetrapib or placebo daily for 18 months. The primary end points were the percent change from baseline in LDL cholesterol at 24 weeks (HDL cholesterol level was a secondary end point) and the safety and side-effect profile of anacetrapib through 76 weeks. Cardiovascular events and deaths were prospectively adjudicated. RESULTS A total of 1623 patients underwent randomization. By 24 weeks, the LDL cholesterol level had been reduced from 81 mg per deciliter (2.1 mmol per liter) to 45 mg per deciliter (1.2 mmol per liter) in the anacetrapib group, as compared with a reduction from 82 mg per deciliter (2.1 mmol per liter) to 77 mg per deciliter (2.0 mmol per liter) in the placebo group (P<0.001)--a 39.8% reduction with anacetrapib beyond that seen with placebo. In addition, the HDL cholesterol level increased from 41 mg per deciliter (1.0 mmol per liter) to 101 mg per deciliter (2.6 mmol per liter) in the anacetrapib group, as compared with an increase from 40 mg per deciliter (1.0 mmol per liter) to 46 mg per deciliter (1.2 mmol per liter) in the placebo group (P<0.001)--a 138.1% increase with anacetrapib beyond that seen with placebo. Through 76 weeks, no changes were noted in blood pressure or electrolyte or aldosterone levels with anacetrapib as compared with placebo. Prespecified adjudicated cardiovascular events occurred in 16 patients treated with anacetrapib (2.0%) and 21 patients receiving placebo (2.6%) (P = 0.40). The prespecified Bayesian analysis indicated that this event distribution provided a predictive probability (confidence) of 94% that anacetrapib would not be associated with a 25% increase in cardiovascular events, as seen with torcetrapib. CONCLUSIONS Treatment with anacetrapib had robust effects on LDL and HDL cholesterol, had an acceptable side-effect profile, and, within the limits of the power of this study, did not result in the adverse cardiovascular effects observed with torcetrapib. (Funded by Merck Research Laboratories; ClinicalTrials.gov number, NCT00685776.).

Analysis of Streptomyces avermitilis genes required for avermectin biosynthesis utilizing a novel integration vector

An integration vector for gene analysis in Streptomyces has been constructed. This vector replicates in Escherichia coli, and integrates into Streptomyces by homologous recombination between a cloned fragment and the genome. To overcome methylation-specific restriction barriers, an E. coli mutant triply defective in DNA methylation was constructed as a source for the integration plasmids. The frequency of integration of pVE616 derivatives into the Streptomyces avermitilis genome was proportional to the size of the cloned DNA. Derivatives of pVE616, containing fragments from pVE650, a plasmid with a 24-kb insert of S. avermitilis DNA, were used in complementation analyses of seven S. avermitilis mutants defective in glycosylation of avermectin (Av). Three complementation groups, located in a 7-kb region, were identified. Derivatives of pVE616, containing fragments from the 18-kb of DNA adjacent to the glycosylation region, were integrated into an Av producer. Av produced from the integrants was substantially reduced, indicating that the 18 kb also encodes gene products which are involved in Av biosynthesis.

Complex organization of the Streptomyces avermitilis genes encoding the avermectin polyketide synthase

The avermectin (Av) polyketide synthase (PKS) and erythromycin (Er) PKS are encoded by modular repeats of DNA, but the genetic organization of the modules encoding Av PKS is more complex than Er PKS. Sequencing of several related DNA fragments from Streptomyces avermitilis that are part of the Av biosynthetic gene cluster, revealed that they encode parts of large multifunctional PKS proteins. The Av PKS proteins show strong similarity to each other, as well as similarity to Er PKS proteins [Donadio et al., Science 252 (1991) 675-679] and fatty acid synthases. Partial DNA sequencing of the 65-kb region containing all the related sequence elements in the avr genes provides evidence for twelve modular repeats encoding FAS-like domains. The genes encoding the Av PKS are organized as two sets of six modular repeats which are convergently transcribed.

Design of the DEFINE trial: Determining the EFficacy and Tolerability of CETP INhibition with AnacEtrapib

BACKGROUND Residual cardiovascular (CV) risk often remains high despite statin therapy to lower low-density lipoprotein cholesterol (LDL-C). New therapies to raise high-density lipoprotein cholesterol (HDL-C) are currently being investigated. Anacetrapib is a cholesteryl ester transfer protein (CETP) inhibitor that raises HDL-C and reduces LDL-C when administered alone or with a statin. Adverse effects on blood pressure, electrolytes, and aldosterone levels, seen with another drug in this class, have not been noted in studies of anacetrapib to date. METHODS Determining the EFficacy and Tolerability of CETP INhibition with AnacEtrapib (DEFINE) is a randomized, double-blind, placebo-controlled trial to assess the efficacy and safety profile of anacetrapib in patients with coronary heart disease (CHD) or CHD risk equivalents (clinical trials.gov NCT00685776). Eligible patients at National Cholesterol Education Program-Adult Treatment Panel III LDL-C treatment goal on a statin, with or without other lipid-modifying medications, are treated with anacetrapib, 100 mg, or placebo for 18 months, followed by a 3-month, poststudy follow-up. The primary end points are percent change from baseline in LDL-C and the safety and tolerability of anacetrapib. Comprehensive preplanned interim safety analyses will be performed at the 6- and 12-month time points to examine treatment effects on key safety end points, including blood pressure and electrolytes. A preplanned Bayesian analysis will be performed to interpret the CV event distribution, given the limited number of events expected in this study. RESULTS A total of 2,757 patients were screened at 153 centers in 20 countries, and 1,623 patients were randomized into the trial. Lipid results, clinical CV events, and safety outcomes from this trial are anticipated in 2010.

Changes in cholesterol absorption and cholesterol synthesis caused by ezetimibe and/or simvastatin in men

This study evaluates changes in cholesterol balance in hypercholesterolemic subjects following treatment with an inhibitor of cholesterol absorption or cholesterol synthesis or coadministration of both agents. This was a randomized, double blind, placebo-controlled, four-period crossover study to evaluate the effects of coadministering 10 mg ezetimibe with 20 mg simvastatin (ezetimibe/simvastatin) on cholesterol absorption and synthesis relative to either drug alone or placebo in 41 subjects. Each treatment period lasted 7 weeks. Ezetimibe and ezetimibe/simvastatin decreased fractional cholesterol absorption by 65% and 59%, respectively (P < 0.001 for both relative to placebo). Simvastatin did not significantly affect cholesterol absorption. Ezetimibe and ezetimibe/simvastatin increased fecal sterol excretion (corrected for dietary cholesterol), which also represents net steady state cholesterol synthesis, by 109% and 79%, respectively (P < 0.001). Ezetimibe, simvastatin, and ezetimibe/simvastatin decreased plasma LDL-cholesterol by 20, 38, and 55%, respectively. The coadministered therapy was well tolerated. The decreases in net cholesterol synthesis and increased fecal sterol excretion yielded nearly additive reductions in LDL-cholesterol for the coadministration of ezetimibe and simvastatin.

Potent nonpeptide GnRH receptor antagonists derived from substituted indole-5-carboxamides and -acetamides bearing a pyridine side-chain terminus

A pyridine side-chain terminus has been incorporated into the indole-5-carboxamide and indole-5-acetamide series of GnRH antagonists. Potent activity was observed in binding and functional assays. Certain branched or cyclic tertiary amides were identified as preferred in each series. Alkylation of the side-chain secondary amine had generally unfavorable effects. Variations of the gem-dialkyl substituents in the indole-5-acetamide series were also investigated.

Efficacy and safety after cessation of treatment with the cholesteryl ester transfer protein inhibitor anacetrapib (MK-0859) in patients with primary hypercholesterolemia or mixed hyperlipidemia

This report describes the lipid and safety data collected during an off-drug period that followed 8 weeks of treatment with the cholesteryl ester transfer protein inhibitor, anacetrapib (ANA). A total of 589 patients with primary hypercholesterolemia or mixed hyperlipidemia were randomized to placebo, atorvastatin (ATV) 20 mg, and varying doses of ANA, provided as monotherapy or coadministered with ATV 20 mg daily. Patients were treated for 8 weeks, followed by an 8-week follow-up period, during which ANA was switched to placebo. At week 16 (8 weeks after ANA was stopped), persistent reductions in low-density lipoprotein cholesterol (LDL-C) were evident for the monotherapy groups receiving ANA 150 and 300 mg (-9.3% and -15.3%, respectively), and residual increases in high-density lipoprotein cholesterol (HDL-C) were observed for the monotherapy groups receiving ANA 40 mg (18.6%), 150 mg (40.5%), and 300 mg (43.4%). The effects on apolipoprotein B and apolipoprotein A-I were consistent with the changes observed for LDL-C and HDL-C, respectively. Corresponding residual changes in LDL-C and HDL-C were also noted in the ATV coadministration groups at the similar doses of ANA compared with ATV 20 mg alone. Residual plasma drug levels accompanied by reductions in cholesteryl ester transfer protein activity were observed at week 16 and may account for the alterations in plasma lipids 8 weeks after cessation of ANA.

Isolation and characterization of the Streptomyces cattleya temperate phage TG1

A temperate actinophage, TG1, was isolated from soil by growth on Streptomyces cattleya and has been shown to be potentially useful for the cloning of DNA in this organism and other streptomycetes. It forms stable lysogens by integration at a unique site on the chromosome. The phage genome consists of 41 kb of double-stranded DNA with cohesive ends. It has unique sites for ClaI, NdeI, PstI, SmaI, and XbaI. The PstI site has been shown to be in a dispensable region of the phage genome. Deletions (2 kb in length) were obtained which retain this site and should be useful for the cloning of DNA.

Characterization of the Streptomyces plasmid pVE1

pVE1 (11.0 kb) was isolated from Streptomyces venezuelae ATCC 14585 and characterized. pVE1 has a broad host range and an apparent copy number of about 100 during exponential growth, rising to 1500 during stationary phase. It is a pock-forming, self-transmissible fertility factor which promotes chromosome recombination in S. lividans at frequencies of about 0.1% per total parents. A detailed restriction map for 15 enzymes was determined. Genes for ThioR (thiostrepton resistance), NeoR (neomycin resistance), and pBR322 derivatives were inserted into pVE1 and the resulting plasmids were analyzed for self-transmissibility and stability. The plasmid has an essential region of approximately 2.5 kb and a region of 1.0-3.6 kb required for conjugation. NeoR and ThioR vectors were constructed with unique HindIII, PvuI, BamHI, EcoRI, BglII, and EcoRV sites available for insertion of foreign DNA.