; for the MK-7009 Protocol 007 Study GroupVaniprevir (MK-7009) is a macrocyclic hepatitis C virus (HCV) nonstructural protein 3/4A protease inhibitor. The aim of the present phase II study was to examine virologic response rates with vaniprevir in combination with pegylated interferon alpha-2a (Peg-IFN-a-2a) plus ribavirin (RBV). In this double-blind, placebo-controlled, dose-ranging study, treatment-naïve patients with HCV genotype 1 infection (n 5 94) were randomized to receive open-label Peg-IFN-a-2a (180 lg/week) and RBV (1,000-1,200 mg/day) in combination with blinded placebo or vaniprevir (300 mg twice-daily [BID], 600 mg BID, 600 mg once-daily [QD], or 800 mg QD) for 28 days, then open-label Peg-IFN-a-2a and RBV for an additional 44 weeks. The primary efficacy endpoint was rapid viral response (RVR), defined as undetectable plasma HCV RNA at week 4. Across all doses, vaniprevir was associated with a rapid two-phase decline in viral load, with HCV RNA levels approximately 3log 10 IU/mL lower in vaniprevir-treated patients, compared to placebo recipients. Rates of RVR were significantly higher in each of the vaniprevir dose groups, compared to the control regimen (68.8%-83.3% versus 5.6%; P < 0.001 for all comparisons). There were numerically higher, but not statistically significant, early and sustained virologic response rates with vaniprevir, as compared to placebo. Resistance profile was predictable, with variants at R155 and D168 detected in a small number of patients. No relationship between interleukin-28B genotype and treatment outcomes was demonstrated in this study. The incidence of adverse events was generally comparable between vaniprevir and placebo recipients; however, vomiting appeared to be more common at higher vaniprevir doses. Conclusion: Vaniprevir is a potent HCV protease inhibitor with a predictable resistance profile and favorable safety profile that is suitable for QD or BID administration. (HEPATOLOGY 2012;56:884-893) S ince 2001, the combination of pegylated interferon alpha (Peg-IFN-a) plus ribavirin (RBV) has been the standard-of-care treatment for patients with hepatitis C virus (HCV) infection. 1-3 However, the recent approval of two novel HCV nonstructural protein (NS)3/4A protease inhibitors (boceprevir and telaprevir) heralds a new era in the treatment of chronic hepatitis C. [4][5][6][7][8] For treatment-naïve patients, the addition of these agents to a Peg-IFN plus RBV backbone increases rates of sustained virologic response (SVR) from 40%-50% to approximately 70%. 4,6 In addition, triple therapy with HCV protease inhibitors can be truncated to 24 or 28 weeks in 50%-60% of treatment-naïve patients who clear the virus early on treatment. 9 However, these firstAbbreviations: AEs, adverse events; APaT, all-patients-as-treated population; AUC, area under the plasma-concentration versus time curve; BID, twice-daily; bp, base pair; C 24h , concentration of drug in the plasma at 24 hours after

Conduction through the cardiac syncytium varies from being nearly continuous, with very well coupled cells, to being clearly discontinuous, with significant conduction delays over very short distances. The Purkinje-ventricular muscle junction (PVJ) sites on the endocardial surface have characteristic delays of conduction and the presence of discrete groups of cells that suggest significant discontinuities of the conduction process at PVJ sites, as compared with the more nearly continuous conduction within either the Purkinje or the ventricular muscle layers of the papillary muscle. The purpose of the present study was to examine the relative sensitivity of conduction at PVJ sites versus conduction within the Purkinje or the ventricular muscle layer of the canine papillary muscle to agents that modulate L-type calcium current. We have used cadmium as a relatively specific blocker of L-type calcium current and isoproterenol as an agent to increase L-type calcium current to test the hypothesis that discontinuous conduction at the PVJ sites would be more sensitive to these agents than would continuous conduction within either the Purkinje layer or the ventricular muscle layer of a canine papillary muscle. Conduction delay at the PVJ sites was significantly increased by cadmium, with some PVJ sites reversibly becoming nonjunctional at 200-400 microM cadmium. Isoproterenol significantly decreased PVJ delay, and this effect was attenuated by carbachol. All of the effects on conduction delay at the PVJ sites were much greater than the effects for the same agents on conduction velocity within either the Purkinje or the ventricular muscle layer of the papillary muscle.

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Previous work has characterized the Purkinje-ventricular junction (PVJ) of papillary muscles as a region of low safety factor with some delay between P and V activation. We have previously shown that the P strand action potential activates a layer of P cells over most of the papillary muscle surface, but activation of the underlying V cells occurs only at specific junctional sites, generally near the base of the muscle. Our present results from both dog and rabbit left papillary muscles show that the junctional regions for propagation from the V layer up into the P layer include not only these specific P-to-V sites but also other sites located more toward the apex of the muscle. These results show that the papillary muscles have regions of potential unidirectional block, although the manifestation of unidirectional block at these sites requires the premature excitation of the ventricular layer.

Background We report on the safety and immunogenicity of V591, a measles vector-based SARS-CoV-2 vaccine candidate. Methods In this multicentre, randomised, placebo-controlled, double-blind, phase 1/2 trial, healthy adults with no history of COVID-19 disease were assigned to intramuscular injection of V591 or placebo (4:1 ratio). In part 1, younger adults (18-55 years) received V591 median tissue culture infectious dose (TCID 50 )-levels of 1×10 5 or 1×10 6 or placebo, 56 days apart. In part 2, younger and older (>55 years) adults received a single dose of one of four (10 4 /10 5 /10 6 /10 7 ) or one of two (10 5 /10 6 ) V591 TCID 50 levels, respectively, or placebo. Primary outcome: safety/tolerability. Secondary outcome: humoral immunogenicity. ClinicalTrials.gov: NCT04498247. Findings From August–December 2020, 444 participants were screened and 263 randomised (210 V591; 53 placebo); 262 received at least one and 10 received two doses of V591 or placebo. Adverse events were experienced by 140/209 (67.0%) V591 dose-group participants and 37/53 (69.8%) placebo-group participants following injection 1; most frequent were fatigue (57 [27.3%] vs 20 [37.7%]), headache (57 [27.3%] vs 19 [35.8%]), myalgia (35 [16.7%] vs 10 [18.9%]), and injection-site pain (35 [16.7%] vs 4 [7.5%]). No deaths nor vaccine-related serious adverse events occurred. At Day 29, no anti-SARS-CoV-2 spike serum neutralising antibody and IgG-responses were identified in placebo or the three lower V591 dose-groups; responses were detected with V591 1×10 7 TCID 50 , although titres were lower than convalescent serum. Interpretation V591 was generally well tolerated, but immunogenicity was insufficient to warrant continued development. Funding Merck Sharp & Dohme, Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.