Evaluation of RNAi therapeutics VIR-2218 and ALN-HBV for chronic hepatitis B: Results from randomized clinical trials.

BACKGROUND & AIMS: Current therapy for chronic hepatitis B virus (cHBV) infection involves lifelong treatment. New treatments that enable HBV functional cure would represent a clinically meaningful advance. ALN-HBV and VIR-2218 are investigational RNA interference therapeutics that target all major HBV transcripts. METHODS: We report on: i) the safety of single doses of VIR-2218 (modified from ALN-HBV by enhanced stabilization chemistry plus technology to reduce off-target, seed-mediated binding while maintaining on-target antiviral activity) and ALN-HBV in humanized mice; ii) a cross-study comparison of the safety of single doses of VIR-2218 and ALN-HBV in healthy human volunteers (n = 24 and n = 49, respectively); and iii) the antiviral activity of two doses of 20, 50, 100, 200 mg of VIR-2218 (total n = 24) vs. placebo (n = 8), given 4 weeks apart, in participants with cHBV infection. RESULTS: In humanized mice, alanine aminotransferase (ALT) levels were markedly lower following administration of VIR-2218 compared with ALN-HBV. In healthy volunteers, post-treatment ALT elevations occurred in 28% of participants receiving ALN-HBV compared with none in those receiving VIR-2218. In participants with cHBV infection, VIR-2218 was associated with dose-dependent reductions in hepatitis B surface antigen (HBsAg). The greatest mean reduction of HBsAg at Week 20 in participants receiving 200 mg was 1.65 log IU/ml. The HBsAg reduction was maintained at 0.87 log IU/ml at Week 48. No participants had serum HBsAg loss or hepatitis B surface antibody seroconversion. CONCLUSIONS: VIR-2218 demonstrated an encouraging hepatic safety profile in preclinical and clinical studies as well as dose-dependent HBsAg reductions in patients with cHBV infection. These data support future studies with VIR-2218 as part of combination regimens with a goal of HBV functional cure. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT02826018 and NCT03672188. IMPACT AND IMPLICATIONS: A significant unmet need exists for therapies for chronic HBV (cHBV) infection that achieve functional cure. We report clinical and non-clinical data on two investigational small-interfering RNAs that target HBx, ALN-HBV and VIR-2218, demonstrating that incorporation of enhanced stabilization chemistry plus technology in VIR-2218 reduces its propensity to cause ALT elevations relative to its parent compound, ALN-HBV. We also show that VIR-2218 reduces hepatitis B surface antigen levels in a dose-dependent manner in participants with cHBV infection. These studies support the continued development of VIR-2218 as part of therapeutic regimens for cHBV infection, with the goal of a functional cure, and are important for HBV researchers and physicians.

Clinical and Preclinical Single-Dose Pharmacokinetics of VIR-2218, an RNAi Therapeutic Targeting HBV Infection.

BACKGROUND AND OBJECTIVE: VIR-2218 is an investigational N-acetylgalactosamine-conjugated RNA interference therapeutic in development for chronic hepatitis B virus (HBV) infection. VIR-2218 was designed to silence HBV transcripts across all genotypes and uses Enhanced Stabilization Chemistry Plus (ESC+) technology. This study was designed to evaluate the single-dose pharmacokinetics of VIR-2218 in preclinical species and healthy volunteers. METHODS: Preclinically, a single subcutaneous dose of VIR-2218 (10 mg/kg) was administered to rats and nonhuman primates (NHPs), and the pharmacokinetics were assessed in plasma, urine, and liver using standard noncompartmental analysis (NCA) methods. Clinically, healthy volunteers were randomized (6:2 active:placebo) to receive a single subcutaneous dose of VIR-2218 (50-900 mg) or placebo. Pharmacokinetics were similarly assessed within human plasma and urine using NCA methods. RESULTS: In rats and NHPs, VIR-2218 was stable in plasma and was converted to AS(N-1)3'VIR-2218, the most prominent circulating metabolite, at < 10% plasma exposure compared with parent. VIR-2218 rapidly distributed to the liver, reaching peak liver concentrations within 7 and 24 h in rats and NHPs, respectively. In humans, VIR-2218 was rapidly absorbed, with a median time to peak plasma concentration (tmax) of 4-7 h, and had a short median plasma half-life of 2-5 h. Plasma exposures for area under the plasma concentration-time curve up to 12 h (AUC0-12) and mean maximum concentrations (Cmax) increased in a slightly greater-than-dose-proportional manner across the dose range studied. Interindividual pharmacokinetic variability was low to moderate, with a percent coefficient of variation of < 32% for AUC and < 43% for Cmax. A portion of VIR-2218 was converted to an active metabolite, AS(N-1)3'VIR-2218, with a median tmax of 6-10 h, both of which declined below the lower limit of quantification in plasma within 48 h. The pharmacokinetic profile of AS(N-1)3'VIR-2218 was similar to that of VIR-2218, with plasma AUC0-12 and Cmax values ≤ 12% of VIR-2218. VIR-2218 and AS(N-1)3'VIR-2218 were detectable in urine through the last measured time point, with approximately 17-48% of the administered dose recovered in urine as unchanged VIR-2218 over 0-24 h postdose. Based on pharmacokinetics in preclinical species, VIR-2218 localizes to the liver and likely exhibits prolonged hepatic exposure. Overall, no severe or serious adverse events or discontinuations due to adverse events were observed within the dose range evaluated for VIR-2218 in healthy volunteers (Vir Biotechnology, Inc., unpublished data). CONCLUSIONS: VIR-2218 showed favorable pharmacokinetics in healthy volunteers supportive of subcutaneous dosing and continued development in patients with chronic HBV infection. CLINICAL TRIAL REGISTRATION NO: NCT03672188, September 14, 2018.

Evaluation of Plazomicin, Tigecycline, and Meropenem Pharmacodynamic Exposure against Carbapenem-Resistant Enterobacteriaceae in Patients with Bloodstream Infection or Hospital-Acquired/Ventilator-Associated Pneumonia from the CARE Study (ACHN-490-007).

INTRODUCTION: CARE was a Phase 3, randomized study evaluating the efficacy and safety of plazomicin-based combination therapy compared with colistin-based combination therapy for the treatment of patients with bloodstream infections or hospital-acquired/ventilator-associated pneumonia due to carbapenem-resistant Enterobacteriaceae (CRE). Adjunctive therapies included either tigecycline or meropenem. We sought to understand the contribution of tigecycline and meropenem to plazomicin-treated-patient outcomes by determining their observed pharmacodynamic exposures against baseline pathogens. METHODS: Blood samples collected for plazomicin therapeutic monitoring were assayed for tigecycline and meropenem concentrations. Population pharmacokinetic models were constructed for each antibiotic. Using the individual Bayesian posterior or a covariate-based model, concentration time profiles were simulated to estimate the pharmacodynamic exposures for each patient. Pharmacodynamic thresholds for plazomicin, tigecycline, and meropenem were a total area under the curve to minimum inhibitory concentration ratio (AUC/MIC) ≥ 85, free (f) AUC/MIC ≥ 0.9, and free time above the MIC (fT > MIC) of ≥ 40%, respectively. RESULTS: Fifteen plazomicin-treated patients were included (12 received tigecycline, 4 received meropenem, 1 received both). Microbiological response was observed in 13 (86.7%) and clinical efficacy was achieved in 11 (73.3%). Plazomicin achieved its pharmacodynamic target in all 15 patients. Meropenem fT > MIC was 0% in all 4 patients, and tigecycline fAUC/MIC was ≥ 0.9 in 9 (75%) patients. Overall, 6 (40%) of 15 patients had a tigecycline or meropenem exposure below the requisite thresholds. Microbiological response and clinical efficacy were observed in 100% (6/6) and 83.3% (5/6) of patients with low threshold attainment by tigecycline and meropenem dosing regimens, respectively. CONCLUSIONS: Plazomicin successfully achieved its requisite pharmacodynamic exposure, and these data suggest that optimization of tigecycline and meropenem therapy was not required for the combination to achieve microbiological response and clinical efficacy against serious CRE infections. TRIAL REGISTRATION: ClinicalTrials.gov number, NCT01970371. FUNDING: Achaogen, Inc.

Once-Daily Plazomicin for Complicated Urinary Tract Infections.

BACKGROUND: The increasing multidrug resistance among gram-negative uropathogens necessitates new treatments for serious infections. Plazomicin is an aminoglycoside with bactericidal activity against multidrug-resistant (including carbapenem-resistant) Enterobacteriaceae. METHODS: We randomly assigned 609 patients with complicated urinary tract infections (UTIs), including acute pyelonephritis, in a 1:1 ratio to receive intravenous plazomicin (15 mg per kilogram of body weight once daily) or meropenem (1 g every 8 hours), with optional oral step-down therapy after at least 4 days of intravenous therapy, for a total of 7 to 10 days of therapy. The primary objective was to show the noninferiority of plazomicin to meropenem in the treatment of complicated UTIs, including acute pyelonephritis, with a noninferiority margin of 15 percentage points. The primary end points were composite cure (clinical cure and microbiologic eradication) at day 5 and at the test-of-cure visit (15 to 19 days after initiation of therapy) in the microbiologic modified intention-to-treat population. RESULTS: Plazomicin was noninferior to meropenem with respect to the primary efficacy end points. At day 5, composite cure was observed in 88.0% of the patients (168 of 191 patients) in the plazomicin group and in 91.4% (180 of 197 patients) in the meropenem group (difference, -3.4 percentage points; 95% confidence interval [CI], -10.0 to 3.1). At the test-of-cure visit, composite cure was observed in 81.7% (156 of 191 patients) and 70.1% (138 of 197 patients), respectively (difference, 11.6 percentage points; 95% CI, 2.7 to 20.3). At the test-of-cure visit, a higher percentage of patients in the plazomicin group than in the meropenem group were found to have microbiologic eradication, including eradication of Enterobacteriaceae that were not susceptible to aminoglycosides (78.8% vs. 68.6%) and Enterobacteriaceae that produce extended-spectrum ß-lactamases (82.4% vs. 75.0%). At late follow-up (24 to 32 days after initiation of therapy), fewer patients in the plazomicin group than in the meropenem group had microbiologic recurrence (3.7% vs. 8.1%) or clinical relapse (1.6% vs. 7.1%). Increases in serum creatinine levels of 0.5 mg or more per deciliter (≥40 µmol per liter) above baseline occurred in 7.0% of patients in the plazomicin group and in 4.0% in the meropenem group. CONCLUSIONS: Once-daily plazomicin was noninferior to meropenem for the treatment of complicated UTIs and acute pyelonephritis caused by Enterobacteriaceae, including multidrug-resistant strains. (Funded by Achaogen and the Biomedical Advanced Research and Development Authority; EPIC ClinicalTrials.gov number, NCT02486627.).

Efficacy of ceftolozane/tazobactam against urinary tract and intra-abdominal infections caused by ESBL-producing Escherichia coli and Klebsiella pneumoniae: a pooled analysis of Phase 3 clinical trials.

OBJECTIVES: The increase in infections caused by drug-resistant ESBL-producing Enterobacteriaceae (ESBL-ENT) is a global concern. The characteristics and outcomes of patients infected with ESBL-ENT were examined in a pooled analysis of Phase 3 clinical trials of ceftolozane/tazobactam in patients with complicated urinary tract infections (ASPECT-cUTI) and complicated intra-abdominal infections (ASPECT-cIAI). METHODS: Trials were randomized and double blind. The ASPECT-cUTI regimen was 7 days of either intravenous ceftolozane/tazobactam (1.5 g) every 8 h or levofloxacin (750 mg) once daily. The ASPECT-cIAI regimen was 4-14 days of either intravenous ceftolozane/tazobactam (1.5 g) plus metronidazole (500 mg) or meropenem (1 g) every 8 h. Baseline cultures were obtained in both indications. Enterobacteriaceae were selected for ESBL characterization based on predefined criteria and were verified genotypically. Outcomes were assessed at the test-of-cure visit 5-9 days post-therapy in ASPECT-cUTI and 24-32 days post-randomization in ASPECT-cIAI among microbiologically evaluable (ME) patients. RESULTS: Of 2076 patients randomized, 1346 were included in the pooled ME population and 150 of 1346 (11.1%) had ESBL-ENT at baseline. At US FDA/EUCAST breakpoints of ≤2/≤1 mg/L, 81.8%/72.3% of ESBL-ENT (ESBL-Escherichia coli, 95%/88.1%; ESBL-Klebsiella pneumoniae, 56.7%/36.7%) were susceptible to ceftolozane/tazobactam versus 25.3%/24.1% susceptible to levofloxacin and 98.3%/98.3% susceptible to meropenem at CLSI/EUCAST breakpoints. Clinical cure rates for ME patients with ESBL-ENT were 97.4% (76/78) for ceftolozane/tazobactam [ESBL-E. coli, 98.0% (49 of 50); ESBL-K. pneumoniae, 94.4% (17 of 18)], 82.6% (38 of 46) for levofloxacin and 88.5% (23 of 26) for meropenem. CONCLUSIONS: Randomized trial data demonstrated high clinical cure rates with ceftolozane/tazobactam treatment of cIAI and cUTI caused by ESBL-ENT.

Outcomes of high-dose levofloxacin therapy remain bound to the levofloxacin minimum inhibitory concentration in complicated urinary tract infections.

BACKGROUND: Fluoroquinolones are a guideline-recommended therapy for complicated urinary tract infections, including pyelonephritis. Elevated drug concentrations of fluoroquinolones in the urine and therapy with high-dose levofloxacin are believed to overcome resistance and effectively treat infections caused by resistant bacteria. The ASPECT-cUTI phase 3 clinical trial (ClinicalTrials.gov, NCT01345929 and NCT01345955 , both registered April 28, 2011) provided an opportunity to test this hypothesis by examining the clinical and microbiological outcomes of high-dose levofloxacin treatment by levofloxacin minimum inhibitory concentration. METHODS: Patients were randomly assigned 1:1 to ceftolozane/tazobactam (1.5 g intravenous every 8 h) or levofloxacin (750 mg intravenous once daily) for 7 days of therapy. The ASPECT-cUTI study provided data on 370 patients with at least one isolate of Enterobacteriaceae at baseline who were treated with levofloxacin. Outcomes were assessed at the test-of-cure (5-9 days after treatment) and late follow-up (21-42 days after treatment) visits in the microbiologically evaluable population (N = 327). RESULTS: Test-of-cure clinical cure rates above 90% were observed at minimum inhibitory concentrations ≤4 µg/mL. Microbiological eradication rates were consistently >90% at levofloxacin minimum inhibitory concentrations ≤0.06 µg/mL. Lack of eradication of causative pathogens at the test-of-cure visit increased the likelihood of relapse by the late follow-up visit. CONCLUSIONS: Results from this study do not support levofloxacin therapy for complicated urinary tract infections caused by organisms with levofloxacin minimum inhibitory concentrations ≥4 µg/mL. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01345929 and NCT01345955.

Efficacy of ceftolozane/tazobactam versus levofloxacin in the treatment of complicated urinary tract infections (cUTIs) caused by levofloxacin-resistant pathogens: results from the ASPECT-cUTI trial.

OBJECTIVES: Empirical fluoroquinolone therapy is widely used in treating complicated urinary tract infections (cUTIs), even in areas of high fluoroquinolone resistance. While it is believed that high antibiotic concentrations in urine might be sufficient to overcome and effectively treat infections caused by resistant bacteria, clinical trial data validating this assumption are limited. This post hoc analysis evaluated the efficacy of ceftolozane/tazobactam versus levofloxacin in the subgroup of patients with cUTIs caused by levofloxacin-resistant pathogens in a randomized, controlled trial (NCT01345929/NCT01345955). METHODS: Hospitalized adults with cUTI/pyelonephritis were randomized to 7 days of 1.5 g of ceftolozane/tazobactam every 8 h or 750 mg of levofloxacin once daily, before availability of culture and susceptibility data. A composite of microbiological eradication and clinical cure 5 to 9 days post-therapy was assessed in the microbiological modified ITT (mMITT; n = 800) and microbiologically evaluable (ME; n = 694) populations. RESULTS: In the mMITT population, there were 212 patients (26.5%) with at least one baseline uropathogen that was resistant to levofloxacin. The majority of uropathogens in this subgroup were Enterobacteriaceae (n = 186) that were susceptible to ceftolozane/tazobactam [MIC ≤2 mg/L, 88.7% (165/186)]. Among patients with levofloxacin-resistant pathogens, ceftolozane/tazobactam demonstrated significantly higher composite cure rates than levofloxacin in both the mMITT [60.0% (60/100) versus 39.3% (44/112); 95% CI for the treatment difference, 7.2%-33.2%] and ME [64.0% (57/89) versus 43.4% (43/99); 95% CI for the treatment difference, 6.3%-33.7%] populations, respectively. CONCLUSIONS: High urinary levels of levofloxacin did not reliably cure cUTIs. Seven day treatment with ceftolozane/tazobactam was more effective than high-dose levofloxacin treatment in patients with cUTI caused by levofloxacin-resistant bacteria, and it may be an alternative treatment in settings of increased fluoroquinolone resistance.

Surgical site infections following transcatheter apical aortic valve implantation: incidence and management.

OBJECTIVE: The present study was undertaken to examine the incidence and management of surgical site infection (SSI) in patients submitted to transapical transcatheter aortic valve implantation (TA-TAVI). METHODS: From April 2007 to December 2011, 154 patients underwent TA-TAVI with an Edwards Sapien bioprosthesis (ES) at the Institut Universitaire de Cardiologie et Pneumologie de Québec (IUCPQ) as part of a multidisciplinary program to prospectively evaluate percutaneous aortic valve implantation. Patient demographics, perioperative variables, and postoperative complications were recorded in a prospective registry. RESULTS: Five (3.2%) patients in the cohort presented with an SSI during the study period. The infections were all hospital-acquired (HAI) and were considered as organ/space SSI's based on Center for Disease Control criteria (CDC). Within the first few weeks of the initial procedure, these patients presented with an abscess or chronic draining sinus in the left thoracotomy incision and were re-operated. The infection spread to the apex of the left ventricle in all cases where pledgeted mattress sutures could be seen during debridement. Patients received multiple antibiotic regimens without success until the wound was surgically debrided and covered with viable tissue. The greater omentum was used in three patients and the pectoralis major muscle in the other two. None of the patients died or had a recurrent infection. Three of the patients were infected with Staphylococcus epidermidis, one with Staphylococcus aureus, and one with Enterobacter cloacae. Patients with surgical site infections were significantly more obese with higher BMI (31.4±3.1 vs 26.2±4.4 p=0.0099) than the other patients in the cohort. CONCLUSIONS: While TA-TAVI is a minimally invasive technique, SSIs, which are associated with obesity, remain a concern. Debridement and rib resection followed by wound coverage with the greater omentum and/or the pectoralis major muscle were used successfully in these patients.

Recurrent sternal infection following treatment with negative pressure wound therapy and titanium transverse plate fixation.

OBJECTIVE: To provide a definition for recurrent sternal infection (RSI), analyse the risk factors and describe the management of this complication following treatment of deep sternal wound infection (DSWI) with horizontal titanium sternal osteosynthesis and coverage with pectoralis major myocutaneous flaps. METHODS: Between 2002 and 2007, 10665 patients were submitted to open-heart surgery (OHS) in our institution, of whom 149 (1.4%) developed a DSWI. Negative pressure wound therapy (NPWT) followed by sternal osteosynthesis with musculocutaneous coverage was used in 92 (61.7%) patients. A retrospective review was done using a prospectively maintained database to identify risk factors for recurrent infection in this group of patients. RESULTS: Of the 92 patients who underwent sternal osteosynthesis, nine (9.8%) developed recurrent sternal infection requiring hardware removal. Univariate analysis showed that preoperative methicillin-resistant Staphylococcus aureus (MRSA) status (33.3% vs 6.1%; p=0.03) and prolonged intubation time in ICU (44.4% vs 14.6%; p<0.05) were significant risk factors. Two-thirds of these patients were also found to be infected with the same germ as the one responsible for their initial DSWI. No death was reported and sternal integrity was preserved in all patients despite plate removal. CONCLUSIONS: To lower the rate of RSI in patients treated with transverse sternal ostheosynthesis along with myocutaneous coverage for DSWI, surgeons must consider the MRSA preoperative status as a significant predictor of RSI and/or persistent infection. Chest-wall integrity in patients with RSI can be maintained after hardware removal, even after only a few weeks following initial plating.

Impact of deep sternal wound infection management with vacuum-assisted closure therapy followed by sternal osteosynthesis: a 15-year review of 23,499 sternotomies.

OBJECTIVE: This study was undertaken to examine the outcome of patients with deep sternal wound infection (DSWI) now treated with vacuum-assisted closure (VAC) therapy as a bridge to sternal osteosynthesis with horizontal titanium plate fixation. METHODS: From 1992 to 2007, a consecutive cohort of 23,499 patients underwent open-heart surgery (OHS) in our institution. The period under study was divided in two according to the use of therapeutic modalities: conventional (1992-2001, N=118 DSWI): debridement/drainage with primary closure and irrigation (N=37), debridement/drainage, open packing followed by pectoralis myocutaneous flaps (PMFs) (N=81); contemporary (2002-2007, N=149 DSWI): conventional treatment (N=24) and VAC therapy (N=125/83.8%). VAC was followed by sternal osteosynthesis with horizontal titanium plates in 92 patients (61.7%). RESULTS: DSWI was diagnosed in 267 out of 23 499 (1.1%) patients of our entire series according to Center for Disease Control - Atlanta (CDC) criteria, 118 out of 13 180 (0.9%) in the first and 149 out of 10 319 (1.4%) in the second period (p=0.001). Hospital mortality (N=267/23,499) has been 10.25% for the entire cohort under study without any difference between groups (1992-2001: 11.4%; 2002-2007: 9.1%, p=0.67). More recently, VAC therapy (N=125) was associated with a lower mortality (4.8% vs 14.1%, p=0.01). Stepwise multivariable logistic regression analysis for both periods revealed that prolonged intubation in the intensive care unit (ICU), use of bilateral internal thoracic artery grafting (BIMA), diabetes, re-operation for bleeding and body mass index (BMI) >30 kgm(-2) are the most powerful predictors of DSWI. In the more recently treated patients using VAC therapy, combined procedures (valve and graft) also emerged as a significant predictor. For the entire study, Staphylococcus epidermidis (49.6%) has been the most frequently identified pathogen, followed by Staphylococcus aureus (38.8%). Methicillin-resistant S.aureus (MRSA) was observed in 4.9% of the cohort. Neither of these bacteria was associated with increased mortality. Survival analysis with Cox regression model and propensity score adjustment in patients with DSWI showed freedom from all-cause mortality at 1, 5 and 10 years to be, respectively, 91.8%, 80.4% and 61.3% compared with 94.0%, 85.5% and 70.2%, respectively, for patients submitted to OHS without DSWI (p=0.01). Early adjusted survival for patients with DSWI treated with VAC therapy was 92.8%, 89.8% and 88.0%, respectively, at 1, 2 and 3 years, compared with 83.0%, 76.4% and 61.3%, respectively, for patients with DSWI treated without VAC (p=0.02). CONCLUSIONS: DSWI remains a major and challenging complication of OHS. VAC therapy with sternal preservation followed by delayed sternal osteosynthesis and PMF has been recently proposed as a new therapeutic strategy. Most patients treated with VAC therapy in our second group showed decreased perioperative mortality and increased short-term survival.

Decoupling of light intensity effects on the growth and development of C3 and C4 weed species through sucrose supplementation.

Light availability has a profound effect on plant growth and development. One of the ways to study the effects of light intensity on plant growth and development without the confounding problem of photosynthate availability is sucrose injection/supplementation. A greenhouse experiment was conducted to evaluate the effects of light levels (0% and 75% shade) and sucrose injection (distilled water or 150 g sucrose l(-1)) on three weed species: redroot pigweed (Amaranthus retroflexus L., C4), lambsquarters (Chenopodium album L., C3) and velvetleaf (Abutilon theophrasti Medic., C3). The average total sucrose uptake was 7.6 and 5.9 g per plant for 0% and 75% shading, respectively, representing 47% of the average total weed dry weight. Plants injected with sucrose had greater dry weights and shoot-to-root ratios under both light levels. In spite of sucrose supplementation the reduction in dry matter due to shading was greater for roots and reproductive structures than vegetative shoot tissues, indicating light level regulation of morphological changes resulting in changed C allocation that are independent of photosynthate availability. Dry weights of plants injected with sucrose under 75% shading were not different from distilled water-injected unshaded plants. However, both sucrose-injected and control plants, regardless of their photosynthetic pathways, underwent similar changes in allocation of dry matter and morphology due to shading, suggesting that these effects are strictly due to light intensity and not related to photosynthate availability.