Use of ribaxamase (SYN-004), a ß-lactamase, to prevent Clostridium difficile infection in ß-lactam-treated patients: a double-blind, phase 2b, randomised placebo-controlled trial.

BACKGROUND: Infections with Clostridium difficile are a health threat, yet no products are currently licensed for prevention of primary C difficile infections. Intravenous ß-lactam antibiotics are considered to confer a high risk of C difficile infection because of their biliary excretion into the gastrointestinal tract and disruption of the gut microbiome. ribaxamase (SYN-004) is an orally administered ß-lactamase that was designed to be given with intravenous ß-lactam antibiotics to degrade excess antibiotics in the upper gastrointestinal tract before they disrupt the gut microbiome and lead to C difficile infection. We therefore aimed to determine whether administration of ribaxamase could prevent C difficile infection in patients being treated with intravenous ceftriaxone for a lower respiratory tract infection, thereby supporting continued clinical development. METHODS: In this parallel-group, double-blind, multicentre, phase 2b, randomised placebo-controlled trial, we recruited patients who had been admitted to a hospital with a lower respiratory tract infection with a pneumonia index score of 90-130 and who were expected to be treated with ceftriaxone for at least 5 days. Patients were recruited from 54 clinical sites in the USA, Canada, Bulgaria, Hungary, Poland, Romania, and Serbia. We randomly assigned patients older than 50 years to groups (1:1) in blocks of four by use of an interactive web portal; these groups were assigned to receive either 150 mg ribaxamase or placebo four times per day during, and for 72 h after, treatment with ceftriaxone. All patients, clinical investigators, study staff, and sponsor personnel were masked to the study drug assignments. The primary endpoint was the incidence of C difficile infection, as diagnosed by the local laboratory, in patients who received at least one treatment dose, and this outcome was assessed during treatment and for 4 weeks after treatment. This study is registered with ClinicalTrials.gov, number NCT02563106. FINDINGS: Between Nov 16, 2015, and Nov 10, 2016, we screened 433 patients for inclusion in the study. Of these patients, 20 (5%) patients were excluded from the study (16 [4%] patients did not meet inclusion criteria; four [1%] patients because of dosing restrictions). We enrolled and randomly assigned 413 patients to groups, of whom 207 patients were assigned to receive ceftriaxone plus ribaxamase and 206 patients were assigned to receive ceftriaxone plus placebo. However, one (<1%) patient in the ribaxamase group withdrew consent and was not treated with ribaxamase. During the study and within the 4 weeks after antibiotic treatment, two (1·0%) patients in the ribaxamase group and seven (3·4%) patients in the placebo group were diagnosed with an infection with C difficile (risk reduction 2·4%, 95% CI -0·6 to 5·9; one-sided p=0·045). Adverse events were similar between groups but more deaths were reported in the ribaxamase group (11 deaths vs five deaths in the placebo group). This disparity was due to the higher incidence of deaths attributed to cardiac-associated causes in the ribaxamase group (six deaths vs one death in the placebo group). INTERPRETATION: In patients treated with intravenous ceftriaxone for lower respiratory tract infections, oral ribaxamase reduced the incidence of C difficile infections compared with placebo. The imbalance in deaths between the groups appeared to be related to the underlying health of the patients. Ribaxamase has the potential to prevent C difficile infection in patients treated with intravenous ß-lactam antibiotics, and our findings support continued clinical development of ribaxamase to prevent C difficile infection. FUNDING: Synthetic Biologics.

The Oral ß-Lactamase SYN-004 (Ribaxamase) Degrades Ceftriaxone Excreted into the Intestine in Phase 2a Clinical Studies.

SYN-004 (ribaxamase) is a ß-lactamase designed to be orally administered concurrently with intravenous ß-lactam antibiotics, including most penicillins and cephalosporins. Ribaxamase's anticipated mechanism of action is to degrade excess ß-lactam antibiotic that is excreted into the small intestine. This enzymatic inactivation of excreted antibiotic is expected to protect the gut microbiome from disruption and thus prevent undesirable side effects, including secondary infections such as Clostridium difficile infections, as well as other antibiotic-associated diarrheas. In phase 1 clinical studies, ribaxamase was well tolerated compared to a placebo group and displayed negligible systemic absorption. The two phase 2a clinical studies described here were performed to confirm the mechanism of action of ribaxamase, degradation of ß-lactam antibiotics in the human intestine, and were therefore conducted in subjects with functioning ileostomies to allow serial sampling of their intestinal chyme. Ribaxamase fully degraded ceftriaxone to below the level of quantitation in the intestines of all subjects in both studies. Coadministration of oral ribaxamase with intravenous ceftriaxone was also well tolerated, and the plasma pharmacokinetics of ceftriaxone were unchanged by ribaxamase administration. Since ribaxamase is formulated as a pH-dependent, delayed-release formulation, the activity of ribaxamase in the presence of the proton pump inhibitor esomeprazole was examined in the second study; coadministration of these drugs did not adversely affect ribaxamase's ability to degrade ceftriaxone excreted into the intestine. These studies have confirmed the in vivo mechanism of action of ribaxamase, degradation of ß-lactam antibiotics in the human intestine (registered at ClinicalTrials.gov under NCT02419001 and NCT02473640).

Tolerability and Pharmacokinetics of SYN-004, an Orally Administered ß-Lactamase for the Prevention of Clostridium difficile-Associated Disease and Antibiotic-Associated Diarrhea, in Two Phase 1 Studies.

BACKGROUND: SYN-004 is an orally administered ß-lactamase enzyme, designed to be given concurrently with certain intravenous ß-lactam antibiotics like cephalosporins. SYN-004 is intended to degrade residual antibiotics excreted into the intestine as a result of hepatobiliary excretion and to prevent the disruption of the gut microbiome by these excess antibiotics. Preserving the gut microbiome is expected to prevent secondary infections by pathogens like Clostridium difficile and protect against other antibiotic-associated diarrheas. METHODS: Two, randomized, double blind, placebo-controlled Phase 1 clinical studies were conducted in normal healthy adult volunteers to assess the tolerability and systemic absorption of single and multiple doses of SYN-004. A single-ascending dose study investigated single oral doses of 75-750 mg SYN-004 and was conducted in 40 subjects (five cohorts of six active and two placebo subjects). A multiple-ascending dose study investigated doses of 75-300 mg SYN-004, administered every 6 h for 7 days and was conducted in 24 subjects (three cohorts of six active and two placebo subjects). The safety and tolerability of SYN-004 was assessed and serial plasma and serum samples were collected to assess the pharmacokinetics and potential immunogenicity of SYN-004. RESULTS: Minimal and mild adverse events were reported in ~30 % of the subjects who received active drug and placebo and no antidrug antibodies were detected in any subject. Analysis of serial plasma samples demonstrated negligible systemic bioavailability of SYN-004 with most plasma concentrations being below the lower limit of quantitation (0.8 ng/mL) for the assay. SYN-004 was well tolerated in the 48 subjects who received active drug, and adverse events in those subjects were comparable to the 16 subjects who received placebo, up to the maximum doses administered in each study. CONCLUSION: SYN-004 was well tolerated up to a single oral dose of 750 mg and multiple doses of 300 mg every 6 h for 7 days. The pharmacokinetic results support that SYN-004 remained localized in the intestine.

The efficacy profile of vilazodone, a novel antidepressant for the treatment of major depressive disorder.

OBJECTIVE: Vilazodone is a novel serotonin reuptake inhibitor and serotonin 1A receptor partial agonist approved for the treatment of major depressive disorder (MDD). This evaluation presents side-by-side efficacy data from two randomized, double-blind, placebo-controlled, short-term 8-week trials (referred to as randomized controlled trial [RCT]-1 [N = 410] and RCT-2 [N = 481]); efficacy data for demographic and clinical subgroups (derived from pooled RCT data); and effectiveness data from a 52-week, open-label, long-term study (N = 616). The objective is to summarize the efficacy profile of vilazodone at its approved dose of 40 mg/day. METHODS: The main assessment in individual pivotal trials and pooled subgroup analyses was the change from baseline to end of treatment (EOT, 8 weeks) in the Montgomery-Åsberg Depression Rating Scale (MADRS) total score. Mixed-effects repeated-measures analyses were conducted in the placebo-controlled trials. Effectiveness analyses in the long-term study included mean MADRS score change over time. RESULTS: Vilazodone-treated patients in both short-term studies showed greater improvement from baseline to EOT in mean MADRS scores than placebo-treated patients (least-squares mean [LSM] treatment difference: -3.2 [p = 0.001], RCT-1; -2.5 [p = 0.009], RCT-2). Clinical Global Impressions-Improvement mean scores at EOT reflected greater improvement with vilazodone compared with placebo in both studies (LSM treatment difference: -0.4 [p = 0.001], RCT-1; -0.3 [p = 0.004], RCT-2). MADRS response rates were significantly greater among patients receiving vilazodone versus those receiving placebo (RCT-1: 40.4% versus 28.1%, respectively [p = 0.007]; RCT-2: 43.7% versus 30.3%, respectively [p = 0.002]). The greater efficacy of vilazodone versus placebo was consistent for the majority of demographic and MDD characteristic subgroups. In the long-term study, the mean MADRS score improved from 29.9 (baseline) to 11.4 (week 8), 8.2 (week 24), and 7.1 (week 52). CONCLUSION: Vilazodone 40 mg/day resulted in clinically meaningful, statistically significant improvement in MDD symptoms in two placebo-controlled, 8-week studies. Findings are supported by subgroup analysis and open-label, long-term effectiveness data. TRIAL REGISTRATION: Randomized controlled trial 1: ClinicalTrials.gov identifier: NCT00285376, http://ClinicalTrials.gov/ct2/show/NCT00285376 ; randomized controlled trial 2: ClinicalTrials.gov identifier: NCT00683592, http://ClinicalTrials.gov/ct2/show/NCT00683592 ; open-label, long-term study: ClinicalTrials.gov identifier: NCT00644358, http://ClinicalTrials.gov/ct2/show/NCT00644358 .

A 1-year, open-label study assessing the safety and tolerability of vilazodone in patients with major depressive disorder.

Vilazodone, a selective serotonin (5-HT) reuptake inhibitor and 5-HT(1A) receptor partial agonist, was efficacious in two 8-week placebo-controlled studies in adults with major depressive disorder. This open-label, multicenter study assessed the long-term safety of vilazodone. Adult patients with a 17-item Hamilton Rating Scale for Depression score of 18 or greater received vilazodone according to a fixed-titration schedule to reach a dose of 40 mg/d continued up to 1 year. Safety assessments included adverse events (AEs), physical examinations, clinical chemistry, electrocardiograms, and the Changes in Sexual Functioning Questionnaire. Effectiveness was assessed with the Montgomery-Åsberg Depression Rating Scale and Clinical Global Impressions scales. The safety population comprised 599 patients; 254 patients completed 1 year of treatment. The most frequent AEs were diarrhea (35.7%), nausea (31.6%), and headache (20.0%); greater than 90% of these AEs were mild or moderate. Adverse events resulting in discontinuation in more than 1% of patients were nausea (1.3%) and diarrhea (1.2%). There were no clinically important changes in physical examinations, electrocardiograms, or clinical chemistries. Mean weight increased by 1.7 kg (observed cases). Changes in Sexual Functioning Questionnaire mean scores (observed cases) improved throughout treatment for both males and females. Montgomery-Åsberg Depression Rating Scale mean scores were 29.9 at baseline, 11.4 at week 8, and 7.1 at week 52 (observed cases). Vilazodone 40 mg/d for 1 year was safe and well tolerated by adults with major depressive disorder.

A randomized, double-blind, placebo-controlled, 8-week study of vilazodone, a serotonergic agent for the treatment of major depressive disorder.

OBJECTIVE: To evaluate the efficacy, and further establish the safety profile, of oral once-daily vilazodone, a potent and selective serotonin 1A receptor partial agonist and reuptake inhibitor, in the treatment of major depressive disorder (MDD). METHOD: This phase 3, randomized, double-blind, placebo-controlled, 8-week study (conducted March 2008-February 2009) enrolled 481 adults with DSM-IV-TR-defined MDD. Patients received vilazodone (titrated to 40 mg/d) or placebo. The primary efficacy endpoint was change in Montgomery-Asberg Depression Rating Scale (MADRS) total score from baseline to end of treatment. Secondary efficacy measures included MADRS and 17-item Hamilton Depression Rating Scale (HDRS-17) response and change in HDRS-17, HDRS-21, Hamilton Anxiety Rating Scale (HARS), Clinical Global Impressions-Severity of Illness (CGI-S), and Clinical Global Impressions-Improvement (CGI-I) scores. The Changes in Sexual Functioning Questionnaire (CSFQ) was administered at baseline and week 8. RESULTS: Vilazodone-treated patients had significantly greater improvement (P = .009) according to the MADRS than placebo patients (intent-to-treat; least-squares mean changes: -13.3, -10.8). MADRS response rates were significantly higher with vilazodone than placebo (44% vs 30%, P = .002). Remission rates for vilazodone were not significantly different based on the MADRS (vilazodone, 27.3% vs placebo, 20.3%; P = .066) or HDRS-17 (vilazodone, 24.2% vs placebo, 17.7%; P = .088). Vilazodone-treated patients had significantly greater improvements from baseline in HDRS-17 (P = .026), HDRS-21 (P = .029), HARS (P = .037), CGI-S (P = .004), and CGI-I (P = .004) scores than placebo patients. Rates of discontinuation due to adverse events were 5.1% (vilazodone) and 1.7% (placebo). The most common adverse events (vilazodone vs placebo) were diarrhea (31% vs 11%), nausea (26% vs 6%), and headache (13% vs 10%). Treatment-related effects on sexual function as measured by the CSFQ were small and similar to placebo. Effects on weight were no different from placebo. CONCLUSIONS: Vilazodone 40 mg/d was well tolerated and effective in adult patients with MDD. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00683592.

Candidate gene analysis identifies a polymorphism in HLA-DQB1 associated with clozapine-induced agranulocytosis.

OBJECTIVE: Clozapine is considered to be the most efficacious drug to treat schizophrenia, although it is underutilized, partially due to a side effect of agranulocytosis. This analysis of 74 candidate genes was designed to identify an association between sequence variants and clozapine-induced agranulocytosis (CIA). METHOD: Blood and medical history were collected for 33 CIA cases and 54 clozapine-treated controls enrolled between April 2002 and December 2003. Significant markers from 4 genes were then assessed in an independently collected case-control cohort (49 CIA cases, 78 controls). RESULTS: Sequence variants in 5 genes were found to be associated with CIA in the first cohort: HLA-DQB1, HLA-C, DRD1, NTSR1, and CSF2RB. Sequence variants in HLA-DQB1 were also found to be associated with CIA in the second cohort. After refinement analyses of sequence variants in HLA-DQB1, a single SNP (single nucleotide polymorphism), 6672G>C, was found to be associated with risk for CIA; the odds of CIA are 16.9 times greater in patients who carry this marker compared to those who do not. CONCLUSIONS: A sequence variant (6672G>C) in HLA-DQB1 is associated with increased risk for CIA. This marker identifies a subset of patients with an exceptionally high risk of CIA, 1,175% higher than the overall clozapine-treated population under the current blood-monitoring system. Assessing risk for CIA by testing for this and other genetic variants yet to be determined may be clinically useful when deciding whether to begin or continue treatment with clozapine.

The Safety and Tolerability Profile of Vilazodone, A Novel Antidepressant for the Treatment of Major Depressive Disorder.

OBJECTIVE: Vilazodone is a selective serotonin reuptake inhibitor and 5-HT1A receptor partial agonist approved for the treatment of major depressive disorder (MDD). This report summarizes the safety and tolerability of vilazodone 40 mg/day during short- and long-term treatment of adult MDD. METHODS: Pooled data from two 8-week, double-blind studies of vilazodone (n = 436) vs placebo (n = 433) and data from one 52-week, open-label study (n = 616, vilazodone only) were analyzed. Patients aged 18-70 with DSM-IV-TR-defined MDD received vilazodone or placebo (8-week studies only) once daily, with food, titrated to 40 mg/day over 2 weeks. Safety and tolerability assessments included adverse events (AEs), laboratory tests, vital signs, electrocardiograms, and weight. RESULTS: The most common AEs in all studies were diarrhea, nausea, and headache. Vilazodone-associated AEs in the two 8-week studies, defined as an incidence rate of ≥5% in the vilazodone group and at least twice that for placebo, were diarrhea (28.0% vs 9.2%), nausea (23.4% vs 5.1%), and insomnia (6.0% vs 2.1%), with the majority reported as mild to moderate and <5% of those patients requiring concomitant (directed) treatment for these conditions. Discontinuation rates due to AEs were 7.1% (vilazodone) and 3.2% (placebo) in the 8-week studies and 20.7% in the 52-week study. Vilazodone had no clinically significant effects on vital signs, laboratory tests, or electrocardiograms. CONCLUSION: Vilazodone 40 mg/day was well tolerated during short- and long-term MDD treatment in these trials. Safety profiles associated with 8- and 52-week exposure were consistent.

Evidence for efficacy and tolerability of vilazodone in the treatment of major depressive disorder: a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: The efficacy and tolerability of vilazodone, a combined selective serotonin reuptake inhibitor and partial 5-hydroxytryptamine-1A (5-HT(1A)) receptor agonist, were evaluated in adult patients with major depressive disorder (MDD). METHOD: This was a randomized, double-blind, placebo-controlled trial conducted from February 2006 to May 2007. Patients aged 18 through 65 years with MDD (DSM-IV criteria) and a baseline 17-item Hamilton Rating Scale for Depression (HAM-D-17) score of >or= 22 were randomly assigned to vilazodone or placebo for 8 weeks. Vilazodone was titrated from 10 mg to 40 mg once a day over 2 weeks. Efficacy was assessed by mean change from baseline to week 8 on the Montgomery-Asberg Depression Rating Scale (MADRS), HAM-D-17, and Hamilton Rating Scale for Anxiety. Response rates were determined at week 8 for the MADRS, HAM-D-17, and Clinical Global Impressions-Severity of Illness (CGI-S) and -Improvement (CGI-I) scales. Data were analyzed using a modified last-observation-carried-forward method in the intention-to-treat (ITT) sample. The Arizona Sexual Experience Scale (ASEX) was also measured at baseline and week 8. RESULTS: Of 410 randomly assigned patients, 198 receiving vilazodone and 199 receiving placebo were included in the ITT population. The mean changes in MADRS and HAM-D-17 total scores from baseline to week 8 were significantly (p = .001 and p = .022, respectively) greater with vilazodone than with placebo. Significant (p < .05) improvements in MADRS and HAM-D-17 scores were noted at week 1, the earliest time point measured. Response rates were significantly higher with vilazodone than with placebo on the MADRS (p = .007), HAM-D-17 (p = .011), and CGI-I (p = .001). Treatment-emergent adverse events with vilazodone included diarrhea, nausea, and somnolence; most adverse events were of mild or moderate intensity. There were no clinically significant differences for either gender in ASEX scores at end of treatment. CONCLUSIONS: Vilazodone is effective for the treatment of MDD in adults, with symptom relief starting at 1 week, and is well tolerated at a dose of 40 mg/day. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00285376.