Edward T. Zito

Efficacy and safety of high-dose rhesus-human reassortant rotavirus vaccine in Native American populations

OBJECTIVESnWe compared the efficacy, safety, and immunogenicity of a rhesus rotavirus tetravalent vaccine (RRV-TV), a rhesus rotavirus monovalent (serotype 1) vaccine (RRV-S1), and placebo in healthy American Indian infants for two rotavirus seasons.nnnSTUDY DESIGNnInfants aged 6 to 24 weeks were enrolled in a randomized, double-blind efficacy study. Infants were orally administered RRV-TV (4 x 10(5) plaque-forming units per dose), RRV-S1 (4 x 10(5) plaque-forming units per dose), or placebo at 2, 4, and 6 months of age. Stools collected during episodes of gastroenteritis were tested for detection of rotavirus antigen. A total of 1185 infants received at least one dose of a study vaccine or placebo, and 1051 received all three doses according to the protocol.nnnRESULTSnDuring the first year of surveillance, the estimates of vaccine efficacy (with 95% confidence interval) for preventing rotaviral gastroenteritis were 50% (26, 67) for RRV-TV and 29% (-1, 50) for RRV-S1. In this population only 6% of rotaviral gastroenteritis episodes among placebo recipients were associated with type G1 disease. For severe disease the estimates of vaccine efficacy were higher: 69% (29, 88) for RRV-TV and 48% (-4, 75) for RRV-S1.nnnCONCLUSIONSnThese data indicate that RRV-TV is moderately efficacious in preventing all episodes of gastroenteritis caused by rotavirus and is most efficacious against the severe disease characteristic of rotaviral illness.

Serologic Correlates of Immunity in a Tetravalent Reassortant Rotavirus Vaccine Trial

The correlation of antibody responses (serum rotavirus IgA and neutralizing antibody to serotype G1-G4 human rotaviruses and rhesus rotavirus [RRV]) in a reassortant rotavirus vaccine trial with protection against rotavirus infection or disease was investigated. Most subjects administered 4 x 10(5) pfu of either the serotype G1 monovalent or serotype G1-G4 tetravalent vaccine seroconverted for at least one of the six antibodies (85% and 91%, respectively). However, fewer than one-third seroconverted to any prototype G1-G4 human rotavirus. Analyses of covariance indicated that higher prevaccination neutralizing antibody titers negatively affected postvaccination titers. Significant relationships were found between several postvaccination rotavirus antibody titers and protection, and serotype-specific correlates of protection were identified between anti-Wa titers and G1 illnesses (P = .03) and between anti-RRV titers and G3 illnesses (P < .001). Overall, however, serotype-specific immunity was no more significant than heterotypic immunity, and no specific titer of any antibody analyzed was a reliable indicator of protection.

A randomized phase I study of the safety and immunogenicity of three ascending dose levels of a 3-antigen Staphylococcus aureus vaccine (SA3Ag) in healthy adults

BACKGROUNDnStaphylococcus aureus is a common cause of healthcare-acquired morbidity and mortality and increased healthcare resource utilization. A prophylactic vaccine is being developed that may reduce this disease burden.nnnMETHODSnVolunteers in good general health aged 50-85 (n=312) and 18-24 (n=96) years were randomized to receive a single intramuscular dose of one of three dose levels of a non-adjuvanted, 3-antigen S. aureus vaccine (SA3Ag) or placebo. SA3Ag antigens included capsular polysaccharides 5 and 8 (CP5 and CP8), each conjugated to cross-reactive material 197 (CRM197), and recombinant clumping factor A (ClfA). Safety, tolerability, and immunogenicity were evaluated.nnnRESULTSnAt day 29 post-vaccination, robust immune responses were observed in both age cohorts at all three SA3Ag dose levels. In the primary analysis population, the 50- to 85-year age stratum, geometric mean-fold-rises in competitive Luminex(®) immunoassay antibody titers from baseline ranged from 29.2 to 83.7 (CP5), 14.1 to 31.0 (CP8), and 37.1 to 42.9 (ClfA), all (P<0.001) exceeding the pre-defined two-fold rise criteria. Similar rises in opsonophagocytic activity assay titers demonstrated functionality of the immune response. Most injection-site reactions were mild in severity and there were no substantial differences (SA3Ag vs. placebo) with regard to systemic or adverse events.nnnCONCLUSIONSnIn this study of healthy adults aged 50-85 and 18-24 years, SA3Ag elicited a rapid and robust immune response and was well tolerated, with no notable safety concerns.

Efficacy of tigecycline versus ceftriaxone plus metronidazole for the treatment of complicated intra-abdominal infections: results from a randomized, controlled trial.

BACKGROUNDnThis randomized, open-label, multi-center trial compared tigecycline (TGC), a broad-spectrum glycylcycline, with ceftriaxone-metronidazole (CTX/MET) for the treatment of complicated intra-abdominal infections (cIAI).nnnMETHODSnEligible subjects were randomized to receive TGC 100u2009mg followed by 50u2009mg q 12u2009h or CTX 2u2009g qd plus MET 1-2u2009g daily for 4-14 days. Subjects were stratified by Acute Physiology and Chronic Health Evaluation (APACHE) II score ≤10 or >10 and could not receive oral therapy. The primary endpoint was clinical response in the clinically evaluable (CE) population at the test of cure (TOC) assessment 8-44 days after the last drug dose.nnnRESULTSnClinical responses in the CE population were 81.8% (162/198) vs. 79.4% (150/189) for TGC and CTX/MET, respectively; a weighted estimate of the difference of 1.6 (95% confidence interval [CI] -6.4, 9.6). In the microbiologically evaluable (ME) population, microbiological eradication rates were 82.4% (98/119) for TGC vs. 79.6% (86/108) for CTX/MET: a difference of 2.7 (95% CI -7.9, 13.3). Common adverse events were nausea (21.6% TGC vs. 21.3% CTX/MET) and vomiting (17.7% TGC vs. 13.2% CTX/MET). Discontinuation rates because of adverse events were 7.8% for TGC and 6.4% for CTX/MET.nnnCONCLUSIONSnTigecycline was effective in the treatment of cIAI and was non-inferior to CTX/MET for the treatment of cIAI in hospitalized adults. Clinical Trials Identifier: NCT00230971.

Shedding of rotavirus after administration of the tetravalent rhesus rotavirus vaccine.

BACKGROUNDnThe tetravalent rhesus rotavirus vaccine (RV-TV) has been administered to several thousand children in multiple settings throughout the world. It has been proved safe and efficacious, resulting in an application for licensure in 1997. However, only limited information has been reported on viral shedding after RV-TV vaccination.nnnMETHODSnStool specimens were collected between Days 3 and 5 after administration of each of 3 doses of RV-TV to 248 subjects 6 to 12 weeks of age in 8 centers across the United States. Rotavirus antigen was measured by an enzyme-linked immunosorbent assay to determine the number of subjects who shed after each dose. The relative quantities of vaccine strains shed were then determined by plaque purification and serotype analysis.nnnRESULTSnRotavirus shedding was detected in 125 (50.4%) subjects, and 19 shed after more than 1 dose. Although fewer subjects shed rotavirus after Dose 2 (14.5%), shedding after Doses 1 (26.0%) and 3 (22.5%) were comparable. After plaque purification and serotyping, most viruses shed (76.2%) were identified as G3 after Dose 1, but a major shift to G2 strains was found after Doses 2 (61.3%) and 3 (69.0%).nnnCONCLUSIONSnSequential RV-TV administrations caused no overall significant decrease in the number of vaccinees who experienced detectable shedding. A major shift in shedding was found from the serotype G3 vaccine strain (RRV) after the first dose of vaccine to the serotype G2 reassortant after Doses 2 and 3.

Safety, tolerability, and immunogenicity of a 4-antigen Staphylococcus aureus vaccine (SA4Ag): Results from a first-in-human randomised, placebo-controlled phase 1/2 study

BACKGROUNDnA prophylactic Staphylococcus aureus four-antigen vaccine (SA4Ag) is under development for prevention of invasive S. aureus disease. A preliminary S. aureus three-antigen vaccine (SA3Ag) was reformulated to include a novel manganese transporter protein (MntC or rP305A). This study describes the first-in-human dose-finding, safety, and immunogenicity results for SA4Ag.nnnMETHODSnIn this double-blind, sponsor-unblind, placebo-controlled, phase 1/2 study, 454 healthy adults aged 18-64years were randomised to receive a single dose of one of three formulations of SA4Ag with escalating dose levels of rP305A or placebo. Functional immune responses were measured using opsonophagocytic activity (OPA) killing and fibrinogen-binding inhibition (FBI) assays; antigen-specific immunogenicity was assessed using a four-plex competitive Luminex® immunoassay (cLIA).nnnRESULTSnA high proportion of SA4Ag recipients met the pre-defined antibody thresholds for each antigen at Day 29. A substantial and dose-level dependent immune response was observed for rP305A, with up to 18-fold rises in cLIA titres at Day 29. Robust functional responses were demonstrated, with >80-fold and >20-fold rises in OPA assay titres at Day 29 using S. aureus strains expressing capsular polysaccharide serotypes 5 and 8, respectively. Durable antibody responses were observed through month 12, gradually waning from peak levels achieved by days 11-15. SA4Ag was well tolerated, and no vaccine-related serious adverse events were reported.nnnCONCLUSIONSnSingle-dose vaccination of SA4Ag in healthy adults aged 18-64years safely induced rapid and robust functional immune responses that were durable through month 12, supporting further development of this vaccine.nnnTRIAL REGISTRATION NUMBERnNCT01364571.

Safety, tolerability, and immunogenicity of a single dose 4-antigen or 3-antigen Staphylococcus aureus vaccine in healthy older adults: Results of a randomised trial

BACKGROUNDnThe decline in immune function with age is a challenge to vaccine development. Following an initial study in adults aged 18-64years, this study evaluated the safety and immunogenicity of Staphylococcus aureus (S. aureus) 4-antigen (SA4Ag) and 3-antigen (SA3Ag) vaccine in older adults. SA3Ag included capsular polysaccharide serotypes 5 and 8 (CP5 and CP8) conjugated to the nontoxic mutant form of diphtheria toxin (CRM197) and a recombinant version of clumping factor A (ClfA). SA4Ag included these antigens, with the addition of a recombinant manganese transporter C (rP305A or MntC). Both vaccines were unadjuvanted.nnnMETHODSnIn this double-blind, sponsor-unblinded, placebo-controlled, phase 1/2 study, 284 healthy adults (aged 65-85years) were randomised to receive a single dose of one of three formulations of SA4Ag with escalating dose levels of rP305A, SA3Ag, or placebo. Functional immune responses were measured using opsonophagocytic activity (OPA) killing and fibrinogen-binding inhibition (FBI) assays; immunogenicity was also assessed using a competitive Luminex® immunoassay (cLIA). T-cell responses were measured in a small subgroup of subjects using intracellular cytokine staining (ICS) assays.nnnRESULTSnThe results demonstrated rapid and robust functional immune responses to all antigens in healthy older adults. A high proportion of active vaccine recipients met the pre-defined antibody thresholds for each antigen at Day 29. SA4Ag elicited a dose-level response to rP305A with up to a 13-fold rise in cLIA titres at Day 29. Opsonophagocytic activity (OPA) assays showed >50- and >20-fold rises in functional titres using S. aureus strains expressing CP5 and CP8, respectively, at Day 29. T-cell cytokine responses were not substantially above background levels. There were no safety concerns in this study population and no increases in adverse events with higher rP305A dose levels.nnnCONCLUSIONSnSingle-dose vaccination of SA4Ag and SA3Ag in healthy adults aged 65-85years safely induced rapid and robust functional immune responses, supporting further development of SA4Ag for the prevention of S. aureus disease in adults up to age 85years.nnnTRIAL REGISTRATION NUMBERnNCT01643941.

SA4Ag, a 4-antigen Staphylococcus aureus vaccine, rapidly induces high levels of bacteria-killing antibodies

BACKGROUNDnStaphylococcus aureus is a leading cause of healthcare-associated infections. No preventive vaccine is currently licensed. SA4Ag is an investigational 4-antigen S. aureus vaccine, composed of capsular polysaccharide conjugates of serotypes 5 and 8 (CP5 and CP8), recombinant surface protein clumping factor A (rmClfA), and recombinant manganese transporter protein C (rMntC). This Phase 1 study aimed to confirm the safety and immunogenicity of SA4Ag produced by the final manufacturing process before efficacy study initiation in a surgical population.nnnMETHODSnHealthy adults (18-<65years) received one intramuscular SA4Ag injection. Serum functional antibodies were measured at baseline and Day 29 post-vaccination. An opsonophagocytic activity (OPA) assay measured the ability of vaccine-induced antibodies to CP5 and CP8 to kill S. aureus clinical isolates. For MntC and ClfA, antigen-specific immunogenicity was assessed via competitive Luminex® immunoassay (cLIA) and via fibrinogen-binding inhibition (FBI) assay for ClfA only. Reactogenicity and adverse event data were collected.nnnRESULTSnOne hundred participants were vaccinated. SA4Ag was well tolerated, with a satisfactory safety profile. On Day 29, OPA geometric mean titers (GMTs) were 45,738 (CP5, 95% CI: 38,078-54,940) and 42,652 (CP8, 95% CI: 32,792-55,477), consistent with 69.2- and 28.9-fold rises in bacteria-killing antibodies, respectively; cLIA GMTs were 2064.4 (MntC, 95% CI: 1518.2-2807.0) and 3081.4 (ClfA, 95% CI: 2422.2-3920.0), consistent with 19.6- and 12.3-fold rises, respectively. Similar to cLIA results, ClfA FBI titers rose 11.0-fold (GMT: 672.2, 95% CI: 499.8-904.2). The vast majority of participants achieved the pre-defined biologically relevant thresholds: CP5: 100%; CP8: 97.9%, ClfA: 87.8%; and MntC 96.9%.nnnCONCLUSIONSnSA4Ag was safe, well tolerated, and rapidly induced high levels of bacteria-killing antibodies in healthy adults. A Phase 2B efficacy trial in adults (18-85years) undergoing elective spinal fusion is ongoing to assess SA4Ags ability to prevent postoperative invasive surgical site and bloodstream infections caused by S. aureus. Clinicaltrials.gov Identifier: NCT02364596.

A comparative evaluation of the safety and immunogenicity of a single dose of unbuffered oral rhesus rotavirus serotype 3, rhesus/human reassortant serotypes 1, 2 and 4 and combined (tetravalent) vaccines in healthy infants

To assess safety and immunogenicity, 213 healthy infants aged 6 weeks to 4 months were randomized to receive a single dose of placebo, a 10(4) or 10(5) p.f.u. dose of rhesus rotavirus (RRV) serotype 3, human-RRV reassortant (VP-7 serotypes 1, 2 or 4) or a 10(4) or 10(5) p.f.u. dose of tetravalent rotavirus vaccine (containing equal parts of serotype 1, 2, 3 and 4 strains). The infants were fed ad libitum before and after vaccination; no buffer was used. For 7 days after vaccination, potential vaccine side effects were monitored, and no significant differences were noted for any symptom evaluated among the single serotype, tetravalent or placebo groups. Sera, obtained before and 28 days after vaccination, were measured for antibody to rotavirus by IgG, IgA and IgM enzyme-linked immunosorbent assay in all subjects, and by neutralizing antibody to the individual serotypes by plaque reduction in placebo and tetravalent vaccinees. The serological response rates for serotypes 1, 2, 3, 4 and the tetravalent vaccine were 25, 12, 19, 11 and 22%, respectively, at 10(4) p.f.u.; 47, 50, 35, 29 and 61%, respectively, at 10(5) p.f.u.; and 37% for placebo. The tetravalent vaccine was more immunogenic at 10(5) than at 10(4) p.f.u. (p = 0.04). Grouped together, the vaccines at 10(5) p.f.u. (single serotype and tetravalent) were more immunogenic than the vaccines at 10(4) p.f.u. (38 of 85 versus 17 of 94 seroresponders; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

A randomized trial of tigecycline versus ampicillin-sulbactam or amoxicillin-clavulanate for the treatment of complicated skin and skin structure infections

BackgroundComplicated skin and skin structure infections (cSSSIs) frequently result in hospitalization with significant morbidity and mortality.MethodsIn this phase 3b/4 parallel, randomized, open-label, comparative study, 531 subjects with cSSSI received tigecycline (100 mg initial dose, then 50 mg intravenously every 12 hrs) or ampicillin-sulbactam 1.5-3 g IV every 6 hrs or amoxicillin-clavulanate 1.2 g IV every 6-8 hrs. Vancomycin could be added at the discretion of the investigator to the comparator arm if methicillin-resistant Staphylococcus aureus (MRSA) was confirmed or suspected within 72 hrs of enrollment. The primary endpoint was clinical response in the clinically evaluable (CE) population at the test-of-cure (TOC) visit. Microbiologic response and safety were also assessed. The modified intent-to-treat (mITT) population comprised 531 subjects (tigecycline, nu2009=u2009268; comparator, nu2009=u2009263) and 405 were clinically evaluable (tigecycline, nu2009=u2009209; comparator, nu2009=u2009196).ResultsIn the CE population, 162/209 (77.5%) tigecycline-treated subjects and 152/196 (77.6%) comparator-treated subjects were clinically cured (difference 0.0; 95% confidence interval [CI]: -8.7, 8.6). The eradication rates at the subject level for the microbiologically evaluable (ME) population were 79.2% in the tigecycline treatment group and 76.8% in the comparator treatment group (difference 2.4; 95% CI: -9.6, 14.4) at the TOC assessment. Nausea, vomiting, and diarrhea rates were higher in the tigecycline group.ConclusionsTigecycline was generally safe and effective in the treatment of cSSSIs.Trial registrationClinicalTrials.gov NCT00368537