Randomized Multicenter Study Comparing Safety and Efficacy of Daptomycin Versus Standard-of-care in Pediatric Patients With Staphylococcal Bacteremia.

BACKGROUND: Staphylococcus aureus, including community-associated methicillin-resistant S. aureus, is an important cause of pediatric bacteremia. Daptomycin is a well-established treatment option for Gram-positive bacteremia in adults, but its safety and efficacy in children require confirmation. METHODS: This was a randomized (2:1), evaluator-blinded, multicenter, phase 4 clinical trial comparing intravenous daptomycin with standard-of-care (SOC) for treatment of S. aureus bacteremia in 1- to 17-year-old patients (Clinicaltrials.gov: NCT01728376). Total treatment duration (intravenous followed by oral step-down therapy) was 5-42 days. Daptomycin was dosed once daily by patient age: 12-17 years, 7 mg/kg; 7-11 years, 9 mg/kg and 1-6 years, 12 mg/kg. The primary objective was to evaluate daptomycin safety in children who received ≥1 dose; secondary objectives included comparing daptomycin efficacy with SOC (the trial was not designed to confirm noninferiority) and pharmacokinetic analysis. RESULTS: Fifty-five children were randomized to daptomycin and 27 to SOC (primarily vancomycin or cefazolin); 90% had S. aureus. In both groups, 15% of patients had drug-related adverse events, primarily diarrhea (4% daptomycin, 8% SOC) and increased creatine phosphokinase (4% daptomycin, 0% SOC). Clinical success (blinded evaluator-assessed complete/partial resolution of bacteremia signs and symptoms 7-14 days after end-of-treatment) rates were similar for daptomycin (88%) and SOC (77%; 95% confidence interval for difference: -9% to 31%). Daptomycin plasma levels across age groups were comparable with those in adults receiving daptomycin at 6 mg/kg. CONCLUSIONS: Once-daily, age-appropriate daptomycin was well tolerated in children with staphylococcal bacteremia; efficacy was comparable with SOC. Daptomycin in age-adjusted doses is a safe treatment alternative in this setting.

Phase IIa study of the immunogenicity and safety of the novel Staphylococcus aureus vaccine V710 in adults with end-stage renal disease receiving hemodialysis.

Bacteremia is the second leading cause of death in patients with end-stage renal disease who are on hemodialysis. A vaccine eliciting long-term immune responses against Staphylococcus aureus in patients on chronic hemodialysis may reduce the incidence of bacteremia and its complications in these patients. V710 is a vaccine containing iron surface determinant B (IsdB), a highly conserved S. aureus surface protein, which has been shown to be immunogenic in healthy subjects. In this blinded phase II immunogenicity study, 206 chronic hemodialysis patients between the ages of 18 and 80 years old were randomized to receive 60 µg V710 (with or without adjuvant), 90 µg V710 (with adjuvant), or a placebo in various combinations on days 1, 28, and 180. All 201 vaccinated patients were to be followed through day 360. The primary hypothesis was that at least 1 of the 3 groups receiving 2 V710 doses on days 1 and 28 would have a ≥2.5 geometric mean fold rise (GMFR) in anti-IsdB IgG titers over the baseline 28 days after the second vaccination (day 56). At day 56, all three groups receiving 2 doses of V710 achieved a ≥2.5 GMFR in anti-IsdB antibodies compared to the baseline (P values of <0.001 for all 3 groups), satisfying the primary immunogenicity hypothesis. None of the 33 reported serious adverse experiences were considered vaccine related by the investigators. V710 induced sustained antibody responses for at least 1 year postvaccination in patients on chronic hemodialysis.

The immunogenicity and safety of different formulations of a novel Staphylococcus aureus vaccine (V710): results of two Phase I studies.

Merck V710 is a novel vaccine that contains the highly conserved Staphylococcus aureus iron surface determinant B (IsdB) protein. V710 has induced positive immune responses in healthy subjects. The purpose of the two studies described herein was to evaluate the immunogenicity and safety of two different formulations of V710. Both studies were randomized, controlled, double-blind, parallel-group trials. Study 1 compared liquid, aluminum-adjuvanted V710 (30 µg) with liquid, non-adjuvanted V710 (30 µg) in a 1:1 ratio in 64 healthy adults (18-70 years). Study 2 compared non-adjuvanted lyophilized V710 (60 µg) with saline placebo in a 4:1 ratio in 51 healthy adults (18-80 years). Blood was collected at screening and up to Day 360 postvaccination in Study 1, and at screening and up to Day 84 postvaccination in Study 2. Sera were analyzed for IsdB-specific antibodies using a total IgG assay. The primary endpoints in Study 1 were the proportion of patients with a positive immune response (≥2-fold rise in IsdB-specific IgG antibody level) the geometric mean concentration (GMC), and the geometric mean-fold rise (GMFR), all from baseline at Day 14. The primary endpoint in Study 2 was the GMFR in IsdB-specific IgG antibody concentration from baseline at Day 14. In Study 1, 84.4% responded in the adjuvanted V710 group, and 71.9% in the non-adjuvanted V710 group. The GMC was 115.4 µg/mL in the adjuvanted group and 99.1 µg/mL in the nonadjuvanted group. The GMFR in antibody concentration in the group receiving aluminum-adjuvanted V710 was 4.5 and the GMFR in the group receiving non-adjuvanted V710 was 4.0. In Study 2, the GMFR in antibody concentration in the V710 group was 5.3, and 80.5% had a positive immune response. None responded in the placebo group. Positive immune response was seen in the active treatment groups over the full duration of each study. There were no serious adverse experiences (AE) in either study, and no patients discontinued due to an AE. There were no clinically meaningful differences in AEs between groups in either study. In conclusion, V710, both with and without aluminum adjuvant, and in both liquid and lyophilized formulations, was immunogenic within 14 days of vaccination. All treatments showed similar safety profiles.