Phase 1 study of MEDI3902, an investigational anti-Pseudomonas aeruginosa PcrV and Psl bispecific human monoclonal antibody, in healthy adults.

OBJECTIVES: MEDI3902 is a bivalent, bispecific human immunoglobulin G1κ monoclonal antibody that binds to both the Pseudomonas aeruginosa PcrV protein involved in host cell cytotoxicity and the Psl exopolysaccharide involved in P. aeruginosa colonization and tissue adherence. MEDI3902 is being developed for the prevention of nosocomial P. aeruginosa pneumonia in high-risk patients. METHODS: This phase 1 dose-escalation study (NCT02255760) evaluated the safety, pharmacokinetics, antidrug antibody (ADA) responses and ex vivo anticytotoxicity and opsonophagocytic killing activities of MEDI3902 after a single intravenous infusion in healthy adults aged 18 to 60 years. Fifty-six subjects were randomized in a 3:1 ratio to receive 250, 750, 1500 or 3000 mg of MEDI3902 or placebo and followed for 60 days afterwards. RESULTS: Treatment-emergent adverse events (TEAEs) were mild or moderate in severity; no serious TEAEs were observed. The most common TEAEs were infusion-related reactions. MEDI3902 exhibited approximately linear pharmacokinetics across the 250, 750 and 1500 mg doses and nonlinear pharmacokinetics between the 1500 and 3000 mg doses. One subject in the 3000 mg group tested positive for ADA on day 61 and had a lower MEDI3902 serum concentration from days 43 to 61 than ADA-negative subjects. Serum anticytotoxicity antibody concentrations and opsonophagocytic killing activity were correlated with MEDI3902 serum concentrations across all doses. CONCLUSIONS: Phase 1 study results of MEDI3902 in healthy subjects support further evaluation of its safety and efficacy in subjects at risk for P. aeruginosa pneumonia.

Pseudomonas aeruginosa PcrV and Psl, the Molecular Targets of Bispecific Antibody MEDI3902, Are Conserved Among Diverse Global Clinical Isolates.

Background: Bispecific antibody MEDI3902, targeting the Pseudomonas aeruginosa type 3 secretion system (PcrV) and Psl exopolysaccharide, is currently in phase 2b development for prevention of nosocomial pneumonia in patients undergoing mechanical ventilation. We surveyed a diverse collection of isolates to study MEDI3902 epitope conservation and protective activity. Methods: P. aeruginosa clinical isolates (n = 913) were collected from diverse patients and geographic locations during 2003-2014. We conducted whole-genome sequencing; performed PcrV and Psl expression analyses via immunoblotting and enzyme-linked immunosorbent assay, respectively; performed crystallography to determine the MEDI3902 PcrV epitope, using anti-PcrV Fab and PcrV components (resolved at 2.8 Å); and evaluated MEDI3902 protective activity against select isolates in vitro and in vivo. Results: Intact psl operon and pcrV genes were present in 94% and 99% of isolates, respectively, and 99.9% of isolates contained at least one of the genetic elements. Anti-Psl binding was confirmed in tested isolates harboring a complete Psl operon or lacking nonessential psl genes. We identified 46 PcrV variant sequences, and MEDI3902-PcrV contact residues were preserved. MEDI3902 maintained potent in vivo activity against various strains, including strains expressing only a single target. Conclusions: Psl and PcrV are highly prevalent in global clinical isolates, suggesting MEDI3902 can mediate broad coverage against P. aeruginosa.