A Bispecific Monoclonal Antibody Targeting Psl and PcrV Enhances Neutrophil-Mediated Killing of <i>Pseudomonas aeruginosa</i> in Patients with Bronchiectasis.

Abstract

<b>Rationale:</b> <i>Pseudomonas aeruginosa</i> infection is associated with worse outcomes in bronchiectasis. Impaired neutrophil antimicrobial responses contribute to bacterial persistence. Gremubamab is a bivalent, bispecific monoclonal antibody targeting Psl exopolysaccharide and the type 3 secretion system component PcrV. <b>Objectives:</b> This study evaluated the efficacy of gremubamab to enhance killing of <i>P. aeruginosa</i> by neutrophils from patients with bronchiectasis and to prevent <i>P. aeruginosa</i>-associated cytotoxicity. <b>Methods:</b> <i>P. aeruginosa</i> isolates from a global bronchiectasis cohort (<i>n</i> = 100) underwent whole-genome sequencing to determine target prevalence. Functional activity of gremubamab against selected isolates was tested <i>in vitro</i> and <i>in vivo</i>. Patients with bronchiectasis (<i>n</i> = 11) and control subjects (<i>n</i> = 10) were enrolled, and the effect of gremubamab in peripheral blood neutrophil opsonophagocytic killing (OPK) assays against <i>P. aeruginosa</i> was evaluated. Serum antibody titers to Psl and PcrV were determined (<i>n</i> = 30; 19 chronic <i>P. aeruginosa</i> infection, 11 no known <i>P. aeruginosa</i> infection), as was the effect of gremubamab treatment in OPK and anti-cytotoxic activity assays. <b>Measurements and Main Results:</b> Psl and PcrV were conserved in isolates from chronically infected patients with bronchiectasis. Seventy-three of 100 isolates had a full <i>psl</i> locus, and 99 of 100 contained the <i>pcrV</i> gene, with 20 distinct full-length PcrV protein subtypes identified. PcrV subtypes were successfully bound by gremubamab and the monoclonal antibody-mediated potent protective activity against tested isolates. Gremubamab increased bronchiectasis patient neutrophil-mediated OPK (+34.6 ± 8.1%) and phagocytosis (+70.0 ± 48.8%), similar to effects observed in neutrophils from control subjects (OPK, +30.1 ± 7.6%). No evidence of competition between gremubamab and endogenous antibodies was found, with protection against <i>P. aeruginosa</i>-induced cytotoxicity and enhanced OPK demonstrated with and without addition of patient serum. <b>Conclusions:</b> Gremubamab enhanced bronchiectasis patient neutrophil phagocytosis and killing of <i>P. aeruginosa</i> and reduced virulence.