Pharmacokinetics and Immunogenicity of ASP0113 in CMV‐Seronegative Dialysis Patients and CMV‐Seronegative and ‐Seropositive Healthy Subjects

Cytomegalovirus (CMV) infection causes significant morbidity and mortality in immunocompromised transplant patients. ASP0113, a first-in-class DNA vaccine containing plasmids encoding CMV phosphoprotein 65 and glycoprotein B (gB), was evaluated in a phase 1b, subject-blinded study in CMV-seropositive (n = 13) and CMV-seronegative (n = 12) healthy and CMV-seronegative dialysis subjects (n = 12) randomized to ASP0113 or placebo. End points included pharmacokinetics, anti-gB antibody levels, phosphoprotein 65-specific T-cell responses measured by ex vivo enzyme-linked immune absorbent spot (ELISpot) assay and 10-day cultured ELISpot and Stat T-cell activation assays, and safety. ASP0113 concentrations peaked at 2-10 and 24-48 hours; the pharmacokinetics were similar across groups. No group demonstrated significant anti-gB antibody responses. T-cell responder rates in the cultured ELISpot assay were 8/12 (66.7%, 95%CI 35% to 90%) and 4/12 (33.3%, 95%CI 10% to 65%) in CMV-seronegative healthy subjects and dialysis patients, respectively, whereas ex vivo ELISpot assay response rates were 4/11 (36.4%, 95%CI 11% to 69%) and 0/12, respectively. Responses peaked at week 27, with lower magnitude observed in CMV-seronegative dialysis patients versus CMV-seronegative healthy subjects. No serious adverse events occurred; the most common adverse event in ASP0113-vaccinated patients was injection-site pain (64.9%). Some CMV-seronegative healthy subjects and dialysis patients had T-cell responses; no humoral responses were detected.