The first-ever chlamydia vaccine to reach human clinical trials has been found to be safe and immunogenic, according to findings published in The Lancet Infectious Diseases.
In the double-blind, parallel, placebo-controlled randomised phase 1 trial, healthy women aged 19-45 years were randomly assigned to three vaccination groups: novel vaccine CTH522 adjuvanted with CAF01 liposomes (CTH522:CAF01; n=15), CTH522 adjuvanted with aluminium hydroxide (CTH522:AH; n=15), or placebo (n=5).
Participants received three intramuscular injections of 85μg vaccine (with adjuvant) or placebo to the deltoid region of the arm at zero, one, and four months, followed by two intranasal administrations of 30μg unadjuvanted vaccine or placebo at months 4.5 and 5.0.
Of the 35 participants, 32 (91%) received all five vaccinations and all were included in the intention-to-treat analyses. No related serious adverse reactions were reported, and intranasal vaccination was not associated with a higher frequency of related local reactions.
Both CTH522:CAF01 and CTH522:AH induced anti-CTH522 IgG seroconversion in all their group participants (15/15) after five immunisations, whereas no participants in the placebo group seroconverted.
CTH522:CAF01 showed accelerated seroconversion, increased IgG titres, an enhanced mucosal antibody profile, and a more consistent cell-mediated immune response profile compared with CTH522:AH.
Preparation of a phase 2 dose optimisation study is currently ongoing.