Safety and Immunogenicity of a Chlamydia Vaccine CTH522

Overview

CHLM-02 was a phase I, double-blind, randomized, placebo-controlled trial of the chlamydia vaccine CTH522. 65 trial participants were randomized into 12 groups and six cohorts (A1 to F2). Cohorts A to E received three intramuscular (IM) injections of CTH522 (Day 0, 28, and 112). Cohorts A to D received CTH522 adjuvanted with Cationic Adjuvant Formulation (CAF®) 01 IM in two doses (85µg \[A to C\] or 15µg \[D\]). Cohort E received 85µg CTH522 adjuvanted with CAF®09b. Cohorts B and C received unadjuvanted CTH522 boost via the topic ocular (TO) or intradermal (ID) route, respectively, jointly with the second and third IM vaccinations. Cohort F received placebo. The effect of mucosal recall on eye immunity with TO CTH522 or placebo was assessed Day 140.

This trial was a phase I, double-blind, parallel, randomised, and placebo-controlled trial of the chlamydia vaccine CTH522 in healthy adults. It was planned to randomize 66 subjects but only 65 subjects were randomized. Cohorts A-D investigated CTH522-CAF01 administered IM in two doses (85 mcg and 15 mcg). Cohort E investigated CTH522-CAF09b administered IM in one dose (85 mcg). Cohort F was the placebo group. The enrolled subjects were to complete 12 trial visits. All subjects in the active cohorts (cohort A-E) were to receive three IM injections of the adjuvanted CTH522 and some (cohort B and C) were to receive the non-adjuvanted CTH522 via the TO or ID route (given at the same time as the 2nd and 3rd IM vaccinations). All active cohorts were to receive TO administration as a boost at Day 140 of either the non-adjuvanted CTH522 (12 mcg in each eye) or placebo. * Cohort A received three IM vaccination of 85 mcg CTH522-CAF01. This cohort was divided into two groups: A1 received ID placebo at Day 28 and Day 112, and TO placebo at Day 140, while A2 received TO placebo at Day 28 and Day 112, and non-adjuvanted TO CTH522 boost at Day 140. * Cohort B received three IM vaccinations of 85 mcg CTH522-CAF01. This cohort was divided into two groups: B1 received TO vaccination of the non-adjuvanted CTH522 at Day 28 and 112 and TO placebo at Day 140, while B2 received the same for Day 28 and 112, but non-adjuvanted TO CTH522 boost at Day 140. The two additional TO doses of CTH522 (12 mcg in each eye) were administered in each eye. The rationale for this schedule was to investigate the impact of simultaneous TO administration of the antigen on the immunogenicity results. * Cohort C received three IM vaccinations of 85 mcg CTH522-CAF01. This cohort was divided into two groups: C1 received ID vaccination of the non-adjuvanted 24 mcg CTH522 at Day 28 and 112 and TO placebo at Day 140, while C2 received the same for Day 28 and 112, but TO 12 mcg CTH522 boost in each eye at Day 140. The rationale for this schedule was to investigate the impact of simultaneous ID administration of the antigen on the immunogenicity results. * Cohort D received three IM vaccinations of 15 mcg CTH522-CAF01. The rationale for the A and D cohorts was to investigate the impact of the two IM CTH522 doses on the immunogenicity results. * Cohort E received three IM vaccinations of 85 mcg CTH522-CAF09b. The rationale for the A and E cohorts was to investigate the impact of the adjuvant on the immunogenicity results. * Cohort F received placebo in the form of 0.9% NaCl saline (IM, ID and TO).