The following is a summary of “An investigation of trachoma vaccine regimens by the chlamydia vaccine CTH522 administered with cationic liposomes in healthy adults (CHLM-02): a phase 1, double-blind trial,” published in the April 2024 issue of Infectious Disease by Pollock et al.
Chlamydia trachomatis, a versatile bacteria lacking a vaccine, causes either eye infection (trachoma) or genital tract infection (chlamydia), depending on the strain.
Researchers conducted a clinical trial to assess the safety and immune response generated by a vaccine candidate (CTH522) delivered via various routes (intramuscular, intradermal, and topical) against Chlamydia trachomatis.
They conducted CHLM-02, a phase 1 trial at the National Institute for Health Research Imperial Clinical Research Facility, London, UK. Healthy men and non-pregnant women aged 18–45 without existing C trachomatis genital infection participated. Using an electronic database, participants were split into six groups (A–F). Groups A–E got the investigational product, while F received a placebo. Injections were received on day 0 and boosters on days 28 and 112, with a recall on day 140. Safety was the main focus, with immunogenicity as secondary.
The results showed 65 participants among 154 screened, with 60 completing the trial (52% women, 71% White, average age 26.8 years). No severe side effects were reported, and most adverse events were mild or moderate (only 1% severe). All active groups (A-E) achieved 100% four-fold seroconversion by day 42, with no seroconversion in the placebo group. Higher serum IgG levels were observed with the 85 μg CTH522-CAF01 dose, although not statistically significant compared to the 15 μg dose. Intradermal CTH522 (group C) induced potent serum IgG neutralization against both trachoma (serovar B) and urogenital (serovar D) strains. Topical ocular CTH522 (group B) led to increased ocular IgA levels at days 28 and 112 compared to baseline (P<0·001). Active vaccine groups, especially B and E, displayed immune responses to CTH522, affirming its safety and immunogenicity for phase 2 trials against ocular trachoma and urogenital chlamydia.
Investigators found CTH522, especially when combined with CAF01 adjuvant, to be safe and effective in generating immune responses, paving the way for larger phase 2 trials against ocular trachoma and urogenital chlamydia.
Source: thelancet.com/journals/laninf/article/PIIS1473-3099(24)00147-6/abstract