Lancet Infect Dis

Early trial results show chlamydia vaccine safe, immunogenic

April 23, 2024

In the CHLM-02 phase I trial at the National Institute for Health Research Imperial Clinical Research Facility in the UK, investigators found that CTH522, a recombinant version of the C. trachomatis major outer membrane molecule, adjuvanted with CAF01 or CAF09b is safe and immunogenic. Intradermal vaccination conferred systemic IgG neutralization breadth, and topical ocular administration increased ocular IgA formation. These findings suggest that CTH522 vaccine regimens against ocular trachoma and urogenital chlamydia should be further tested in phase 2 clinical trials.

• Between 2020 and 2022, of 154 participants screened, 65 were randomly assigned, and 60 completed the trial (52% women; 71% White; mean age, 26.8 years). Participants were assigned into six groups by the electronic database in a pre-prepared randomization list (A-F). Groups A-E received investigational medicinal product and group F received placebo only.
• There was 100% four-fold seroconversion rate by day 42 in the active groups (A-E) and no seroconversion in the placebo group.
• Serum IgG anti-CTH522 titers were higher after 85 μg CTH522-CAF01 than 15 μg, although not significantly (intention-to-treat median IgG titer ratio groups A-C:D=5.6; p=0.062), with no difference after three injections of 85 μg CTH522-CAF01 compared with CTH522-CAF09b (group E). Intradermal CTH522 (group C) induced high titers of serum IgG anti-CTH522 neutralizing antibodies against serovars B (trachoma) and D (urogenital). Topical ocular CTH522 (group B) at day 28 and 112 induced higher total ocular IgA compared with baseline (p<0.001).

Source:

Pollock KM, et al. (2024, April 10). Lancet Infect Dis. 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. https://pubmed.ncbi.nlm.nih.gov/38615673/