Safety and Immunogenicity of a Chlamydia Vaccine CTH522

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).

Inclusion criteria

IC1: Healthy males and females between 18-45 years old on the day of the first vaccination.

IC2: Has been properly informed about the trial and signed the consent form.

IC3: Is willing and likely to comply with trial procedures.

IC4: Is prepared to grant authorised persons access to his/her trial-related medical record.

IC5: Is willing to use acceptable contraceptive measures during the trial (two weeks before and two weeks after the trial). Heterosexually active female capable of becoming pregnant must agree to use hormonal contraception, intrauterine device, intrauterine hormone releasing system, or to complete abstinence from at least two weeks before the first vaccination until at least two weeks after the last. Complete abstinence (defined as refraining from heterosexual intercourse) must be in line with the preferred and usual lifestyle of the subject. Periodic abstinence (e.g. calendar, ovulation, symptothermal, post-ovulation methods), withdrawal and progestogen-only oral hormonal contraception, where inhibition of ovulation is not the primary mode of action, are not acceptable methods of contraception.

Exclusion criteria

EX1: Is positive for C. trachomatis via urine PCR or has a known history of C. trachomatis.

EX2: Is positive for gonorrhoea via urine PCR test, or HIV, hepatitis B/C, syphilis via blood tests.

EX3: Has a significant active disease such as cardiac, liver, immunological, neurological, psychiatric, or clinically significant abnormality of haematological or biochemical parameters.

EX4: Has BMI ≥ 35 kg/m2.

EX5: Is currently participating in another clinical trial with an investigational or noninvestigational drug or device, or was treated with an investigational drug within 28 days before the first vaccination.

EX6: Has received, or plans to receive, any immunisation within 14 days of the start of the trial or during the trial immunisations.

EX7: Is currently receiving treatment with systemic immunosuppressive agents. Topical steroids are allowed unless applied to the IM or ID injection site.

EX8: Has a condition which in the opinion of the investigator is not suitable for participation in the trial.

EX9: Is known or confirmed to have an allergy to any of the vaccine constituents.

EX10: Is unable to refrain from the use of contact lenses. Contact lenses should be avoided two days before TO administration and for seven days later (longer if any ongoing local eye AE).

EX11: Has any evident ocular disease upon ophthalmoscopic exam at screening or any medical history of ocular disease that, in the opinion of the investigator, may impact the subject's participation in the trial.

EX12: Is pregnant (positive pregnancy test) or breastfeeding or not willing to use contraception during the trial.

EX13: Has confirmed a history of pelvic inflammatory disease or significant gynaecological diseases.