Phase One Clinical Trials Of World’s First Vaccine for First Chlamydia Shows Positive Results
Recent phase 1 clinical trials of a vaccine called CTH22 by Statens Serum Institut in Copenhagen, Denmark , which acts against genital chlamydia has proven to be positive with the vaccine being effective, safe and also immunogenic in healthy women participants.
The vaccine is administered either as an adjuvanted intramuscular vaccine or unadjuvanted intransal vaccine booster, and does not have any serious related adverse events except for mild local injection-site reactions. The vaccine induced seroconversion in all 30 participants in two treatment groups.
Dr. Peter Andersen, PhD, head of the study commented to Thailand Medical News,” "Given the impact of the chlamydia epidemic on women's health, reproductive health, infant health through vertical transmission, and increased susceptibility to other sexually transmitted diseases, a global unmet medical need exists for a vaccine against genital chlamydia. This new vaccine could have enormous public health and economic impact.”
Chlamydia is the most common bacterial sexually transmitted infection worldwide. Several strategies , including diagnostic testing, effective treatment, and targeting screening and treatment programs have failed to curb the epidemic. Unlike ocular chlamydia, there has been no vaccines in existence against Chlamydia trachomatis
s since the 1960s when the disease was formally discovered.
The vaccine antigen, CTH522 is a recombinant engineered version of the C. trachomatis
major outer membrane protein and the adjuvants included were either cationic liposomal adjuvant CAF01 or aluminum hydroxide, a form of aluminum often used as a vaccine adjuvant.
Volunteers in the trial were healthy females aged 19-45 who were not pregnant and agreed to two approved forms of contraception or to abstain from sexual intercourse during the trial period. These females had a BMI of <35, no history of pelvic inflammatory disease or other significant gynecological diseases, and tested negative for HIV, hepatitis B, hepatitis C, syphilis, gonorrhea, and C. trachomatis
The dosing schedule was three intramuscular doses of CTH522 with one of the two adjuvants at 0, 1 and 4 months, followed by two intranasal boosts (one in each nostril) of unadjuvanted CTH522 at 4.5 and 5 months, or comparable dosing with placebo. The 35 female participants were segregated accordingly, 15 in the CTH522:CAF01 group and 15 in the CTH522:AH group and five in the placebo group ,all with an intention-to-treat analysis.
Safety was the primary outcome, and the most common local reactions were injection site pain, tenderness, and movement impairment, though nearly all participants reported these were mild symptoms lasting a median of 2-4 days. There were 13 treatment-emergent adverse events ,five in the CTH522CAF01 group, six in the CTH522:AH group, and two in the placebo group. These included muscular skeletal stiffness, oropharyngeal pain, and nasopharyngitis.
Immunogenicity was a secondary outcome, and all 15 participants in both groups achieved a higher than four-fold IgG seroconversions after the three intramuscular immunizations.
Preparation of a phase II dose optimization study is currently ongoing.
Abraham S, et al "Safety and immunogenicity of the chlamydia vaccine candidate CTH522 adjuvanted with CAF01 liposomes or aluminum hydroxide: a first-in-human, randomised, double-blind, placebo-controlled, phase 1 trial" Lancet Infect Dis 2019; DOI: 10.1016/S1473-3099(19)30279-8.
Poston TB and Darville T "First genital chlamydia vaccine enters in-human clinical trial" Lancet Infect Dis 2019; DOI: 10.1016/S1473-3099(19)30290-7.