FDA fast-tracks Sanofi's experimental chlamydia vaccine

 There are currently no approved vaccines to protect against chlamydia – the most common sexually transmitted bacterial infection – but Sanofi is hoping to change that.

The French pharma group has just been granted a fast-track designation from the FDA for a preclinical-stage mRNA-based vaccine candidate that is due to start a phase 1/2 trial in the coming days and is one of just a couple of candidates ready for human testing.

Chlamydia – caused by the organism Chlamydia trachomatis – caused an estimated 128.5 million new infections in 2020, according to the World Health Organization (WHO), with a global prevalence of 4% for women and 2.5% for men.

The infection is easily cured with antibiotics and usually does not lead to any long-term problems if treated promptly. However, it can be present without symptoms, preventing or delaying treatment, and can contribute to pelvic inflammatory diseases in women, which can lead to pregnancy complications or infertility. Another major issue with chlamydia is that infection can dramatically increase a person's risk of contracting other STIs including HIV.

Given that backdrop, it's not surprising that the FDA has decided to accelerate its review of Sanofi's candidate, assuming it shows safety and efficacy in clinical trials.

The drugmaker said its shot has been designed to protect against primary genital tract infection and reinfection by C trachomatis. Its phase 1/2 trial – lasting 18 months and due to complete in 2028 – will be carried out in an estimated 1,560 people aged between 18 and 29 years old, according to its listing on the clinicaltrials.gov register.

It will enrol chlamydia seropositive and seronegative men and women with a new sexual partner within the last six months, more than one current partner, a partner with a prior or current STI, or inconsistent condom use. Participants will be treated with three doses of the mRNA vaccine at low, medium, and high doses – given by intramuscular injection – or a matched placebo.

"Millions of people currently live with undiagnosed chlamydia, including asymptomatic infection that can also cause severe long-term health effects if left untreated," said Jean-François Toussaint, Sanofi's global head of vaccines R&D.

"Antibiotics to treat chlamydia have not been successful in controlling rising infection rates," he added. "With our programme, we aim to make chlamydia a preventable disease through vaccination."

Another candidate chlamydia vaccine – CTH522 from Denmark's Statens Serum Institut (SSI), which is a conventional recombinant shot based on a bacterial membrane protein – has been shown to be safe and immunogenic in early-stage healthy volunteer trials and is being prepared for additional studies to see if it can prevent infections.

https://pharmaphorum.com/news/fda-fast-tracks-sanofis-experimental-chlamydia-vaccine