Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

RecruitingRare disease

Study on Doxycycline for Reducing Bacterial STIs in MSM and TGW with HIV

Verified siteRegistered drug
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the effectiveness of a treatment called doxyPEP in reducing the occurrence of certain bacterial sexually transmitted infections (STIs) among men who have sex with men (MSM) and transgender women (TGW) living with HIV in Belgium. The bacterial STIs being studied include infections caused by Neisseria gonorrhoeae, Chlamydia trachomatis, and Treponema pallidum. The treatment involves the use of a medication called Doxycycline, which is a type of antibiotic. Participants in the study will receive either the doxyPEP treatment or a placebo.

The purpose of the study is to determine if doxyPEP can effectively reduce the rate of these bacterial infections compared to a placebo. The study will be conducted in a double-blind manner, meaning neither the participants nor the researchers will know who is receiving the actual treatment or the placebo. This helps ensure the results are unbiased. Participants will be randomly assigned to either the doxyPEP group or the placebo group and will switch between the two during the study period, which is known as a cross-over design.

Throughout the study, participants will be monitored for any symptoms of the bacterial STIs being studied. The trial will also look at other factors, such as the presence of resistance genes and changes in the natural bacteria found in the body. The study is expected to continue until 2027, with recruitment starting in 2025. This research aims to provide valuable insights into the potential benefits of using doxyPEP as a preventive measure for bacterial STIs in individuals living with HIV.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, you will be asked to provide informed consent. This means you agree to participate and follow the study procedures.

    You must meet certain criteria, such as being 18 years or older, identifying as a man who has sex with men or as a transgender woman, living with HIV, and having an undetectable viral load for at least 6 months.

  2. Step 2

    Randomization

    You will be randomly assigned to one of two groups. One group will receive the doxycycline medication, and the other will receive a placebo. A placebo is a substance with no active medication, used to compare effects.

  3. Step 3

    Medication administration

    If you are in the doxycycline group, you will take doxycycline EG 100 mg tablets orally. The dosage and frequency will be explained to you by the study team.

    If you are in the placebo group, you will take placebo capsules that look like the doxycycline tablets but contain no active medication.

  4. Step 4

    Follow-up visits

    You will have regular follow-up visits at the study center. During these visits, your health will be monitored, and any side effects or symptoms will be recorded.

    The study team will assess the incidence of bacterial sexually transmitted infections, such as Neisseria gonorrhoeae, Chlamydia trachomatis, and Treponema pallidum.

  5. Step 5

    Cross-over phase

    After a certain period, you will switch to the other group. If you were initially taking doxycycline, you will now take the placebo, and vice versa.

    This phase helps to compare the effects of doxycycline and placebo more accurately.

  6. Step 6

    Completion of the study

    At the end of the study, you will have a final visit to assess your health and gather any remaining data.

    The study is expected to end by May 31, 2027.

Who can join the trial?

7 criteria

  • Able and willing to provide informed consent and follow the study procedures. Informed consent means you understand the study and agree to participate.
  • Aged 18 years or older.
  • Assigned male sex at birth. This means you were identified as male when you were born.
  • Identifying as gay, bisexual, or other men who have sex with men, or as transgender women. Transgender women are individuals who were assigned male at birth but identify and live as women.
  • Living with HIV. HIV is a virus that affects the immune system.
  • Having an undetectable viral load for 6 months or more. This means the amount of HIV in your blood is so low that it can't be measured by standard tests.
  • Having had at least one bacterial sexually transmitted infection in the past 24 months or having had 5 or more sex partners in the past 6 months.

Who cannot join the trial?

5 criteria

  • Individuals who are not male. This study is only for male participants.
  • Individuals who are not within the specified age range. The study is for adults only.
  • Individuals who are not living with HIV. This study is specifically for those who have HIV.
  • Individuals who are not MSM (men who have sex with men) or TGW (transgender women).
  • Individuals who are part of a vulnerable population. This means people who might need special protection or care.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

DoxyPEP is a medication being tested in this clinical trial to see if it can help reduce the number of certain bacterial infections in people living with HIV. These infections include Neisseria gonorrhoeae, Chlamydia trachomatis, and Treponema pallidum. The trial is focused on men who have sex with men (MSM) and transgender women (TGW) in Belgium. The goal is to find out if taking DoxyPEP can lower the chances of getting these infections compared to not taking it. DoxyPEP is being studied to see if it can be a helpful tool in preventing these infections in people who are already living with HIV.

What is already known about the treatment

DoxyPEP – DoxyPEP is administered orally in the form of a pill and is currently being studied in clinical trials to evaluate its effectiveness in reducing bacterial sexually transmitted infections (STIs) among men who have sex with men (MSM) and transgender women (TGW) living with HIV. This medication is being investigated for its potential to lower the incidence of infections caused by bacteria such as Neisseria gonorrhoeae, Chlamydia trachomatis, and Treponema pallidum. DoxyPEP works by interfering with the bacteria's ability to produce proteins, which are essential for their growth and survival, effectively stopping the infection. It is classified as an antibiotic, specifically a tetracycline, and is being explored for its preventive benefits in the context of STIs.

Investigated diseases

  • Neisseria gonorrhoeae infection

    This disease is caused by the bacterium Neisseria gonorrhoeae, which primarily affects the mucous membranes of the reproductive tract. It can also infect the mouth, throat, eyes, and rectum. The infection often begins with mild symptoms or none at all, but it can progress to cause pain during urination and discharge from the genitals. If left untreated, it can lead to more severe complications, including pelvic inflammatory disease in women and epididymitis in men. The disease can also increase the risk of acquiring or transmitting HIV. It is primarily spread through sexual contact.

  • Chlamydia trachomatis infection

    This disease is caused by the bacterium Chlamydia trachomatis, which infects the genital tract, rectum, and eyes. It often presents with mild symptoms or none at all, making it difficult to detect without testing. When symptoms do occur, they may include genital pain and discharge. If untreated, the infection can lead to serious reproductive and other health problems, including infertility. It is one of the most common sexually transmitted infections and is spread through sexual contact. The infection can also be passed from an infected mother to her baby during childbirth.

  • Treponema pallidum infection

    This disease is caused by the bacterium Treponema pallidum, which leads to syphilis. The infection progresses through several stages, starting with a painless sore at the site of infection. If untreated, it can advance to a rash, followed by a latent stage with no symptoms. In its late stages, it can cause severe damage to the heart, brain, and other organs. The disease is primarily transmitted through sexual contact, but it can also be passed from mother to child during pregnancy. Early detection and treatment are crucial to prevent progression.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-521153-16-00Estimated enrolment200 patientsSponsorInstitute Of Tropical Medicine

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.