Early Latent SyphilisPhase 3NCT05069974
Alternative Antibiotics for Syphilis
A Phase 3 study testing Linezolid 600 mg (post-interim) and Benzathine Penicilllin G (post-interim) in people with Early Latent Syphilis and Primary Syphilis, run by Fundación FLS de Lucha Contra el Sida, las Enfermedades Infecciosas y la Promoción de la Salud y la Ciencia at 11 sites in 2 countries.
Trial summary
The Trep-AB clinical trial will test the efficacy of an investigational neuropenetrative drug, Linezolid (LZD), compared to standard treatment, Benzathine penicillin G (BPG), for early syphilis in humans. Read more about this study
- Who is it for?
- Ages 18 to 99 years
- Conditions the study is for
- Early Latent Syphilis, Primary Syphilis, Secondary Syphilis
- What is being tested?
- Linezolid 600 mg (post-interim) and Benzathine Penicilllin G (post-interim)
- Type of treatment
- Pill or oral medicine, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 165 participants
- Where
- 11 sitesin 2 countries
- Study dates
- 14 Oct 2021to 15 Apr 2026
- Phase
- Phase 3
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 99 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age 18 years or older at baseline visit.
- Primary, secondary or early latent syphilis diagnosis based on SEIMC/IUSTI Guidelines*
- Primary syphilis is defined as typical ulcer (chancre) and one of the following: detection of T.p. by Polymerase chain reaction (PCR), positive darkfield examination (DFE) or positive serological test (RPR≥1:4) for syphilis.
- Secondary syphilis is defined based on typical clinical symptoms with positive treponemal and non-treponemal tests (RPR≥1:4).
- Early latent syphilis is defined as positive serological treponemal and non-treponemal tests (RPR≥1:4) with no clinical evidence of infection, with a previous negative syphilis serology,or a four-fold increase in RPR titer of a non-treponemal test within the past 12 months.Serological tests for syphilis performed within 10 days prior to study inclusion visit willbe acceptable for enrollment.
- Signature of written informed consent.
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- Ability to comply with the requirements of the study protocol.
- If women of childbearing potential, use of a highly effective method of contraception (abstinence,hormonal contraception, intra-uterine device [IUD], or anatomical sterility in self or partner)committed during 1 week after last IMP administration.
- If men, use of condom during heterosexual intercourse and use of a highly effective method ofcontraception (abstinence, hormonal contraception, intra-uterine device [IUD], or anatomical sterilityin self or partner) in female partner committed during 1 week after last IMP administration.
- For inclusion purposes, positive point of care tests (POCT) will be accepted in selected patients without previous syphilis history and negative serological tests for syphilis during the last 12 months (Syphilis rapid diagnostic test [RDT] or Chembio DPP syphilis screen \& confirm assay [DPP]), or with a previous history of syphilis and negative non-treponemal tests during the last 12 months (DPP). Further confirmation by the methods described in a), b) or c) will be necessary. Participants whose diagnosis is not confirmed will be excluded from the efficacy analyses.
Who cannot join
- Known allergy to any of the IMPs and/or excipients, particularly known hypersensitivity to penicillin, cephalosporins or other beta-lactam agents and/or allergy to soya or peanut.
- Lactose or galactose intolerance or glucose-galactose malabsorbtion.
- Diagnosis criteria of symptomatic neurosyphilis.
- Pregnant or breastfeeding women.
- Current treatment with any drugs likely to interact with the study medication (see Appendix 6).
- Have taken any antibiotics with potential activity against syphilis (e.g. beta lactams, cephalosporines, macrolides, tetracyclines) within 1 week prior to randomization.
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- Uncontrolled hypertension, pheochromocytoma, thyrotoxicosis, carcinoid syndrome, bipolar disorder, incapacitating psycho-affective disturbance, acute confusional state.
- Renal function impairment requiring hemodialysis.
- Symptomatic concomitant STI (i.e., gonococcus, chlamydia, lymphogranuloma venereum, Mycoplasma genitalium) or other infection disease requiring antibiotic treatment potentially active against syphilis.
- Having received treatment for the early syphilis recently diagnosed (In the previous 6 months)
Trial locations and contacts
11 sites in 2 countries.
11 sites in 2 countries
United Kingdom6 sites
Leeds Sexual Health
Leeds
Trafalgar Clinic and Waldron Centre Lewisham
Lewisham
56 Dean Street
London
Mortimer Market Centre
London
Saint Mary's Hospital
London
North Manchester General Hospital and Central Manchester Foundation Trust
Manchester
Spain5 sites
CAP Drassanes-Hospital Universitari Vall d'Hebron
Barcelona, Barcelona, 08001
Barcelona Checkpoint
Barcelona, Barcelona, 08015
Hospital Clínic de Barcelona
Barcelona, Barcelona, 08036
Hospital Germans Trias Pujol
Barcelona, Barcelona, 08916
Hospital 12 de Octubre
Madrid, Madrid
About this study
Official title: Oral and Neuro-Penetrative Alternative Antibiotics for Patients With Syphilis
The Trep-AB clinical trial will test the efficacy of an investigational neuropenetrative drug, Linezolid (LZD), compared to standard treatment, Benzathine penicillin G (BPG), for early syphilis in humans. The overarching idea of the work proposed herein is to investigate the use of LZD to treat syphilis, conducting a randomized controlled clinical trial to evaluate this new indication of a known antibacterial agent.
Read the detailed description
The syphilis epidemic is rampant around the world, and therapeutic options are restricted to an antibiotic, intramuscular (IM) benzathine penicillin G (BPG), which does not efficiently cross the blood-brain barrier. Treponema pallidum (T.p.), the bacteria that causes syphilis, invades the central nervous system (CNS) in 40% of patients, usually without symptoms. The prognostic implications of CNS invasion are the potential for severe neurologic complications, and treatment failure due to sequestered bacteria in the CNS. When indicated, the only way to identify and treat neurosyphilis is by lumbar puncture to examine the cerebrospinal fluid (CSF), followed by intravenous (IV) Benzyl penicillin therapy. The invetigators have carried out in silico studies showing that oxazolidinones are potentially active against T.p., are neuropenetrative and can be administered orally. The invetigators have carried out preclinical studies using an in vitro culture system for T.p. and the use of the syphilis animal model with rabbits to test different antibiotics. The invetigators have confirmed that LZD was the best compound that could go on to be tested in clinical trials to treat syphilis.
The Trep-AB clinical trial will test the non-inferiority of an investigational neuropenetrative drug, LZD, compared to standard treatment BPG, for early syphilis in humans conducting a randomized controlled clinical.
Primary objective is to demonstrate the non-inferiority of LZD treatment compared with standard BPG treatment to cure patients with early syphilis. Seconday objective is to isolate T.p. strains in clinical samples to subtype DNA from patients at baseline and during recurrence or treatment failure.
PROTOCOL HISTORY
05 Oct 2021 - Initial registration. The Trep-AB master protocol was registered as a two-arm, open-label, randomised non-inferiority trial comparing linezolid 600 mg once daily for 5 days with BPG for early syphilis. The planned recruitment target was 360 participants (180 per treatment group).
Oct 2022 - Prespecified interim analysis. After 59 participants had been enrolled in the pre-interim phase, recruitment to the linezolid 600 mg once-daily for 5 days regimen was discontinued because the prespecified futility criterion was met.
02 Feb 2023 - Major protocol amendment.
- Following the interim analysis, the protocol was amended to evaluate an optimised linezolid regimen of 600 mg twice daily for 10 days, marking the transition from the pre-interim to the post-interim phase of the trial. The amended regimen replaced the discontinued 600 mg once-daily for 5 days regimen; the two linezolid regimens were not evaluated concurrently.
- The eligibility criteria, BPG comparator, primary endpoint, non-inferiority objective, and overall statistical framework remained unchanged.
- The sample size for the post-interim phase was recalculated using revised efficacy assumptions observed in pre-interim phase (95% vs 90%), resulting in a recruitment target of 165 participants, instead of 360.
Registry update following the amendment. When the registry was updated to reflect the major protocol amendment, the optimised linezolid regimen was added to the existing record without clearly indicating that it replaced the discontinued regimen. Consequently, the registry could be interpreted as describing a three-arm study comprising BPG and both linezolid regimens, although no three-arm comparison was conducted. Similarly, the registered total sample size of 224 represented the 59 participants enrolled during the pre-interim phase plus the planned 165 participants for the post-interim phase; it was not the target sample size for a single three-arm or pooled comparison.
17 Oct 2023 - Added UK participation and additional recruiting sites.
2024-2025 - Subsequent amendments addressed sdministrative and operational aspects of the study without changing the primary endpoint or statistical framework.
Current registry record. The registry has been updated to clarify the sequential structure of the trial. The pre-interim phase evaluated linezolid 600 mg once daily for 5 days and was discontinued for futility; the post-interim phase evaluated linezolid 600 mg twice daily for 10 days in newly randomised participants. The present report concerns the post-interim phase only. The two phases were not concurrent, and participants from the pre-interim phase are not included in the primary efficacy analysis reported here.
- Conditions
- Early Latent Syphilis, Primary Syphilis, Secondary Syphilis
- Being tested
- Linezolid 600 mg (post-interim), Benzathine Penicilllin G (post-interim)
- Keywords
- Syphilis, Benzathine penicillin G, RPR, Treponema pallidum, Linezolid
- Medical subject headings
- Syphilis, Latent, Syphilis, primary, Syphilis, secondary, Syphilis, Treponemal Infections
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Linezolid 600 mg (post-interim)Drug
Linezolid 600mg every 12hours during 10 days
Benzathine Penicilllin G (post-interim)Drug
Single dose of intramuscular BPG 2.4 MUI
| Study group | Role | What they receive |
|---|---|---|
| Post-interim - Linezolid 600 mg every 12 hours for 10 days | Experimental | After randomized to the experimental arm, the patient will take 1 tablet of Linezolid every 12hours during 10 days. Receives: Drug: Linezolid 600 mg (post-interim) |
| Post-interim - Benzathine penicillin G 2.4 MUI single dose | Active comparator | After randomized to the control arm, the patient will receive a single dose of 2.4MUI intramuscular BPG. Receives: Drug: Benzathine Penicilllin G (post-interim) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Proportion of participants achieving overall treatment success
Overall treatment success was defined as achievement of all outcome components applicable to the participant: clinical cure, serological cure, and absence of molecularly confirmed relapse.
Measured: at week 48
Secondary outcomes (9)
Proportion of patients with clinical resolution of primary syphilis lesions (clinical cure, primary).
Assesment of clinical resolution defined as the complete healing of primary syphilis lesions within 2 weeks from treatment start.
Measured: at week 2
Proportion of patients with clinical resolution of secondary syphilis lesions (clinical cure, secondary).
Assesment of clinical resolution defined as the complete healing of secondary syphilis lesions within 6 weeks from treatment start.
Measured: at week 6
Proportion of patients with adequate serological response (serological cure, week 48).
Assessment of adequate serological response defined as a four-fold decline in rapid plasma reagin (RPR) titer or seroreversion to negative.
Measured: at week 48
Proportion of patients with allelic variation in T. pallidum strain(s) DNA in recurrent syphilis or suspected treatment failure (absence of relapse).
Assessment of re-infection in recurrent syphilis as defined by allelic variation in core genes of T. pallidum strain(s) compared to baseline using a molecular method (MLST-WGS) in ulcer or mucosa lesions swabs, plasma, or oral swabs.
Measured: From date of randomization until date of first documented recurrence or treatment failure, assesed up to 48 weeks
Proportion of patients with adequate serological response (serological cure, week 12).
Assessment of adequate serological response defined as a four-fold decline in rapid plasma reagin (RPR) titer or seroreversion to negative.
Measured: at week 12
Proportion of patients with adequate serological response (serological cure, week 24).
Assessment of adequatesserological response defined as a four-fold decline in rapid plasma reagin (RPR) titer or seroreversion to negative.
Measured: at week 24
Proportion of patients with antibiotic resistance genotype.
Assesment of allelic variation in core genes conferring antimicrobial resistance in clinical specimens from patients who are considered to have treatment failure compared to patients with adequate clinical and serological response.
Measured: From date of randomization until date of first documented recurrence, assesed up to 48 weeks
Proportion of participants experiencing adverse events.
Assesment of adverse events related to LZD treatment compared with adverse events related to standard BPG treatment in participants with early syphilis.
Measured: up to 12 weeks
Proportion of patients who have a change in the RPR titer within 2 weeks after treatment start of primary syphilis.
Assessment of RPR titer variation at week 2 from treatment start of patients with primary syphilis.
Measured: at 2 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Oct 2021
- Study start14 Oct 2021
- Primary completion15 Apr 2026
- Study completion15 Apr 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Early Latent SyphilisStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Open-label, non inferiority, randomized clinical trial. Eligible patients will be randomized to recieve Linezolid (experimental arm) or BPG (control arm).
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 165 participants (actual)
Sponsor and investigators
- Lead sponsor
- Fundación FLS de Lucha Contra el Sida, las Enfermedades Infecciosas y la Promoción de la Salud y la Ciencia
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Oriol Mitja, Fundación FLS de Lucha Contra el Sida, las Enfermedades Infecciosas y la Promoción de la Salud y la Ciencia
- Investigators
- Oriol Mitjà Villar, PhD, Principal investigator, Fundación FLS de Lucha Contra el Sida, las Enfermedades Infecciosas y la Promoción de la Salud y la Ciencia
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05069974
- Sponsor's protocol ID
- Trep-AB
- Other IDs
- 2020-005604-19
- Status last verified
- Jul 2026
- First submitted
- 16 Sep 2021
- Last updated
- 29 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Ubals M, Nadal-Baron P, Arando M, Rivero A, Mendoza A, Descalzo Jorro V, Ouchi D, Perez-Mana C, Alvarez M, Alemany A, Hoyos-Mallecot Y, Nunley E, Lieberman NAP, Greninger AL, Galvan-Casas C, Suner C, G-Beiras C, Paredes R, Rodriguez-Gascon A, Canut A, Garcia-Patos V, Farre M, Marks M, Giacani L, Vall-Mayans M, Mitja O. Oral linezolid compared with benzathine penicillin G for treatment of early syphilis in adults (Trep-AB Study) in Spain: a prospective, open-label, non-inferiority, randomised controlled trial. Lancet Infect Dis. 2024 Apr;24(4):404-416. doi: 10.1016/S1473-3099(23)00683-7. Epub 2024 Jan 8.
PubMed 38211601
Study at a glance
From the registry record, last updated by the sponsor on 29 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Oral and Neuro-Penetrative Alternative Antibiotics for Patients With Syphilis
- ClinicalTrials.gov ID
- NCT05069974
- Acronym / sponsor ID
- Trep-AB
- Conditions
- Early Latent Syphilis, Primary Syphilis, Secondary Syphilis
- Keywords
- Syphilis, Benzathine penicillin G, RPR, Treponema pallidum, Linezolid
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 165 participants (actual)
- Lead sponsor
- Fundación FLS de Lucha Contra el Sida, las Enfermedades Infecciosas y la Promoción de la Salud y la CienciaUniversity, hospital or other
- Study start
- 14 Oct 2021 (actual)
- Primary completion
- 15 Apr 2026 (actual)
- Study completion
- 15 Apr 2026 (actual)
- First posted
- 6 Oct 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The Trep-AB clinical trial will test the efficacy of an investigational neuropenetrative drug, Linezolid (LZD), compared to standard treatment, Benzathine penicillin G (BPG), for early syphilis in humans. The overarching idea of the work proposed herein is to investigate the use of LZD to treat syphilis, conducting a randomized controlled clinical trial to evaluate this new indication of a known antibacterial agent.
Detailed description
The syphilis epidemic is rampant around the world, and therapeutic options are restricted to an antibiotic, intramuscular (IM) benzathine penicillin G (BPG), which does not efficiently cross the blood-brain barrier. Treponema pallidum (T.p.), the bacteria that causes syphilis, invades the central nervous system (CNS) in 40% of patients, usually without symptoms. The prognostic implications of CNS invasion are the potential for severe neurologic complications, and treatment failure due to sequestered bacteria in the CNS. When indicated, the only way to identify and treat neurosyphilis is by lumbar puncture to examine the cerebrospinal fluid (CSF), followed by intravenous (IV) Benzyl penicillin therapy. The invetigators have carried out in silico studies showing that oxazolidinones are potentially active against T.p., are neuropenetrative and can be administered orally. The invetigators have carried out preclinical studies using an in vitro culture system for T.p. and the use of the syphilis animal model with rabbits to test different antibiotics. The invetigators have confirmed that LZD was the best compound that could go on to be tested in clinical trials to treat syphilis.
The Trep-AB clinical trial will test the non-inferiority of an investigational neuropenetrative drug, LZD, compared to standard treatment BPG, for early syphilis in humans conducting a randomized controlled clinical.
Primary objective is to demonstrate the non-inferiority of LZD treatment compared with standard BPG treatment to cure patients with early syphilis. Seconday objective is to isolate T.p. strains in clinical samples to subtype DNA from patients at baseline and during recurrence or treatment failure.
PROTOCOL HISTORY
05 Oct 2021 - Initial registration. The Trep-AB master protocol was registered as a two-arm, open-label, randomised non-inferiority trial comparing linezolid 600 mg once daily for 5 days with BPG for early syphilis. The planned recruitment target was 360 participants (180 per treatment group).
Oct 2022 - Prespecified interim analysis. After 59 participants had been enrolled in the pre-interim phase, recruitment to the linezolid 600 mg once-daily for 5 days regimen was discontinued because the prespecified futility criterion was met.
02 Feb 2023 - Major protocol amendment.
- Following the interim analysis, the protocol was amended to evaluate an optimised linezolid regimen of 600 mg twice daily for 10 days, marking the transition from the pre-interim to the post-interim phase of the trial. The amended regimen replaced the discontinued 600 mg once-daily for 5 days regimen; the two linezolid regimens were not evaluated concurrently.
- The eligibility criteria, BPG comparator, primary endpoint, non-inferiority objective, and overall statistical framework remained unchanged.
- The sample size for the post-interim phase was recalculated using revised efficacy assumptions observed in pre-interim phase (95% vs 90%), resulting in a recruitment target of 165 participants, instead of 360.
Registry update following the amendment. When the registry was updated to reflect the major protocol amendment, the optimised linezolid regimen was added to the existing record without clearly indicating that it replaced the discontinued regimen. Consequently, the registry could be interpreted as describing a three-arm study comprising BPG and both linezolid regimens, although no three-arm comparison was conducted. Similarly, the registered total sample size of 224 represented the 59 participants enrolled during the pre-interim phase plus the planned 165 participants for the post-interim phase; it was not the target sample size for a single three-arm or pooled comparison.
17 Oct 2023 - Added UK participation and additional recruiting sites.
2024-2025 - Subsequent amendments addressed sdministrative and operational aspects of the study without changing the primary endpoint or statistical framework.
Current registry record. The registry has been updated to clarify the sequential structure of the trial. The pre-interim phase evaluated linezolid 600 mg once daily for 5 days and was discontinued for futility; the post-interim phase evaluated linezolid 600 mg twice daily for 10 days in newly randomised participants. The present report concerns the post-interim phase only. The two phases were not concurrent, and participants from the pre-interim phase are not included in the primary efficacy analysis reported here.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
- Model description
- Open-label, non inferiority, randomized clinical trial. Eligible patients will be randomized to recieve Linezolid (experimental arm) or BPG (control arm).
| Arm | Type | Receives |
|---|---|---|
| Post-interim - Linezolid 600 mg every 12 hours for 10 days | Experimental | Drug: Linezolid 600 mg (post-interim)After randomized to the experimental arm, the patient will take 1 tablet of Linezolid every 12hours during 10 days. |
| Post-interim - Benzathine penicillin G 2.4 MUI single dose | Active comparator | Drug: Benzathine Penicilllin G (post-interim)After randomized to the control arm, the patient will receive a single dose of 2.4MUI intramuscular BPG. |
Who may qualify
- Ages
- 18 to 99 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (10 listed)
- Age 18 years or older at baseline visit.
- Primary, secondary or early latent syphilis diagnosis based on SEIMC/IUSTI Guidelines*
- Signature of written informed consent.
- Ability to comply with the requirements of the study protocol.
- If women of childbearing potential, use of a highly effective method of contraception (abstinence,hormonal contraception, intra-uterine device [IUD], or anatomical sterility in self or partner)committed during 1 week after last IMP administration.
Key exclusion criteria (10 listed)
- Known allergy to any of the IMPs and/or excipients, particularly known hypersensitivity to penicillin, cephalosporins or other beta-lactam agents and/or allergy to soya or peanut.
- Lactose or galactose intolerance or glucose-galactose malabsorbtion.
- Diagnosis criteria of symptomatic neurosyphilis.
- Pregnant or breastfeeding women.
- Current treatment with any drugs likely to interact with the study medication (see Appendix 6).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Linezolid 600 mg (post-interim)Linezolid 600mg every 12hours during 10 days | Drug | Post-interim - Linezolid 600 mg every 12 hours for 10 days |
| Benzathine Penicilllin G (post-interim)Single dose of intramuscular BPG 2.4 MUI | Drug | Post-interim - Benzathine penicillin G 2.4 MUI single dose |
Primary outcome
Proportion of participants achieving overall treatment success
Time frame: at week 48
Overall treatment success was defined as achievement of all outcome components applicable to the participant: clinical cure, serological cure, and absence of molecularly confirmed relapse.
9 secondary outcomes
Proportion of patients with clinical resolution of primary syphilis lesions (clinical cure, primary).
Time frame: at week 2
Proportion of patients with clinical resolution of secondary syphilis lesions (clinical cure, secondary).
Time frame: at week 6
Proportion of patients with adequate serological response (serological cure, week 48).
Time frame: at week 48
Proportion of patients with allelic variation in T. pallidum strain(s) DNA in recurrent syphilis or suspected treatment failure (absence of relapse).
Time frame: From date of randomization until date of first documented recurrence or treatment failure, assesed up to 48 weeks
Proportion of patients with adequate serological response (serological cure, week 12).
Time frame: at week 12
Proportion of patients with adequate serological response (serological cure, week 24).
Time frame: at week 24
Proportion of patients with antibiotic resistance genotype.
Time frame: From date of randomization until date of first documented recurrence, assesed up to 48 weeks
Proportion of participants experiencing adverse events.
Time frame: up to 12 weeks
Proportion of patients who have a change in the RPR titer within 2 weeks after treatment start of primary syphilis.
Time frame: at 2 weeks
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Jul 2026.
- Derived from this study: PubMed 38211601Ubals M, Nadal-Baron P, Arando M, Rivero A, Mendoza A, Descalzo Jorro V, Ouchi D, Perez-Mana C, Alvarez M, Alemany A, Hoyos-Mallecot Y, Nunley E, Lieberman NAP, Greninger AL, Galvan-Casas C, Suner C, G-Beiras C, Paredes R, Rodriguez-Gascon A, Canut A, Garcia-Patos V, Farre M, Marks M, Giacani L, Vall-Mayans M, Mitja O. Oral linezolid compared with benzathine penicillin G for treatment of early syphilis in adults (Trep-AB Study) in Spain: a prospective, open-label, non-inferiority, randomised controlled trial. Lancet Infect Dis. 2024 Apr;24(4):404-416. doi: 10.1016/S1473-3099(23)00683-7. Epub 2024 Jan 8.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Oriol Mitjà Villar, PhD principal investigator
Fundación FLS de Lucha Contra el Sida, las Enfermedades Infecciosas y la Promoción de la Salud y la Ciencia
11 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Linezolid 600 mg (post-interim) and Benzathine Penicilllin G (post-interim) in people with Early Latent Syphilis and Primary Syphilis, run by Fundación FLS de Lucha Contra el Sida, las Enfermedades Infecciosas y la Promoción de la Salud y la Ciencia at 11 sites in 2 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 10 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 29 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 11 sites in United Kingdom, Spain. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Proportion of participants achieving overall treatment success (time frame: at week 48). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05069974, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Jul 2026.