AzTrials
AzTrials

Venous Thrombosis Deep (Limbs)Phase 3COLTNCT07432529

Design and Rationale of the COLT Study

A Phase 3 study testing Colchicine 0.5 MG Oral Tablet in people with Venous Thrombosis Deep (Limbs) and Post-thrombotic Syndrome, run by Azienda Sanitaria Locale ASL 6, Livorno.

Not yet recruiting

Opening soon. The study is approved but enrolment has not started yet. Sites may already take enquiries.

Sites and contacts
Official record
Search all trials

Trial summary

Deep vein thrombosis (DVT) is a condition in which a blood clot forms in the deep veins of the leg and can lead to long-term problems such as leg pain, swelling, and reduced quality of life. Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
Colchicine 0.5 MG Oral Tablet
Type of treatment
Pill or oral medicine
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
940 participants
Where
No sites listed yet
Study dates
1 Jun 2026to 1 Jun 2027
Phase
Phase 3
Are there results?
Not yet: the study is under way

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 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Age ≥18 years at the time of screening.
  • Objectively confirmed first, symptomatic acute proximal lower-limb deep vein thrombosis (DVT), involving the popliteal vein or more proximal veins, diagnosed within the previous 48 hours.
  • Planned initiation of standard anticoagulation therapy, including:
  • Low-molecular-weight heparin (LMWH) bridging to vitamin K antagonists (VKA) or direct oral anticoagulants (DOACs),
  • DOAC monotherapy according to local guidelines,
  • Fondaparinux or other guideline-recommended regimens. Note: Standard anticoagulation regimens include dose reduction of apixaban or rivaroxaban at the sixth month, as per local practice.
  • Ability and willingness to provide written informed consent and comply with all study procedures.

Who cannot join

  • Participants meeting any of the following criteria will be excluded:
  • History of prior DVT in the same limb.
  • Known contraindications to anticoagulation or anticipated inability to comply with study procedures.
  • Current use of colchicine or clinical indication requiring colchicine therapy.
  • Known hypersensitivity or allergy to colchicine.
  • Severe hepatic impairment, defined as ALT or AST >3× upper limit of normal, or severe renal impairment (creatinine clearance <30 mL/min).
Show all 17Show fewer
  • Active malignancy with an estimated life expectancy <12 months.
  • History of active or chronic gastrointestinal disease that may interfere with colchicine tolerance, including:
  • Inflammatory bowel disease (Crohn's disease or ulcerative colitis),
  • Collagenous colitis,
  • Irritable bowel syndrome,
  • Chronic or recurrent diarrhea.
  • Recent (<30 days) or ongoing use of systemic immunosuppressive therapy, including but not limited to corticosteroids, cyclosporine, or tumor necrosis factor-alpha inhibitors.
  • Pregnancy or breastfeeding, or unwillingness to use effective contraception during the study period.
  • Concomitant use of strong CYP3A4 inhibitors or P-glycoprotein inhibitors contraindicated with colchicine.
  • Major bleeding event within the past 30 days or assessed as high bleeding risk by the investigator.
  • Inability or unwillingness to provide informed consent or to comply with study procedures.

Trial locations and contacts

No sites are listed yet. Contact the study team or a site near you to ask about taking part.

Nicola Mumoli NM Dr contact

+39 0331699111

nimumoli@tiscali.it

About this study

Official title: Design and Rationale of the COLT Study: a Multicentre, Randomised, Double-blind, Placebo-controlled Trial of COLchicine as Adjunctive Therapy to Standard Anticoagulation in Acute Proximal Deep Vein Thrombosis of the Lower Limbs

Deep vein thrombosis (DVT) is a condition in which a blood clot forms in the deep veins of the leg and can lead to long-term problems such as leg pain, swelling, and reduced quality of life. Standard treatment with blood-thinning medication lowers the risk of complications, but some patients still develop long-term damage to the veins. Inflammation is thought to play an important role in these complications.

This study will evaluate whether adding colchicine, an anti-inflammatory medication already used for other conditions, to standard anticoagulant therapy can improve outcomes in patients with acute DVT. Participants will be randomly assigned to receive either colchicine or a placebo, in addition to usual blood-thinning treatment, and will be followed for one year.

The main goal of the study is to determine whether colchicine reduces the risk of developing long-term vein problems after DVT. The study will also assess the risk of new blood clots, vein recovery, quality of life, and the safety of colchicine treatment.

Read the detailed description

Deep vein thrombosis (DVT) of the lower limbs is a serious condition in which a blood clot forms in the deep veins of the leg. DVT can lead to long-term complications such as post-thrombotic syndrome (PTS), chronic leg swelling, pain, skin changes, and impaired quality of life. Standard treatment with anticoagulants helps prevent clot progression and reduces the risk of recurrent venous thromboembolism (VTE), but many patients still develop long-term vein damage.

Inflammation is believed to play a key role in clot development, vein-wall injury, and delayed resolution of DVT. Colchicine is an anti-inflammatory medication that has been widely used in other cardiovascular and inflammatory conditions and has a favorable safety profile when used in low doses. Preliminary studies suggest colchicine may help reduce inflammation associated with DVT and promote vein recovery.

The COLT-DVT study is a multicenter, randomized, double-blind, placebo-controlled clinical trial being conducted in Italy. The study will enroll approximately 940 adult patients with a first episode of acute proximal DVT of the lower limbs. Participants will be randomly assigned in a 1:1 ratio to receive either low-dose colchicine or a matching placebo, in addition to standard anticoagulant therapy. Colchicine treatment will be administered as 0.5 mg twice daily for the first month, followed by 0.5 mg once daily for the subsequent five months. Participants will be followed for a total of 12 months.

The main goal of the study is to determine whether the addition of colchicine reduces the incidence of post-thrombotic syndrome one year after DVT. Secondary objectives include assessing recurrent VTE, vein reopening and valve function via duplex ultrasound, health-related quality of life using validated questionnaires, and the safety and tolerability of colchicine treatment.

This study aims to provide new evidence on whether targeting inflammation in DVT can improve patient outcomes, reduce long-term complications, and potentially change standard care practices. Participants will be closely monitored for safety, and any side effects will be recorded and managed according to standard clinical practice.

Being tested
Colchicine 0.5 MG Oral Tablet, Placebo
Keywords
Deep vein thrombosis, Venous thromboembolism, Post-thrombotic syndrome, Colchicine, Anticoagulation therapy, Randomized controlled trial, Inflammation
Medical subject headings
Venous Thrombosis, Postthrombotic Syndrome, Venous Thromboembolism, Venous Insufficiency, Inflammation

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Colchicine 0.5 MG Oral TabletDrug

    Low-dose colchicine added to standard anticoagulant therapy for acute proximal deep vein thrombosis. Colchicine is administered 0.5 mg twice daily for the first month, then 0.5 mg once daily for the next five months. Participants are monitored for post-thrombotic syndrome, recurrent venous thromboembolism, vein recanalization, quality of life, and safety over 12 months.

  • PlaceboDrug

    Matching placebo administered alongside standard anticoagulant therapy on the same schedule as colchicine. Participants are monitored for the same outcomes and safety measures.

Study groups in NCT07432529
Study groupRoleWhat they receive
Arm 1 - Colchicine + Standard AnticoagulationExperimentalParticipants in this arm will receive low-dose colchicine in addition to standard anticoagulant therapy for deep vein thrombosis. Colchicine will be administered as 0.5 mg twice daily for the first month, followed by 0.5 mg once daily for the subsequent five months. Participants will be monitored for safety, efficacy, and outcomes including post-thrombotic syndrome, recurrent venous thromboembolism, vein recanalization, and quality of life over a 12-month follow-up period.
Receives: Drug: Colchicine 0.5 MG Oral Tablet
Arm 2 - Placebo + Standard AnticoagulationPlacebo comparatorParticipants in this arm will receive a matching placebo in addition to standard anticoagulant therapy for deep vein thrombosis. Placebo will be administered following the same schedule as colchicine (0.5 mg twice daily for one month, then 0.5 mg once daily for five months). Participants will be monitored for the same outcomes and safety measures over a 12-month follow-up period.
Receives: Drug: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Post-thrombotic syndrome (PTS)

    To determine whether addition of low-dose colchicine to standard anticoagulation reduces the incidence of PTS at 12 months in patients with acute proximal lower-limb DVT. PTS is defined as: chronic clinical condition that occurs after DVT, presenting with symptoms such as leg pain, heaviness, cramps, pruritus, and paresthesia, and signs such as edema, skin hyperpigmentation, venous ectasia, lipodermatosclerosis, or venous ulcer, in the previously thrombosed limb, between 3 to 12 months after the acute event, and not explained by other causes [31]. A Villalta score > 5 is considered diagnostic for PTS.

    Measured: From the start of treatment to the 12-month follow-up visit

  2. Recurrent venous thromboembolism.

    To evaluate the effect of low-dose colchicine added to standard anticoagulation on the incidence of recurrent venous thromboembolism (VTE), defined as objectively confirmed recurrent DVT and/or pulmonary embolism (PE), within 12 months of the index event.

    Measured: From the start of treatment to the 12-month follow-up visit

Secondary outcomes (5)
  1. Longitudinal evaluation of PTS severity

    Subgroup analysis evaluating differences in efficacy of low-dose colchicine added to standard anticoagulation in mild (5-9) to moderate (10-14) to severe PTS (> 15).

    Measured: From the start of treatment to the 12-month follow-up visit

  2. Venous healing and function on imaging

    To assess the effect of colchicine on venous recanalization and valvular competence at 3 months using duplex ultrasound, including:

    1. vein compressibility,
    2. residual vein obstruction,
    3. presence of venous reflux.

    Measured: From the start of treatment to the 12-month follow-up visit

  3. Change From Baseline in Health-Related Quality of Life (HRQOL) as Measured by the VEINES-QOL/Sym Questionnaire

    Change from baseline in health-related quality of life as measured by the Venous Insufficiency Epidemiological and Economic Study - Quality of Life/Symptoms (VEINES-QOL/Sym) questionnaire.

    The VEINES-QOL score ranges from 0 to 100, with higher scores indicating better quality of life. The VEINES-Sym score ranges from 0 to 100, with higher scores indicating fewer symptoms.

    Measured: From the start of treatment to the 12-month follow-up visit

  4. Adverse event and treatment discontinuation

    To determine the 12-months safety profile of colchicine in this population (major and clinically relevant non-major bleeding, defined by ISTH definitions, gastrointestinal adverse events, neutropenia).

    Measured: From the start of treatment to the 12-month follow-up visit

  5. Adherence and persistence to colchicine therapy

    To evaluate adherence and persistence to colchicine treatment and to explore their association with clinical outcomes, including PTS severity and recurrent VTE.

    Measured: From the start of treatment to the 12-month follow-up visit

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted25 Feb 2026
  2. Study start1 Jun 2026 (estimated)
  3. Primary completion1 Jun 2027 (estimated)
  4. Study completion1 Jun 2027 (estimated)

Resources

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
Prevention
Allocation
Randomised
Intervention model
Parallel groups
Model description
This is a randomized, double-blind, placebo-controlled, parallel-group study. Participants with acute proximal deep vein thrombosis (DVT) will be randomly assigned in a 1:1 ratio to receive either low-dose colchicine or a matching placebo, in addition to standard anticoagulant therapy. The parallel design ensures that each group receives its assigned treatment concurrently, allowing for a clear comparison of outcomes between colchicine and placebo. Participants, investigators, and study staff will be blinded to treatment assignment to reduce bias. The main goal is to evaluate whether colchicine reduces the risk of post-thrombotic syndrome, recurrent venous thromboembolism, and other clinical outcomes, while monitoring safety and tolerability over a 12-month follow-up period.
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
940 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07432529
Sponsor's protocol ID
COLT123
Acronym
COLT
Status last verified
Feb 2026
First submitted
14 Feb 2026
Last updated
25 Feb 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes: De-identified individual participant data (IPD) underlying the results reported in this study, including the analyzable dataset and data dictionary, will be made available.

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing Colchicine 0.5 MG Oral Tablet in people with Venous Thrombosis Deep (Limbs) and Post-thrombotic Syndrome, run by Azienda Sanitaria Locale ASL 6, Livorno.

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 7 inclusion and 17 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: opening soon, as of the sponsor's last update on 25 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. 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?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Nicola Mumoli NM Dr (+39 0331699111, nimumoli@tiscali.it), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Post-thrombotic syndrome (PTS) (time frame: From the start of treatment to the 12-month follow-up visit). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
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 25 Feb 2026.

Free account

Log in to keep searching

You’ve used your 3 free searches. AzTrials is free: log in or create a free account to keep searching clinical trials and save the ones you want to follow.

Create a free accountLog in