Venous ThromboembolismPhase 1/2NCT04504318
Apixaban vs Enoxaparin Following Microsurgical Breast Reconstruction-An RCT
A Phase 1/2 study testing Apixaban 2.5 MG Oral Tablet and Enoxaparin 40Mg/0.4mL Prefilled Syringe in people with Venous Thromboembolism, run by Stanford University at 1 site in United States.
Trial summary
Subcutaneous enoxaparin is currently the gold standard for VTE chemoprophylaxis. However, the efficacy of chemoprophylaxis with subcutaneous enoxaparin is affected by patient-level factors, thus, resulting in VTE events despite guideline-compliant prophylaxis. Read more about this study
- Who is it for?
- Ages 18 to 89 years, women only
- Conditions the study is for
- Venous Thromboembolism
- What is being tested?
- Apixaban 2.5 MG Oral Tablet and Enoxaparin 40Mg/0.4mL Prefilled Syringe
- Type of treatment
- Pill or oral medicine, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 82 participants
- Where
- 1 siteUnited States
- Study dates
- 12 Aug 2020to 19 Jun 2024
- Phase
- Phase 1/2
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 89 years
- Women only
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Adult (>18 years) women
- Scheduled to undergo unilateral or bilateral microsurgical breast reconstruction with free abdominal flaps (i.e. muscle-sparing transverse rectus abdominis musculocutaneous [TRAM] and/or deep inferior epigastric artery perforator [DIEP]) flap)
- Caprini score of 6 or greater.
- Ability to understand and the willingness to sign a written informed consent document.
Who cannot join
- Contraindication to the use of apixaban or enoxaparin
- Active bleeding
- History of bleeding disorder
- History of coagulopathy
- History of heparin-induced thrombocytopenia
- History of liver disease
Show all 13Show fewer
- History of renal disease (creatinine clearance <30 mL/min; serum creatinine >1.6 mg/dL)
- Major neurosurgical intervention (brain/spine) within the past 90 days
- Ophthalmologic procedure within the past 90 days
- Uncontrolled hypertension
- History of alcohol and/or substance abuse
- Need for therapeutic anticoagulation
- Pregnant or Nursing
Trial locations and contacts
1 site in 1 country.
United States1 site
Stanford University Medical Center
Stanford, California, 94305
About this study
Official title: A Randomized Controlled Trial Comparing Apixaban Versus Enoxaparin Following Microsurgical Breast Reconstruction
Subcutaneous enoxaparin is currently the gold standard for VTE chemoprophylaxis. However, the efficacy of chemoprophylaxis with subcutaneous enoxaparin is affected by patient-level factors, thus, resulting in VTE events despite guideline-compliant prophylaxis. A population at particular risk is the growing number of patients who undergo autologous breast reconstruction. Direct oral anticoagulants (DOAC) might be a less invasive, yet, more efficacious mode of chemoprophylaxis in this patient population. Hence, the proposed work has the potential to cause a paradigm shift in chemoprophylaxis guidelines in a large population of patients undergoing plastic surgery.
- Conditions
- Venous Thromboembolism
- Being tested
- Apixaban 2.5 MG Oral Tablet, Enoxaparin 40Mg/0.4mL Prefilled Syringe
- Medical subject headings
- Venous Thromboembolism
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Apixaban 2.5 MG Oral TabletDrug
Patients will be assigned to the respective study groups postoperatively upon arrival in the post-anesthesia care unit. Hence, surgeons are blinded at the time of surgery as to study group assignment. Chemoprophylaxis will continue for the duration of the hospitalization.
Enoxaparin 40Mg/0.4mL Prefilled SyringeDrug
Patients will be assigned to the respective study groups postoperatively upon arrival in the post-anesthesia care unit. Hence, surgeons are blinded at the time of surgery as to study group assignment. Chemoprophylaxis will continue for the duration of the hospitalization.
| Study group | Role | What they receive |
|---|---|---|
| Apixaban | Experimental | Patients assigned to this group will receive Apixaban 2.5 mg PO BID starting 12 hours after completing skin closure. Receives: Drug: Apixaban 2.5 MG Oral Tablet |
| Enoxaparin | Active comparator | Patients assigned to this group will receive Enoxaparin 40 mg SC QD starting 12 hours after completing skin closure. Receives: Drug: Enoxaparin 40Mg/0.4mL Prefilled Syringe |
What is being measured
The primary outcome is the main question the study is designed to answer.
Apixaban vs. Enoxaparin - Number of Participants With Bleeding Events
To examine the rate of bleeding events in patients receiving oral apixaban versus subcutaneous enoxaparin following microsurgical breast reconstruction
Measured: 90-day events
Secondary outcomes (1)
Apixaban vs. Enoxaparin - Number of Participants With Venous Thromboembolism (VTE) Events
To examine the rate of VTE events in patients receiving oral apixaban versus subcutaneous enoxaparin following microsurgical breast reconstruction
Measured: 90 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Aug 2020
- Study start12 Aug 2020
- Primary completion19 Jun 2024
- Study completion19 Jun 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Venous ThromboembolismStudies of the same condition, open and under way.
- More trials run by Stanford UniversityThe sponsor's other registered studies.
- 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 1/2
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Care provider
- Enrolment
- 82 participants (actual)
Sponsor and investigators
- Lead sponsor
- Stanford University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Arash Momeni, Stanford University
- Investigators
- Arash Momeni, MD, Principal investigator, Stanford University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04504318
- Sponsor's protocol ID
- IRB-49355
- Status last verified
- Jun 2025
- First submitted
- 5 Aug 2020
- Last updated
- 22 Jun 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 22 Jun 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Randomized Controlled Trial Comparing Apixaban Versus Enoxaparin Following Microsurgical Breast Reconstruction
- ClinicalTrials.gov ID
- NCT04504318
- Acronym / sponsor ID
- IRB-49355
- Conditions
- Venous Thromboembolism
- Phase
- Phase 1/2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 82 participants (actual)
- Lead sponsor
- Stanford UniversityUniversity, hospital or other
- Study start
- 12 Aug 2020 (actual)
- Primary completion
- 19 Jun 2024 (actual)
- Study completion
- 19 Jun 2024 (actual)
- First posted
- 7 Aug 2020 (actual)
- Results
- Posted 22 Jun 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Subcutaneous enoxaparin is currently the gold standard for VTE chemoprophylaxis. However, the efficacy of chemoprophylaxis with subcutaneous enoxaparin is affected by patient-level factors, thus, resulting in VTE events despite guideline-compliant prophylaxis. A population at particular risk is the growing number of patients who undergo autologous breast reconstruction. Direct oral anticoagulants (DOAC) might be a less invasive, yet, more efficacious mode of chemoprophylaxis in this patient population. Hence, the proposed work has the potential to cause a paradigm shift in chemoprophylaxis guidelines in a large population of patients undergoing plastic surgery.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (care provider)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Apixaban | Experimental | Drug: Apixaban 2.5 MG Oral TabletPatients assigned to this group will receive Apixaban 2.5 mg PO BID starting 12 hours after completing skin closure. |
| Enoxaparin | Active comparator | Drug: Enoxaparin 40Mg/0.4mL Prefilled SyringePatients assigned to this group will receive Enoxaparin 40 mg SC QD starting 12 hours after completing skin closure. |
Who may qualify
- Ages
- 18 to 89 years
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Adult (>18 years) women
- Scheduled to undergo unilateral or bilateral microsurgical breast reconstruction with free abdominal flaps (i.e. muscle-sparing transverse rectus abdominis musculocutaneous [TRAM] and/or deep inferior epigastric artery perforator [DIEP]) flap)
- Caprini score of 6 or greater.
- Ability to understand and the willingness to sign a written informed consent document.
Key exclusion criteria (13 listed)
- Contraindication to the use of apixaban or enoxaparin
- Active bleeding
- History of bleeding disorder
- History of coagulopathy
- History of heparin-induced thrombocytopenia
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 |
|---|---|---|
| Apixaban 2.5 MG Oral TabletPatients will be assigned to the respective study groups postoperatively upon arrival in the post-anesthesia care unit. Hence, surgeons are blinded at the time of surgery as to study group assignment. Chemoprophylaxis will continue for the duration of the hospitalization. | Drug | Apixaban |
| Enoxaparin 40Mg/0.4mL Prefilled SyringePatients will be assigned to the respective study groups postoperatively upon arrival in the post-anesthesia care unit. Hence, surgeons are blinded at the time of surgery as to study group assignment. Chemoprophylaxis will continue for the duration of the hospitalization. | Drug | Enoxaparin |
Primary outcome
Apixaban vs. Enoxaparin - Number of Participants With Bleeding Events
Time frame: 90-day events
To examine the rate of bleeding events in patients receiving oral apixaban versus subcutaneous enoxaparin following microsurgical breast reconstruction
1 secondary outcome
Apixaban vs. Enoxaparin - Number of Participants With Venous Thromboembolism (VTE) Events
Time frame: 90 days
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Jun 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
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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.
Arash Momeni, MD principal investigator
Stanford University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1/2 study testing Apixaban 2.5 MG Oral Tablet and Enoxaparin 40Mg/0.4mL Prefilled Syringe in people with Venous Thromboembolism, run by Stanford University at 1 site in United States.
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 4 inclusion and 13 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 22 Jun 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. 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 combined phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 22 Jun 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
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?
Apixaban vs. Enoxaparin - Number of Participants With Bleeding Events (time frame: 90-day events). 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 22 Jun 2025.