Healthy VolunteersPhase 1NCT06444178
Assessment of Gastrointestinal Blood Loss After Receiving Aspirin or Aspirin Plus Rivaroxaban, or Aspirin Plus REGN9933, or Aspirin Plus REGN7508 in Healthy Adult Participants
A Phase 1 study testing Aspirin, REGN9933 and REGN7508 in people with Healthy Volunteers, run by Regeneron Pharmaceuticals at 1 site in United Kingdom.
Trial summary
This study is researching experimental drugs called REGN9933 and REGN7508 (called "study drugs") and comparing their effects to approved treatments of rivaroxaban and aspirin (called "standard treatments"). Read more about this study
- Who is it for?
- Ages 18 to 55 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy Volunteers
- What is being tested?
- Aspirin, REGN9933 and REGN7508
- Type of treatment
- Pill or oral medicine, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 224 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 30 Sep 2024to 9 Jul 2025
- Phase
- Phase 1
- 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 55 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Body mass index between 18.0 and 32.5 kg/m2 (inclusive) at the screening visit
- Judged by the investigator to be in good health based on medical history, physical examination, vital sign measurements, and electrocardiograms (ECGs) performed at screening and/or prior to administration of initial dose of study treatment
- Normal aPTT, normal PT, and normal platelet counts at screening period and at the day 1 visit as defined by the local laboratory
- Hemoglobin values within the normal range, per local laboratory, at the screening and day 1 visits
- Negative FOBT at Baseline (visit 2) and visit 3 as defined in the protocol
Who cannot join
- History of any major surgical procedure or clinically significant physical trauma in the last 6 months, in the opinion of the investigator, that may pose a risk to the participant by study participation
- Whole blood donation within the previous 56 days or plasma donation within the previous 7 days prior to the screening visit
- Hospitalized for any reason within 30 days of the screening visit
- Estimated glomerular filtrate rate (eGFR) of <60 mL/min/1.73m2 at screening as described in the protocol.
- Current smoker or former smoker, including e-cigarettes, who stopped smoking within 12 months prior to the screening visit
- History of illicit drug or alcohol abuse within the last 2 years prior to the day 1 visit
Show all 9Show fewer
- Use of any prescription and nonprescription medications or nutritional supplements from approximately 2 weeks or 5 half-lives, as described in protocol
- Has elective surgery planned to occur prior to end of study (EOS)
- Note: Other Protocol Defined Inclusion/ Exclusion Criteria Apply
Trial locations and contacts
1 site in 1 country.
About this study
Official title: A Parallel Group Study in Healthy Participants to Quantitate Increases in Subclinical Gastrointestinal Blood Loss Following Administration of Aspirin Alone or in Combination With Rivaroxaban or Factor XI Inhibitors (REGN9933 or REGN7508)
This study is researching experimental drugs called REGN9933 and REGN7508 (called "study drugs") and comparing their effects to approved treatments of rivaroxaban and aspirin (called "standard treatments"). Aspirin will be given alone or in combination with the study drugs or the other standard treatments to look at their effects on blood loss in the intestines.
The aim of the study is to see if aspirin alone or the study drugs REGN9933 and REGN7508, when taken with aspirin, cause less minor intestinal bleeding than standard treatments rivaroxaban with aspirin.
Read more
The study is looking at several other research questions, including:
- What side effects may happen from taking the study drug
- How much study drug is in the blood at different times
- Whether the body makes antibodies against the study drug (which could make the drug less effective or could lead to side effects)
- Conditions
- Healthy Volunteers
- Being tested
- Aspirin, REGN9933, REGN7508, Rivaroxaban
- Keywords
- Gastrointestinal (GI) bleeding, Fecal occult blood testing (FOBT)
- Medical subject headings
- Hemorrhage
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
AspirinDrug
Oral administration
REGN9933Drug
Administered intravenous (IV)
REGN7508Drug
Administered IV
RivaroxabanDrug
Oral administration
| Study group | Role | What they receive |
|---|---|---|
| Arm 1: Aspirin | Active comparator | Randomized 1:1:1:1 Receives: Drug: Aspirin |
| Arm 2: Aspirin + REGN9933 | Experimental | Randomized 1:1:1:1 Receives: Drug: Aspirin; Drug: REGN9933 |
| Arm 3: Aspirin + REGN7508 | Experimental | Randomized 1:1:1:1 Receives: Drug: Aspirin; Drug: REGN7508 |
| Arm 4: Aspirin + Rivaroxaban | Active comparator | Randomized 1:1:1:1 Receives: Drug: Aspirin; Drug: Rivaroxaban |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in fecal hemoglobin content (FHC)
Measured: Baseline and up to day 22
Secondary outcomes (12)
Incidence of treatment-emergent adverse events (TEAE)
Measured: Up to day 100
Severity of TEAE
Measured: Up to day 100
Incidence of major bleeding
Measured: Up to day 100
Incidence of clinically relevant non-major (CRNM) bleeding
Measured: Up to day 100
Concentrations of REGN9933
Measured: Up to day 29
Concentrations of REGN7508
Measured: Up to day 29
Change in activated partial thromboplastin time (aPTT)
Measured: Baseline and up day 29
Change in prothrombin time (PT)
Measured: Baseline and up day 29
Incidence of Anti-drug antibody (ADA) to REGN9933
Measured: Up to day 29
Titer of ADA to REGN9933
Measured: Up to day 29
Incidence of ADA to REGN7508
Measured: Up to day 29
Titer of ADA to REGN7508
Measured: Up to day 29
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 Jun 2024
- Study start30 Sep 2024
- Primary completion7 Apr 2025
- Study completion9 Jul 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy VolunteersStudies of the same condition, open and under way.
- More trials run by Regeneron PharmaceuticalsThe 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
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 224 participants (actual)
Sponsor and investigators
- Lead sponsor
- Regeneron Pharmaceuticals
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Clinical Trial Management, Study director, Regeneron Pharmaceuticals
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06444178
- Sponsor's protocol ID
- R9933-HV-2424
- Status last verified
- Jul 2025
- First submitted
- 30 May 2024
- Last updated
- 16 Jul 2025
- Results posted
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.
Study at a glance
From the registry record, last updated by the sponsor on 16 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Parallel Group Study in Healthy Participants to Quantitate Increases in Subclinical Gastrointestinal Blood Loss Following Administration of Aspirin Alone or in Combination With Rivaroxaban or Factor XI Inhibitors (REGN9933 or REGN7508)
- ClinicalTrials.gov ID
- NCT06444178
- Acronym / sponsor ID
- R9933-HV-2424
- Conditions
- Healthy Volunteers
- Keywords
- Gastrointestinal (GI) bleeding, Fecal occult blood testing (FOBT)
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 224 participants (actual)
- Lead sponsor
- Regeneron PharmaceuticalsIndustry (pharma, biotech, devices)
- Study start
- 30 Sep 2024 (actual)
- Primary completion
- 7 Apr 2025 (actual)
- Study completion
- 9 Jul 2025 (actual)
- First posted
- 5 Jun 2024 (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.
This study is researching experimental drugs called REGN9933 and REGN7508 (called "study drugs") and comparing their effects to approved treatments of rivaroxaban and aspirin (called "standard treatments"). Aspirin will be given alone or in combination with the study drugs or the other standard treatments to look at their effects on blood loss in the intestines.
The aim of the study is to see if aspirin alone or the study drugs REGN9933 and REGN7508, when taken with aspirin, cause less minor intestinal bleeding than standard treatments rivaroxaban with aspirin.
The study is looking at several other research questions, including:
- What side effects may happen from taking the study drug
- How much study drug is in the blood at different times
- Whether the body makes antibodies against the study drug (which could make the drug less effective or could lead to side effects)
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Arm 1: Aspirin | Active comparator | Drug: AspirinRandomized 1:1:1:1 |
| Arm 2: Aspirin + REGN9933 | Experimental | Drug: Aspirin, Drug: REGN9933Randomized 1:1:1:1 |
| Arm 3: Aspirin + REGN7508 | Experimental | Drug: Aspirin, Drug: REGN7508Randomized 1:1:1:1 |
| Arm 4: Aspirin + Rivaroxaban | Active comparator | Drug: Aspirin, Drug: RivaroxabanRandomized 1:1:1:1 |
Who may qualify
- Ages
- 18 to 55 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Body mass index between 18.0 and 32.5 kg/m2 (inclusive) at the screening visit
- Judged by the investigator to be in good health based on medical history, physical examination, vital sign measurements, and electrocardiograms (ECGs) performed at screening and/or prior to administration of initial dose of study treatment
- Normal aPTT, normal PT, and normal platelet counts at screening period and at the day 1 visit as defined by the local laboratory
- Hemoglobin values within the normal range, per local laboratory, at the screening and day 1 visits
- Negative FOBT at Baseline (visit 2) and visit 3 as defined in the protocol
Key exclusion criteria (9 listed)
- History of any major surgical procedure or clinically significant physical trauma in the last 6 months, in the opinion of the investigator, that may pose a risk to the participant by study participation
- Whole blood donation within the previous 56 days or plasma donation within the previous 7 days prior to the screening visit
- Hospitalized for any reason within 30 days of the screening visit
- Estimated glomerular filtrate rate (eGFR) of <60 mL/min/1.73m2 at screening as described in the protocol.
- Current smoker or former smoker, including e-cigarettes, who stopped smoking within 12 months prior to the screening visit
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 |
|---|---|---|
| AspirinOral administration | Drug | Arm 1: Aspirin, Arm 2: Aspirin + REGN9933, Arm 3: Aspirin + REGN7508, Arm 4: Aspirin + Rivaroxaban |
| REGN9933Administered intravenous (IV) | Drug | Arm 2: Aspirin + REGN9933 |
| REGN7508Administered IV | Drug | Arm 3: Aspirin + REGN7508 |
| RivaroxabanOral administration | Drug | Arm 4: Aspirin + Rivaroxaban |
Primary outcome
Change in fecal hemoglobin content (FHC)
Time frame: Baseline and up to day 22
12 secondary outcomes
Incidence of treatment-emergent adverse events (TEAE)
Time frame: Up to day 100
Severity of TEAE
Time frame: Up to day 100
Incidence of major bleeding
Time frame: Up to day 100
Incidence of clinically relevant non-major (CRNM) bleeding
Time frame: Up to day 100
Concentrations of REGN9933
Time frame: Up to day 29
Concentrations of REGN7508
Time frame: Up to day 29
Change in activated partial thromboplastin time (aPTT)
Time frame: Baseline and up day 29
Change in prothrombin time (PT)
Time frame: Baseline and up day 29
Incidence of Anti-drug antibody (ADA) to REGN9933
Time frame: Up to day 29
Titer of ADA to REGN9933
Time frame: Up to day 29
Incidence of ADA to REGN7508
Time frame: Up to day 29
Titer of ADA to REGN7508
Time frame: Up to day 29
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 16 Jul 2025.
- Individual participant dataSharing planned: Yes. All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.
Related trials for Healthy Volunteers
Not yet recruiting
Neuroergonomic Analysis of a Brain-Computer Interface Device (BCI)
Healthy Volunteers - Male and Female
RecruitingPhase 1
First-in-Human Trial to Assess REGN20423 in Healthy Adult Participants and Adult Participants With Atopic Dermatitis
Healthy Volunteer, Atopic Dermatitis
Not yet recruitingObservational study
Establishment of Biobank of Nasal Epithelium Samples From Healthy Volunteers
Healthy
RecruitingObservational study
Improved Methods of Cell Selection for Bone Marrow Transplant Alternatives
Graft-Versus-Host Disease, Graft-versus-leukemia
Not yet recruitingObservational study
Screening Protocol
Pain
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.
Clinical Trial Management study director
Regeneron Pharmaceuticals
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing Aspirin, REGN9933 and REGN7508 in people with Healthy Volunteers, run by Regeneron Pharmaceuticals at 1 site in United Kingdom.
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 5 inclusion and 9 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 16 Jul 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 Kingdom. 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 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.
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?
Change in fecal hemoglobin content (FHC) (time frame: Baseline and up to day 22). 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 16 Jul 2025.