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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 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)

Status
Completed
Phases
Phase 1
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT06444178
Enrollment
224
Registered
2024-06-05
Start date
2024-09-30
Completion date
2025-07-09
Last updated
2025-07-16

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Healthy Volunteers

Keywords

Gastrointestinal (GI) bleeding, Fecal occult blood testing (FOBT)

Brief 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). 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)

Interventions

DRUGAspirin

Oral administration

Administered intravenous (IV)

Administered IV

DRUGRivaroxaban

Oral administration

Sponsors

Regeneron Pharmaceuticals
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
18 Years to 55 Years
Healthy volunteers
Yes

Inclusion criteria

Key Inclusion Criteria: 1. Body mass index between 18.0 and 32.5 kg/m2 (inclusive) at the screening visit 2. 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 3. Normal aPTT, normal PT, and normal platelet counts at screening period and at the day 1 visit as defined by the local laboratory 4. Hemoglobin values within the normal range, per local laboratory, at the screening and day 1 visits 5. Negative FOBT at Baseline (visit 2) and visit 3 as defined in the protocol Key

Exclusion criteria

1. 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 2. Whole blood donation within the previous 56 days or plasma donation within the previous 7 days prior to the screening visit 3. Hospitalized for any reason within 30 days of the screening visit 4. Estimated glomerular filtrate rate (eGFR) of \<60 mL/min/1.73m2 at screening as described in the protocol. 5. Current smoker or former smoker, including e-cigarettes, who stopped smoking within 12 months prior to the screening visit 6. History of illicit drug or alcohol abuse within the last 2 years prior to the day 1 visit 7. Use of any prescription and nonprescription medications or nutritional supplements from approximately 2 weeks or 5 half-lives, as described in protocol 8. Has elective surgery planned to occur prior to end of study (EOS) Note: Other Protocol Defined Inclusion/

Design outcomes

Primary

MeasureTime frame
Change in fecal hemoglobin content (FHC)Baseline and up to day 22

Secondary

MeasureTime frame
Severity of TEAEUp to day 100
Incidence of major bleedingUp to day 100
Incidence of clinically relevant non-major (CRNM) bleedingUp to day 100
Concentrations of REGN9933Up to day 29
Concentrations of REGN7508Up to day 29
Incidence of treatment-emergent adverse events (TEAE)Up to day 100
Change in prothrombin time (PT)Baseline and up day 29
Incidence of Anti-drug antibody (ADA) to REGN9933Up to day 29
Titer of ADA to REGN9933Up to day 29
Incidence of ADA to REGN7508Up to day 29
Titer of ADA to REGN7508Up to day 29
Change in activated partial thromboplastin time (aPTT)Baseline and up day 29

Countries

United Kingdom

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026