New blood clot drug tested in humans for first time
NCT ID NCT06665828
First seen Jun 27, 2026 · Last updated Jun 27, 2026
Summary
This early-stage trial tested the safety of a new drug called REGN9533 in 72 healthy adults. REGN9533 is a monoclonal antibody that blocks factor XII, a protein involved in blood clotting. The goal was to see if it is safe and how the body processes it, before testing it in people with blood clot disorders.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- REGN9533 (a monoclonal antibody that blocks factor XII, a protein involved in blood clotting)
- What this could lead to
- If successful, this could lead to a new treatment to prevent dangerous blood clots (thromboembolic diseases) with potentially fewer bleeding risks than current options.
- What could go wrong
- This is a very early Phase 1 trial in only 72 healthy people, so it is not designed to prove effectiveness. The drug may cause unexpected side effects or fail in later studies.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
-
Phase 1
The first testing in people. Mainly checks safety and dose, usually in a small group.
- Participants
-
72 people
The number who actually took part.
- Started
-
Mar 2025
- Finished
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Jan 2026
- Lead sponsor
-
A company
The lead sponsor is a pharmaceutical, biotech, or medical-device company.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
-
18 to 55 years
- Sex
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Anyone
- Healthy volunteers
-
Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Key Inclusion Criteria: 1. Has a body mass index between 18 and 32 kg/m2, inclusive 2. Is 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 drug 3. Normal aPTT, normal PT, and normal platelet counts as described in the protocol 4. Hemoglobin values at screening period and at day -1 as described in the protocol 5. Negative Fecal Occult Blood Test (FOBT) during screening period 6. Normal Bleeding Time Test (BTT) at day -1 as defined by the study site Key Exclusion Criteria: 1. History of any major surgical procedure or clinically significant physical trauma within the last 6 months that in the opinion of the investigator may pose a risk to the participant by study participation 2. History of clinically significant bleeding, requiring hospitalization or blood products within the last 6 months, that in the opinion of the investigator may pose a risk to the participant by study participation 3. History of bleeding diathesis (eg, including, but not limited to Hemophilia A or B, von Willebrand's Factor deficiency, fibrinogen deficiency, and other inherited or acquired bleeding disorders) 4. History of clinically significant cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematological, psychiatric, or neurological disease, as assessed by the investigator, that may confound the results of the study or poses an additional risk to the participant by study participation 5. Is a current smoker including e-cigarettes or other nicotine-containing products; or is a former smoker including e-cigarettes or other nicotine-containing products which they have used at any time within 3 months prior to the screening visit 6. Has a confirmed positive drug test result at the screening visit and/or prior to randomization; or a history of recreational drug use (eg, marijuana) and/or drug or alcohol abuse within a year prior to the screening visit 7. Any malignancy, except for non-melanoma skin cancer or cervical/anus in-situ, that have been resected with no evidence of metastatic disease for 3 years prior to the screening visit 8. Has a history of significant multiple and/or severe allergies (eg, latex gloves), or has had an anaphylactic reaction to prescription or non-prescription drugs or food Note: Other protocol-defined Inclusion/Exclusion Criteria apply
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As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
-
SGS Belgium NV_Edegem
Edegem, Antwerp, 2650, Belgium
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