Safety and tolerability assessment of REGN9533 in healthy adults

A Phase 1, Randomized, Double-Blind, Placebo Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single Ascending Doses of REGN9533, a Monoclonal Antibody Against Factor XII, in Healthy Adults

Phase 1 Interventional Regeneron Pharmaceuticals · NCT06665828

This study is testing the new drug REGN9533 in healthy adults to see if it's safe and how well the body tolerates it.

Quick facts

PhasePhase 1
Study typeInterventional
Enrollment56 (estimated)
Ages18 Years to 55 Years
SexAll
SponsorRegeneron Pharmaceuticals Industry-sponsored
Locations1 site (Edegem, Antwerp)
Trial IDNCT06665828 on ClinicalTrials.gov

What this trial studies

This clinical trial aims to evaluate the safety and tolerability of the drug REGN9533 in healthy adult participants. It is the first time this drug will be administered to humans, and the study will monitor side effects, blood concentration levels, and the body's immune response to the drug. Additionally, the trial will determine the optimal dosage of REGN9533 for future studies targeting thromboembolic diseases. Participants will receive either REGN9533 or a matching placebo during the trial.

Who should consider this trial

Good fit: Ideal candidates are healthy adults aged 18 to 65 with a body mass index between 18 and 32 kg/m2.

Not a fit: Patients with a history of significant bleeding or recent major surgeries may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could pave the way for future treatments for thromboembolic diseases.

How similar studies have performed: Other studies have shown success in assessing the safety of new drugs in healthy volunteers, making this approach well-established.

Eligibility criteria

Show full inclusion / exclusion criteria
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

Where this trial is running

Edegem, Antwerp

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Healthy Volunteer
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.