A Trial to Learn if Single Ascending Intravenous (IV) Doses of REGN7508 Are Safe and Well Tolerated, and How it Works in the Body of Healthy Adult Participants

A Phase 1, Randomized, Double-Blind, Placebo-Controlled, Single-Center Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single Ascending Doses of REGN7508, a Monoclonal Antibody Against Factor XI, in Healthy Adult Subjects

This study is researching an experimental drug called REGN7508 (called "study drug"). The aim of this study is to see how safe and tolerable the study drug is in healthy participants.

This 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)

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 echocardiograms (ECGs) performed at screening and/or prior to administration of initial dose of study drug
3. Participant is in good health based on laboratory safety testing obtained at the screening visit and/or prior to administration of initial dose of study drug
4. Normal activated partial thromboplastin time (aPTT), normal prothrombin time (PT), and normal platelet counts at screening period and at the day -1 visit as defined by the local laboratory
5. Hemoglobin value ≥11.0 g/dL for females and ≥12.9 g/dL for males at the screening and day 1 visits

Key Exclusion Criteria:

1. History of any major surgical procedure or clinically significant physical trauma, 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. History of clinically significant cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematological, psychiatric, neurological, or dermatologic 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, as defined in the protocol
4. Estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73m2 at screening
5. Current smoker or former smoker, including e-cigarettes, who stopped smoking within 12 months prior to the screening visit
6. Confirmed positive drug test result at the screening visit and/or prior to randomization or a history of drug abuse within a year prior to the screening visit
7. History of alcohol abuse within the last 2 years prior to the day 1 visit
8. Any malignancy, except for nonmelanoma 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
9. History of significant multiple and/or severe allergies (eg, latex gloves) or has had an anaphylactic reaction to prescription or nonprescription drugs or food

NOTE: Other Protocol Defined Inclusion / Exclusion Criteria Apply