This clinical research trial will evaluate the safety and tolerability of an experimental drug, ALN-F1202, in healthy participants.

The purpose of this trial is to learn about how safe and tolerable the experimental drug is. The trial is looking at several other research questions, including:

• What side effects may happen from taking the experimental drug?
• How much experimental drug is in the blood at different times?
• Whether the body makes antibodies against the experimental drug (which could make the drug less effective or could lead to side effects).
• What is the best dose of the experimental drug?

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. Is in good health based on laboratory safety testing obtained at the screening visit, as described in the protocol
4. Normal aPTT, normal PT, and normal platelet counts at screening period and at day -1 as defined by the local laboratory
5. Hemoglobin values at screening period and at day -1 as described in the protocol

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 screening
3. History of clinically significant bleeding, requiring hospitalization or blood products, that in the opinion of the investigator may pose a risk to the participant by study participation
4. History of bleeding diathesis as described in the protocol
5. Members of the clinical site study team and/or his/her immediate family, unless prior approval granted by the sponsor
6. Presents any concern to the study investigator that might confound the results of the study or poses an additional risk to the participant by their participation in the study

NOTE: Other protocol-defined inclusion/exclusion criteria apply

All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.

When Regeneron has:

• received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication or has globally discontinued development of the product for all indications on or after April 2020 and has no plans for future development
• made the study results publicly available (e.g., scientific publication, scientific conference, clinical trial registry)
• the legal authority to share the data, and
• ensured the ability to protect participant privacy

Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf