This study is researching an experimental drug called REGN13335. This is the first time that REGN13335 will be given to people. This study will enroll healthy adults.

The aim of the study is to see how safe and tolerable REGN13335 is in healthy volunteers.

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 present in the blood of study participants 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. Has a body mass index between 18 and 32 kg/m^2, inclusive, at the screening visit
2. Is judged by the investigator to be in good health based on medical history, physical examination, vital sign measurements, laboratory safety tests, and electrocardiograms (ECGs) performed prior to administration of study drug (ie, screening and baseline visit)

Key Exclusion Criteria:

1. History of clinically significant cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematological, psychiatric or neurological disease, as assessed by the investigator

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