The primary objective of the study is to evaluate the safety and tolerability of single ascending doses of REGN5069 administered intravenously (IV) and subcutaneously (SC) in healthy male and female participants.

The secondary objectives of the study are to characterize the pharmacokinetics (PK) profile of single IV and SC doses of REGN5069 in healthy participants and assess the immunogenicity of REGN5069 in healthy participants administered single IV or SC doses of REGN5069

Key Inclusion Criteria:

• Participant is judged by the investigator to be in good health based on medical history, physical examination, vital sign measurements, and ECG performed at screening and/or prior to study drug dosing
• Participant is in good health based on laboratory safety testing obtained at the screening visit
• Willing and able to comply with clinic visits and study-related procedures
• Provide informed consent signed by study participant or legally acceptable representative

Key Exclusion Criteria:

• History of clinically significant cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematological, psychiatric or neurological disease
• Has any physical examination findings and/or history of any illness that might confound the results of the study or poses an additional risk to the subject by study participation
• Hospitalization for any reason within 60 days of the screening visit
• Current cigarette smoker or former smoker (cigarettes or e-cigarettes) who stopped smoking within 3 months prior to screening
• History of drug or alcohol abuse within a year prior to the screening visit
• Presence of HIV, hepatitis B, or hepatitis C seropositivity at screening or within 3 months prior to dosing with the exception of false positive screening tests as documented by polymerase chain reaction or Western blot
• Any malignancy within the past 5 years, except for basal cell or squamous epithelial cell carcinomas of the skin or carcinoma in situ of the cervix or anus, that have been resected, with no evidence of metastatic disease for 3 years

Note: Other protocol Inclusion/Exclusion Criteria apply