This is a randomized, double-blind, placebo-controlled single-dose study of the safety and tolerability of intravenously administered REGN475 in healthy volunteers. The primary objective of the study is to assess the safety and tolerability of REGN475. The secondary objectives are to characterize the pharmacokinetic and immunogenicity profiles of REGN475.

Key Inclusion Criteria:

• Male or female volunteers, in general good health and 21 to 65 years of age.
• Female volunteers must be post-menopausal for at least 1 year or surgically sterile.

Key Exclusion Criteria:

• Significant concomitant illness such as, but not limited to, cardiac, renal, neurological, endocrinological, GI, hepatic, metabolic or lymphatic disease that would adversely affect the subject's participation in this study or interpretation of safety/ PK data
• Participation in any clinical research study evaluating another investigational drug or therapy within 3 weeks or at least 5 half-lives of the investigational drug, whichever is longer, prior to the Screening Visit.