Safety Study of a Single Dose of REGN88(SAR153191)in Patients With Rheumatoid Arthritis

This is a multi-center, randomized, double blind, placebo-controlled, single dose escalation study of the safety and tolerability of subcutaneously administered REGN88 in rheumatoid arthritis patients who are receiving concomitant methotrexate.

Three (3) sequential dose cohorts of 5 subjects (4:1 active: placebo) will be dosed SC with REGN88 or placebo. Subjects who complete the study will participate in 14 study visits over 16 weeks.

Inclusion criteria

• Male or female ≥ 18 years of age
• Subjects must weigh > 50 kg and < 100 kg
• Diagnosis of Rheumatoid Arthritis (RA) as defined by the 1987 revised American College of Rheumatology (ACR) criteria with disease duration of no less than 6 months and ACR class I-III
• For women of childbearing potential, a negative serum pregnancy test at the Screening Visit (Visit 1) and a negative urine pregnancy test at Day -1
• For men and women of childbearing potential, willingness to utilize adequate contraception and not become pregnant (or have their partner[s] become pregnant) during the full course of the study.

Exclusion criteria

• A history of Listeriosis or active tuberculosis (TB)
• Persistent chronic or active recurring infection requiring treatment with antibiotics, antivirals, or antifungals within 4 weeks prior to the Screening Visit
• History of prior articular or prosthetic joint infection
• History of a hypersensitivity reaction, other than localized injection site reaction (ISR), to any biological molecule
• Significant concomitant illness such as, but not limited to cardiac, renal, neurological, endocrinological, metabolic or lymphatic disease that would adversely affect the subject's participation in this study
• Received administration of any live (attenuated) vaccine within 3 months prior to the Screening Visit