The main purposes of this study are to describe the pharmacodynamic effects, safety and pharmacokinetics of a single dose of sarilumab.

Inclusion Criteria:

1. Patients with RA as defined by the 2010 revised American College of Rheumatology (ACR)
2. ACR Class I-III functional status, based on the 1991 revised criteria
3. Treated for a minimum of 12 weeks with Methotrexate with a stable dose of MTX for at least 8 weeks prior to screening visit

Exclusion Criteria:

1. Patients less than 18 years of age or minimum legal age
2. Prior treatment with any biologic anti-Interleukin 6 (IL-6) or IL-6 Receptor (IL-6R) antagonists
3. Use of parenteral corticosteroids or intra-articular corticosteroids within 4 weeks prior to screening
4. Use of oral corticosteroids in a dose higher than prednisone 10 mg or equivalent per day, or a change in dosage within 4 weeks prior to randomization
5. Participation in any clinical research study that evaluated an investigational drug or therapy within 5 half-lives or 60 days of the screening visit, whichever is longer
6. Treatment with oral/ biologic DMARDs (disease-modifying antirheumatic drugs), other than MTX, within a certain amount of time prior to screening visit
7. Active or suspected TB or at high risk of contracting TB
8. Fever, or chronic, persistent, or recurring infections requiring active treatment
9. HIV positive

Note: The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial therefore not all inclusion/ exclusion criteria are listed.