Primary Objective:

To assess the safety and tolerability of a single dose of subcutaneously administered sarilumab in Japanese patients with rheumatoid arthritis (RA) who are receiving concomitant treatment with methotrexate.

Secondary Objective:

To assess the pharmacokinetic profile of a single subcutaneous (SC) dose of sarilumab in Japanese RA patients.

Total study duration per patient is up to 88 days

1. Screening: 3 to 28 days
2. Treatment: 1 day
3. Follow-up: 57± 3 days after dosing

Inclusion criteria:

1. Male or female Japanese who are 20 to 65 years of age
2. Diagnosis of rheumatoid arthritis (RA) ≥ 3 months duration
3. Treated for a minimum of 8 weeks with Methotrexate (MTX) and with a stable dose of MTX (6-16 mg/week) for a minimum of 4 weeks prior to the screening visit

Exclusion criteria:

1. Autoimmune or inflammatory systemic or localized joint disease other than RA

2. Women of a positive pregnancy test

3. Latent or active tuberculosis

4. Prior treatment with anti-interleukin-6 (anti-IL-6) or anti-interleukin-6 receptor (IL-6R) antagonist

5. Treatment with anti-TNF agents, as follows:

   1. Etanercept: within 28 days prior to randomization
   2. Infliximab, adalimumab, golimumab, certolizumab pegol: within 42 days prior to randomization

6. Received any live, attenuated vaccine within 3 months prior to the randomization visit (eg, varicella-zoster, oral polio, rubella vaccines)

7. Significant concomitant illness such as, but not limited to, cardiovascular, renal, neurological, endocrinological, gastrointestinal, hepato-biliary, metabolic, pulmonary or lymphatic disease that would adversely affect the patient's participation in the study.

8. Received surgery within 4 weeks prior to the screening visit or planned surgery during the study

9. History of a systemic hypersensitivity reaction

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.