Primary Objective:

To describe the safety and tolerability, including laboratory abnormalities following a single dose of sarilumab or tocilizumab administered subcutaneously (SC) as monotherapy in Japanese patients with rheumatoid arthritis (RA).

Secondary Objectives:

To describe the laboratory abnormalities (absolute neutrophil count [ANC], platelet counts, total cholesterol, high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol, and liver function tests [LFTs]) following a single dose of sarilumab or tocilizumab administered SC as monotherapy in Japanese patients with RA.

To describe the pharmacokinetics (PK) of sarilumab and tocilizumab.

Total study duration (per patient) is expected to be up to 71 days including screening (3 to 28 days before dosing).

Inclusion criteria:

• Patients with rheumatoid arthritis (RA) as defined by the American College of Rheumatology (ACR)/European League against Rheumatism (EULAR) 2010
• Rheumatoid Arthritis Classification Criteria.
• ACR Class I-III functional status, based on the 1991 revised criteria.

Exclusion criteria:

• Patients less than 20 years of age.
• Prior treatment with any biologic anti-interleukin-6 (anti-IL-6) or interleukin-6 receptor (IL-6R) antagonist.
• Any parenteral or intraarticular glucocorticoid injection within 4 weeks prior to randomization.
• Treatment with prednisone higher than 10 mg or equivalent per day, or change in dosage within 4 weeks prior to randomization.
• Treatment with disease-modifying antirheumatic drugs (DMARDs), immunosuppressive agents, tumor necrosis factor (TNF) antagonists or any other RA-directed biologic agents within a certain amount of time prior to randomization.
• 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.
• Active or suspected tuberculosis (TB) or at high risk of contracting TB.
• Fever, or chronic, persistent, or recurring infection(s) requiring active treatment.
• The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.