Due to small number of participants entering randomization. Not a safety issue.

Primary Objective:

To demonstrate the treatment effect of sarilumab and methotrexate (MTX) compared to etanercept and MTX in participants with rheumatoid arthritis (RA) and an inadequate response to adalimumab and MTX by evaluation of the Disease Activity Score for 28 joints (DAS28).

Secondary Objectives:

To assess the signs and symptoms of RA in participants taking sarilumab in combination with MTX.

To assess the quality of life of participants with RA taking sarilumab in combination with MTX.

To assess the safety and tolerability of sarilumab in combination with MTX in participants with RA.

The maximum study duration per participant enrolled in the open label run-in phase and was eligible to enroll in the randomized phase of main study was 54 weeks:

• open label screening period of up to 4 weeks
• open-label treatment period of 16 weeks
• randomized screening period of 2 to 4 weeks
• randomized treatment post-treatment safety follow-up period of 6 weeks.

The maximum study duration per participant enrolled only in the open label run-in phase and was not eligible to enroll in the randomized phase of main study was 26 weeks:

• open label screening period of up to 4 weeks
• open-label treatment period of 16 weeks
• open label treatment post-treatment safety follow-up period of 6 weeks.

The maximum study duration per participant enrolled in the open label run-in phase and was eligible to enroll in the sarilumab sub-study was 82 weeks:

• open label screening period of up to 4 weeks
• open-label treatment period of 16 weeks
• screening period of 2 to 4 weeks
• sarilumab treatment period of 52 weeks
• sub-study post-treatment safety follow-up period of 6 weeks.

Inclusion criteria:

• Diagnosis of RA >/= 3 months duration.
• Continuous treatment of MTX 10 - 25 mg/week (or per local labeling requirements if the dose range differs) for at least 12 weeks before screening visit and on a stable dose for 8 weeks before screening visit.
• Active disease defined as: at least 6/66 swollen and 8/68 tender joints and high sensitivity C-reactive protein > 10 mg/L.

Exclusion criteria:

• Age < 18 years.
• Use of parenteral corticosteroids or intra-articular corticosteroids within 4 weeks of the screening visit.
• Use of oral corticosteroids in a dose higher than prednisone 10 mg or equivalent per day, or a change in dosage within 4 weeks of the screening visit.
• Prior treatment with a tumor necrosis factor (TNF)-alpha inhibitor, or other biological disease modifying anti-rheumatoid drug (DMARD) or Janus Kinase inhibitor.
• New treatment with or dose-adjustment of on-going nonsteroidal anti-inflammatory drugs (NSAIDs) or cyclo-oxygenase-2 (COX-2) inhibitors within 4 weeks of the screening visit.
• Treatment with traditional oral DMARD /immunosuppressive agents other than MTX within 4 weeks or 12 weeks before the screening visit, depending on DMARD.

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