Primary Objective:

To assess, in the same study, the safety of sarilumab and tocilizumab in participants with rheumatoid arthritis (RA) who were inadequate responders to or intolerant of tumor necrosis factor (TNF) antagonists.

Total study duration was up to 34 weeks: Screening up to 28 days, treatment phase of 24 weeks, and post-treatment follow-up of 6 weeks.

After completion of the treatment phase of this study, participants were eligible to enter a long term safety study (LTS11210) for active treatment with SAR153191 (REGN88).

Inclusion criteria:

Diagnosis of RA was, according to the American College of Rheumatology (ACR)/European League against Rheumatism (EULAR) 2010 Rheumatoid Arthritis Classification Criteria with ≥ 3 months disease duration

ACR Class I-III functional status, was based on the 1991 revised criteria. Moderate-to-severely active RA. Anti-TNF therapy failures, was defined as participants with an inadequate clinical response was defined by the investigator, after being treated for at least 3 consecutive months, and/or intolerance to at least 1 TNF-antagonist, resulting in or requiring their discontinuation. TNF-antagonists were include, but were not limited to, etanercept, infliximab, adalimumab, golimumab and/or certolizumab pegol

Continuous treatment with one or a combination of non-biologic disease modifying antirheumatic drugs (DMARDs) for at least 12 consecutive weeks prior to screening and on a stable dose(s) for at least 6 consecutive weeks prior to screening:

• Methotrexate - 10 to 25 milligram/week orally or parenteral (or per local labelling requirements if the dose range differs)
• Leflunomide - 10 to 20 mg orally daily
• Sulfasalazine (SSZ) - 1000 to 3000 mg orally daily
• Hydroxychloroquine (HCQ) - 200 to 400 mg orally daily

Exclusion criteria:

Participants <18 years of age. Use of parenteral corticosteroids or intra-articular corticosteroids within 4 weeks prior to screening

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 screening

Past history of, or current, autoimmune or inflammatory systemic or localized joint disease(s) other than RA

History of juvenile idiopathic arthritis or arthritis onset prior to age 16. Severe systemic RA, including but not limited to vasculitis, pulmonary fibrosis, and/or Felty's syndrome

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 was longer

Participants with active tuberculosis or latent tuberculosis infection. Prior or current history of interstitial lung disease. Prior treatment with anti-interleukin (IL) -6 or anti-IL-6R therapies, including but not limited to tocilizumab or sarilumab

Treatment with anti-TNF agents, as follows:

• Etanercept: within 28 days prior to randomization
• Infliximab, adalimumab, golimumab, certolizumab pegol: within 42 days prior to randomization

Treatment with RA-directed biologic agents with non- TNF-α antagonist mechanisms without adequate washout as follows:

• Anakinra: within 28 days prior to randomization
• Abatacept: within 42 days prior to randomization
• Rituximab or other cell depleting agent: Within 6 months prior to randomization or until total lymphocyte count and CD 19+ lymphocyte count were normalized, or whichever was longer

Prior treatment with a janus kinase (JAK) inhibitor (eg, tofacitinib). Participants with a history of invasive opportunistic infection. Prior or current history of malignancy, including lymphoproliferative diseases, other than adequately-treated carcinoma in-situ of the cervix, nonmetastatic squamous cell or basal cell carcinoma of the skin, within 5 years prior to the randomization (baseline) visit

Prior or current history of other significant concomitant illness(es) that, according to Investigator's judgement, was adversely affect the participant's participation in the study.

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