The purpose of the study is to compare the efficacy, safety and immunogenicity of MSB11456 and EU approved RoActemra® in participants with moderately to severely active rheumatoid arthritis.

Participants will be randomized at the beginning of the Core Treatment Period (Baseline to Week 24) to receive either MSB11456 or EU approved RoActemra® once a week (QW). At the beginning of the Extended Treatment Period (Week 24 to Week 52), participants who received RoActemra® will be re-randomized to either continue receiving RoActemra® QW or switch to receive MSB11456 QW.

Inclusion Criteria:

• Are ≥18 years of age.
• Diagnosis of rheumatoid arthritis according to the revised 1987 ACR/European League Against Rheumatism (EULAR) Classification 2010 criteria with disease duration of ≥6 months.
• Have moderately to severely active rheumatoid arthritis.
• Must have been treated with methotrexate for at least 12 consecutive weeks immediately prior to randomization and are on a stable dose between 10 and 25 mg/week methotrexate for the last 8 weeks prior to screening.
• Have had previous inadequate clinical response to at least one modifying anti-rheumatic drug.
• Women of childbearing potential (i.e., considered fertile following menarche and until becoming postmenopausal unless permanently sterile) can participate only if they have a negative serum pregnancy test at screening and a negative urine pregnancy test at Day -1 before randomization. Women of childbearing potential must have used and agree to use a highly effective contraception (i.e., methods with a failure rate of less than 1% per year), for 4 weeks before randomization and must agree to continue to practice adequate contraception for 3 months after the last study drug administration.
• Must voluntarily give written informed consent before any study-related activities are performed. Participants must read and fully understand the Informed Consent Form and the requirements of the study. Participants must be willing to comply with all study visits and assessments. Participants must be willing to complete each study procedure. Note: A separate Informed Consent Form (containing important information about COVID 19, clinical research study participation and participant consent) will be provided to and signed by each participant to provide information on the general risks of study participation related to COVID-19 and to document that it is understood by the participant. Another separate Informed Consent Form will be required to be understood and signed by partners of male participating patients who become pregnant during the study or within 10 weeks after the participating patient's last dose of study drug.

Exclusion Criteria:

• American College of Rheumatology functional class IV as defined by the ACR classification of functional status or wheelchair/bedbound.

• Previously received tocilizumab, an investigational or licensed biosimilar of tocilizumab or any interleukin-6 acting drugs.

• Prior use of targeted synthetic disease-modifying anti-rheumatic drugs like janus kinase inhibitors.

• Prior use of more than 2 biologic treatments for rheumatoid arthritis.

• Received a live or attenuated vaccine within 4 weeks prior to randomization.

• Participant is considered by the Investigator, for any reason, to be an unsuitable candidate for the study. Investigator should specifically evaluate the participant's eligibility taking into consideration COVID-19 risk factors and situation.

• Has a serious and/or unstable and/or poorly controlled medical condition such as but not limited to poorly controlled diabetes, unstable ischemic heart disease, uncontrolled hypertension or other cardiovascular, cerebrovascular, cardiovascular, gastrointestinal disease, hepatic, renal, hematological, endocrine, nervous system or pulmonary disease or other relevant medical condition or a history of clinically significant disease or any other condition that, in the opinion of the Investigator, would put the participant at risk by participation in the study.

• Confirmed or, based on the signs and symptoms observed at the time of assessment, suspected active COVID-19 infection at the time of screening and/or randomization.

• Has had any infection as follows:

  1. Herpes zoster or any opportunistic invasive infection within 6 months of screening.
  2. Frequent, chronic or recurrent infections.
  3. A positive test for human immunodeficiency virus subtype 1 (HIV-1) or 2 (HIV-2), hepatitis C antibody, hepatitis B surface antigen and/or core antibody for immunoglobulin G and/or immunoglobulin M or total immunoglobulin at screening.
  4. A serious infection within 8 weeks prior to randomization.
  5. Required treatment with oral antibiotics and/or anti-fungal drugs within 14 days prior to randomization.

• Medical evidence of active or latent tuberculosis as indicated by a positive QuantiFERON®-TB Gold Plus test, chest X-ray and/or clinical examination or has had active or latent tuberculosis disease at any time in the past.

• Received a COVID 19 vaccine within 4 weeks prior to randomization, are receiving ongoing COVID-19 vaccination at the time of screening or plan to receive COVID-19 vaccination before the completion of the Week 30 visit of the study. COVID-19 vaccination is considered ongoing if a multidose regimen has been started but has not been completed.