Study to Evaluate Adverse Events and Change in Disease Activity in Participants Between 18 to 75 Years of Age Treated With Subcutaneous (SC) Injections of ABBV-154 for Moderately to Severely Active Rheumatoid Arthritis (RA)

Rheumatoid Arthritis (RA) is an inflammatory disease of the joints causing pain, stiffness, swelling and loss of joint function. This study evaluated how safe and effective ABBV-154 is in participants treated for moderately to severely active RA. Adverse events and change in the disease activity were assessed.

ABBV-154 is an investigational drug being evaluated for the treatment of RA. Study doctors placed the participants in 1 of 5 treatment groups or arms; each arm received a different treatment. There was a 1 in 5 chance that participants were assigned to placebo. Participants 18-75 years of age with moderate to severe RA were enrolled. Around 425 participants were to be enrolled in the study at approximately 270 sites worldwide.

The study was comprised of a 12 week placebo-controlled period, a double-blind long term extension (LTE) period 1 of 66 weeks, a LTE period 2 of 104 weeks and a follow-up visit 70 days after the last dose of the study drug. In the LTE period 1, participants in the placebo group were re-randomized to receive ABBV-154 at 1 of 2 different doses SC every other week (EOW). Other participants remained on their previous dose and dosing regimen of ABBV-154.

There may have been a higher treatment burden for participants in this trial compared to their standard of care. Participants attended regular visits during the study at a hospital or clinic. The effect of the treatment was checked by medical assessments, blood tests, and side effects, and completing questionnaires.

Participants were randomly assigned at a ratio of 1:1:1:1:1 to ABBV-154 at either 40 mg, 150 mg, 340 mg, subcutaneously (SC) EOW; 340 mg SC every 4 weeks (E4W); or placebo SC EOW. Randomization was stratified by baseline glucocorticoid (yes/no); number of prior failed biologic and/or targeted synthetic disease-modifying anti-rheumatic drugs (b/tsDMARDs) (1; 2 or more); and prior anti-TNF failure (yes/no) and if yes, further stratification by prior adalimumab use (yes/no).

After 12 weeks, participants receiving placebo were re-randomized to receive ABBV-154 150 mg SC EOW or 340 mg SC EOW for the long-term extension (LTE) periods. At re-randomization, participants were stratified by baseline glucocorticoid use (yes/no) and prior adalimumab use (yes/no). Participants from the other dose groups were to continue with their respective dose and dosing regimen.

The primary analysis was conducted after all ongoing participants completed Week 12 or withdrew from the study. A final analysis was to be conducted after all participants completed LTE period 2 and a safety follow-up visit or withdrew from the study. The study was terminated before any participants entered LTE Period 2.

Eligibility Criteria:
Inclusion Criteria:

* Clinical diagnosis of rheumatoid arthritis(RA) with fulfillment of the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria for RA.
* Participant has \>= 6 swollen joints (based on 66 joint count) and \>=6 tender joints (based on 68 joint count) at baseline.
* Participant must have had an inadequate response to at least one prior biologic and/or targeted synthetic disease-modifying anti-rheumatic drugs (b/tsDMARDs) treatment for RA.
* Participants must be on stable dose of methotrexate (MTX).

Exclusion Criteria:

- Participant discontinued prior adalimumab therapy due to intolerability or toxicity.