A Study to Evaluate the Change in Disease State and Adverse Events in Adult Participants With Polymyalgia Rheumatica (PMR) Dependent on Glucocorticoid Treatment, Receiving Subcutaneous Injections of ABBV-154

Polymyalgia rheumatica (PMR) is an inflammatory disease causing shoulder, hip, and neck pain and stiffness, in adults aged 50 years or older. This study evaluates how safe and effective ABBV-154 is in participants with glucocorticoid-dependent PMR. Adverse events and change in disease activity will be assessed.

ABBV-154 is an investigational drug being evaluated for the treatment of PMR. Participants will be randomized into 1 of 4 treatment groups or arms, each arm receiving a different treatment. There is a 1 in 4 chance that a participant will be assigned to placebo. Around 160 participants, of at least 50 years of age, with PMR will be enrolled in the study at approximately 95 sites worldwide.

The study is compromised of a 52 week double-blind, placebo-controlled period and a follow-up visit 70 days after the last dose of the study drug. All participants will receive a glucocorticoid taper along with the assigned dose of ABBV-154 or placebo, subcutaneously (SC) every other week (eow).

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