A Study to Evaluate Efficacy and Safety of Upadacitinib in Adults With Axial Spondyloarthritis

* Study 1: * Must have a clinical diagnosis of ankylosing spondylitis (AS) and meet the modified New York Criteria for AS, * Must not have total spinal ankylosis * Must have been previously exposed to 1 or 2 bDMARDs (at least 1 tumor necrosis factor \[TNF\] inhibitor or 1 interleukin \[IL\]-17 inhibitor \[IL-17i\]), and must have discontinued the bDMARD therapy due to either lack of efficacy (after at least 12 weeks of treatment with a bDMARD at an adequate dose) or intolerance (irrespective of treatment duration). Prior exposure to two bDMARDs was allowed for no more than 30% of patients; among patients with prior exposure to two bDMARDs, a lack of efficacy to one bDMARD and intolerance to another was permitted, but a patient could not have a lack of efficacy to two bDMARDs * Study 2: * Must have a clinical diagnosis of nr-axSpA fulfilling the 2009 Assessment of SpondyloArthritis international Society (ASAS) classification criteria for axSpA but not meeting the radiologic criterion of the modified New York criteria for AS * Must have objective signs of active inflammation consistent with axSpA on magnetic resonance imaging (MRI) of sacroiliac (SI) joints or based on high sensitivity C-reactive protein (hsCRP) \> the upper limit of normal (ULN). * Prior treatment with at most one bDMARD (either TNF inhibitor or IL-17i) is allowed for at least 20% but no more than 35% of enrolled patients who had to discontinue the prior bDMARD due to either lack of efficacy (after ≥ 12 weeks at an adequate dose) or intolerance (regardless of treatment duration). * Must have a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score ≥ 4 at the Screening and Baseline Visits. * Must have a Total Back Pain score ≥ 4 based on a 0 - 10 numerical rating scale at the Screening and Baseline Visits. * Has had an inadequate response to at least 2 nonsteroidal anti-inflammatory drugs (NSAIDs) over an at least 4-week period in total at maximum recommended or tolerated doses, or has an intolerance to or contraindication for NSAIDs as defined by the Investigator.

* Must not have been exposed to any Janus kinase (JAK) inhibitor (including but not limited to upadacitinib \[Rinvoq®\], tofacitinib \[Xeljanz®\], baricitinib \[Olumiant®\], filgotinib, ruxolitinib \[Jakafi®\], abrocitinib \[PF-04965842\], and peficitinib \[Smyraf®\]). * Prior bDMARD therapy must be washed out. * Participant must not have a history of an allergic reaction or significant sensitivity to constituents of the study drug.