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

This protocol includes 2 standalone studies with randomization, data collection, analysis and reporting conducted independently. The main objectives of this protocol are: * To evaluate the efficacy of upadacitinib compared with placebo on reduction of signs and symptoms in adults with active axial spondyloarthritis (axSpA) including biologic disease-modifying antirheumatic drug inadequate responders (bDMARD-IR) ankylosing spondylitis (AS) (Study 1) and non-radiographic axial spondyloarthritis (nr-axSpA) (Study 2). * To assess the safety and tolerability of upadacitinib in adults with active axSpA including bDMARD-IR AS (Study 1) and nr-axSpA (Study 2). * To evaluate the safety and tolerability of upadacitinib in extended treatment in adult participants with active axSpA including bDMARD-IR AS who have completed the Double-Blind Period (Study 1) and nr-axSpA who have completed the Double-Blind Period (Study 2). * To evaluate the maintenance of disease control after withdrawal of upadacitinib.