A Study to Learn if Bimekizumab Given in Different Ways is Safe and Moves Similarly Throughout the Body Over Time in Adults

Prior treatment

• Recent live vaccines (within 8 weeks) or Bacillus Calmette-Guerin (BCG) (within 1 year)

Other illness

• Serious organ system disorders (e.g., heart, liver, kidney, gastrointestinal, neuro)
• Severe psychiatric issues or substance abuse in the past year
• Recent or chronic infections, including tuberculosis (TB) or nontuberculous mycobacterium (NTMB)
• Other inflammatory diseases (e.g., rheumatoid arthritis (RA), lupus, inflammatory bowel disease (IBD))

Other

• Recent use of glucagon-like peptide-1 (GLP-1) agonists (within 28 weeks)

• Be 18+ years old and legally able to consent
• Have active psoriatic arthritis (PsA) or axial spondyloarthritis (axSpA), suitable for bimekizumab treatment
• Weigh between 45-100 kg (females) or 50-100 kg (males).
• Be biologic disease-modifying anti-rheumatic drug (bDMARD)-naïve or have stopped bDMARDs ≥3 months or 5 half-lives ago