Phase IIIb TOGETHER-PsA trial: Ixekizumab + tirzepatide in adults with PsA and obesity/overweight

Results from the randomized, multicenter, open-label phase IIIb TOGETHER-PsA (NCT06588296) trial evaluating ixekizumab + tirzepatide (n = 138) vs ixekizumab alone (n = 133) in patients with psoriatic arthritis (PsA) and obesity or overweight with ≥1 weight-related comorbidity were presented by Laura Coates at the European Alliance of Associations for Rheumatology (EULAR) 2026 Congress, June 3–6, 2026, London, UK. The primary endpoint was simultaneous achievement of American College of Rheumatology 50% response (ACR50) and ≥10% weight reduction. 

Key data: The proportion of patients demonstrating simultaneous achievement of ACR50 and ≥10% weight reduction was greater with ixekizumab + tirzepatide vs ixekizumab alone at Week 12 (10.3% vs 0%), Week 24 (27.7% vs 1.5%), and Week 36 (31.7% vs 0.8%; all p < 0.001). The proportion of patients achieving ACR50 alone also favored ixekizumab + tirzepatide at Week 4 (11.1% vs 3.9%), Week 12 (29.2% vs 17.2%), Week 24 (34.8% vs 21.9%), and Week 36 (33.5% vs 20.4%; all p < 0.05). Overall, 75.4% vs 72.0% of patients experienced treatment-emergent adverse events (TEAEs) with ixekizumab + tirzepatide vs ixekizumab alone. The most common TEAEs in the ixekizumab + tirzepatide group vs the ixekizumab alone group were nausea (29.7% vs 3.0%), diarrhea (18.1% vs 3.8%), constipation (16.7% vs 3.0%), injection site reaction (15.2% vs 16.7%), and vomiting (10.9% vs 0.8%).

Key learning: Ixekizumab + tirzepatide demonstrated clinically meaningful improvements in PsA disease control and weight reduction compared with ixekizumab alone, with a safety profile that is consistent with established profiles of the individual therapies. These findings support a parallel treatment approach targeting both PsA and obesity/overweight and suggest obesity as a modifiable contributor to PsA disease activity.