TOGETHER-PsA: Weight Loss Plus PsA Control with Ixekizumab and Tirzepatide
Key Takeaways
The combintation of met all primary and secondary endpoints in a phase 3b psoriatic arthritis (PsA) trial targeting patients with obesity or overweight.
The combination yielded a 64% relative increase in ACR50 responses over ixekizumab alone.
Findings suggest PsA outcomes may improve when obesity is treated concurrently, supporting a paradigm shift in care.
In the phase 3b TOGETHER-PsA trial, ixekizumab (Taltz, Eli Lilly) used in combination with tirzepatide (Zepbound, Eli Lilly) was more effective than ixekizumab monotherapy in adults with active psoriatic arthritis (PsA) who also have obesity or are overweight with at least one weight-related condition.
Researchers for the open-label study included patients with a high disease burden (mean BMI 37.6 kg/m²), most of whom had prior exposure to advanced therapies. The study met its primary endpoint at 36 weeks, with 31.7% of patients on the combination therapy achieving both ≥50% improvement in PsA activity (ACR50) and ≥10% weight reduction, compared to 0.8% on ixekizumab alone (P < 0.001). Concomitant use of tirzepatide was associated with a 64% relative increase in the proportion of patients reaching ACR50 vs. ixekizumab alone (33.5% vs. 20.4%, P < 0.05). Adverse events included nausea, diarrhea, and injection site reactions, which were consistent with known safety profiles.
"While treatment guidelines for psoriatic arthritis recommend management of obesity, the reality is these two chronic diseases are often addressed separately and moving the needle in PsA has remained challenging," said Joseph F. Merola, MD, Professor and Chair, Department of Dermatology and Professor of Internal Medicine in the Division of Rheumatic Diseases, UT Southwestern Medical Center, in the news release. "The observed benefit with treatment using ixekizumab and tirzepatide appears to meaningfully impact psoriatic disease activity, indicating that for many patients, PsA is an obesity-related condition. This integrated therapy approach represents a potential paradigm shift and could lead to better outcomes for those living with both diseases."
Source: Eli Lilly press release. January 9, 2026.