Lilly’s Taltz and Zepbound Show Superior Results in Phase 3b Psoriatic Arthritis Trial

Recent advancements in the treatment of psoriatic arthritis (PsA) have emerged from the TOGETHER-PsA Phase 3b trial, which evaluated the combination of Lilly’s Taltz (ixekizumab) and Zepbound (tirzepatide). This study focused on adults with active PsA who also struggle with obesity or overweight conditions.

Taltz and Zepbound Phase 3b Trial Overview

On January 8, 2026, Eli Lilly and Company announced that the TOGETHER-PsA study met its primary endpoint at 36 weeks. This endpoint involved a 50% improvement in PsA activity, defined as an ACR50 response, as well as a ≥10% weight reduction. The combination of Taltz and Zepbound achieved this in 31.7% of participants, compared to just 0.8% in the Taltz monotherapy group.

Study Design and Outcomes

• The TOGETHER-PsA trial is an open-label, multicenter study involving 271 participants.
• Patients were randomized to receive either Taltz alone or in combination with Zepbound.
• The average BMI of participants was 37.6 kg/m², indicative of high obesity levels within the group.
• Both treatment arms focused on counseling for a reduced-calorie diet and increased physical activity.

The results indicated not only a significant improvement in PsA symptoms but also addressed the associated issue of obesity, with over 65% of U.S. adults with PsA identified as having obesity or overweight conditions.

Integrated Treatment Approach

Experts believe the results signify a potential paradigm shift in managing PsA. According to Dr. Mark Genovese, senior vice president at Lilly, Taltz is now the first biologic to be integrated with an incretin therapy to tackle obesity in patients. This approach could significantly enhance treatment outcomes.

Adverse Events and Safety Profile

The combined treatment of Taltz and Zepbound led to mild to moderate adverse events. The most common issues noted in more than 5% of patients included:

• Nausea
• Diarrhea
• Constipation
• Injection site reactions

In the Taltz monotherapy group, common adverse events included injection site reactions and upper respiratory tract infections.

Future Directions

The findings from the TOGETHER-PsA trial are set to be discussed at upcoming medical meetings and with regulatory bodies. Additionally, results from an ongoing study (TOGETHER-PsO), focusing on moderate-to-severe plaque psoriasis in conjunction with obesity management, are expected in mid-2026.

The TOGETHER-PsA study demonstrates the potential of integrated therapies to enhance the standard of care for patients battling both PsA and obesity. With these developments, there is hope for significantly improved outcomes for millions of individuals facing these interconnected health challenges.