Lilly Reports Positive Results for Taltz and Zepbound Combination in Psoriatic Arthritis
Eli Lilly has reported positive one-year results from a Phase 3b clinical trial evaluating the combination of Taltz (ixekizumab) and Zepbound (tirzepatide) in adults living with active psoriatic arthritis and obesity or overweight. The findings showed greater improvements in disease activity, physical function and metabolic health compared with Taltz alone.
The results come from the TOGETHER-PsA study, which evaluated whether treating psoriatic arthritis and obesity together could improve outcomes for patients with both conditions. The 52-week findings were presented at the American College of Rheumatology (ACR) Convergence 2026 and published in the journal Arthritis & Rheumatology on November 11, 2026.
At one year, 43.7% of patients receiving Taltz and Zepbound achieved ACR50, meaning their psoriatic arthritis disease activity improved by at least 50%. In comparison, only 15.7% of patients receiving Taltz alone achieved the same result.
The combination also showed strong results in reducing body weight. Around 85.7% of patients receiving both medicines achieved at least 10% weight loss, compared with 6.7% of those taking Taltz alone.
Another important finding was that 39.2% of patients receiving the combination achieved both a 50% reduction in disease activity and at least 10% weight loss at one year. This compared with just 1.7% in the Taltz-only group.
Improvements in Physical Function and Metabolic Health
Beyond reducing disease activity and body weight, the combination showed improvements in several measures linked to patients’ daily lives.
Patients receiving both medicines reported better physical function and reduced fatigue. The treatment combination also improved several metabolic measures, including body mass index (BMI), blood pressure, blood glucose, HbA1c, triglycerides and total cholesterol.
Interestingly, improvements in psoriatic arthritis disease activity were observed as early as Week 4 in patients receiving the combination, before clinically meaningful weight loss occurred.
Mark Genovese, Senior Vice President of Immunology Development at Lilly, said the one-year findings demonstrated the lasting benefits of combining the two medicines. He highlighted improvements in disease control, physical function and fatigue as important outcomes for people living with both conditions.
Philip Mease, Director of Rheumatology Research at Swedish Medical Center and a study author, said managing both psoriatic arthritis and obesity is important because the conditions can affect each other and make treatment more challenging.
Understanding the TOGETHER-PsA Study
The TOGETHER-PsA Phase 3b trial was an open-label study involving 271 adults with active psoriatic arthritis and obesity or overweight with at least one additional weight-related health condition.
Participants received either Taltz alone or Taltz combined with Zepbound. The primary endpoint was assessed at Week 36, when the combination demonstrated statistically significant improvements compared with Taltz alone. The 52-week findings provide additional exploratory evidence of the durability of these benefits.
Taltz is an injectable medicine developed by Lilly that blocks interleukin-17A (IL-17A), a protein involved in inflammation. It is approved for treating several inflammatory conditions, including psoriatic arthritis and plaque psoriasis.
Zepbound is an injectable medicine containing tirzepatide. It works by activating GIP and GLP-1 hormone receptors, helping regulate appetite, food intake and body weight. It is approved in the US for chronic weight management in eligible adults and for certain patients with obstructive sleep apnea.
The combination’s safety findings were generally consistent with the known safety profiles of the individual medicines.
Addressing Two Connected Health Conditions
Psoriatic arthritis is a chronic inflammatory disease that affects the joints and can also cause skin problems. Obesity is common among people living with the condition and may contribute to greater disease activity and poorer treatment outcomes.
According to Lilly, approximately 65% of people with psoriatic arthritis in the US also have obesity or overweight alongside at least one weight-related health condition.
The latest findings highlight the potential benefits of addressing inflammation and excess body weight together. Lilly believes this approach could help improve treatment outcomes for people facing both conditions.
The company continues to explore ways to address the combined impact of immune-related and metabolic diseases through its clinical development programmes.