Medicine company Eli Lilly and Company (NYSE: LLY) on Wednesday reported 52-week Phase 3b results showing sustained improvements in disease activity, physical function and metabolic outcomes when Taltz (ixekizumab) and Zepbound (tirzepatide) were used together in adults with psoriatic arthritis and obesity or overweight.

The TOGETHER-PsA study found that 43.7% of patients receiving the combination achieved an ACR50 response, representing at least a 50% reduction in disease activity, compared with 15.7% receiving Taltz alone. The benefit was evident from Week 4, before clinically meaningful weight loss had occurred.

This combination also maintained or improved patient-reported outcomes, including physical function and fatigue, between Weeks 36 and 52. Improvements were also recorded in body weight, body mass index, blood pressure, glucose, HbA1c, triglycerides and total cholesterol compared with Taltz monotherapy.

Lilly said the primary endpoint, combining an ACR50 response with at least 10% weight reduction, was achieved by 39.2% of patients receiving both medicines at Week 52, compared with 1.7% on Taltz alone. Weight reduction of at least 10% was achieved by 85.7% and 6.7% of patients respectively.

The 52-week findings were presented at ACR Convergence 2026 and published simultaneously in Arthritis & Rheumatology. The study involved 271 participants, with both treatment groups also receiving advice on reduced-calorie diets and increased physical activity.

Adverse events associated with the combination were generally mild to moderate and consistent with the known safety profiles of both medicines. The most common included nausea, diarrhoea, constipation, injection-site reactions and vomiting.