Eli Lilly Reports TOGETHER‑PsA Phase 3b Trial Met Primary And Secondary Endpoints With Taltz And Zepbound In Adults With PsA And Obesity

At 36 weeks, the TOGETHER-PsA study met its primary endpoint of 50% improvement in psoriatic arthritis (PsA) activity based on ACR50 in addition to ≥10% weight reduction with concomitant Taltz and Zepbound compared to Taltz monotherapy  

In a key secondary endpoint, use of Taltz and Zepbound delivered a 64% relative increase in the proportion of patients achieving ACR50 compared to Taltz alone (33.5% of patients vs. 20.4%, p<.05)

Taltz is now the first and only biologic for PsA with data supporting a potential comprehensive treatment approach alongside an incretin therapy for patients who also have obesity (BMI ≥30 kg/m²) or overweight (BMI 27-29.9 kg/m²) with at least one weight-related condition

INDIANAPOLIS, Jan. 8, 2026 /PRNewswire/ -- Eli Lilly and Company (NYSE:LLY) today announced positive topline results from the novel TOGETHER-PsA open-label Phase 3b trial evaluating the concomitant use of Taltz (ixekizumab) and Zepbound (tirzepatide) compared to Taltz alone in adults with active psoriatic arthritis (PsA) and obesity or overweight with at least one weight-related condition. At 36 weeks, treatment with concomitant Taltz and Zepbound met the primary and all key secondary endpoints for superiority to Taltz monotherapy. TOGETHER-PsA is the first controlled study to evaluate an incretin therapy used with a PsA biologic. An estimated 65% of adults with PsA in the U.S. also have obesity (BMI ≥30 kg/m²) or overweight (BMI 27-29.9 kg/m²) with at least one additional weight-related comorbidity,1 highlighting a need for integrated treatment approaches that address the full burden of their diseases.

In the study, 31.7% of patients in the Taltz plus Zepbound treatment arm achieved a 50% improvement in PsA activity, based on American College of Rheumatology 50 (ACR50), and weight reduction of at least 10%, compared to 0.8% of patients on Taltz monotherapy, meeting the primary endpoint (p<.001). In a key secondary endpoint, Taltz plus Zepbound delivered a 64% relative increase over Taltz monotherapy in the proportion of patients who achieved ACR50 (33.5% of patients vs. 20.4%, respectively, p<.05), demonstrating that treatment of obesity or overweight with Zepbound reduced the burden of PsA.2,3 The study population included patients with a high disease burden at baseline and an average BMI of 37.6 kg/m2 across both arms. Patients had high disease activity and meaningful functional impairment.4 More than 60% had prior experience with one or more advanced therapies, reflecting a difficult-to-treat patient population.