Eli Lilly and Company (NYSE:LLY) released detailed 52-week results from its TOGETHER-PsA Phase 3b clinical trial on November 11, 2026, showing efficacy outcomes for the concomitant use of Taltz (ixekizumab) and Zepbound (tirzepatide) compared to Taltz alone in adults with active psoriatic arthritis and obesity or overweight.

Key Highlights

  • ACR50 at Week 52: 43.7% of patients in the Taltz and Zepbound arm achieved ACR50 at one year, compared to 15.7% in the Taltz-alone arm, according to the filing.
  • Primary endpoint at Week 36: The combined proportion achieving both ACR50 and at least 10% weight reduction was 31.7% (Taltz plus Zepbound) versus 0.8% (Taltz alone).
  • Weight reduction at Week 52: 85.7% of patients in the combination arm achieved at least 10% weight reduction, compared to 6.7% in the monotherapy arm.
  • Study size: A total of 271 participants were randomized 1:1 in the multicenter, assessor-blinded, open-label study (NCT06588296).
  • Fatigue improvement: FACIT-Fatigue change from baseline at Week 52 was 9.7 for the combination arm versus 4.8 for Taltz alone.
  • Data presentation: Findings were featured as an oral presentation at ACR Convergence 2026 and simultaneously published in Arthritis and Rheumatology.
  • Safety profile: Adverse events in the combination arm were described as "generally mild to moderate" and consistent with the known safety profile of each medicine, according to the filing.

TOGETHER-PsA 52-Week Results Show Combination Arm Gains Across Disease and Metabolic Measures

According to the filing, the TOGETHER-PsA trial enrolled adults with active psoriatic arthritis and obesity or overweight (BMI of at least 30 kg/m2, or at least 27 to less than 30 kg/m2) with at least one additional weight-related comorbid condition. Participants were randomized 1:1 to receive either Taltz alone or Taltz concomitantly with Zepbound, both administered subcutaneously. The company disclosed that patients in TOGETHER-PsA had a mean BMI of 37.6 at baseline and that both arms received counseling on a reduced-calorie diet and increased physical activity.

The filing states that at the 36-week primary endpoint, treatment with Taltz and Zepbound was statistically superior to Taltz alone on the primary endpoint and all key secondary endpoints. At Week 52, pre-specified exploratory analyses showed the combination arm maintained or further improved outcomes. Beyond the ACR50 result, the filing reported that Minimal Disease Activity (MDA) was achieved by 28.2% of patients in the combination arm versus 13.6% for Taltz alone at Week 52. DAPSA change from baseline was -32.2 for the combination arm and -20.3 for Taltz alone. The filing also noted that a greater proportion of patients achieved ACR50 in the Taltz and Zepbound arm as early as Week 4, "before clinically meaningful weight loss was observed."

The company disclosed that metabolic measures, including BMI, body weight, systolic blood pressure, glucose, HbA1c, triglycerides, and total cholesterol, showed improvements in the combination arm versus Taltz monotherapy. The filing noted that the most common adverse events occurring in at least 5% of participants in the concomitant treatment arm included nausea, diarrhea, constipation, injection site reactions, vomiting, urinary tract infections, sinusitis, dizziness, and headache. The filing also noted that approximately 65% of people with PsA in the U.S. also have obesity or overweight with at least one weight-related comorbidity. The company stated that the Week 52 analyses are "pre-specified, exploratory objectives without multiplicity control" and that comparisons between timepoints are "descriptive and not tested or controlled for multiplicity."

What Was Disclosed

Eli Lilly disclosed 52-week efficacy, patient-reported, and safety data from the TOGETHER-PsA Phase 3b trial evaluating Taltz plus Zepbound versus Taltz alone in 271 adults with psoriatic arthritis and obesity or overweight, with findings presented at ACR Convergence 2026 and published in Arthritis and Rheumatology.