Lilly Reports 43.7% ACR50 Response With Taltz and Zepbound at Week 52
Key Facts
On August 31, Lilly announced week 52 results from the TOGETHER-PsO and TOGETHER-PsA trials, two open-label Phase 3b studies comparing Taltz and Zepbound used together with Taltz alone. In the psoriatic arthritis trial, 43.7% of participants achieved an ACR50 response with the two drugs at week 52, compared with 15.7% with Taltz alone. The measure captures a 50% improvement in disease activity and was a key secondary outcome in the trial. The primary outcome combined an ACR50 response with at least 10% weight loss. Lilly said ACR50 improvement emerged as early as week 4, before clinically meaningful weight loss occurred.
At week 52, 39.2% of participants who received both drugs achieved the primary composite outcome in TOGETHER-PsA, compared with 1.7% of those who received Taltz alone. The measure requires both a reduction of at least 50% in psoriatic arthritis activity and weight loss of at least 10%. These rates therefore differ from the 43.7% ACR50 rate, which does not require meeting the weight-loss criterion. The results thus report separate outcomes for joint improvement and for the combination of improvement and weight loss. The company described the week 52 analyses as exploratory and prespecified, with no adjustment for multiple comparisons.
In the parallel TOGETHER-PsO trial, which studied plaque psoriasis, 30.6% achieved the primary composite outcome of complete skin clearance under the PASI 100 measure together with at least 10% weight loss, compared with 4.4% with Taltz alone at week 52. Lilly said improvements in body mass index, blood pressure, glucose, glycated hemoglobin, triglycerides and total cholesterol were sustained or improved further among those who used both drugs, compared with monotherapy. The trials included adults with skin or joint conditions, as well as obesity or overweight and a weight-related comorbidity. The company estimated that 65% of people with psoriatic arthritis in the United States have obesity or overweight along with at least one weight-related condition. According to the company, this estimate places those comorbidities within the population targeted by the trial.
Lilly said adverse events among participants who received Taltz and Zepbound together were generally mild to moderate, and their types were consistent with the known safety profile of each drug. The trials included groups of 274 adults in TOGETHER-PsO and 271 adults in TOGETHER-PsA, with participants randomly assigned in a 1:1 ratio to Taltz alone or the combination treatment. Participants also received dietary guidance and advice on physical activity. The week 52 data were prespecified as exploratory objectives; the company also said comparisons across periods were descriptive and were not tested or statistically adjusted for multiple comparisons. Accordingly, the results provide response rates within the trials, while the long-term comparisons remain exploratory, as characterized by Lilly.
Lilly announced on March 28 that detailed results from the TOGETHER-PsA trial had been presented at a meeting of the American Academy of Dermatology and published in the journal Arthritis & Rheumatology. In a statement issued on November 5, the company said an oral presentation of the detailed results would be given at the ACR Convergence conference in Orlando, which ran from November 6 to 11. The company scheduled the presentation for November 11, 2026, between 9:45 and 10:00 a.m. Eastern Time. The presentation follows the announcement of the week 52 results in August and provides an opportunity to present details at the conference. Lilly had also published week 36 results, when the ACR50 rate in TOGETHER-PsA was 33.5% with both drugs, compared with 20.4% with Taltz alone; the company described the difference as a 64% relative increase.