Indianapolis, Indiana, USA, October 9, 2026
Eli Lilly and Company has announced new exploratory findings from its Phase 3b TOGETHER-PsO clinical trial, providing further insights into the relationship between psoriasis and obesity. The study evaluated the combined use of Taltz (ixekizumab), an interleukin-17A (IL-17A) inhibitor, and Zepbound (tirzepatide), a dual GIP and GLP-1 receptor agonist, compared with Taltz alone in adults with moderate-to-severe plaque psoriasis and obesity or overweight accompanied by at least one additional weight-related comorbidity. The new biomarker analysis was presented at the 2026 Fall Clinical Dermatology Conference in Las Vegas, Nevada. The findings indicated broader changes in inflammatory and metabolic biomarkers among patients receiving both medicines, with differences observed as early as Week 12. The research adds to the growing scientific interest in immunometabolic health, which examines how immune activity and metabolic conditions interact and influence disease outcomes.
Phase 3b Study Examines Combined Psoriasis and Obesity Treatment
The TOGETHER-PsO study is an open-label Phase 3b clinical trial designed to investigate whether addressing psoriasis and obesity simultaneously can improve patient outcomes beyond treatment with a psoriasis biologic alone. Participants received Taltz alongside Zepbound or Taltz alone, allowing researchers to assess changes in disease activity, body weight and selected biological markers. The analysis focused on changes in inflammatory pathways and biomarkers associated with psoriasis and metabolic dysfunction. Earlier results from the study showed that the combination achieved statistically superior outcomes at Week 36 compared with Taltz monotherapy, including improved skin clearance and clinically meaningful weight reduction. In the primary endpoint analysis, 27.1% of participants receiving both medicines achieved complete skin clearance, measured by the Psoriasis Area and Severity Index (PASI 100), together with at least 10% weight loss, compared with 5.8% receiving Taltz alone. The latest exploratory analysis builds on these findings by investigating biological changes that may help explain the differences in clinical response. However, biomarker associations do not independently establish causation, and further research is required to understand the mechanisms involved.
Biomarker Findings Highlight Inflammatory Pathways
The prespecified exploratory analysis found that Taltz plus Zepbound produced broader changes in inflammatory immune activity than Taltz alone, including changes involving neutrophils, immune cells that contribute to inflammatory responses. Researchers also reported that changes in a subset of neutrophil-associated markers mediated part of the additional PASI response observed with the combination. These findings suggest that the relationship between obesity and psoriasis may involve interconnected inflammatory and metabolic processes rather than two entirely separate conditions. The results provide a basis for further investigation into how weight management may influence inflammatory skin disease and treatment responses. The analysis was discussed at the 2026 Fall Clinical Dermatology Conference, where researchers examined emerging evidence relevant to chronic inflammatory skin conditions. The findings remain exploratory, and they do not establish that every biomarker change directly causes improvements in psoriasis. Additional studies will be needed to confirm the observed associations, identify the biological pathways involved and determine whether the results can guide clinical treatment decisions. Nevertheless, the research expands the scientific understanding of how metabolic health may interact with immune-mediated disease.
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Lilly Advances Research Into Immunometabolic Health
The findings support Eli Lilly’s broader research strategy focused on developing treatment approaches that address the interconnected burden of chronic diseases. Psoriasis and obesity frequently coexist, and people living with both conditions may face additional challenges in achieving sustained disease control. By studying Taltz and Zepbound together, Lilly is investigating whether treating inflammation and excess body weight concurrently can deliver broader benefits than addressing psoriasis alone. Taltz targets IL-17A, a cytokine involved in inflammatory pathways associated with psoriasis, while tirzepatide acts on GIP and GLP-1 receptors to support weight management. The combination is being evaluated in a clinical research setting; these findings do not mean the medicines have received specific regulatory approval for combined treatment of psoriasis and obesity. Further clinical evidence will be necessary to establish the long-term benefits, risks and appropriate use of this approach in different patient populations. The latest TOGETHER-PsO biomarker findings represent an additional step in understanding immunometabolic interactions and may help guide future research into integrated treatment strategies for people affected by chronic inflammatory and metabolic conditions.
Source: Eli Lilly and Company press release
