Eli Lilly said that its weight-loss medicine Zepbound, when used in combination with psoriasis treatment Taltz, delivered stronger outcomes than Taltz alone in patients living with both psoriasis and obesity in a late-stage study.
The psoriasis trial enrolled 274 patients and evaluated whether the addition of Zepbound could enhance both dermatologic and weight-loss outcomes. After 36 weeks of treatment, 27.1% of patients receiving Taltz plus Zepbound achieved complete skin clearance and at least 10% weight loss. By comparison, 5.8% of those treated with Lilly Zepbound-Taltz alone met the same combined endpoint, allowing the study to reach its primary goal.
Nearly all participants had psoriasis affecting sensitive areas such as the face, scalp or genitals, regions that are often difficult to treat. Psoriasis is a chronic condition that causes itchy, scaly patches on the skin. Lilly noted that in the U.S., about 61% of people with psoriasis also have obesity or are overweight with at least one weight-related co-morbidity.
The study, known as Together-PsO, also met each of its secondary endpoints. Among additional measures, 41% of patients receiving the combination therapy achieved complete skin clearance compared with 29% of those on Taltz monotherapy.
Lilly said the trial population reflected a high disease burden, which is frequently linked to poorer outcomes. The company added that multiple studies have shown patients with a higher body mass index (BMI) are less likely to achieve skin clearance. In this trial, the average BMI of participants was just over 39.
“For people living at the intersection of these chronic inflammatory diseases, these PASI 100 results represent far more than a clinical milestone they demonstrated what becomes possible when we address both simultaneously,” Adrienne Brown, Lilly’s immunology chief, said in a release.
Adverse events during the study were generally mild to moderate and consistent with the safety profile of the two medicines. Lilly said detailed results will be published in a peer-reviewed journal and discussed with regulators.
In a separate late-stage study in psoriatic arthritis, known as Together-PsA, 31.7% of patients who received Lilly Zepbound-Taltz combo achieved at least a 50% reduction in psoriatic arthritis disease activity and at least 10% weight loss after 36 weeks. That compared with 0.8% of patients treated with Taltz alone who met the same combined outcome. The 36-week Together-PsA trial also reported that 32% of patients receiving the combination achieved a 50% improvement in PsA activity on the American College of Rheumatology 50 clinical benchmark and lost at least 10% of their body weight, versus 1% of patients on Taltz alone.
“Psoriasis and obesity share underlying inflammatory pathways, yet they are too often treated in silos despite psoriasis treatment guidelines calling for obesity management,” Mark Lebwohl, M.D., of the Icahn School of Medicine at Mount Sinai, the trial’s principal investigator, added in the release. “The findings show that treating psoriasis and obesity or overweight at the same time, significantly improved outcomes, reinforcing psoriasis as an obesity-related condition and supporting a potential comprehensive approach to care.”
With blockbuster obesity drugs, Eli Lilly and Novo Nordisk have continued to explore additional indications for incretin-based treatments. Zepbound, a GIP/GLP-1 medicine signed off by the FDA in 2023, garnered sales of $13.5 billion last year and was later endorsed for sleep apnea in 2024. Lilly has also reported data with the molecule in heart failure and metabolic dysfunction-associated steatohepatitis (MASH).
Taltz, an IL-17A antagonist cleared by the FDA for psoriasis in 2016 and for PsA the following year, generated $2.5 billion in sales through the first nine months of 2025. Lilly’s immunology portfolio also includes Olumiant (rheumatoid arthritis, alopecia areata), Omvoh (ulcerative colitis) and Ebglyss (atopic dermatitis).
