With their blockbuster obesity drugs, Eli Lilly and Novo Nordisk have uncovered a variety of ailments the incretin treatments can combat.
Chalk up another new potential expansion for Lilly as it has found in a phase 3b trial that combining Zepbound and its autoimmune treatment Taltz can provide added benefits for psoriasis patients who are obese or overweight.
The results come six weeks after the Indianapolis drugmaker revealed the success of another phase 3b trial of patients with psoriatic arthritis (PsA), which was dubbed Together-PsA.
Meanwhile, the psoriasis trial of 274 patients met its primary endpoint, showing that after 36 weeks Taltz and Zepbound provided complete skin clearance (PASI 100) and at least 10% weight loss in 27% of participants, compared to 6% who reached those standards on Taltz alone.
Additionally, the trial, which is called Together-PsO, made a clean sweep, scoring on each of its secondary endpoints, including one that showed 41% of those talking the combo achieved complete skin clearance compared to 29% of patients on monotherapy.
In the U.S., approximately 61% of people with psoriasis are also overweight or obese and have at least one weight-related comorbidity, Lilly explained, “highlighting a need for comprehensive treatment approaches.”
The study enrolled patients with a very high burden of disease, which is often associated with poorer outcomes. It has been shown in multiple studies that those with a higher body mass index (BMI) are less likely to achieve skin clearance, according to the drugmaker. In Lilly’s 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 in the study were generally consistent with the safety profile of the two medicines.
Lilly said it will discuss the results with regulators.
“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.”
In the Together-PsA trial, which also lasted 36 weeks, 32% of patients receiving Taltz plus Zepbound 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, compared to just 1% of patients who received Taltz alone.
Based on the data Lilly has presented with the combo in both indications, the company “can start to crack open the immunology market,” which has been “dominated” by companies such as AbbVie, Johnson & Johnson, Sanofi and Novartis, Umer Raffat, an analyst with Evercore ISI, wrote in a note to investors.
Wall Street may be “underestimating the sheer upside” for Lilly’s immunology franchise “given emerging clinical data as well as commercial rebate strategies,” Raffat added.
The company’s immunology portfolio includes Olumiant (rheumatoid arthritis, alopecia areata), Omvoh (ulcerative colitis) and Ebglyss (atopic dermatitis). For Lilly’s emergence in the treatment area, Raffat credited its “incredibly talented” R&D chief Dan Skovronsky, M.D., Ph.D.
Taltz, which is an IL-17A antagonist, was cleared by the FDA for psoriasis in 2016 and for PsA the following year. Through the first nine months of 2025, the monoclonal antibody generated $2.5 billion in sales.
The FDA signed off on GIP/GLP-1 medicine Zepbound in 2023, and it garnered sales of $13.5 billion last year. The U.S. regulator endorsed the dual-action treatment for sleep apnea in 2024. Lilly also has turned out impressive data with the molecule in heart failure and metabolic dysfunction-associated steatohepatitis (MASH).
As for Novo Nordisk, it has scored expansions for its obesity drug Wegovy as a treatment for MASH and to reduce the risk of cardiovascular events in people who are overweight or obese and who have heart issues.