As glucagon-like peptide-1 (GLP-1) drugs continue to find new applications beyond weight loss, Eli Lilly is intensifying its focus on expanding the therapeutic uses of its tirzepatide franchise. Tirzepatide, marketed as Zepbound for weight management, is being tested in combination therapies targeting diseases within immunology and inflammation.
Last month, Eli Lilly shared results from a Phase 3b trial evaluating tirzepatide combined with Taltz—an established autoimmune drug—for treating psoriatic arthritis (PsA). The combination therapy achieved the primary and all key secondary endpoints, showing a 50% improvement in PsA symptoms. Patients receiving both tirzepatide and Taltz experienced a 10% reduction in body weight over 36 weeks, compared to a 0.8% reduction in those treated with Taltz alone.
“These results further support existing treatment guidelines for psoriatic arthritis that recommend treatment of comorbid obesity and shed further light on how incretins may have a positive effect on other diseases independent from weight loss,” said Dan Skovronsky, chief scientific and product officer at Lilly, during the company’s fourth quarter and full year earnings presentation.
Lilly is also testing other combinations in its immunology pipeline. According to Skovronsky, tirzepatide is being studied with Omvoh—an interleukin inhibitor—in Phase 3b trials for Crohn’s disease and ulcerative colitis. Additionally, brenipatide, another GIP/GLP-1 agonist developed by Lilly, is currently under investigation in a Phase 2 asthma study.
Industry analysts see promise in this approach. Myles Minter, biotech analyst and partner at William Blair, told BioSpace that centralized mechanisms affecting multiple diseases make immunology and inflammation an attractive area for single-product strategies. He referenced the significant success of AbbVie’s Skyrizi and Rinvoq—which generated nearly $26 billion in combined revenue during 2025—as evidence of the sector's potential.
During Lilly’s earnings call Q&A session, Seamus Fernandez from Guggenheim Securities asked why the company could not apply its broad strategy for obesity to immunology. Skovronsky replied: “There is really promising breaking science, including treating immunology diseases earlier, and we’re doing everything in our power to harness this science.” He described current trials with incretins in immunology as “promising.”
When Citibank analyst Geoff Meacham asked whether Lilly prioritizes the drug or the indication when considering Zepbound combinations for immunology or oncology applications, Adrienne Brown—president of Lilly Immunology—responded: “Patients who have both immune diseases and obesity tend to have a higher disease burden. So we’re really excited about the opportunity to find new ways to combat the . . . diseases and potentially unlock better, longer-lasting results for these patients.” She added that Lilly has “broad efforts underway to look at additional combinations” within immunology.
The interest in pipeline-in-a-product strategies continues as pharmaceutical companies pursue therapies addressing multiple indications through combination approaches—a trend highlighted by strong sales performances among established players like AbbVie.
