Eli Lilly And Company (LLY), Regeneron Pharmaceuticals (REGN) announced an update on their ongoing clinical study.
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The Phase 2 study “A Study of Tirzepatide (LY3298176) Plus Mibavademab Compared With Tirzepatide Alone in Adult Participants With Obesity” tests whether adding Regeneron’s antibody mibavademab to Eli Lilly’s tirzepatide drives extra weight loss versus tirzepatide alone. It is a proof-of-concept trial that could shape the next wave of obesity drug combinations and help both companies defend share in a fast-growing market.
The study evaluates once-weekly tirzepatide, an injectable obesity and diabetes drug, given under the skin. It is combined with mibavademab, an experimental antibody from Regeneron, or matching placebos to see if the combo improves weight loss and remains safe for long-term use.
The trial is interventional and randomized, meaning participants are assigned by chance to different treatment groups. It is double-blind and placebo-controlled, so neither patients nor doctors know who gets active drug or placebo, and the main goal is to assess treatment benefit on weight loss in adults with obesity.
The study was first submitted on 16 April 2024, marking the official start of regulatory tracking and investor visibility. The most recent update was filed on 4 May 2026, signaling that the trial has moved to completed status and that fresh information is now available to inform expectations for future data releases.
The trial is listed as completed, which means the main treatment phase and follow-up are done and data are being analyzed. For investors, this narrows the timeline to top-line results, a key catalyst for LLY and REGN valuation as obesity remains one of the most important drivers of long-term revenue growth in large-cap pharma.
If the combo shows meaningfully better weight loss with an acceptable safety profile, it could extend the life cycle of tirzepatide and open a new royalty and co-development path with Regeneron. This would strengthen Lilly’s lead versus Novo Nordisk and give Regeneron a more visible seat in the obesity field, potentially lifting both names on positive headlines.
On the other hand, mixed or negative results may limit upside for tirzepatide beyond its current label and push investors toward other combination stories in the sector. Given high expectations already priced into obesity leaders, market reactions to any efficacy or safety surprises could be sharp, especially around the first public data release.
The study is now completed and recently updated, and investors can track further detail and status changes on the ClinicalTrials portal.
To learn more about LLY’s potential, visit the Eli Lilly And Company drug pipeline page.