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Eli Lilly's Rare Weight Loss Data Miss Could Benefit Competitors

On Thursday, Eli Lilly and Co.’s (NYSE:LLY) weight loss rival Novo Nordisk A/S (NYSE:NVO), along with smaller firms, Terns Pharmaceuticals, Inc. (NASDAQ:TERN), Viking Therapeutics Inc. (NASDAQ:VKTX), and Structure Therapeutics Inc. (NASDAQ:GPCR) are trading higher.

What Happened

Lilly released topline data from the Phase 3 ATTAIN-1 trial evaluating orforglipron that showed an average weight loss of 12.4% (27.3 lbs) compared to 0.9% (2.2 lbs) with placebo, below the 15% expectations. Orforglipron could be the first small-molecule weight-loss pill if it launches in 2026.

William Blair analysts described this as a “once-in-a-blue-moon” miss for Lilly’s otherwise dominant obesity franchise. They highlighted that orforglipron’s 9.1% placebo-adjusted weight loss at the 36 mg dose underperformed compared to weekly subcutaneous Wegovy, which delivers 12–13% weight loss.

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Additionally, gastrointestinal side effects were comparable to Wegovy, but orforglipron had a higher treatment discontinuation rate (5.1–10.3% vs. 7.0% for Wegovy, 2.6% for placebo).

They also noted early plateauing of weight loss and persistent side effects as potential liabilities for orforglipron, as previously flagged during the ACHIEVE-1 presentation at the American Diabetes Association.

This rare underperformance opens the door for smaller biopharma competitors, analyst Andy Hsieh of William Blair noted.

“From ...