Eli Lilly's Obesity Combo Beats Tirzepatide in a Study as Shares Erase an Early Pop

A midstage trial showed the company's eloraTZP combination cut weight by 23.3% against 14.8% for tirzepatide alone, though dropout rates ran higher and the stock gave back a morning gain.

Eli Lilly shares jumped early Wednesday. They touched a session high of $1,215, then handed the gain back, trading around $1,181 by early afternoon and slipping 0.3% below Tuesday’s close of $1,184.63. The reversal followed midstage results for an experimental obesity treatment that outperformed one of the company’s own best-selling drugs.

The treatment, eloraTZP, pairs tirzepatide with eloralintide, an experimental compound that acts on the amylin receptor. Tirzepatide is the active ingredient in Lilly’s Mounjaro and Zepbound. Both are already on the market, cleared for type 2 diabetes and obesity. In a Phase 2b study of 367 adults with obesity or overweight and type 2 diabetes, the highest dose of the combination reduced body weight by an average of 23.3%, or 54.1 pounds, over 48 weeks. The efficacy gap was wide. Tirzepatide alone at 15 milligrams produced a 14.8% reduction, or 34.4 pounds, from an average starting weight of 232.4 pounds.

The combination also sharpened blood-sugar control. It lowered A1C, a measure of average blood glucose, by 2.9 percentage points from a starting level of 8.1%, against 2.4 points for tirzepatide by itself. The gap held here too. Lilly presented the data at the European Association for the Study of Diabetes meeting in Milan.

The trade-off showed up in tolerability. Discontinuations linked to side effects ran from 10.8% to 27.0% across the eloraTZP dose groups, compared with 2.9% among patients taking tirzepatide alone. The most common adverse events were gastrointestinal and generally mild to moderate, the company said, and concentrated in the weeks when doses were being raised. Lilly said it plans to begin Phase 3 testing of an eloraTZP co-formulation by the end of the year, using a revised schedule for stepping up the dose.

Wednesday’s swing plays out over a strong stretch for the stock. The shares are up 11% across the past 90 trading sessions, and they sit about 7% under their high over that window. The 52-week range runs from $623.78 to $1,292.65, keeping the price in the upper half of the past year. The company carries a market value above $1.1 trillion. Volume looked ordinary. Through the first hours it tracked near the stock’s 20-day average of 2.2 million shares, a busy tape without the surge that a genuine surprise tends to bring.

Lilly and Novo Nordisk lead the market. A widening field of developers has crowded in behind them in obesity drugs, and each new readout now meets a high bar set by the last. The tirzepatide franchise has driven much of Lilly’s multiyear climb, which is part of why a combination leaning on the same molecule drew close reading. Investors weighed two things at once: how much more weight the pairing takes off, and what patients give up to stay on it.

The next marker is the Phase 3 program Lilly intends to start by year-end. A co-formulation would fold both compounds into a single product, and the revised dose-escalation schedule the company flagged is aimed squarely at the dropout figures from this study. The Milan meeting may also yield fuller late-breaking detail. Wednesday’s close is the next tell.

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