Pfizer ends development of weight-loss pill danuglipron

Pfizer on Monday said it has discontinued development of experimental weight-loss pill danuglipron after a trial patient experienced potential drug-induced liver injury which resolved after the medication was stopped.

Pfizer had been testing multiple doses of a once-a-day version of the oral drug candidate after scrapping development of a twice-daily version in late 2023 because most patients dropped out of a midstage trial due to high rates of side effects such as nausea and vomiting.

Danuglipron is part of a class of drugs designed to target an intestinal hormone called GLP-1.

The weight-loss category has drawn high interest from pharmaceutical companies and investors, with annual sales forecast to hit $150 billion in coming years as new, highly effective medicines have sparked outsized demand.

The market is currently dominated by Novo Nordisk's Wegovy and Eli Lilly's Zepbound, both of which are given as weekly injections. Several companies are working on potentially more convenient GLP-1 pills, including Lilly, which is expected to announce Phase 3 trial results for its drug orforglipron any day now.

Shares of Lilly climbed 1.7% in U.S. premarket trading, while Novo Nordisk's Copenhagen-listed shares rose over 4%.

The news also lifted shares of obesity drug developers Viking Therapeutics up 20%, Structure Therapeutics up 13.2% and Altimmune up 3.2% before the bell, while Pfizer's shares fell 1%.

Pfizer said dose-optimization studies of once-daily danuglipron met key pharmacokinetic objectives and the overall frequency of liver enzyme elevations across 1,400 study participants was in line with approved drugs in the class. One patient, however, developed liver injury.

Pfizer said that "after a review of the totality of information, including all clinical data generated to date for danuglipron and recent input from regulators," it decided to discontinue studying the molecule.

The company said it will continue development of its experimental oral drug targeting a different hormone, GIPR, and other earlier obesity program research.

"Cardiovascular and metabolic diseases including obesity remain important areas of unmet medical need, and we plan to continue applying our global capabilities to advance a pipeline of investigational treatments," Pfizer's chief scientific officer, Chris Boshoff, said in a statement.

Pfizer said data from the danuglipron clinical program will be presented at a future scientific meeting or submitted for publication in a peer-reviewed journal.