Pfizer said today it has discontinued development of experimental weight-loss pill danuglipron after a trial patient experienced potential drug-induced liver injury that resolved after the medication was stopped.
The company had been testing multiple doses of a once-a-day version of the oral drug after scrapping development of a twice-daily version in late 2023 because most patients dropped out of a mid-stage trial due to frequent episodes of nausea and vomiting, among other side effects.
Pfizer’s danuglipron could have been a convenient alternative in the lucrative weight-loss drug market, currently dominated by Novo Nordisk’s Wegovy and Eli Lilly’s Zepbound, which are given as weekly injections.
The category has drawn high interest from pharmaceutical companies and investors, and is estimated to hit $150 billion in sales in the coming years.
Danuglipron is part of a class of drugs designed to target an intestinal hormone called GLP-1.
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 2.5% in early trading, while Novo Nordisk’s Copenhagen-listed shares rose over 3%.
The discontinuation of danuglipron sends Pfizer back to the starting block, BMO Capital Markets analyst Evan Seigerman said, noting that its other obesity drugs are all in the early stages of clinical testing. Seigerman said Pfizer could now pursue a deal or partnership in the near term.
Shares of smaller weight-loss treatment developers such as Viking Therapeutics and Structure Therapeutics also rose between 8% and 15% on the news.
Pfizer said dose-optimization studies of once-daily danuglipron showed that 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.
“After a review of the totality of information, including all clinical data generated to date for danuglipron and recent input from regulators,” Pfizer said it has decided to discontinue studying the molecule.
It will continue development of its experimental oral drug targeting a different hormone, GIPR, and other earlier obesity program research.
Data from the danuglipron clinical program will be presented at a future scientific meeting or submitted for publication in a peer-reviewed journal, Pfizer said.
