Pfizer ends development of weight-loss pill danuglipron

Pfizer signage is displayed at the Pfizer NYC Headquarters, Thursday, April 10, 2025, in New York. (AP Photo/Yuki Iwamura)

Pfizer said on Monday 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.

Several companies are developing weight-loss pills, encouraged by the massive popularity of the injectable drugs that target an intestinal hormone called GLP-1. Lilly is expected to announce Phase 3 trial results for its pill orforglipron any day now.

BMO Capital Markets analyst Evan Seigerman said Pfizer’s discontinuation of its GLP-1 pill sends the company back to the starting block as 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 10% on the news.

Shares of Lilly climbed 2.6%, while Novo Nordisk’s Copenhagen-listed shares rose over 3%. Pfizer’s shares rose about 1%, less than the 1.5% rise in the broader S&P 500 index.

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.

By Deena Beasley

(Reporting By Deena Beasley in Los Angeles and Christy Santhosh in Bengaluru; Editing by Leslie Adler and Shinjini Ganguli)