Pfizer pulls the plug on promising weight-loss pill due to liver risk

USA – Pfizer has announced that it is stopping development of its much-anticipated weight-loss pill, danuglipron, after spotting early signs of liver toxicity during late-stage clinical trials.

This move deals a serious blow to the company’s goal of catching up with market leaders in the obesity drug space.

Danuglipron was part of a new wave of oral weight-loss medications aiming to challenge injectable drugs like Novo Nordisk’s Wegovy and Eli Lilly’s Zepbound.

These two injectable GLP-1 drugs currently dominate the weight-loss market, with huge demand worldwide.

Pfizer once had high hopes for danuglipron, especially its once-daily version, which it believed had strong potential due to its better convenience and tolerability compared to other oral options.

The company had earlier dropped a twice-daily version of the drug because of stomach side effects and high dropout rates in clinical trials.

Unfortunately, the same concerns have now appeared with the once-daily formula. During the trials, some patients showed higher levels of liver enzymes—a possible sign of liver stress or damage. One patient even showed signs of possible drug-related liver injury, though they had no symptoms and recovered once the treatment was stopped.

Pfizer said in a statement that the liver enzyme changes seen were similar to what’s been found with other GLP-1 medications, but after reviewing all the data and receiving feedback from health regulators, the company decided to end the danuglipron program entirely.

This leaves Pfizer with just one obesity drug in development—PF-07976016, an experimental oral medicine that targets both GLP-1 and gastric inhibitory peptide (GIP) pathways. That drug is currently in phase 2 trials.

“We are disappointed to stop work on danuglipron, but patient safety comes first,” said Dr. Chris Boshoff, Pfizer’s Chief Scientific Officer.

“We will continue to push forward with our research to develop new treatments that can improve care for people struggling with obesity.”

Pfizer’s exit from the danuglipron project also highlights the difficult road to developing safe and effective oral weight-loss drugs.

While injections have proven highly successful, creating a pill that matches their safety and effectiveness has been much harder than expected.

Pfizer now joins other companies in racing to bring an oral solution to market. Novo Nordisk is testing an oral version of semaglutide and a newer drug called amycretin.

Eli Lilly is working on orforglipron, now in phase 3 trials. Big names like Roche, Amgen, and AstraZeneca also have oral obesity drugs in the pipeline.