Pfizer ends Danuglipron development after liver injury in trial

USA—Pfizer Inc. has decided to halt the development of its once-daily oral obesity drug, danuglipron, after a clinical trial revealed a potential drug-induced liver injury in one participant.

This marks a significant setback for the pharmaceutical giant as it seeks to compete in the lucrative obesity treatment market, currently dominated by injectable drugs like Novo Nordisk’s Wegovy and Eli Lilly’s Zepbound.

The decision follows previous challenges with danuglipron, during which Pfizer abandoned a twice-daily version of the drug in late 2023 due to high rates of side effects such as nausea and vomiting.

This led to more than half of the trial participants discontinuing their participation.

Despite promising weight-loss results in these trials, safety concerns ultimately outweighed the benefits.

Danuglipron belongs to a class of drugs targeting the GLP-1 hormone, which plays a role in appetite regulation and weight management.

While Pfizer’s dose-optimization studies for the once-daily formulation met key pharmacokinetic benchmarks, the occurrence of liver enzyme elevations and one case of liver injury prompted the company to reassess its strategy.

 After reviewing all available clinical data and consulting regulators, Pfizer concluded that further development of danuglipron was not viable.

This decision underscores the challenges Pfizer faces in its efforts to establish a foothold in the booming obesity treatment market, projected to reach US$130 billion by 2030.

 The company has been striving to diversify its portfolio and recover from declining revenues as demand for COVID-19-related products declines.

However, it remains behind competitors like Eli Lilly, whose Zepbound generated nearly US$5 billion in sales in 2024, and Novo Nordisk, which has seen unprecedented success with its weight-loss treatments.

Pfizer’s struggles are compounded by a series of setbacks in its internal pipeline and acquisitions that have yet to deliver blockbuster drugs.

The company’s shares have fallen over 60% since their peak during the pandemic in 2021, adding pressure on CEO Albert Bourla to deliver new growth drivers.

Despite discontinuing danuglipron, Pfizer remains committed to developing other obesity treatments.

It plans to focus on earlier-stage programs targeting different mechanisms, such as the GIPR hormone.

According to Chris Boshoff, Pfizer’s chief scientific officer, obesity and related metabolic diseases remain critical areas of unmet medical need.

The company will continue leveraging its research capabilities to pursue innovative solutions.

This development highlights both the promise and complexity of creating effective obesity treatments.

While injectable drugs have set a high bar for efficacy, pharmaceutical companies are racing to develop convenient oral alternatives that could capture even greater market share.