Pfizer will end development of daily weight-loss pill after liver injury

Pfizer announced on Monday that it is halting development of its oral weight-loss pill after one patient experienced liver issues. 

The company said it halted development of danuglipron, an oral drug being investigated for chronic weight management, after discovering that a "participant in one of the dose-optimization studies experienced potential drug-induced liver injury," which was resolved after the patient stopped using the drug. 

Among the over 1,400 people who took the drug, the number of cases with raised liver enzymes was about the same as what’s seen with other approved drugs in the same category.  

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"While we are disappointed to discontinue the development of danuglipron, we remain committed to evaluating and advancing promising programs in an effort to bring innovative new medicines to patients," Chris Boshoff, chief scientific officer for Research and Development at Pfizer, said in a statement.  

The company said the data from danuglipron's second clinical development program will be presented at a scientific forum or submitted for publication in a peer-reviewed journal in the future, although it didn't specify when. 

The company's decision marks a major setback for the pharmaceutical giant as it competes with rivals Eli Lilly and Novo Nordisk in the lucrative weight-loss drug market. Morgan Stanley Research re-evaluated the global market for obesity drugs, and is now expecting it to reach between $105 billion and $144 billion in 2030. That's up from an earlier projection of $77 billion. In 2023, sales of branded obesity drugs notched $6 billion, according to Morgan Stanley Research. 

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Competition in the space is intensifying, with Novo Nordisk and Eli Lilly vying for dominance by lowering the cost of their blockbuster weight-loss drugs for cash-paying patients – effectively expanding access for those without insurance through their own self-pay pharmacy programs.

This isn't the first setback for Pfizer's danuglipron, either. The company scrapped development of its twice-daily weight-loss pill in 2023 after a clinical trial showed "high rates" of adverse side effects among users.

At the time, the company said "most common adverse events were mild and gastrointestinal in nature consistent with the mechanism" but, many people experienced nausea, up to 73%, vomiting, up to 47%, and diarrhea, up to 25%. 

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"High discontinuation rates, greater than 50%, were seen across all doses compared to approximately 40% with placebo," it added. 

FOX Business' Greg Norman contributed to this report.