Pfizer is stopping development of its experimental oral GLP-1 drug for obesity, the company announced Monday, after a patient in a trial suffered a liver injury potentially caused by the drug.
The patient did not experience any symptoms, and the injury resolved after discontinuation of the drug, Pfizer said in a statement. After reviewing all clinical data for the medicine and consulting with regulators, Pfizer said it decided to halt research on it.
The case occurred in a “doze optimization” trial, aimed at finding the highest tolerable dose in a short amount of time.
“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,” said Chris Boshoff, Pfizer’s chief scientific officer and president of research and development.
Boshoff said Pfizer is going to continue development of another other weight loss drug, called a GIP antagonist.
Still, the company said its drug met key trial objectives and “confirmed a formulation and dose with the potential to deliver a competitive efficacy and tolerability profile in Phase 3 testing.”
The company added that the overall frequency of liver enzyme elevations across the 1,400-participant safety database of the medicine was in line with other medicines in the class.
Pfizer’s decision is a setback for the company, which had been trying to win a share of the booming GLP-1 market dominated by blockbuster drugs Wegovy and Zepbound from rivals Novo Nordisk and Eli Lilly respectively.
Pfizer previously discontinued a twice-daily version of the pill in December 2023 after patients had trouble tolerating the drug in a mid-stage study.
GLP-1 drugs can cause substantial weight loss, but they are delivered by injection, making them more difficult to manufacture. They have also faced demand-induced shortages. Oral drugs are easier to make and would be more widely available, though Pfizer’s was not as effective as other experimental oral drugs.
