Pfizer discontinues its oral GLP-1 danuglipron after a liver injury case

Pfizer announced on April 14, 2025 that it is discontinuing development of danuglipron (PF-06882961), an oral GLP-1 receptor agonist it had been testing for chronic weight management ^[1]. The company pointed to a single case of potential drug-induced liver injury in a trial participant, along with a review of all its clinical data and recent feedback from regulators ^[1].

What Pfizer said

The company's dose-optimization studies of once-daily danuglipron formulations (NCT06567327 and NCT06568731) met their key pharmacokinetic goals and identified a formulation and dose that Pfizer believed could deliver competitive efficacy and tolerability in Phase 3 testing, based on earlier studies of a twice-daily version ^[1].

But Pfizer also disclosed that across a safety database of more than 1,400 participants, the overall frequency of liver enzyme elevations was "in-line with approved agents in the class" ^[1]. One asymptomatic participant in a dose-optimization study experienced potential drug-induced liver injury that resolved after the drug was stopped ^[1]. STAT reported that Pfizer decided to halt research after reviewing all clinical data and consulting with regulators, capping more than two years of stock-moving news about the program ^[2].

"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, MD, PhD, Pfizer's chief scientific officer and president of research and development ^[1][2].

Pfizer said it plans to continue development of its oral GIPR antagonist candidate and other earlier-stage obesity programs ^[1]. Data from the danuglipron program will be presented at a scientific forum or submitted for publication in a peer-reviewed journal at some future date ^[1]; no date has been announced.

Why it matters for patients

Danuglipron was never approved and was never available outside of clinical trials, so no one taking a prescription GLP-1 medicine today loses access because of this decision. What changes is the outlook for future competition.

Most GLP-1 medicines for weight management are injections. An effective, widely available pill could expand choices and, over time, affect pricing and supply dynamics. Pfizer's exit removes one candidate from the small group of companies pursuing oral GLP-1s in late-stage testing, and it leaves Pfizer without a late-stage obesity asset.

The liver signal deserves context rather than alarm. Pfizer described the frequency of liver enzyme elevations across its 1,400-plus participant database as similar to already-approved drugs in the GLP-1 class ^[1]. The event that appears to have tipped the decision involved one participant who had no symptoms and whose case resolved after stopping danuglipron ^[1]. Pfizer did not release detailed lab values, the participant's dose, or how long the abnormality lasted, and those specifics are not yet known from the sources here. It is also important to note that danuglipron is a different molecule from semaglutide (Ozempic, Wegovy, Rybelsus), tirzepatide (Mounjaro, Zepbound) or orforglipron (Foundayo). A safety finding with one oral small-molecule GLP-1 does not automatically apply to others, and the sources do not report any regulatory action against approved GLP-1 medicines.

The episode is also a reminder of how drug development works. A candidate can hit its pharmacokinetic targets and still be shelved when a safety question emerges ^[1]. For people following the pipeline in hopes of more affordable or more convenient options, that means timelines can shift quickly, and announcements about "promising" early candidates are not guarantees.

What happens next

Pfizer said it will keep working on an oral GIPR antagonist candidate and earlier obesity programs, but the company did not give timelines, trial start dates or regulatory filing targets in its announcement ^[1]. Its disclosure notice states the information was current as of April 14, 2025, and that Pfizer assumes no obligation to update forward-looking statements ^[1].

The company's own risk language acknowledges uncertainty about whether or when those remaining candidates will advance to later studies, whether regulators would approve them, and whether they would succeed commercially ^[1].

For now, the practical takeaway is narrow: one oral GLP-1 candidate is out of the race, and the full danuglipron dataset has not yet been published. Decisions about any currently approved medicine are between a patient and their clinician.