Danuglipron

No — Pfizer discontinued danuglipron's entire development program on 14 April 2025, after a liver-injury signal in its once-daily reformulation followed years of real, substantial Phase 2 efficacy data. This is a genuinely different kind of "unapproved" than most compounds this site covers: a large, well-resourced pharma program that showed real weight loss in a real trial, and still didn't survive the safety bar — the same category of concern that had already killed a related Pfizer compound two years earlier.

What it is

Danuglipron (internal code PF-06882961) is a synthetic, non-peptide small molecule designed to activate the GLP-1 receptor orally — discovered and developed entirely in-house at Pfizer, not licensed from an outside company. It targets the same receptor, by a broadly similar non-peptide mechanism, as orforglipron, Eli Lilly's competing small-molecule oral GLP-1 drug covered on its own page on this site; a published pharmacology comparison found the two molecules bind the human GLP-1 receptor at similar but distinct sites, with both favoring G-protein/cAMP signaling over the beta-arrestin recruitment that peptide GLP-1 drugs produce (Sloop et al., Sci Transl Med 2024;16(778):eadp5765, DOI 10.1126/scitranslmed.adp5765, PMID 39693407). Pfizer and Lilly were racing toward the same regulatory finish line, by different chemistry, from roughly the same starting point — only one of the two crossed it.

Two formulations, two rounds of Phase 2 data

Danuglipron was first developed as a twice-daily tablet. A Phase 2b trial in adults with obesity, topline results announced 30 November 2023, found statistically significant, dose-dependent weight loss across all doses tested: mean placebo-adjusted reductions ranging from roughly 6.9% to 11.7% at 32 weeks, versus a 1.4% gain on placebo. But tolerability was a real problem at that dosing schedule — nausea occurred in up to 73% of participants on some doses, vomiting in up to 47%, and more than half of participants on every active dose discontinued treatment, versus roughly 40% on placebo. Because of that tolerability burden, Pfizer did not advance the twice-daily formulation into Phase 3, choosing instead to develop a once-daily, modified-release version. By July 2024, Pfizer reported that dose-optimization studies of the once-daily formulation had met their pharmacokinetic goals, with a safety profile consistent with the earlier twice-daily results and, at that point, no liver enzyme elevations observed among more than 1,400 participants in the combined safety database — a genuinely positive interim signal that came before the finding described below.

Why Pfizer walked away

On 14 April 2025, Pfizer announced it was discontinuing danuglipron's entire development program, for every indication under study, including type 2 diabetes. The trigger was a single participant in a once-daily dose-optimization study who developed an asymptomatic, potentially drug-induced liver injury, which resolved after the drug was stopped. Pfizer's own account is that the overall rate of liver enzyme elevations across the full development program remained in line with other approved drugs in the GLP-1 class, and that the once-daily formulation had otherwise met its pharmacokinetic and tolerability objectives — but after reviewing the complete clinical dataset and consulting with regulators, the company chose to end the program rather than carry an unresolved hepatic signal into a Phase 3 trial.

Not Pfizer's first oral GLP-1 casualty

Danuglipron was not Pfizer's only in-house attempt at a small-molecule oral GLP-1 drug. A second candidate, lotiglipron, was discontinued on 26 June 2023 — before danuglipron's twice-daily Phase 2b results were even reported — after elevated liver transaminase levels appeared during Phase 1 and Phase 2 testing. Pfizer stated at the time that no patient had reported liver-related symptoms, but the biomarker signal was significant enough that the company stopped the program and redirected its full attention to danuglipron instead. That means both of Pfizer's wholly-owned oral GLP-1 candidates were ultimately stopped over a liver-related signal, two years apart — a pattern worth noting as a fact about this specific company's two internal programs, not a claim about the broader small-molecule GLP-1 mechanism itself, which orforglipron's own approval and safety record (covered on its page) doesn't show the same pattern.

Where this leaves the field

As of this review, danuglipron has no path back: Pfizer owns the molecule outright, developed it entirely in-house, and has not indicated any plan to revive it or license it to another company — a different situation from some other shelved GLP-1-family drugs this site covers, where an original developer walked away and a second company later picked up the rights. The oral small-molecule GLP-1 category that danuglipron was racing to enter now has one approved member instead of two: orforglipron (Foundayo), reaching the US market in April 2026 by a different company and a different chemical scaffold. The other existing oral GLP-1 option, Novo Nordisk's Rybelsus (oral semaglutide), remains a peptide requiring a specific absorption-enhancing formulation and fasting/water restrictions — a genuinely different category from either small molecule, discussed on orforglipron's own page.