While obese patients lost significant amounts of weight, many reported high rates of side effects such as nausea and vomiting.
"While the most common adverse events were mild and gastrointestinal in nature consistent with the mechanism, high rates were observed, up to 73% nausea, 47% vomiting and 25% diarrhea," the pharma giant said.
"High discontinuation rates, greater than 50%, were seen across all doses compared to approximately 40% with placebo."
Like semaglutide, the active ingredient in Wegovy and Ozempic, danuglipron is a glucagon-like peptide-1 (GLP-1).
Shares of Pfizer fell by 5% to $28.98 in the wake of the announcement, the lowest price since March 2020.
However, Pfizer is still seeking to release a once-daily weight loss pill, which is in development. The company hopes that adapting the drug’s release mechanism will improve side effects.
"Results from ongoing and future studies of the once-daily danuglipron modified release formulation will inform a potential path forward with an aim to improve the tolerability profile and optimize both study design and execution," said Dr. Mikael Dolsten, Pfizer's chief scientific officer.
Initial data from the new formulation will not be released until early 2024.
The news marks the second time that Pfizer has dropped an obesity drug this year, after abandoning lotiglipron, another once-daily GLP-1, due to problems around liver safety.
Pfizer’s delay to the booming and lucrative obesity market will likely cause concern for the drugmaker, as its rivals Eli Lilly and Novo Nordisk are ploughing ahead with their oral obesity drugs.
Eli Lilly’s orforglipron, which achieved 14.7% weight loss at 36 weeks in a phase 2 trial, is estimated to launch in 2025.
In addition, Novo Nordisk said the oral version of its semaglutide drug led to 15% weight loss in its latest study, with the company planning to file US and European approval later this year.