Dec 1 (Reuters) - Pfizer said on Friday it would not advance a twice-daily version of oral weight-loss drug danuglipron into late-stage studies after most patients in a mid-stage trial dropped out with high rates of side effects such as nausea and vomiting.

The decision marks a blow to Pfizer's ambitions to become an early contender in the lucrative market for weight-loss drugs.

Danuglipron belongs to the same class of diabetes and obesity treatments as Novo Nordisk's Wegovy and Ozempic, and Eli Lilly's Mounjaro and Zepbound.

Pfizer said it would instead focus on a once-daily, modified release version of danuglipron and "gathering the data to understand its potential profile". Data on how this version interacts with the human body is expected sometime next year.

In the current study of the twice-daily version, Pfizer said the drug, however, met the main goal of reducing weight in adults with obesity and without type 2 diabetes.

Observed mean weight loss in the trial, across doses, ranged between 6.9% and 11.7% in patients on the drug at 32 weeks, versus weight gain of 1.4% for placebo.

That compared to a nearly 15% drop observed with the highest dose of Eli Lilly's once-daily experimental orforglipron pill after 36 weeks of treatment in a trial of obese or overweight patients.

"We believe an improved once-daily formulation of danuglipron could play an important role in the obesity treatment paradigm," Pfizer's Chief Scientific Officer Mikael Dolsten said in a statement.

Pfizer said while the common side effects in the twice-daily version study were mild, it saw high rates of those events in the trial. High discontinuation rates, greater than 50%, were seen across all doses compared to about 40% with placebo.

It said that up to 73% of patients in the trial had nausea; up to 47% vomiting and up to 25% diarrhea. However, no new safety signals were observed in the study, Pfizer said. (Reporting by Manas Mishra in Bengaluru and Michael Erman in New York; Editing by Shinjini Ganguli)