* Pfizer ( PFE ) hopes once-a-month shot can differentiate the

drug from rivals

* Mean vomiting rate in midstage study was 23%

* Compound was acquired in $10 billion Metsera deal last

year

By Michael Erman

NEW YORK, June 6 (Reuters) - Pfizer ( PFE ) presented

data on Saturday that showed a monthly dose of an experimental

obesity drug it acquired through its purchase of Metsera last

year had a similar side-effect profile as rival Novo Nordisk's

weekly injection Wegovy.

The drugmaker hopes the compound, called berobenatide, can

be the first GLP-1 weight-loss drug offered as a monthly shot as

the company works to differentiate the compound from blockbuster

drugs like Wegovy and Eli Lilly's ( LLY ) Zepbound.

In February, Pfizer ( PFE ) said the compound showed up to 12.3%

weight loss in patients without diabetes in its mid-stage

VESPER-3 trial.

Analysts are looking to the drug's side-effect profile to

assess whether it will be commercially viable.

Pfizer ( PFE ) executives said most patients experienced few or mild

side effects, with gastrointestinal events largely limited to

early doses and clustered close to when patients received the

shot. The results were presented at the American Diabetes

Association meeting in New Orleans.

"Because of the very long half life here, you get a very

smooth profile compared to weeklies," Pfizer ( PFE ) Chief Internal

Medicine Officer Jim List said in an interview. "When you give

it monthly ... it's very front-loaded. It does not persist

through the month."

List said that researchers did see an increase in adverse

events after patients went from a weekly to a monthly dose in

the trial, so the company plans to increase the dose more

gradually in its late-stage program.

Pfizer ( PFE ) presented data on Saturday showing that the mean

nausea rate in all the arms of the VESPER-3 study was around 38%

and the mean vomiting rate was about 23.3%.

Last month, JP Morgan analyst Chris Schott said that

investors would be looking for the vomiting rate for the drug in

the trial to be "20-25% or lower."

Around 25% of patients on Novo Nordisk's Wegovy vomited

during that company's weight-loss trial, while around 44%

reported nausea.

The experimental drug sits at the center of Pfizer's ( PFE ) obesity

strategy following its $10 billion acquisition of Metsera last

year. That brought the drugmaker a new pipeline of metabolic

therapies after it was forced to discontinue two of its own

weight-loss drug candidates due to liver safety concerns.

Pfizer ( PFE ) is hoping monthly dosing of berobenatide can

differentiate the drug from the weekly injections on the market,

arguing that less frequent dosing could improve adherence and be

attractive to a different set of patients.