LONDON, May 14 (Reuters) - Patients taking Novo

Nordisk's popular Wegovy obesity treatment maintained

an average of 10% weight loss after four years on the treatment,

the company said on Tuesday.

The Danish drugmaker presented the new long-term data at the

European Congress on Obesity in Venice, Italy, gleaned from a

large study for which the majority of the results had been

published last year.

"This is the longest study we've conducted so far of

semaglutide for weight loss," Martin Holst Lange, Novo's head of

development, said in an interview, referring to the active

ingredient in Wegovy and the company's diabetes drug Ozempic.

"We see that once the majority of the weight loss is

accrued, you don't go back and start to increase in weight if

you stay on the drug," he added.

The data could bolster the company's case as it tries to

convince insurers and governments to reimburse Wegovy and

deflect notions that it is a lifestyle drug.

Shares were up 1.1% at 0820 GMT, but analysts and investors

said the rise was likely driven by strong data released by the

company late on Monday from a late-stage trial of its hemophilia

A drug.

Markus Manns, a portfolio manager at Union Investment in

Germany and a Novo Nordisk shareholder, told Reuters that the

data, which is better than the drug for the same disease from

Swiss pharma company Roche, "unlocks another $2 billion

opportunity" for the company.

Wegovy was the first to market from a newer generation of

medicines known as GLP-1 agonists, originally developed for

diabetes, that provide a new way to address record obesity

rates. Eli Lilly ( LLY ) launched its rival drug Zepbound in the

United States in December. Neither company has been able to

produce enough to meet unprecedented demand.

Dr. Simon Cork, Senior Lecturer in Physiology from Anglia

Ruskin University, said Britain's public health service's

decision to limit coverage of the medicine to two years was

"because of questionable long-term effectiveness".

The new data showing benefits continuing to four years may

go some way to negating that argument, he said.

The 17,604-patient trial tested Wegovy not for weight loss

but for its heart protective benefits for overweight and obese

patients who had preexisting heart disease but not diabetes.

Participants were not required to track diet and exercise

because it was not an obesity study.

Patients in the trial called Select lost an average of

nearly 10% of their total body weight after 65 weeks on Wegovy.

That percentage weight-loss was roughly sustained year-on-year

until the end of about four years, where weight loss stood at

10.2%, the company said.

Wegovy and Zepbound are being tested to assess their

benefits in a variety of other medical uses such as lowering

heart attack risk and for sleep apnea and kidney disease.

The weight loss in the heart trial was less than the average

of 15% weight loss in earlier Wegovy obesity studies before the

drug was launched in the United States in June 2021.