HELSINKI, Sept 26 (Reuters) - Finnish drugmaker Orion

wants to boost sales in the United States on the back

of the success of its prostate cancer drug Nubeqa, which it is

developing jointly with German partner Bayer, Orion's

chief executive Liisa Hurme told Reuters.

The two companies announced on Thursday that sales of Nubeqa

have been worth more than a billion euros this year, making it

Orion's first "blockbuster" product, and that Bayer is seeking

approval from U.S. authorities to expand its use to a new

patient group.

Nubeqa, also known as darolutamide, is Bayer's third best

selling drug globally with sales growing most rapidly in the

U.S., Hurme said.

That encouraged Orion to establish a research centre in the

U.S. last year, with an eye on growth opportunities in a country

that accounts for roughly half of the world's drug market, Hurme

said.

"We are in the U.S. in order to develop our own innovations

in that market ourselves," she said, referring to Orion's

ODM-111 molecule for pain treatment and Orion's cooperation with

U.S. based drugmaker Merck & Co ( MRK ) in the development of

opevesostat, used against metastatic castration-resistant

prostate cancer, among other products.

"Pain is highly undertreated and especially in the U.S., the

use of opiates is a major problem," she added, referring to the

expansion of drug misuse.

Bayer said it was submitting an application to the U.S. Food

and Drug administration for a third indication for darolutamide

to be used in combination with androgen deprivation therapy in

patients with metastatic hormone-sensitive prostate cancer,

following a successful phase III trial.