UPDATE 3-GTx shares soar on prostate-cancer drug data

(Adds comments, byline, updates shares)

By Lewis Krauskopf

NEW YORK, Feb 25 (Reuters) - Biotechnology company GTx Inc (GTXI.O) said on Monday that a late-stage trial showed its experimental drug reduced spinal fractures and other side effects caused by a common treatment for advanced prostate cancer, sending its shares up 41 percent.

The drug, toremifene citrate, cut the incidence of certain types of vertebral fractures by 50 percent compared with a placebo. All patients in the 1,389-person, Phase 3 trial were taking androgen deprivation therapy, the most common treatment for advanced prostate cancer, according to GTx.

Toremifene, given in an 80 milligram dose, also met other goals in the study, including increased bone mineral density and lower levels of "bad" LDL cholesterol and triglycerides.

Studies have shown that men on androgen deprivation therapy are at risk for fractures, while ADT has also been associated with increased risk of cardiovascular disease and death, GTx said.

"Androgen deprivation therapy is the cornerstone treatment for men with advanced prostate cancer, but has been associated with serious side effects," Dr. Matthew Smith, the lead researcher of the study and a professor at Harvard Medical School, said in a statement.

The Memphis, Tennessee-based company, which licensed rights to the drug from Finland's Orion Corp (ORNBV.HE), plans to seek U.S. approval for toremifene by this summer and expects a priority review, putting it on track for approval by the end of this year or early 2009.

GTx Chief Executive Officer Mitchell Steiner said toremifene has the potential to reach annual sales of $200 million to $400 million for this use in the United States.

The company plans to market the drug on its own, Steiner said.

"Our focus has been in urology and oncology, so this product fits very nicely in that," Steiner said in an interview.

GTx plans to release a 1,600-patient study by the end of next month of a 20 mg toremifene dose as a preventative measure for men at high risk of developing invasive prostate cancer. Steiner projects a market potential for that use to be equal to the market for treating ADT side effects.

GTx currently markets a 60 mg dose of toremifene as a breast cancer treatment, under the brand name Fareston, but sales expectations for that use are very small.

GTx shares were up $5.31 at $18.20 in afternoon Nasdaq trading, where it ranked third among percentage gainers. Orion gained 1.4 percent in Helsinki. (Reporting by Lewis Krauskopf in New York and Agnieszka Flak in Helsinki; Editing by Lisa Von Ahn/Andre Grenon)