UPDATE 1-GTx cites favorable trend in prostate cancer study

(Adds CEO quotes, details on drug trials, treatment, byline)

By Ransdell Pierson

NEW YORK, Sept 16 (Reuters) - U.S. biotechnology company GTx Inc (GTXI.O) said on Tuesday favorable safety and efficacy trends were seen for its experimental drug toremifene among patients with advanced prostate cancer tested in a late-stage trial.

The drug was studied to see if it could help lessen worrisome side effects, including bone loss and bone fractures, caused by a standard means of treating advanced prostate cancer called androgen deprivation therapy (ADT).

ADT, such as Abbott Laboratories' (ABT.N) Lupron, helps treat prostate cancer by dramatically reducing levels of the male hormone testosterone. But it can weaken bones and leave men at high risk of fractures.

Almost 1,400 patients were studied in the Phase 3 trial sponsored by GTx. While continuing with ADT, they were also given either toremifene or placebo and followed for two years.

Among men who began the trial with detectable levels of a protein called PSA that is considered to be a marker for prostate cancer, 27 percent of those given toremifene saw levels of PSA increase during the study. That was statistically better than the 37 percent of patients receiving placebos whose PSA levels progressed.

"If the PSA level goes up, that suggests the underlying cancer may be starting to grow and progress," GTx Chief Executive Officer Mitchell Steiner said in an interview.

The better PSA trend seen among patients taking toremifene suggest it is safe, in terms of not promoting cancer and possibly even slowing down its progression, said Steiner, a urologist who founded the biotechnology company a decade ago.

The company is conducting a separate late-stage trial to definitively show whether toremifene prevents or slows down prostate cancer. Results from the study are expected in the second quarter of 2009, Steiner said.

"The new PSA data give us more confidence in our ongoing cancer-prevention trial," Steiner said. He noted that should that trial succeed, it could position his medicine to be both a means of controlling prostate cancer and to reduce side effects of ADT.

Steiner said the separate trial described on Tuesday also showed that 24 percent of patients receiving placebos developed either non-traumatic fractures -- such as from falls -- or lost more than 7 percent of their bone mineral density.

That compared with only 10.5 percent of those taking toremifene, Steiner said, a favorable difference he described as highly statistically significant.

Previously presented data showed that toremifene met its primary goal of the trial, by reducing new vertebral fractures by 54 percent.

Men undergoing androgen deprivation therapy are more than three times as likely to suffer fractures as post-menopausal women in the general population, Steiner said.

That is because ADT, by blocking testosterone, also almost eliminates levels of bone-protective estrogen in men, Steiner said. (Reporting by Ransdell Pierson, editing by Maureen Bavdek and Gunna Dickson)