GTx (NASDAQ:GTXI) said Wednesday it achieved positive results for a drug in clinical trials being developed as a treatment for prostate cancer.

In the Phase II trial of pharmacokinetic-pharmacodynamic, or GTx-758, the drug reduced serum free testosterone in healthy males, the form of testosterone in which prostate cancer cells grow.

A reduction in serum free testosterone markedly below levels achieved with standard therapies, may result in improved tumor control in first line therapy, said GTx chief medical officer Ronald A. Morton, Jr.

The trial also showed suppressed serum total testosterone to castrate levels and increased serum sex hormone binding globulin (SHBG), a protein that binds to testosterone.

“Achieving medical castration in healthy young male volunteers, a population in whom it is more difficult to reduce testosterone to castration levels, provides the scientific evidence of its potential as a new hormonal treatment for advanced prostate cancer,” said Mitchell S. Steiner, MD, CEO of GTx.

Next year, the drugmaker is planning to initiate additional clinical trials evaluating the drug for first line treatment in men with advanced prostate cancer and second line treatment in men with the disease who have failed LHRH treatment.