With its initial public offering yet to price, GTx Inc. said it began a Phase III study with Acapodene (toremifene citrate) tablets for reducing skeletal fractures and other complications of androgen deprivation therapy in men with prostate cancer.
The Memphis-based firm, still in a quiet period related to its IPO, said in a press release that the 24-month, placebo-controlled trials are expected to enroll 1,200 patients.
Androgen deprivation is the standard therapy for prostate cancer, and involves either the surgical removal of the testes or treatment with drugs such as Abbott Park, Ill.-based Abbott Laboratories Inc.'s Lupron (leuprolide) or Zoladex (goseralin), from London-based AstraZeneca plc, both of which are leutinizing hormone-releasing hormone (LHRH) agonists to stop the production of testosterone.
Side effects of LHRH agonists include bone loss leading to osteoporosis and skeletal fractures, hot flashes and gynecomastia, or abnormally large breasts - all of which Acapodene is believed to help, GTx said.
The drug is a non-steroidal small molecule that binds and selectively modulates the estrogen receptor, one in a class of drugs known as SERMs that have been shown to stimulate estrogen receptors in bone and block estrogen receptors in the breast as well as, possibly, the prostate.
Acapodene, GTx's most advanced product candidate, also is in a Phase IIb trial for reducing the incidence of prostate cancer in men with precancerous lesions known as prostatic intraepithelial neoplasia.
In its October prospectus related to its IPO, in which the company hopes to raise as much as $86.25 million, GTx said 515 patients had been enrolled in the trial, and an interim analysis in April of the first 120 patients showed those given Acapodene had a 10 percent to 17 percent incidence of prostate cancer (depending on the dose) 12 months after being diagnosed with high-grade PIN, compared to a 23 percent incidence in the placebo group. (See BioWorld Today, Oct. 17, 2003.)
The reduction is about 26 percent to 57 percent in the drug group, and the last patient is scheduled to complete the trial in May 2004, with final results expected in the third quarter of that year and a pivotal Phase III trial next in line.
Another modulator of hormone effects, Andarine, is in development for cachexia, or muscle wasting, which occurs in various types of cancer. The drug has completed three Phase I trials, and a Phase II dose-finding trial for cachexia caused by non-small-cell lung cancer is expected in the first half of 2004.