GTx-758 to enter Phase IIb clinical trial


GTx, Inc. has announced this morning that the company is planning a Phase IIb clinical trial of its oral, selective estrogen receptor agonist (GTx-758, also known as  Capesaris™) as a potential first-line treatment for advanced prostate cancer.

The planned, randomized, open-label Phase IIb trial will be initiated within the next couple of months, and will compare the effectiveness and safety of GTx-758 to that of Lupron Depot® (leuprolide acetate for depot suspension) in men with advanced prostate cancer.

According to the corporate guidance from GTx, the initial results of this Phase IIb trial (i.e., the percentage of patients who are castrate within 60 days of initiation of treatment) should be available before the end of 2011.

It is worth noting that, although some clinicians believe that it is important for castrate levels of serum testosterone to fall to < 20 ng/dl, the U.S. Food & Drug Administration continues to set the level of effectiveness for hormone therapy for the treatment of prostate cancer at a serum testosterone level of < 50 ng/dl, which should be maintained from day 28 through day 365 of any randomized Phase III clinical trial. In other words, if GTx-758 is to be approved as a form of androgen deprivation therapy (ADT) for the initial treatment of advanced prostate cancer, it will need to meet that standard in a head to head comparison to an LHRH agonist (presumably leuprolide acetate) and have at least a comparable safety profile.

Additional information on the ClinicalTrials.gov web site states that, “because it is a selective [estrogen receptor] agonist, GTx-758 may maintain bone, does not induce hot flushes, avoids adverse lipid changes and body fat composition changes, and does not have the acute testosterone surge that are associated with other forms of ADT.”

2 Responses

  1. I have just started this treatment and would be interested in other’s experiences.

  2. Dear Jerry:

    You are actually the very first patient who I have heard of who is on GTx-758. You might want to join our social network, because I am sure some of the 3,000+ members of that network would like to know about your experience on this drug!

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