Overview
We are a clinical-stage biopharmaceutical company focused on developing novel proprietary therapies for the treatment of prostate cancer and other hormonally-driven diseases. Our lead drug candidate, galeterone, is a highly selective, multi-targeted, oral small molecule drug candidate that we believe has advantages over existing prostate cancer therapies. As of February 28, 2015, we have administered galeterone to over 250 prostate cancer patients and healthy volunteers in Phase 1 and Phase 2 clinical trials. In these trials, galeterone was well tolerated and in multiple prostate cancer patient populations showed clinically meaningful reductions in levels of prostate specific antigen, or PSA, a biochemical marker used to evaluate prostate cancer patients for signs of response to therapy. We are currently preparing to initiate our pivotal Phase 3 clinical trial of galeterone in the first half of 2015. We refer to this trial as our ARMOR3-Splice Variant, or ARMOR3-SV, trial.
We are focusing our initial development of galeterone on the treatment of patients with castration resistant prostate cancer, or CRPC, whose prostate tumor cells express an altered androgen receptor that is truncated. We intend to conduct our pivotal Phase 3 clinical trial in these patients who we believe may not be effectively treated by the therapies approved by the U.S. Food and Drug Administration, or FDA, in recent years. We believe that one of galeterone’s multiple mechanisms of action, androgen receptor degradation, provides an opportunity to treat this population of patients. In our ongoing Phase 2 clinical trial of galeterone, which we refer to as our ARMOR2 trial, we observed clinically meaningful PSA reductions in patients that were identified as having altered androgen receptors that were truncated in a retrospective subset analysis of seven such patients. Six of these patients showed clinically meaningful PSA reductions of at least 50%. Although our initial development focus is on galeterone for the treatment of this population of patients, we are conducting our ongoing ARMOR2 trial of galeterone in multiple CRPC patient populations.
Galeterone acts by disrupting the androgen receptor signaling pathway, which is the primary pathway that drives prostate cancer growth. The pathway is ordinarily activated by the binding of male hormones, or androgens, such as testosterone and the more potent androgen dihydrotestosterone, or DHT, to the ligand binding domain of androgen receptors in prostate cancer cells. Galeterone disrupts the activation of the pathway through multiple mechanisms of action:
We believe that, in comparison to therapies that act solely through CYP17 inhibition or androgen receptor antagonism, galeterone’s unique combination of mechanisms of action may provide galeterone with advantages in efficacy in the treatment of CRPC and may reduce the risk of or delay the development of resistance to therapy and provide efficacy in patients with tumors resistant to other treatments.
The truncated androgen receptors for which we are developing galeterone are missing the end of the receptor that contains the ligand binding domain. We describe patients with these truncated androgen receptors as having C-terminal loss. An example of one such truncated androgen receptor with C-terminal loss is the splice variant AR-V7, which is the most prevalent of the splice variants that cause C-terminal loss. We plan to conduct our pivotal Phase 3 clinical trial in patients with AR-V7. In patients with C-terminal loss, including AR-V7, the lack of a functional ligand binding domain causes the truncated androgen receptor to be constitutively active, or continuously signaling, meaning that activation of the androgen receptor pathway and tumor growth occurs even in the absence of androgens and androgen binding. In clinical trials conducted by researchers at MD Anderson