ESSA Pharma Inc., a pharmaceutical company focused on the development of small molecule drugs for the treatment of cancer, has filed with the US Food and Drug Administration (FDA) an Investigation New Drug (IND) application related to the company's proposed clinical trial of EPI-506 in prostate cancer patients.  Approval of the IND application is required in order for ESSA to commence human testing of EPI-506 in the US.

The IND application is a complete description of the chemistry, non-clinical pharmacodynamics and pharmacokinetics, animal toxicology, manufacturing, and other relevant information related to EPI-506 as a potential treatment for patients with advanced prostate cancer.

"The novel mechanism of action of EPI-506 holds high potential to successfully treat advanced prostate cancer that is refractory to current therapies." said Dr. Frank Perabo, ESSA's chief medical officer.  "This IND filing is therefore a very important step toward bringing this unique treatment option to patients."

If the FDA review process results in approval to commence human testing of EPI-506, ESSA expects to recruit the first patient into its proposed phase 1/2 clinical trial of EPI-506 in 3Q/2015.  The company also intends to seek approval from the Health Protection Branch (HPB) in Canada to include Canadian sites in the phase 1/2 study, and plans to file a Clinical Trial Authorization application with the HPB in order to obtain that approval.

EPI-506 was designed to block a novel target on the androgen receptor, the N-terminal domain. Inhibition of the N-terminal domain of androgen receptor has the potential to block tumor growth after current hormone-therapy drugs have failed.  That potential has been demonstrated in several well-accepted in vitro and in vivo studies showing that EPI-506 inhibits tumor growth in those prostate cancer models.  The target patient population for EPI-506 – metastatic castration resistant prostate cancer (mCRPC) patients who have failed current hormone therapies – represents the greatest unmet medical need in this therapeutic area.

In its upcoming phase 1/2 clinical trial, ESSA intends to demonstrate the maximum tolerated-dose, pharmacokinetics, safety and efficacy of EPI-506 in treating prostate cancer patients who have failed abiraterone or enzalutamide or both, the current standard-of-care drugs in metastatic CRPC.

Prostate cancer is the second most commonly diagnosed cancer among men and the fifth most common cause of male cancer death worldwide (Globocan, 2012).  Adenocarcinoma of the prostate is dependent on androgen for tumor progression and depleting or blocking androgen action has been a mainstay of hormonal treatment for over 6 decades.  Although tumors are often initially sensitive to medical or surgical therapies that decrease levels of testosterone (i.e., ADT), disease progression despite castrate levels of testosterone generally represents a transition to the lethal variant of the disease (mCRPC) and most patients ultimately succumb to the illness.