FDA Grants Fast Track Designation to Novel Androgen Receptor in mCRPC

A Fast Track designation has been granted by the FDA to EPI-7386, a selective androgen receptor inhibitor, which is a potential treatment for adult patients with metastatic castration-resistant prostate cancer (mCRPC) that is resistant to standard-of-care therapy.¹

"We are pleased with the FDA's decision to grant Fast Track designation for development of EPI-7386 to treat mCRPC patients resistant to standard-of-care treatments," said David R. Parkinson, MD, chief executive officer of ESSA Pharma, in a statement. "This designation signifies recognition of the unmet medical need for new and effective treatments for this patient population. EPI-7386 may represent a promising novel treatment option for these patients and the designation offers the opportunity to interact more closely with the FDA during the development of EPI-7386."

The investigational agent is currently being evaluated in a phase 1 clinical trial (NCT04421222). The first-in-human study will enroll 40 patients with mCRPC to assess the safety, pharmacokinetics, and anti-tumor activity of EPI-7386. ESSA Pharm, Inc, announced in July that the first patient with mCRPC was dosed in the study. In addition, another 10 patients were being prepared to enroll in the dose-expansion cohort, which will expand the study to an additional 2 cancer treatment sites.²

Patients who are included in the phase 1 study of EPI-7368 are divided into 5 cohorts, based on the dose level of the agent administered to them. In cohort 1, patients received 200 mg of EPI-7368, cohort 2 is given 400 mg, cohort 3 receives 600 mg, cohort 4 is administered 800 mg, and cohort 5 received 1000 mg. The primary end point of the study safety defined by dose-limiting toxicities. In the phase 1b portion of the study, the primary end point is the proportion of patients from baseline with a decline in prostate-specific antigen (PSA) blood concentration of ≥50% at any time during daily treatment with EPI-7368.¹

To be eligible for the study, patients are required to be at least 18 years of age with histologically, pathologically, or cytologically confirmed disease without small cell features. Patients’ disease must be confirmed as metastatic and any toxicities were required to be resolved. Additionally, patients must have adequate organ function and an ECOG performance status of 0 to 1. Castration for patients enrolled into the study occurs at screening.

Individuals who have had biologic anti-cancer therapy or a cytotoxic chemotherapy within 4 weeks prior to the start of study drug are excluded from the study, in addition to those with who used hormonal agents with anti-tumor activity against prostate cancer within 4 weeks prior, had intervention with any chemotherapy, investigational agents, or other anti-cancer drugs within 14 days, used radium-223 dichloride or other radioligand/radiopharmaceutical within 28 days,received limited-field palliative bone radiotherapy >5 fractions and/or any radiotherapy within 2 weeks, or received a blood transfusion within 28 days. In terms of comorbidities, patients with intra-cerebral disease, or brain metastases were required to have the conditions resolved within 4 weeks prior to enrollment. Patients with spinal cord compression, an invasive malignancy within 3 years, a gastrointestinal disorder affecting absorption, significant cardiovascular disease, or concurrent disease are completely ineligible to enroll in the study.

With a Fast Track designation, the development of EPI-7368 will be expedited and enhance the chances of the drug receiving Priority Review and accelerated approval by the FDA.

_References:

_{1. ESSA Pharma announces Fast Track designation granted by the FDA to EPI-7386 for the treatment of metastatic castration-resistant prostate cancer. News release. September 14, 2020. Accessed September 14, 2020. https://bit.ly/3c41i7N​}

_{2. ESSA Pharma announces first patient dosed in a phase 1 clinical trial of EPI-7386 for metastatic castration-resistant prostrate cancer. News release. July 15, 2020. Accessed September 14, 2020. https://bit.ly/2DZDg17​}