Tuesday, February 14, 2023
ESSA Pharma Inc., a clinical-stage pharmaceutical company focused on developing novel therapies for the treatment of prostate cancer, today announced that further analyses of initial clinical data from two Phase 1 studies of EPI-7386 in patients with metastatic castration-resistant prostate cancer ("mCRPC") will be presented at the 2023 American Society of Clinical Oncology Genitourinary Cancers Symposium ("ASCO GU"), taking place February 16-19, 2023, in San Francisco, California and online. EPI-7386 is a first-in-class N-terminal domain androgen receptor ("AR") inhibitor that suppresses androgen activity through a novel mechanism of action. The two poster presentations are available on the ASCO GU Digital Program and the "Publications" section of the Company's website at www.essapharma.com.
"We are encouraged that EPI-7386 has continued to be well-tolerated and safe as well as demonstrate initial anti-tumor activity both as a monotherapy and in combination with enzalutamide in patients with metastatic castration-resistant prostate cancer," said David Parkinson, MD, President and CEO of ESSA. "Although the clinical data is still in the early stages, with longer follow-up we observe that EPI-7386 in combination with enzalutamide continues to show deep and sustained prostate-specific antigen ("PSA") declines, which may indicate the potential for long-term treatment benefits. We look forward to further exploring the potential clinical benefit of EPI-7386 in combination with enzalutamide as we look to enroll patients in the final cohort of the dose escalation study and prepare to enroll approximately 120 patients in the randomized Phase 2 study at clinical sites across the U.S., Canada, and Australia."
Title: Phase 1/2 Study of EPI-7386 in Combination with Enzalutamide (Enz) Compared with Enz Alone in Subjects with Metastatic Castration-Resistant Prostate Cancer (mCRPC)
Presenting Author: Andrew Leonard Laccetti, MD, MS, Memorial Sloan Kettering Cancer Center
The Phase 1/2 multicenter, open-label clinical trial is enrolling mCRPC patients on androgen deprivation therapy who are naïve to second-generation antiandrogens but may have been treated previously with one line of prior chemotherapy in the metastatic hormone-sensitive prostate cancer setting. The current presentation of data is an update on the first two cohorts of patients which was previously presented at the Prostate Cancer Foundation Scientific Retreat in October 2022. In this update, EPI-7386 in combination with enzalutamide continues to be safe and well-tolerated at the doses tested with clinically relevant drug exposures of both enzalutamide and EPI-7386 with deep and durable PSA reductions continuing through 13 cycles of dosing in some patients. Five of six evaluable patients achieved a PSA90 (≥90% decline in PSA) during the study with these PSA responses being maintained or further deepening during the course of the study. These rapid and deep PSA declines occurred both in patients who have and have not received prior chemotherapy. A further analysis shows that four of six evaluable patients' PSA levels reached <0.2 ng/mL, one of the most stringent measures of PSA decline.
Title: Oral EPI-7386 in Patients with Metastatic Castration-Resistant Prostate Cancer
Presenting Author: Russell Kent Pachynski, MD, Washington University School of Medicine
The data reported are from 45 heavily pretreated mCRPC patients from both the phase 1a and 1b patient populations. Updated results of EPI-7386 as a monotherapy demonstrate that EPI-7386 continues to be safe and well-tolerated with clinically relevant drug exposures reached at all dose levels tested. Similar to what was reported previously at the Prostate Cancer Foundation Scientific Retreat in October 2022, clinically important signals of anti-tumor activity of EPI-7386 were observed in a subset of these patients (those with less than 3 lines of treatment for mCRPC, lack of visceral disease, no prior chemotherapy and lack or few non-AR mutations).
Part 1b of the study is open with enrollment focused on pre-chemotherapy, post-second-generation antiandrogen treated mCRPC patients in one cohort, and treatment-naïve non-mCRPC patients in a window of opportunity proof-of-concept second cohort. Two doses will be evaluated based on FDA Project Optimus recommendations.