EPIX: Multiple Ongoing Studies of EPI-7386…

By David Bautz, PhD

NASDAQ:EPIX

READ THE FULL EPIX RESEARCH REPORT

Business Update

Multiple Ongoing Studies of EPI-7386

ESSA Pharma Inc EPIX is developing EPI-7386 as a treatment for prostate cancer. It is a member of a novel class of compounds known as ‘anitens', which specifically target the androgen receptor (AR). The AR is the main signaling mechanism driving the growth of prostate tumors. Anitens bind the AR at the N-terminal domain (NTD), which is unique compared to other available anti-androgen therapies that target the ligand binding domain (LBD). The following graphic shows the structure of the AR along with the various resistance mechanisms that develop to counteract therapies that target the LBD. Anitens are fully differentiated from current AR-targeted therapies through binding of the NTD.

The company is currently conducting a Phase 1a monotherapy trial of EPI-7386 in patients with metastatic castration-resistant prostate cancer (mCRPC) who had progressed on two or more systemic therapies, including at least one second generation anti-androgen therapy (NCT04421222). Recently, ESSA provided an update on initial data from the trial that showed EPI-7386 was safe and well tolerated with no dose limiting toxicities, drug exposures for all doses tested in the Phase 1 trial reached levels above the minimum predicted target drug threshold and doses of EPI-7386 > 400 mg QD had AUC concentrations above the highest target drug threshold, patients that had fewer prior therapies generally stayed on treatment longer, and on-target anti-androgen effects were observed. A full analysis of the data can be found in our previous report (link).

We anticipate ESSA initiating the Phase 1b expansion study in the third quarter of calendar 2022. This study will involve two dosing cohorts (600 mg QD and 400 or 600 mg BID), with eligible patients having ≤ 3 prior lines of therapy, no visceral disease, and no prior chemotherapy. A third cohort (the "Window of Opportunity") will consist of non-metastatic CRPC patients with the same two dosing schedules that will receive 12 weeks of EPI-7386 therapy before initiating standard of care therapy. This will help gather important information on the activity of EPI-7386 in less heavily pretreated patients.

In regards to combination trials:

• ESSA is currently conducting a Phase 1/2 study of EPI-7386 in combination with enzalutamide in patients with mCRPC who have not been treated with second-generation anti-androgens. The preliminary results from the first cohort of patients showed that the drugs can be dosed together safely and results in active drug levels of both EPI-7386 and enzalutamide. The trial is currently enrolling the second cohort of patients.

• Janssen is continuing to enroll patients in the Phase 1/2 trial of EPI-7386 in combination with apalutamide or abiraterone acetate plus prednisone in earlier line mCRPC patients.

• Bayer will be initiating a Phase 1/2 trial of EPI-7386 in combination with darolutamide in earlier line mCRPC patients.

• ESSA will be initiating a Phase 2 investigator-sponsored neoadjuvant study to investigate EPI-7386 and darolutamide compared to darolutamide alone in patients undergoing prostatectomy for high-risk localized prostate cancer. This study should commence before the end of 2022.

Financial Update

On May 9, 2022, ESSA announced financial results for the third quarter of fiscal year 2022 that ended June 30, 2022. The company reported a net loss of $8.8 million, or $0.20 per share, for the third quarter of fiscal year 2022 compared to a net loss of $8.8 million, or $0.21 per share, for the third quarter of fiscal year 2021. R&D expenses for the three months ending June 30, 2022 were $6.4 million compared to $6.2 million for the three months ending June 30, 2021. The increase was primarily due to preclinical and clinical data analysis associated with the Phase 1a clinical study. G&A expenses for the third quarter of fiscal year 2022 were $2.9 million compared to $3.1 million for the third quarter of fiscal year 2021. The decrease was primarily due to decreased professional fees and non-cash share based compensation expenses.

As of June 30, 20212, ESSA had approximately $174.6 million in cash, cash equivalents, and short-term investments. As of August 4, 2022, the company had approximately 44.1 million shares outstanding and, when factoring in stock options and warrants, a fully diluted share count of approximately 55.2 million.

Conclusion

We look forward to continued updates from the company's combination trial of EPI-7386 and enzalutamide along with the dose expansion portion of the Phase 1a monotherapy trial. The company is well financed to execute on its business plan and has sufficient capital to complete the Phase 1a dose escalation and expansion monotherapy studies, the Phase 1 combination studies with antiandrogens, a potential Phase 2 pivotal study, preparatory work for a Phase 3 confirmatory study, and pipeline expansion. With no changes to our model our valuation remains at $25 per share.

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