ESSA Pharma Inc., a clinical-stage pharmaceutical company focused on developing novel therapies for the treatment of prostate cancer, entered into a clinical trial support agreement with Janssen Research & Development LLC, to enable evaluation of ESSA’s first-in-class N-terminal domain androgen receptor inhibitor, EPI-7386, in combination with apalutamide as well as the combination of EPI-7386 with abiraterone acetate plus prednisone in patients with prostate cancer.

ESSA will sponsor and conduct a Phase 1 clinical trial evaluating the safety, pharmacokinetics, drug-drug interactions, and preliminary anti-tumor activity of EPI-7386 when administered in combination with either apalutamide or abiraterone acetate plus prednisone. Janssen will supply apalutamide and abiraterone acetate. ESSA will retain all rights to EPI-7386.

Cohort A of the Phase 1 clinical trial will assess EPI-7386 in combination with abiraterone acetate plus prednisone in patients with metastatic castration-resistant prostate cancer (“mCRPC”) and high-risk metastatic castration-sensitive prostate cancer (“mCSPC”). Cohort B is a Window of Opportunity study in which patients with non-metastatic CRPC will receive up to 12 weeks of single agent EPI-7386 before adding standard-of-care apalutamide.

“We are pleased to have this agreement in place in order to further investigate EPI-7386 in combination with apalutamide and abiraterone acetate plus prednisone in a variety of prostate cancer patient populations,” said David Parkinson, President and CEO of ESSA. “Preliminary clinical data from EPI-7386 combination studies with standard-of-care antiandrogens in mCRPC patients have shown a favorable safety profile and encouraging early signs of anti-tumor activity.”

The U.S. FDA has granted Fast Track designation to EPI-7386 for the treatment of adult male patients with mCRPC resistant to standard-of-care treatment. ESSA is also conducting a Phase 1/2 clinical trial (NCT05075577) of EPI-7386 in combination with enzalutamide in metastatic CRPC patients who have not yet been treated with second-generation antiandrogen therapies. ESSA retains all rights to EPI-7386 worldwide.