ESSA Pharma's EPI-7386 Monotherapy / Combo Therapy Show Early Activity Against Prostate Cancer

ESSA Pharma Inc EPIX presented clinical results from the Phase 1a dose-escalation study of EPI-7386 as a monotherapy for metastatic castration-resistant prostate cancer (mCRPC) resistant to current standard-of-care therapies.
The initial data from 36 patients demonstrate that EPI-7386 was well-tolerated, exhibited a favorable pharmacokinetic profile, and demonstrated initial anti-tumor activity in a heavily pretreated group of patients.
In five patients with measurable disease who were on therapy for more than 12 weeks, tumor volume decreased in all five patients.
PSA decreases or PSA stabilization was observed in a clinical subset of patients with no visceral disease and fewer DNA genomic aberrations in non-AR oncogenic pathways.
In 17 patients with measurable ctDNA levels at baseline, ctDNA declines were observed in patients harboring AR point mutations, AR gain/amplification, and AR truncations, suggesting EPI-7386's potential activity against these tumors.
The company expects to initiate the Phase 1b monotherapy expansion study in Q3 2022 and will plan to enroll two dose cohorts into this study following recent guidance from the FDA from Project Optimus.
In addition to these studies, EPI-7386 is under evaluation in earlier lines of therapy in Phase 1/2 trials combining EPI-7386 with approved second-generation antiandrogens.
Price Action: EPIX shares closed 3.02% at $4.10 during after-hours trading on Monday.