ESSA Pharma Ends Phase 2 Trial for Prostate Cancer Drug Following Lack of Efficacy; Stock Drops 70%

ESSA Pharma (NASDAQ: EPIX) announced the termination of its Phase 2 trial evaluating masofaniten in combination with enzalutamide for patients with metastatic castration-resistant prostate cancer (mCRPC) who had not previously received second-generation antiandrogens. Following an interim analysis that showed no added benefit of masofaniten with enzalutamide over enzalutamide alone, ESSA’s stock dropped 70% premarket.

The analysis revealed that enzalutamide alone produced a higher-than-expected PSA90 response rate, a key marker of treatment efficacy. Given that the combination was unlikely to meet the study’s primary endpoint, ESSA concluded that masofaniten would not deliver the anticipated clinical impact. Although the combination was generally well-tolerated, ESSA decided to end all studies involving masofaniten, both as a standalone and in combination therapies, to focus on strategic alternatives.

In light of this decision, ESSA’s board and management are now exploring strategic options, prioritizing efficient use of resources and capital to deliver the best value to shareholders. The company’s liquidity remains stable, with $126.8 million in available cash reserves as of September 2024 and no long-term debt.