Essa Pharma (NASDAQ:EPIX) has announced its decision to terminate the Phase 2 clinical trial evaluating masofaniten in combination with enzalutamide using a 2:1 randomization versus enzalutamide single agent in patients with metastatic castration-resistant prostate cancer (mCRPC) who have not received second-generation antiandrogens.
The company explained that the decision was based on a protocol-specified interim review of the safety, pharmacokinetic, and efficacy data. This review revealed a much higher rate of PSA90 response among patients treated with enzalutamide monotherapy compared to what historical data suggested. Senior management and the BOD mutually agreed on this decision.
Additionally, the company states that no clear efficacy benefit was observed with the combination of masofaniten plus enzalutamide compared to enzalutamide single agent. A futility analysis determined a low likelihood of achieving the study’s prespecified primary endpoint. The combination of masofaniten plus enzalutamide was well-tolerated, with no new safety signals and a safety profile consistent with previous Phase 1 studies.
“Providing a meaningful clinical benefit to patients in our clinical trials, along with a robust safety profile, is of utmost importance to us at ESSA,” said David Parkinson, MD, president and CEO of Essa. “We designed this randomized study to rigorously evaluate the clinical benefit of adding masofaniten to enzalutamide.”
“We made the difficult decision to terminate this Phase 2 study following the interim analysis because we concluded that the emerging efficacy profile of masofaniten combined with enzalutamide would not likely meet the primary endpoint of the study, nor our internal requirements for a prostate cancer therapy candidate. We would like to thank our partners, investigators, employees, and most importantly, the patients and their families involved in our clinical trials,” Dr. Parkinson added.
