Janssen Drops Out of Prostate Cancer Clinical Trial Due to Lack of Patients

In a partnered Phase 1 clinical trial with ESSA Pharma Inc. to evaluate the safety and efficacy of a small molecule inhibitor to treat metastatic castration-resistant prostate cancer, Janssen decided to suspend the study due to trouble enrolling participants. ESSA said it would continue developing the drug, EPI-7386, on its own and in partnerships with Bayer and Astellas.

A Bump in the Road for EPI-7386

The Phase 1 clinical trial sponsored by Janssen started recruiting in March this year to evaluate the safety and efficacy of EPI-7386 in combination with Janssen’s Erleada and Zytiga in patients with a specific type of prostate cancer. 

While the trial started well, recruiting and administering treatment to three patients, as the months went on, Janssen had difficulty recruiting eligible patients for the study, prompting the company to suspend the clinical trial. Of the three that received treatment, though, ESSA said the patients tolerated the drug combination well, and two even achieved a prostate-specific antigen reduction of 90%.

CEO of ESSA, David Parkinson, expressed his disappointment that Janssen decided to suspend the trial. Still, he left his quote on a promising note, “We are in discussions with Janssen to supply abiraterone acetate and apalutamide for an ESSA-sponsored combination study and expect to provide more details in the coming months.”

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Moving Forward with the Promising Prostate Cancer Candidate

The FDA granted EPI-7386 Fast Track Designation in September 2020, and since then, ESSA has placed most of its focus on the promising drug. EPI-7386 is a small molecule inhibitor of the N-terminal domain of the androgen receptor. 

Independently, ESSA is performing a Phase 1 clinical trial studying the safety and efficacy of EPI-7386 alone in patients with castration-resistant prostate cancer. The study includes 74 participants and is set to end next April. 

The drug is also in a Phase ½ study studying its effects in combination with Xtandi. While ESSA is sponsoring the trial, Astellas is providing Xtandi for the study set to end in August 2025. The study includes 150 participants with metastatic castration-resistant prostate cancer.

ESSA also announced a clinical collaboration with Bayer last April to combine EPI-7386 with Nubeqa. The trial has yet to start, but ESSA said Bayer would sponsor the study, while ESSA retains the rights to EPI-7386 in this and all other partnerships. 

Janssen’s decision to suspend the Phase 1 clinical trial studying the safety and efficacy of EPI-7386 in combination with Erleada and Zytiga is a hiccup for ESSA but certainly not the end of the drug’s path. With the potential to continue a relationship with Janssen and its other partnerships with Astellas and Bayer, ESSA is sure to continue developing the drug, which could have great potential in treating prostate cancer. 

Author

Reed Slater