A new study called the PHAROS trial is exploring a drug known as (R)-9bMS for men with advanced prostate cancer that has stopped responding to common hormone treatments. The trial specifically focuses on patients with castration-resistant prostate cancer (CRPC) who have already tried options like enzalutamide or abiraterone without success.

Prostate cancer cells often use a protein called ACK1 to grow and become more aggressive. (R)-9bMS is designed to block ACK1’s activity, and laboratory studies suggest that this could help slow or even halt tumor progression. Researchers have noted that (R)-9bMS may lower the levels of proteins, including AR-V7, which make prostate cancer resistant to current medications. Early test-tube and animal studies have also hinted that the drug can make cancer cells respond better to standard therapies.

The PHAROS trial is in its initial phase, enrolling up to thirty patients at a single clinic. Because this is an early-stage study, the main questions are whether (R)-9bMS is safe, what side effects might arise, and how well patients tolerate the drug. While different doses will be tested, each participant will receive the medication by mouth on a daily schedule. Beyond safety, the researchers will look for early signals that (R)-9bMS can shrink tumors or slow disease progression. They will also collect data to see if the drug affects the body’s immune response in a helpful way.

If the results show that (R)-9bMS is both safe and effective, it could represent a fresh therapeutic path for men who have run out of good options. It might also open the door to combining this ACK1 inhibitor with other emerging prostate cancer treatments, especially if it can help re-sensitize the disease to drugs that stopped working.

Clinical trial.