Dr. Stein on Trials Investigating Biomarkers in Prostate Cancer

Mark Stein, MD, medical oncologist, Rutgers Cancer Institute of New Jersey, discusses trials investigating the use of circulating tumor cells as biomarkers for patients with prostate cancer.

Stein explains that these types of trials typically look to assess patients' survival. However, this can take a very long time, and it can slow trials down significantly. Thus, as an alternative, investigators have been looking at decreases in circulating tumor cells as a clinical endpoint in a trial to see if that varaible is correlated with survival in any way.

One such trial, says Stein, retrospectively showed that this decrease in circulating tumor cells can, indeed, be used as a surrogate. Additional studies with circulating tumor cells embedded into the trial design are now planned to definitively establish that those changes can be used as a surrogate for overall survival, and therefore expedite trial development.

Another exciting area of development has been utilizing changes in the androgen receptor to understand if tumors will still respond to hormonal therapies. Specifically, drugs such as enzalutamide (Xtandi) or abiraterone acetate (Zytiga) have become routine parts of practice with castration-resistant prostate cancer.

What has been shown thus far is that cells with a mutation in the androgen receptor do not appear to respond to hormonal therapy. According to Stein, this information is important to know up front, and it could also be an important mechanism of resistance.