A Phase III Study of Enzalutamide Alone and with Atezolizumab Immunotherapy in Men with Advanced Prostate Cancer

Full Title

CO39385: A Phase III, Multicenter, Randomized Study Of Atezolizumab (Anti-PD-L1 Antibody) In Combination With Enzalutamide Versus Enzalutamide Alone In Patients With Metastatic Castration-Resistant Prostate Cancer After Failure Of An Androgen Synthesis Inhibitor And Failure Of, Ineligibility For, Or Refusal Of A Taxane Regimen


Prostate cancers initially need the male hormone testosterone for growth. Hormone therapies that lower the level of testosterone are among the most effective treatments for prostate cancers that have spread to other organs (metastasized). The benefits of hormone treatments do not last, however. Over time, many prostate cancers continue to grow despite hormonal therapies; these are called “castration-resistant prostate cancers” (CRPC).

Enzalutamide is a drug used to treat CRPC. It works by blocking a protein called the androgen receptor. In this study, researchers want to learn if adding the immunotherapy drug atezolizumab to enzalutamide treatment is more effective than enzalutamide alone in men with CRPC. Patients will receive enzalutamide plus atezolizumab or enzalutamide alone.

Atezolizumab is designed to improve the immune system’s ability to recognize and destroy cancer cells by blocking PD-L1, a protein made by some cancers. It is approved for treating bladder cancer and lung cancer; its use in this study is considered investigational. Atezolizumab is given intravenously (by vein). Enzalutamide is taken orally (by mouth).


To be eligible for this study, patients must meet several criteria, including but not limited to the following:

  • Patients must have CRPC that has continued to grow despite prior treatment that included a taxane (or they could not receive a taxane) and also an inhibitor of androgen production (such as abiraterone).
  • At least 4 weeks must pass between the completion of previous therapy and entry into the study.
  • Patients must be physically well enough that they are fully ambulatory, capable of all self care, and are capable of all but physically strenuous activities. As an example, patients must be well enough that they would be able to carry out office work or light housework.
  • This study is for men age 18 and older.

For more information about this study and to inquire about eligibility, please contact Dr. Dana Rathkopf at 646-422-4379.