A Study to Learn How Enzalutamide, Apalutamide and Bicalutamide Affect the Way Fezolinetant is Processed in Men With Prostate Cancer

Hormone therapy, or androgen deprivation therapy (ADT) is a standard way to treat prostate cancer. It works by reducing the amount of testosterone in the body. One of the side effects of hormone therapy is hot flashes. There is an unmet medical need to treat hot flashes in men undergoing hormone therapy for prostate cancer. This study will help researchers understand if hormone therapy (enzalutamide, apalutamide or bicalutamide) affects the way fezolinetant is processed by the body in men with prostate cancer. The main aim of this study is checking levels of fezolinetant in the blood over time to learn how long it takes to get into the blood, spread through the body and be cleared from the body. Men with prostate cancer or healthy men can take part. The men with prostate cancer will have already been taking standard hormone therapy (enzalutamide, apalutamide or bicalutamide) for a few months. Men cannot take part if they have recently had major surgery, have had an infection, have a heart condition, or have gut problems. Men with prostate cancer cannot take part if they have other cancers, have recently had certain treatments for prostate cancer, have certain ongoing medical conditions or any chronic disease. This includes any liver problems. There will be 4 groups in this study: Group 1 - men with prostate cancer who are taking enzalutamide will be given fezolinetant. Group 2 - men with prostate cancer who are taking apalutamide will be given fezolinetant. Group 3 - men with prostate cancer who are taking bicalutamide will be given fezolinetant. Group 4 - healthy men will only be given fezolinetant. The men taking part in the study will stay in the clinic for a few days and nights. The men will have nothing to eat or drink for several hours before taking 1 tablet of fezolinetant. Blood samples will be taken and health checks done. During their stay, the men with prostate cancer will continue to be given the standard dose of their hormone therapy. All the men in the study will continue to have regular health checks and will be asked if they have any medical problems. After the men leave the clinic, they will return to the clinic about a week later for a final health check.