Additional Study Information: The purpose of this study is to help researchers understand more about the possible effectiveness and safety of apalutamide when given to patients with or without intermittent Androgen Deprivation Therapy (ADT) to treat metastatic Castration-Sensitive Prostate Cancer (mCSPC). Apalutamide is a type of drug that blocks the action of testosterone. By blocking the action of testosterone, it may slow down or stop the growth of prostate cancer cells. ADT works by stopping the body's production of testosterone. The reason for using ADT is that prostate cancer needs androgen to grow and survive so by starving the cancer of androgen it is hoped that the cancer will stop growing. Apalutamide is not being used in accordance to its labeling.