Oxo-MDV 3100 (Oxo-enzalutamide) is an impurity of Enzalutamide (M199800), which is an androgen-receptor antagonist that blocks androgens from binding to the androgen receptor and prevents nuclear translocation and co-activator recruitment of the ligand-receptor complex. Enzalutamide has been shown to induce tumor cell apoptosis, and is used for the treatment of castration-resistant prostate cancer. Molecular Formula: C21H16F4N4O3 Molecular Weight: 448.37