This is a phase II study to evaluate efficacy, safety, toxicity, and feasibility of the addition of enzalutamide to leuprolide for a total duration of 24 months in patients with very high-risk prostate cancer or pelvic node positive disease receiving radiotherapy. Very high-risk prostate cancer is defined as 2 or more of the following characteristics: 1) cT3a/b, 2) PSA ≥20 and <150, 3) Gleason 8-10, and 4) ≥33% core involvement.