Inclusion Criteria:

          -  A candidate for radical prostatectomy (RP) or status post RP. Eligible to receive
             study intervention between Day 29 and Day 90 post-RP. Post RP prostate-specific
             antigen (PSA) of <= 0.2 nanograms per milliliter (ng/mL). Has not received other
             treatment for prostate cancer

          -  Have recovered from RP procedure and have had no worsening in cardiac risk in the
             peri-operative period per the clinical judgement of the investigator

          -  Adequate organ function (hepatic, renal, hematologic and cerebral) determined at the
             discretion of the treating physician

          -  Eastern Cooperative oncology Group (ECOG) Performance Status Score of 0 or 1

          -  Histologically confirmed adenocarcinoma of the prostate and categorized as high risk
             for recurrent prostate cancer. High risk can be defined based on PSA alone or biopsy
             or RP specimen as follows: PSA greater than or equal to (>=) 20 ng/ml or; Gleason
             Score >= 9 in any core on biopsy or; Gleason Score >= 8 (4+4 or 5+3) in greater than
             (>) 80 percentage (%) of 2 cores on biopsy or; Gleason Score = 8 (4+4 or 5+3) in 1
             core as long 5 or more other cores with minimum Gleason Score of 4+3 on biopsy. The
             determination of high risk may be based on pathology report of biopsy or equivalent
             criteria from radical prostatectomy

        Exclusion Criteria:

          -  History or presence of soft tissue/bone metastasis or metastasis in distant lymph
             nodes (pelvic lymph nodes below the iliac bifurcation that are less than (<) 2
             centimeter (cm) in diameter [short axis] either radiographically or pathologically are
             allowed.)

          -  History of bilateral orchiectomy

          -  Received an investigational intervention <= 4 weeks before the planned first dose of
             study intervention

          -  History of seizure or any condition that in the opinion of the investigator may
             predispose to seizure or treatment with drugs known to lower the seizure threshold
             within 4 weeks prior to starting treatment with apalutamide

          -  Allergy or hypersensitivity to apalutamide, or excipients, unable or unwilling to take
             androgen deprivation therapy (ADT)