Inclusion Criteria:

          -  Subjects must have biopsy-confirmed adenocarcinoma of the prostate

          -  Subjects must discontinue all systemic or experimental therapies started for
             metastatic hormone-sensitive prostate cancer (mHSPC) for at least 2 weeks prior to
             registration with no evidence of a falling PSA (prostate specific antigen) after
             washout. LHRH (luteinizing hormone-releasing hormone) analogues must be continued if
             they have not undergone orchiectomy. (Subjects who recently started systemic therapy
             for metastatic castration-resistant prostate cancer (mCRPC) are eligible to enroll if
             new therapy was started ≤ 14 days to consent date.)

          -  Subjects must have progressive metastatic castration-resistant prostate cancer based
             on at least one of the following criteria while having castrate levels (<50 ng/dL) of
             testosterone:

          -  A) PSA progression defined as a 25% increase over baseline value with an increase in
             the absolute value of at least 2.0 ng/mL that is confirmed by another PSA level with a
             minimum of a 1-week interval.

          -  B) Progression of bidimensionally measurable soft tissue or nodal metastasis by CT
             scan or MRI based on RECIST criteria

          -  C) Progression of bone disease on bone scan as defined by two new lesions arising

          -  Subjects must have oligometastatic prostate cancer, defined as between 1 and ≤5
             treatment sites that can be treated within a radiotherapy treatment field.

          -  Subjects must be medically fit to undergo radiotherapy and systemic therapy as
             determined by the treating physician.

          -  Age ≥ 18

          -  ECOG ≤ 2 (Eastern Cooperative Oncology Group scoring system used to quantify general
             well-being and activities of daily life; scores range from 0 to 5 where 0 represents
             perfect health and 5 represents death)

          -  No prior invasive malignancy in the past 3-years unless disease free for a minimum of
             2 years. Exceptions include non-melanomatous skin cancer and in situ cancers of the
             bladder or head and neck are permissible.

          -  Subjects must freely sign informed consent to enroll in the study.

          -  Subjects must use contraception up to 90 days after last drug dose.

        Exclusion Criteria:

          -  Planned systemic therapy with Radium-223 dichloride or sipuleucel-T

          -  Life expectancy estimate of <3 months

          -  Presence of known parenchymal brain metastasis

          -  Uncontrolled intercurrent illness

          -  Inability to undergo radiotherapy, systemic treatment, CTs or bone scans

          -  Biopsy proven pure small cell or neuroendocrine prostate cancer